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STATICAL ESS ATS.-

CONTAINING

VEGETABLE STATICKS;

//f7^ Or, an Account of fome /i tx-r-tfY^' ^

Statical Experiments

ON THE

SAP in VEGETABLES.

BEING

An Essay towards a Natural Hiftory of Vegetation: Of. Ufe to thofe who are curious in the Culture and Improve- ment of Gardening, &c.

ALSO

A Specimen of an Attempt to Analyfe the Air, by a great Variety of Chymio-Statical Experiments, which were read at feveral Meetings before the Royal Society.

VOL. I.

^uideji in bis, in quo non naturae ratio intelligent is appareat ? Tul.de Nat. Deor. ——Etenim Experimentorum longe wajor eft fubtilitasy quam fenfus ipjius .

Itaque eo rem deducimus, ut fenfus tantum de Experimento, Experimentum

de rejitdicet. Fran, de Verul. Inftauratio magna.

By STEPH. BALES, D, D. F. R. S.

Rector of Faringdon^ Hampjhire^ and Minifter of Teddington, Middle/ex.

The Third Edition, with Amendments.

LONDON:

Printed fo> W. Innys and R. Manby, at the Weft-End of St. Paul's;' T.Woodward, at the Half-Moon ovcr-againft . St. Dunfian's Church in Fleet-ftreet ; and J. Pe el e, at Locke's Hetfti in Amm-Cormi . M . dc c. xxx nil.

2 IE 5 5

Feb. 1 6, 1726-7. Imprimatur.

Isaac Newton, Pr.Reg.Soc,

>r^uAo^A~

T O

His Royal Highness.

GEORGE

Prince of WALES.

May it pleafe Tour fioyal Highnefs,

I Humbly offer the following Expe- riments to Your Highnefs's Patro- nage, to proted; them from the reproaches that the ignorant are apt A 2 unrea-

DEDICATION.

unreafonably to call on refearches of this kind, notwithftanding they are the only folid and rational means whereby we may ever hope to make any real advance in the knowledge of Nature : A knowledge, worthy the attainment of Princes.

And as Solomon, the greateft and wifeft of men, difdained not to in- quire into the nature of Plants, from the Cedar in Lebanon, to the Hyjfop that fpringeth out of the wall : So it will not, I prefume, be an unaccept- able entertainment to Your Royal Highnefs, at leaft at Your leifure hours ; but will rather add to the pleafure, with which vegetable Na- ture in her prime verdure charms us : To fee the fteps fhe takes in her pro- ductions, and the wonderful power fhe therein exerts : The admirable

pro-

DEDICATION.

provision fhe has made for them, not only vigoroufly to draw to great heights plenty of nouriihment from the earth ; but alfo more fublimed and exalted food from the air, that wonderful fluid, which is of fuch importance to the life of Vegetables and Animals ; and which, by infinite combinations with natural bodies, pro- duces innumerable furprizing effects, many inftances of which I have here (hewn,

The fearching into the works of Nature, while it delights and inlarges the mind, and ftrikes us with the ftrongeft aflurance of the wifdom and power of the divine Architect, in framing for us fo beautiful and well- regulated a world, it does at the fame time convince us of his conftant bene- volence and goodnefs towards us.

A 3 That

DEDICATION.

That this great Author of Nature may ftiower down on Your Royal Highnefs an abundance of his Blef- fings, both Spiritual and Temporal, is the fincere prayer of

Tour Royal Highnefs s Mojl Obedient,

Humble Servant \

Stephen Hales,

the

THE

PREFACE.

THERE have been, within lefs than a Century, very great and ufeful dif cover ies made in the amazingly beautiful Jlruclure and nature of the animal economy ; neither have Plants pajfed unobferved in this inquifitive age, which has with fuch diligence extended its inquiries, infome degree, into almofl every branch of Nature s inexhauflible fund of wonderful works.

We find in the Philofophical Tranf- aElions, and in the Hijlory of the Royal Academy of Sciences, accounts of many curious Experime?its and Obfervations made from time to time on Vegetables, by fever al ingenious and inquifitive Per- fons : But our country7nan Dr. Grew, 0*fc/ Malpighi, were the firfi, who, tho

A 4 in

ii The Preface.

in very dijlani countries, did nearly at the fame time, unknown to each other, engage in a very diligent and thorough inquiry into the JlruSlure of the vejfels of Plants ; a province, which till then had lai?i uncultivated. They have given us very accurate and faithful accounts of the flruElure of the parts, which they carefully traced, from their firft minute origin, the feminal Plants, to their full growth and maturity, thro their Roots, Trunk, Bark, Branches, Gems, Shoots, JLeaves, Bloffoms and Fruit. In all which they obferv d an exacl and regular fymmetry of parts mojl curioufly wrought in fuch manner, that the great work of Vegetation might effectually be carried on, by the uniform co-operation of the fever al parts, according to the different offices afftgned them by Nature.

Had they fortuned to have fallen into this fat teal way of inquiry, perfons of

their

The Preface. iii

their great application andfagacity had doubtlefs made confiderable advances in the knowledge of the nature of Plants. This is the only fur e way to meafure the fever al quantities ofnourifhment, which Plants imbibe and perfpire, and thereby to fee what influence the different fates of Air have on them. This is the likeliefl method to find out the Sap's velocity , and the force with which it is imbibed : As alfo to ejlimate the great power that Nature exerts in extending and pufhing forth her produElions by the expanfion of the Sap.

About twenty years fince, I made feveral hcemaflatical Experiments on Dogs ; and fix years afterwards re- peated the fame on Horfes and other Animals, in order to find out the real force of the blood in the Arteries, fome of which are mentioned in the third chapter of this book : At whicb times I

wifhed

iv The Preface.

wiped I could have made the like Ex~ periments, to dif cover the force of the Sap in Vegetables ; but defpaired of ever efieEling it, till, about feven years fince, by mere accident I hit upon it<> while I was endeavouring by fever always to flop the bleeding of an old Jlem of a Vine, which was cut too near the bleed- ing feaf on, which I feared might kill it: Having, after other means proved inef- feSlual, tied a piece of bladder over the tranfverfe cut of the Stem, I found the force of the Sap did greatly exte?2d the bladder ; whence I concluded, that if a long glafs-tube were fixed there in the fame mamier, as I had before done to the Arteries of fever al living Animals, I fhould thereby obtain the real afc end- ing force of the Sap in that Stem, which fucceeded according to my expeSlation : and hence it is, that I have been irf en- fib ly led on to make farther a?id far- ther

The Preface. v

ther refearches by variety of Expert ments.

As the Art ofPhyfick has of late years been much improved by a greater know- ledge of the animal (economy ; fo doubt- lefs a farther infight into the vegetable eeconomy mufl needs proportionably im- prove our skill in Agriculture and Gar- denings which gives me reafon to hopey that inquiries of this kind will be accept- able to many, who are intent upon im- proving thofe innocent, delightful, and beneficial Arts : Since they cannot be in- fenfible, that the moft rational ground for Succefs in this laudable Purfuit mufl arifefrom a greater infight into the na- ture of Plants.

Finding by many Experiments in the

fifth chapter, that the Air is plentifully

infpired by Vegetables, not only at their

roots, but alfo thro feveral pjhrts of their

trunks and branches ; this put ??}e upon

making

vi The Preface.

making a more particular inquiry into the nature of the Air, and to dif cover , if pojfible, wherein its great importance to the life and fupport of Vegetables might conftft ; on which account I was obliged to delay the Publication of the reft of thefe Experimettts, which were read two years Jince before the Royal So- ciety•, till I had made fome progrefs in this inquiry : An account of which I have given in the Jixth chapter.

JVhere it appears by many chymio- ftatical Experiment s, that there is dif- fufed thro all natural mutually attraEl- ing bodies \ a large proportion of parti- cles ^ which ^ as the firft great Author of this important difcoveryy Sir Ifaac Newton, obferves, are capable of being thrown off from denfe bodies by heat or fermentation into a vigoroufly elaftick and perma?/iently repelling ft ate ; and alfo of returning by fermentation, and

fome-

The Preface, vii

fometimes without it, into denfe bodies : It is by this amphibious property of the Air, that the main and principal ope- rations of Nature are carried on ; for a mafs of mutually attraSling particles y without being blended with a due pro- portion of elaflick repelling ones, would, in many cafes, foon coalefce into ajlug- gifh lump. It is by thefe properties of the particles of matter ', that he fo Ives the principal Phenomena of Nature. And Dr. Freind has from the fame principles given a very ingenious Ratio- nale of the chief operations in Chymiflry. It is therefore of importance to have thefe very operative properties of natu- ral bodies further afcertained by more Experiments and Obfervatio?ts : And it is with fatisfa&ion, that we fee them more and more confirmed to us, by every farther inquiry we make, as the follow- ing Experiments will plainly prove, by

Jhewing

viii The Preface.

Jhewing how great the power of the at- traEiio?i of acid fulphureous particles inujl be at fo?ne little diflance from the point of contaEi) to be able mojl readily tofubdue and fix elajlick aereal parti- cles y which repel with a force fuperior to vafil incumbent prejfures : Which particles we find are thereby changed from a ftrongly repelling^ to as firongly an attraSling Jlate : And that elafii- city is no immutable property of air, is further evident from thefe Experi- ments ; becaufe it were impojfible for fuch great quantities of it to be confined in the fubfiances of Animals and Vege- tables, in an elafiickfiate, without rend- ing their confiituent parts with a vafl explofion.

I have been careful in making, and

faithful in relating the refult of thefe

Experiments ; and wijh I could be as

happy in drawing the proper inferences

from

The Preface. ix

from them. However I may falljhort at jirji fetting out in this flatical way of inquiring into the nature of Plants^ yet there is good reafon to believe^ that conjiderable advances in the knowledge of their nature may, in procefs of time^ be 7nade by refearches of this kind.

And I hope the publication of this Specimen of what I have hitherto done, will put others upon the fa7ne purfuits> there beings in fo large a fields and among fuch an innwnerable variety of fubje&S) abundant room for many heads and hands to be employed in the work : For the wonderful and fecret operations of Nature are fo involved and intricate y fo far out of the reach of our fenfes^ as they prefent themf elves to us in their na- tural order j that it is impojfible for the moft fagacious and penetrating Genius to pry into themy unlefs he will be at the paws of analyfmg Nature by a numerous

and

x The Preface.

and regular feries of Experiments^ which are the only Jolid fowtdation whence we may reafonably expeEl to make any ad- vance in the real knowledge of the ?iature cf things.

I muft not omit here publiekly to ac- htowledge^ that I have in fever al refpeEls been much obliged to my late ingenious and learned neighbour and friend 'Robert Mather, of the Inner-Temple, Efq^for his afftflance herein.

Whereas fome complain, that they do not under- fland the fignification of thofe fhort figns or characters, which are here made ufeof in many of the calculations, and which are ufual in Algebra ; this mark -f- fignifies more, or to be added to. Thus page 18, line 4, 6 ounces -j- 240 grains, is as much as to fay, 6 ounces more by, or to be added to 240 grains. And in line 16, of the fame page, this mark x or crofs figni- fies multiplied by •, the two fhort parallel lines fignify equal to ; thus 1820 x 4= 7280 : 1, is as much as to fay, 1820 multiplied by 4 equal to 7280 is to 1.

THE

THE

CONTENTS.

CHAP. I.

Experiments, Jhewing the quantities of moijiure imbibed and perfpired by Plants and 'Trees. Page 4

CHAP. II.

Experiments, whereby to find out the force with which Trees imbibe moijiure. 84

CHAP. III.

Experiments, Jhewing the force of the fap in the Vine in the bleeding feajon. 108

CHAP. IV.

Experiments, Jhewing the ready lateral motion of the Sap, and confequently, the lateral communication of the Sap-ve'ffels. The free pajfage of it, from the fmall Branches to- wards the Stem, as well as from the Stem to the Branches, with an account of Jbme Experiments, relating to the Circulation, or Non-circulation of the Sap. 3 28

a CHAP,

The Contents.

CHAP. V.

Experiments, whereby to prove, that a con*

Jiderable quantity of air is infpired by

Plants, 155

CHAP. VI.

A Specimen of an attempt to analyfe the Air by chymio-ftatical Experiments^ which Jhew in how great a proportion Air is wrought i?ito the compojition of Animal^ Vegetable, and Mineral Sub/lances : And withal, how readily it refumes its elajlick State, when in the dijfolution of thofe Sub/lances it is dif engaged from them. i6z

CHAP. VII,

Of Vegetation. 318

The Conclujiou. 35?

A Table where to find each Experiment,

Experiment	Page	Experiment	Page
I.	4	38.	118
2.	14	39*	126
3-	17	40.	128
4-	*9	41.	131
5-	20	42.	m
6.	27	43-	134
7-	28	44.	137
8.	29	45* 46-	138
9-	3i	47.	155
io.	39	48.	156
II.	41	49>5°>5*-	1*73
12.	43	52, 53. 54.	175
13* I4>	45	55> 56-	176
I5>	46	57-	if?
16,	47	58, 59-	178
17.	49	60, 6i, 62.	179
18.	50	63, 64-	180
19.	52	65, 66,	181
20.	57	67, 68, 69, 70.	182
21.	85	71,72.	i«3
22.	86	73> 74.	184
33.	90	75-	it;
24.	91	76.	188
25.	94	77.	189
26,	95	Exper. on Calc.	} i93
27.	97	Human.
28,29,	98	78, 79.	199
30.	99	80,81.	202
3*.	JOI	82.	203
3*.	102	83.	204
33>	103	84.	205
34.	108	85, 86.	206
35.	no	87.	207
3&	112	88,89.	209
?7-	IJ5	9°> 91-	217 Expe-

A Table where to find each Experiment.

Experiment	Page	Experiment		Page
92-	219	1 10.		244
93-	220	III.		248
94.	221	IL2.		252
95.	222	H3-		253
96,97.	224	114.		2 55
98.	225	**5-		263
9g.	226	116.		264
100.	227	117.		273
101.	228	•118.		281
102.	229	119.		288
103.	230	120.		299
104.	23I	121.		3C4
105, 106.	232	122.		329
107.	236	123.		33i
108.	238	124.		344
109.	• 239
A Table	where to	find each Figure.
Figure	Page	Figure		Page
I, 2.	28	24.		132
3> 4, 5-	42	25, 26.		134
6.	44	27, 28,	29, 30	IS2
7> 8> 9-	5°	3^32-		160
10, u> 12.	94	33. 34-		168
i3> 14.	93	35* 36>	37-	210
15, 16, 17, i	S. 1 12	3s. 39-		266
19.	1*5	40,4^	42,43,	44. 346
20, 21.	us	45, 46.		350
22, 23.	J3°

THE

THE

INTRODUCTION.

TH E farther refearches we make in- to this admirable fcene of things* the more beauty and harmony we fee in them : And the ftronger and clearer convi&icns they give us, of the being, power and wifdom of the divine Architect, who has made all things to concur with a won- derful conformity, in carrying on, by va- rious and innumerable combinations of mat- ter, fuch a circulation of caufes and efFe&s, as was neceffary to the great ends of na- ture.

And fince wc are allured that the all-wife Creator has obferved the moil exadl propor- tions, of number , weight and meafure, in the make of all things ; the mbft likely way therefore, to get any infight into the na- ture of thofe parts" of the creation, whicl} come within our obfervation, muft in all reafon be to number, weigh and meafure- And we have much encouragement to pur-

B fu*

2 Vegetable Staticks.

fue this method, of fcarching into the nature of things, from the great fuccefs that has attended any attempts of this kind.

Thus, in relation to thofe Planets which revolve about our Sun, the great Philofo- pher of our age has, by numbering and meafuring, difcovered the exact proportions that are obferved in their periodical revo- lutions and diflances from their common centres of motion and gravity : And that God has not only comprehended the dujl of the earth in a meafurey and 'weighed the mountains in fcales, and the hills in a ba- lance^ Ifai. xl. j 2. but thathealfo holds the vaft revolving Globes, of this our folar Sy- ftem, moft exactly poifed on their common centre of gravity.

And if we reflect: upon the difcoveries that have been made in the animal oecono- my, we fhall find that the moft confider- able and rational accounts of it have been chiefly owing to the ftatical examination of their fluids, viz. by inquiring what quan- tity of fluids, and folids diflblved into fluids, the animal daily takes in for its fupport and nouriihment : And with what force, and different rapidities, thofe fluids are car- ried

Vegetable Stathks. 3

ried about in their proper channels, accord- ing to the different fecretions that are to be made from them : And in what pro- portion the recrementitious fluid is convey- ed away, to make room for frefh fupplies; and what portion of this recrement nature allots to be carried off, by the feveral kinds of emunctories, and excretory dufts.

And fince in vegetables, their growth, and the prefervation of their vegetable life, is promoted and maintained, as in animals, by the very plentiful and regular motion of their fluids, which are the vehicles or- dained by nature, to carry proper nutriment to every part ; it is therefore reafonable to hope, that in them alio, by the fame me- thod of inquiry, considerable difcoveries may in time be made, there being, in many refpedls, a great analogy between plants and animals.

B 2 CHAP

4 Vegetable Staticks.

CHAP. I.

Experiments, jhewing the quantities imbibed and perfpired by Plants and Trees.

Experiment I.

JUL Y 3. 1724. in order to find out the quantity imbibed and perfpired by the Sun-flower, I took a garden-pot (Fig. 1.) with a large Sun-flower, a, 3 feet-}-| high, which was purpofely planted in it when young; it was of the large annual kind.

I covered the pot with a plate of thin milled lead, and cemented all the joints fill, fo as no vapour could pafs, but only air, thro' a fmall glafs tube d, nine inches long, which was fixed purpofely near the ftcm of the plant, to make a free communication with the outward air, and that under the leaden plate.

I cemented alfo another fhort glafs tube g into the plate, two inches long, and one inch in diameter. Thro' this tube I watered the plant, and then flopped it up with a cork ; I flopped up alfo the holes /, /, at the bottom of the pot with corks.

I weighed

Vegetable Static fa. 5

I weighed this pot and plant morning and evening, for fifteen feveral days, from July 3. to Aug. 8. after which I cut off the plant clofe to the leaden plate, and then covered the ftump well with cement ; and upon weighing found there perfpired thro* the unglazed porous pot two ounces every twelve hours day ; which being allowed in the daily weighing of the plant and pot, I found the greateft perfpiration of twelve hours in a very warm dry day, to be one pound fourteen ounces; the middle rate of perfpiration one pound four ounces. The perfpiration of a dry warm night, without any fenfible dew, was about three ounces 5 but when any fenfible, tho' fmall dew, then the perfpiration was nothing; and when a large dew, or fome little rain in the night, the plant and pot was increafed in weight two or three ounces. N. B. The weights I made ufe of were Avoirdupoife weights.

I cut off all the leaves of this plant, and laid them in five feveral parcels, according to their feveral fizes ; and then meafured the furface of a leaf of each parcel, by lay- ing over it a large lattice made with threads, io which the little fquares were \ of an inch B ^ each*

6 Vegetable Staticks.

each 5 by numbring of which I had the iur- face of the leaves in fquare inches, which multiplied by the number of the leaves in the correfponding parcels, gave me the area of all the leaves; by which means I found the furface of the whole plant, above ground, to be equal to 5616 fquare inches, or 39 fquare feet.

I dug up another Sun-flower, nearly of the fame fize, which had eight main roots, reaching fifteen inches deep and fideways from the flem : It had befides a very thick bufh of lateral roots, from the eight main roots, which extended every way in a he- mifphere, about nine inches from the flem and main roots.

In order to get an eftimate of the length of all the roots, I took one of the main roots, with its laterals, and meafured and weighed them ; and then weighed the other feven roots, with their laterals ; by which means I found the fum of the length of all the roots, to be no lefs than 1448 feet.

And fuppofing the periphery of thefe roots, at a medium, to be 0.13 1 of an inch, then their furface will be 2276 fquare inches, or 15. 8 fquare feet; that is equal

to

Vegetable Stoticks. 7

to 0.4. of the furface of the plant above ground.

If, as above, twenty ounces of water, at a medium, perfpired in twelve hours day, (/. e.) thirty-four cubicle inches of water, (a cubick inch of water weighing 254 grains) then the thirty-four cubick inches divided by the furface of all the roots, is = 2286 fquare inches ; (/. e.) -~js is = -~j; this gives the depth of water imbibed by the whole furface of the roots, viz ^ part of an inch.

And the furface of the plan: above ground being 5616 fquare inches, by which divide- ing the 34 cubick inches, viz. v|i6,3= 1T7* this gives the depth perfpired by the whole furface of the plant above ground, viz. 7^7. part of an inch.

Hence, the velocity with which water enters the furface of the roots to fupply the expence of perfpiration, is to the velocity, with which their fap perfpires, as 165 : 6jy or as FTT : ,^-j, or nearly as 5 : 2.

The area of the tranfverfe cut of the mid- dle of the ftem is a fquare inch ; therefore the areas, on the furface of the leaves, the roots and ftem, are 5616, 2276. 1,

B4 The

8 Vegetable Statich.

The velocities, in the furfaceof the leaves, roots, and tranfverfe cut of the ftem, are gained by a reciprocal proportion of the furfaces.

*g ^leaves — 5616 3= 2276

Now, their perfpiring 34 cubick inches in twelve hours day, there muft fo much pafs thro' the ftem in that time; and the velo- city would be at the rate of 34 inches in twelve hours, if the ftem were quite hollow.

In order therefore to find out the quan- tity of folid matter in the ftem, July 2jth at 7. a. m. I cut up even with the ground a Sun-flower; it weighed 3 pounds; in thirty days it was very dry, and had wafted in all 2 pounds* 4 ounces ; that is | of its whole weight: So here is a fourth part left for folid parts in the ftem, (by throwing a piece of green Sun-flower ftem into water, I found it very near of the fame fpecifick gravity with water) which filling up fo muchofthe ftem, the velocity of the fap muft be increas- ed proportionably, viz. $ part more, (by

reafon

Vegetable Staticks. 9

reafon of the reciprocal proportion) that 34 cubick inches may pafs the ftem in twelve hours ; whence its velocity in the ftem will be 45 | inches in twelve hours, fuppofing there be no circulation, nor return of the lap downwards.

If there be added to 34, (which is theleaft velocity) -j of it = 1 1 -j, this gives the greateft velocity, viz. 45-j. The fpaces being as 3 : 4. the velocities will be 4 : 3 :: 454-: 34.

But if we fuppofe the pores in the fiirfacc of the leaves to bear the fame proportion, as the area of the fap-veffels in the ftem do to the area of the ftem; then the velocity, both in the leaves, root and ftem, will be increafed in the fame proportion.

A pretty exaft account having been taken, of the weight, iize, and furface of this plant, and of the quantities it has imbibed and perfpired, it may not be improper here, to enter into a comparifon, of what is taken in and perfpired by a human body, and this plant.

The weight of a well-fized man is equal to 160 pounds: The weight of the Sun- flower is 3 pounds ; fo their weights are to cash other as 160:3, or as 53: 1.

The

io Vegetable Statu ks.

The lurface of fiich human body is equal to 15 fquare feet, or 2160 fquare inches.

The furface of the Sun-flower is 5616 fquare inches 5 fo its furface is, to the furface of a human body, as 26 : 10.

The quantity perfpired by a man in twenty- four hours is about 3 1 ounces, as Dr. Keill found. Vid. Medic. Stai.Britan. p. 14.

The quantity perfpired by the plant, in the fame time, is 22 ounces, allowing two ounces for the perfpiration of the beginning and ending of the night in July, viz. after evening, and before morning weighing, juft before and after night.

So the perfpiration of a man to the Sun- flower is as 141 : 100.

Abating the fix ounces of the thirty-one ounces, to be carried off by refpiration from the lungs in the twenty-four hours ; ( which I have found by certain experiment to be fo much, if not more ) the twenty-five ounces multiplied by 43 8> the number of grains in an ounce Avoirdupois, the producl: is 10950 grains; which divided by 254, the number of grains in a cubick inch of water, gives 43 cubick inches perfpired by a man : which divided by the furface of his body,

viz.

Vegetable Staticks. 1 1

viz. 2160 fquare inches, the quotient is near- ly y_ part of a cubick inch perfpired off a fquare inch in twenty-four hours. Therefore in equal furfaces, and equal times, the man perfpires f0, the plant 7£T, or as 50 : 15.

Which excefs in the man is occafioned by the very different degrees of heat in each: For the heat of the plant cannot be greater than the heat of the circumambient air, which heat in Summer is from 25 to 35 de- grees above the freezing point, {vide Exp. 20.) but the heat of the warmeft external parts of a man's body is 54 fuch degrees, and the heat of the blood 64 degrees; which is nearly equal to water heated to fuch a degree as a man can well bear to hold his hand in, ffirring it about 5 which heat is fufficient to make a plentiful evaporation.

£>u. Since then the perfpirations of equal areas in a man and a Sun-flower, are to each other as 165 : 50, or as 3 JL : 1 ; andfincethp degrees of heat areas 2 : 1, muff not thefum or quantity of the areas of the pores lying in equal furfaces, in the man and Sun-flower, be as 1 2. : 1 ? for it feems that the quantities of the evaporated fluid will be as the degrees of heat, and the fum of the areas of the pores, taken together. Dr.

12 Vegetable Staticks.

Dr. Keill, by eftimating the quantities of the feveral evacuations of his body, found that he eat and drank every 24 hours, 4 pounds 10 ounces.

The Sun-flower imbibed and perfpired in the fame time 22 ounces 5 fo the man's food, to that of the plant, is as 74 ounces to 22 ounces, or as 7:2.

But compared bulk for bulk, the plant im- bibes 17 times more frefti food than the man: For deducing 5 ounces, which Dr. Keill al- lows for the faces ahi, there will remain 4 pounds 5 ounces of frefh liquor, which en- ters a mans veins; and an equal quantity paffes off every 24 hours. Then it will be found, that 17 times more new fluid enters the fap-veffels of the plant, and paffes off in 24 hours, than there enters the veins of a man, and paffes off in the fame time.

And fince, compared bulk for bulk, the plant perfpires feventeen times more than the man, it was therefore very neceffary, by giving it an extenfive furface, to make a large provifion for a plentiful perfpiration in the plant, which has no other way of dis- charging fuperfluities 5 whereas there is pro- vifion made in man, to carry off above

half

Vegetable Staticks. 13

half of what he takes in, by other eva- cuations.

For fince neither the furface of his body was extenfive enough to caufe fufficient ex- halation, nor the additional wreak, arifing from the heat of his blood, could carry off above half the fluid which was neceflary to be difcharged every 24 hours; there was a neceffity of providing the kidneys, to per- colate the other half through.

And whereas it is found, that 17 times more enters, bulk for bulk, into the fap-vef- fels of the plant, than into the veins of a man, and goes off in 24 hours: One reafon of this greater plenty of frefh fluid in the vege- table than the animal body, may be, becaufe the fluid which is filtrated thro' the roots im- mediately from the earth, is not near fo full freighted with nutritive particles as the chyle which enters the lacteals of animals 5 which defect it was neceffary to fupply by the en- trance of a much greater quantity of fluid.

And the motion of the fap is thereby much accelerated, which in the heartlefs vegetable would otherwife be very flow; it having probably only a progreffive, and not a circu- lating motion, as in animals.

Since

14 Vegetable Staticks.

Since then a plentiful perfpiration is found fo neceffary for the health of a plant or tree, 'tis probable that many of their dis- tempers are owing to a ftoppage of this per- fpiration, by inclement air.

The perfpiration in men is often flopped to a fatal degree ; not only by the inclemen- cy of the air, but by intemperance, and vio- lent heats and colds. But the more tempe- rate vegetables perfpiration can be flopped only by inclement air -, unlefs by an un- kindly foil, or want of genial moifture, it is depriv'd of proper or fufficient nourishment. As Dr. Keill obferv'd in himfelf a con- fiderable latitude of degrees of healthy per- fpiration, from a pound and a half to 3 pounds ; I have alfo obferved a healthy latitude of perfpiration in this Sun-flower, from 16 to 28 ounces, in twelve hours day. The more it was watered, the more plentifully it per- fpired, (ceteris paribus ) and with fcanty watering the perfpiration much abated.

Experiment II.

From July 3d. to Aug. 3d. I weighed for nine feveral mornings and evenings a

middle-

Vegetable Staticks. 1 5

middle- fized Cabbage plants which grew in a garden pot, and was prepared with a leaden cover, as the Sun-flower, Exper. ijl. Its greater! perfpiration in twelve hours day was 1 pound 9 ounces; its middle perfpira- tion 1 pound 3 ounces, = 32.7 cubick inches* Its furface 2736 fquare inches, or 19 fquare feet. Whence dividing the 32 cubick inches by 2736 fquare inches, it will be found that a little more than the— of an inch depth perfpires off its furface in twelve hours day.

The area of the middle of the Cabbage flem is -ff|- of a fquare inch ; hence the ve- locity of the fap in the ftem is, to the ve- locity of the perfpiring fap on the furface of the leaves, as 2736 : |££ : : 4268 : 1 .

for i!36Ji_LL6 68. But if an allow-

ioo T

ance is to be made for the folid parts of the

flem, (by which the paffage is narrowed) the

velocity will be proportionally increafed.

The length of all its roots 470 feet, their

periphery at a medium ~T of an inch, hence

their area will be 256 fquare inches nearly;

which being fo frnall in proportion to the

area of the leaves, the fap muft go with

above

\6 Vegetable Staticks.

above ten times the velocity through the furfdce of the roots, that it does thro* the furface of the leaves.

And fetling the roots, at a medium, at 12 inches long, they muft occupy a hemifphere of earth two feet diameter, that is, 2.r cu- bick feet of earth.

By comparing the furfaces of the roots of plants, with the furface of the fame plant above ground, we fee the neceifity of cut- ting off many branches from a tranfplanted tree: For if 256 fquare inches of root in furface was neceffary to maintain this Cab- bage in a healthy natural ftate: fuppofe, upon digging it up, in order to tranfplant, half the roots be cut off, ( which is the cafe of moft young tranfplanted trees) then it's plain, that but half the ufual nourifliment can be car- ried up through the roots on that account ; and a very much lefs proportion on account of the fmall hemifphere of earth, the new planted fhortened roots occupy ; and on ac- count of the loofe pofition of the new turn- ed earth, which touches the roots at firft but in few points. This (as well as experi- ence) ftrongly evinces the great neccffity of

well watering new plantations.

Which.

Vegetable Stathks* \f

Which yet muft be done with caution, for the skilful and ingenious Mr. Philip Miller F. R. S. Gardener of the Botanick garden at Cbelfea, in his very ufeful Gardeners Dicti- onary, fays, <c As to the watering of all new* <c planted trees, I mould advile it to be done " with great moderation, nothing being <c more injurious to them than over-water- <c ing of them. Vide Planting!' And I ob- served, that the dwarf pear-tree, whofe root was fet in water, in Exper. 7. decreafed very- much daily in the quantity imbibed ; viz. be- caufe the fap-veffels of the roots, like thofe of the cut off boughs, in the fame Experiment, were fo faturated and clogged with moifture, by ftanding in water, that more of it could not be drawn up to fup*, port the leaves*

Experiment IIL

From July 28. to Aug. 25. 1 weighed for twelve feveral mornings and evenings, a thriving Vine growing in a pot ; I was fur- niflied with this and other trees, from his Majefty's garden at Hampton-court , by the

C favour

18 Vegetable Statich.

favour of the eminent Mr. Wife. This vine was prepared with a cover, as the Sun- flower was. Its greateft perfpiration in 12 hours day, was 6 Ounces + 240 grains; its middle perfpiration 5 ounces -\- 240 grains — 10 g~ cubick inches.

The fur face of its leaves was 1820 fquare inches, or 12 fquare feet +92 fquare inches; whence dividing g\ cubick inches, by the area of the leaves, it is found that -^j part of an inch in depth, perfpires off in 12 hours day.

The area of a tranfverfe cut of its ftem, was equal to 4- of a fquare inch: hence the fap's velocity here, to its velocity on the fur- face of the leaves, w7 ill be as 1820 x 4 = 7280 : 1. Then the real velocity of the fap's motion in the ftem is = 7^f =38 inches in twelve hours.

This is lbppoiing the ftem to be a hollow tube: but by drying a large vine-branch, (m the chimney corner) which I cut off in the bleeding feaibn, I found the folid parts were •f of the ftem ; hence the cavity thro* which the fap paflte, being fo much narrowed, its velocity will be 4 times as great, viz. 152

inches in 12 hours.

But

Vegetable Statich. 19

But it is further to be confidered, that if the lap moves in the form of vapour, and not of water, being thereby rarefied, its ve- locity will be increafed in a direct propor- tion of the fpaces, which the fame quan- tity of water and vapour would occupy 5 And if the vapour is fuppofcd to occupy 10 times the fpace which it did, when in the form of water, then it muft move ten times fafler; fo that the fame quantity or weight of each may pafs in the fame time, thro* the fame bore or tube : And fuch allow- ance ought to be made in all thefe calcu- lations concerning the motion of the fap in vegetables.

Experiment IV.

From July 29. to Aug. 25. I weighed for 12 feveral mornings and evenings, a pa- radife flock Apple-tree, which grew in a garden por, covered with lead, as the Sun- flower : it had not a bufhy head full of leaves, but thin fpread, being in all but 163 leaves, whofe furface was equal to 1589 fquare inches, or 1 1 fquare feet + 5 fquare inches,

C 2 The

io Vegetable Staticks.

The greateil quantity it perfpired in 12 hours day, was 1 1 ounces, its middle quan- tity 9 ounces, or 15 \ cubick inches.

The 15- cubick inches perfpired, divided by the furface 1589 fquajre inches, gives the depth perfpired off the furface in 12 hours day, viz. -—r of an inch.

The area of a tranfverfe cut of its fiem, \ of an inch fquare, whence the fap's velocity here, will be to its velocity on the furface of the leaves, as 1589 x 4 = 6356:1.

Experiment V.

From Jit ly 28. to Aug. 25. I weighed for 10 feveral mornings and evenings a very thriving Limon-tree, which grew in a gar- den pot, and was covered as above: Its great- eft perfpiration in 12 hours day was 8 ounces, its middle perfpiration 6 ounces, equal to ic-J cubick inches, In the night it perfpired fometimes half an ounce, fometimes nothing, and fometimes increafed 1 or 2 ounces in weight, by large dew or rain.

The furface of its leaves was 2557 fquare inches; or 17 fquare feet ~p 109 fquare inches; diyiding then the 10 cubick inches perfpired by this furface, gives the

depth

21

So the feveral fore- going perfpirations in equal areas are,

Vegetable Statkh. depth perfpired in 12 hours day, viz. T|j of an inch.

-~T in the vine in 12 hours day.

jo- in a man, in a day and a night. T£T in a fun -flower, in a day and night. jo in a cabbage, in 1 % hours day.

T£- in an apple- tree, in 12 hours day. -j^ in a limon-tree, in 12 hours day. The area of the tranfverfe cut of the Hem of this Limon-tree was — 1 44 of a fquare inch ; hence the fap's velocity here, will be to its velocity on the furface of the

leaves, as 1768: 1 for2*57 x IOO= 17- 7 J 144

This is fuppofing the whole ftem to be a hol- low tube; but the velocity will be increafed both in the ftem and in the leaves, in propor- tion as the paffagc of the fap is narrowed by the folid parts.

By comparing the very different degrees of perfpiration, in thefe 5 plants and trees*

C 3 we

2 1 Vegetable Staticks.

we may obferve, that the Limon-tree, which is an ever-green, perfpires much lefs than the Sun-flower, or than the Vine or the Apple- tree, whofe leaves fall off in the winter; and as they perfpire lefs, fo are they the better able to furvive the winter's cold, becaufe they want proportionably but a very fmall fupply of frcuh nourifhment to fup- port them ; like the exangueous tribe of animals, fiogs, toads, tortoifes, ferpents, infecls, &c. which as they perfpire little, fo do they live the whole winter without food. And this I find hold true in 12 other different forts of ever-greens, on which I have made Experiments.

The above- mention'd Mr. Miller made the like Experiments in the Botanick-gar- den at Cbelfea, on a Plantain-tree, an Aloe, and a Paradife Apple-tree; which he weigh- ed morning, noon, and night, for feveral fuccefiive days. I ihall here infert the di- aries of them, as he communicated them to mc, that the influence of the different tem- peratures of the air, on the perfpiration of thtfe plants, may the better be feen.

The pots which he made ufe of were glazed, and had no holes in their bottoms as

garden

Vegetable Staticks. 25

garden pots ufually have 3 fo that all the moifture, which was wanting in them upon weighing, muft neceflarily be imbibed by the roots of thofe plants, and thence per- fpired off thro' their leaves.

A Diary of the perfpiration of the Mufa Ar- bor, or Plantain-tree of the Weft-Indies. The whole furface oj the plant was 14 fquare feet^ 8 + \ inches. The different degrees of heat of the air are here noted by the degrees above the freezing point in my Thermometer, defcritid in Exper. 20.

1726 Weigh at 6

May.

*7 18

19

20 21

22 23

Morn, pd. ou

38 S 37 ij

37 4

36 14 36 10

36 14 36* 6

Weight at 12 Noon, pd. ou. 38 o

33

37 Si*?

37 *

36 12

37 o

3* rt

IS

48 So

3*1

Weight at 6 Even.

pd. ou.

37 H

37 3i

37 °

36 n 36 15-

36 n£

3i

36

44

IS

3i

This evening T2 ounces of water were poured removed from the ftove into a cool room, where Sun, the windows being North-weft.

C4

M B. This plant flood in a ftove, with a fmall fire in it $ the af- pedt of the ftove was South- eaft.

A hot clear day. Thi morning he obferve large drops of water a the extremity of ever leaf, and we may obferve that it perfpires very much this day, J An extreme hot clear day.

Moderately hot, but clear. This morn. 12, ounces of water poured into the pot. Mixture of Sun and Clouds.

Much thunder, fome rain and hail at a diftance. A gloomy day, but no rain.

into the potj and it was it had a free air, but no

Calm

24

Vegetable Statich.

jyii	Weight	H	Weight	S	Weight	H
	ac 6	2	at	12	n	at 6	D~
May	Morn.	3	Noon.	D	Even.	2
	pd. OU.		pd.	ou		pJ. ou.	•
*4	27 OO	*7	37	00	*rt	36 irf	*fi	Calm cloudy weather.
*5	37 00	"3	3*	!4i	26	36 13	23	A pretty clear day.
26	36 12	22	3^	1 1	V	36' 10	24 1	A hot day.
*7	36 IC-7	*3	36	*i	i6i	36 6	l/i	A very hot day.
2S	36 6~	iii	36	J	H	S^ 3z	23	Some rain and cloudy. At this time, the under leaves of the plant be- gan to witherand decay ; ^nd the top leaf" to un- fold, and fpread abroad j butthey are obferved ne- ver to grow bigger, af-
*9 50 "June.	36 2 36 |£	20 T9	3^ 3<5	1	21	36 1 36 0	22	tei they arefully opened. A temperate day. Temperate weather not^ very clear.
1	ur ■*	iS	35"	M:	'rf	3T «3l	18	Some rain. The whole plant begins to change colour, and appear fickly,
*	$* «*	I9i	35"	11 2	23	35- 11	irj	He then removed the plant imp the ftove again in order to recover it j but it continued to fade, and in 2 or 5 days died.
	3f 10	284	3>"	4	36	3f »i	54	A cool and cloudy dav.
4	35- co	** Si	H	3*	34 M	1 9 1 A warm day : and the
1		1			1		1	whole plant decayed.

We may obferve from this diary, that this plant, when in the ftove, ufually per- fpired more in fix hours before noon than in fix hours after noon ; and that it perfpired much lefs in the night, than in the day time : And fometimes increafed in weight in the night, by imbibing the moifture of the ambient air j and that both in the ftove and

in

Vegetable Statich. 25

in the cool room. Upon making an eftimate of the quantity perfpired off a fquare inch of this plant, in 1 2 hours day, it comes but to TyT of a cubick inch, on the 18 th day of May, when by far its greateft perfpiration was $ for on feveral other days it was much lefs.

A Diary of the Aloe Africana Caulefcens foliis fpinofis, maculis ab utraque parte al- bicantibus not at is, Commelini Hort. Amjl. commonly called the Carolina Aloe. 7/ was a large plant of its kind. It food in a glafs-cafey which had a South afpeSi without a fire.

1726/weight	H	Weight	a	Weight
1 at 6 |	at 1 2 | q	at 6	n
May.	Morn. ! 3	Noon. J 2	Night	3
	pd. ou.1 '	r
18	4.1 6 if	41 2^36	-M 3	3oi
19	+ i 1728^	40 14 j2.i£	4.0 1 2	30
26	<J.O I2jl6£	40 10 '31	40 8i;29A
21	40 Q-I27	40 6\ 30	40 ^28
22	40 6	VI	40 rf	29	40 4	*7i
*3	41 10	Hi	ft* H	"	..,	"4

This evening promif- ingfome rain, he fet the pot out to receive a little j and then wiping the leaden furnace of the pot dry, he fet it into the glafs-cafe again.

Now the pot broke, and hindered any fur- ther obfervations.

We may obferve, that tms Aloe increafed in weight moll nights, and perfpired moil in the morning. A Diary

26 Vegetable Statkks.

A Diary of a fmall Parad ife- Apple, with one Upright ft em 4 feet high; and two fmall lateral branches about 8 inches long. This plant food under a cover of wood, which was open on all fides.

iji6

May 18

J9 20 2.1

*4

16 *7

36 12

16 7

3« 3^

36 OO

IS 4

J 4

33

1

18$

17

i8£

16

l*i

rZ

7^28

37 3

36 14.

36 ioj

3<* T

36 1

3f

IS *3

34 6i

37

3 +

IS Sh^

37 1 !*o I

36 13^19 The leaves very dry, 36 9 J20iand become fpeckled for a, 120 jwant of dew. 2 J.' x 2I.I Then he removed the ^ .'plant into the ftove, to try what efFedt that would have on its per- fpiration.

At this time the leaves were withered with the heat, and hung down as if they would fall off". At this time feveral of the leaves began to fall off.

All the leaves fallen off, except a few fmall ones, at the extremities of the branches which had put out, fince the plant was in the ftove. The earth it ftood in was very moift all the time.

IS 00

34

3°

In OBober 1J25. Mr. Miller took up an African Briony-root, which when cleared from the mould, weighed eight ounces i-j he laid it on a fhelf in the ftove, where it remained till rfie March following; when upon weighing he found it had loft of its

weight.

Vegetable Staticks. 27

weight. In April it fhot out 4 branches, two of which were £| feet long, the other two were one of them 14 inches, the other 9 inches, in length : Thefe all produced fair large leaves. It had loft i| ounce in weight, and in three weeks more it loft 2\ ounces more, and was much withered.

Experiment VI.

Spear-mint being a plant that thrives mod kindly in water, ( in order the more ac- curatelv to obferve what water it would imbibe and perfpire by night and day, in wet or dry weather ) I cemented at r a plant of it m. into the inverted fyphon ryxb ( Fig. 2.) The fyphon was \ inch diam. at b9 but larger at r.

I filled it full of water, the plant imbibed the water fo as to make it fall in the day (in March) near an inch and half from b to t, and in the night £ inch from t to i : but one night, when it was fo cold, as to make the Thermometer fink to the freezing point, then the mint imbibed nothing, but hung down its head; as did alfo the young beans in the garden, their fap being great-

1 8 Vegetable Stattcks.

ly condenfed by cold. In a rainy day the mint imbibed very little.

I purfued this Experiment no farther, Dr. Woodward having long fince, from feveral curious experiments and obfervations, given an account in the Philofophical Tranfaftions, of the plentiful perfpirations of this plant.

Experiment VIL

In Augufl, I dug up a large dwarf Pear- tree, which weighed 71 pounds 8 ounces; I fet its root in a known quantity of wa- ter -y it imbibed 15 pounds of water in ten hours day, and perfpired at the fame time 15 pounds 8 ounces.

In July and Augujl I cut off feveral branches of Apple-trees, Pear, Cherry, and Apricot-trees, two of a fort ; they were of feveral fizes from 3 to 6 feet long, with pro- portional lateral branches ; and the tranfverfe cut of the largeft part of their ftems was about an inch diameter.

I ftripped the leaves off of one bough of

each fort, and then fet their ftems in fepa-

rate glaffes, pouring in known quantities of

water.

The

Vegetable Stathh. tp

The boughs with leaves on them im- bibed fome 15 ounces, fome 20 ounces 25 or 30 ounces in 12 hours day, more or lefs, in proportion to the quantity of leaves they had ; and when I weighed them at night, they were lighter than in the morning.

While thofe without leaves imbibed but one ounce, and were heavier in the even- ing than in the morning, they having per- fpired little.

The quantity imbibed by thofe with leaves decreafed very much every day, the fap- veffels being probably fhrunk at the tranf- verfe cut, and too much faturate with wa- ter, to let any more pafs ; fo that ufually in 4 or 5 days the leaves faded and withered much.

I repeated the fame Experiment with Elm- branches, Oak, Ofier, Willow, Sallow, Afpen, Curran, Goosberry, and Philbert branches; but none of thefe imbibed fo much as the foregoing, and feveral forts of ever-greens very much lefs.

Experiment VIII. Angufi 15. I cut off a large Rujet-pipin, with two inches item, and its 12 adjoining

leaves;

30 Vegetable Staticks.

leaves ; I fet the ftem in a little phial of wa- ter : it imbibed and perfpired in three days |- of an ounce.

At the fame time I cut off from the fame tree another bearing twig of the fame length, with 12 leaves on it, but no apple; it im- bibed in the fame three days near | of an ounce.

About the fame time I fet in a phial of water a fhort ftem of the fame tree, with two large Apples on it without leaves; they imbibed near \ ounce in two days.

So in this Experiment, the apple and the leaves imbibe -f- of an ounce; the leaves alone near -f , but the two large apples im- bibed and perfpired but \ part fo much as the 12 leaves; tlien one apple imbibed the ~ part of what was imbibed by the 12 leaves; there- fore two leaves imbibe and perfpire as much as one apple; whence their perfpirations feem to be proportionable to their furfaces -, the furface of the apple being nearly equal to the fum of the upper and under furfaces of the two leaves.

Whence it is probable, that the ufe of thefe leaves ( which are placed, juft where the fruit joins to the tree) is to bring nou-

rimment 4

Vegetable Stattch. 31

rifhment to the fruit. And accordingly I obferve, that the leaves, next adjoining to bloffoms, are, in the fpring, very much ex- panded, when the other leaves, on barren {hoots, are but beginning to (hoot: And that all peach leaves are pretty large before the bloffom goes off: And that in apples and pears the leaves are one third or half grown before the bloffom blows : So provident is nature in making timely pro- vifion for the nourifliing the yet embryo fruit.

Experiment IX.

July 15. I cut off two thriving Hop-vines near the ground, in a thick fhady part of the garden, the pole ftill ftanding; I ftrip- ped the leaves off one of thefe vines, and fet both their ftems in known quantities of water, in little bottles 5 that with leaves imbibed in 12 hours day 4 ounces, and that without leaves \ of an ounce.

I took another hop-pole with its vines on it, and carried it out of the hop-ground, into a free open expofurej thefe imbibed and perfpired as much more as the former

in

\i Vegetable Staticks.

in the hop- ground: Which is doubtlefs the reafon why the hop-vines on the out- fides of gardens, where mod expofed to the air, are fhort and poor, in comparifon of thofe in the middle of the ground ; rciz. be- caufe being much dried, their fibres harden fooner, and therefore they cannot grow fo kindly as thofe in the middle of the ground j which by (hade are always kept moifter, and more duftile.

Now there being iooo hills in an acre of hop-ground, and each hill having three poles, and each pole three vines, the num- ber of vines will be 9000 -, each of which imbibing 4 ounces, the fum of all the ounces, imbibed in an acre in 12 hours day, will be 36000 ounces, = 15768000 grains = 62047 cubick inches or 202 ale gallons; which divided by 6272640, the number of fquare inches in an acre, it will be found, that the quantity of liquor perfpired by all the hop- vines, will be equal to an area of liquor, as broad as an acre, and -—- part of an inch deep, befides what evaporated from the earth.

And this quantity of moifture in a kind- ly ftate of the air is daily carried off, in

a fuffi-

Vegetable Staticks. 3}

a fufficient quantity, to keep the hops in a healthy (late $ but in a rainy moift ftate of air, without a due mixture of dry wea- ther, too much moifture hovers about the hops, fo as to hinder iri a good meafure the kindly perfpiration of the leaves, whereby the flagnating fap corrupts, and breeds mol- dy fen, which often fpoils vaft quantises of flourishing hop-grounds. This was the cafe in the year 1723, when 10 or 14 days al- moft, continual rains fell, about the latter half of July, after four months dry weather; upon which the moft flouriming and pro- mifing hops were all infected with mold or fen, in their leaves and fruit, while the then poor and unpromifing hops efcaped, and pro- duced plenty ; becaufe they being fmall, did hot perfpire fo great a quantity as the others; nor did they confine the perfpired vapour, io much as the large thriving vines did, in their fhady thickets.

This rain on the then warm earth made the grafs moot out as faft as if it were in a hot-bed ; and the apples grew fo precipi- tately, that they were of a very flamy conlli- tution, fo as to rot more remarkably than had ever been remembred.

D The

34 Vegetable Statkks.

The planters obferve, that when a mold or fen has once feized any part of the ground, it foon runs over the whole; and that the grafs, and other herbs under the hops, are infected with it.

Probably becaufe the fmall feeds of this quick growing mold, which foon come to maturity, are blown over the whole ground: Which fpreading of the feed may be the reafon why fome grounds are infected with fen for feveral years fucceffively ; viz. from the feeds of the laft year's fen: Might it not then be advifeable to burn the fenny hop- vines as foon as the hops are picked, in hopes thereby to deftroy fome of the feed of the mold ?

u Mr. Aujlin of Canterbury obferves fen " to be more fatal to thofe grounds that fl are low and iheltered, than to the high " and open grounds; to thofe that are fhelv- M ing to the North, than to the (helving " to the South ; to the middle of grounds, " than to the outrides; to the dry and 11 gentle grounds, than to the moift and ftifF " grounds. This was very apparent through - cc out the Plantations, where the land had tJ the fame workmanfhip and help beflowed

" upon

Vegetable Statich. 35

€c upon it, and was wrought at the fame lc time j but if in either of thefe cafes there " was a difference, it had a different effed: ; " and the low and gentle grounds, that lay " neglected* were then feen tefs diftempered " than the open and moift, that were care* " fully managed and looked after.

" The honey dews are obferved to come <c about the i ith of June, which by the mid- <c die of July turn the leaves black, and make « them ftink."

I have in July (the feafon for fire-blafts* as the planters call them) feen the vines in the middle of a hop-ground all fcorehed up, almoft from one end of a large ground to the other, when a hot gleam of Sun* ihine has come immediately after a fhower of rain ; at which time the vapours are of- ten feen with the naked eye, but efpecially with reflecting Telefcopes, to afcend to plentifully, as to make a clear and diftind: objedt become immediately very dim and tremulous. Nor was there any dry gravelly vein in the ground, along the courfe of this fcorch. It was therefore probably owing to the much greater quantity of torch- ing vapours in the middle than outlides of

D 2 the

$6 Vegetable Staticks.

the ground ; and that being a denfer me- dium, it was much hotter than a more rare medium.

And perhaps, the great volume of amend- ing vapour might make the Sun-beams con- verge a little toward the middle of the ground, that being a denfer medium, and thereby increafe the heat considerably ; for I obferv- ed, that the courfe of the fcorched hops was in a line at right angles, to the Sun- beams about eleven o' clock, at which time the hot gleam was: The hop-ground was in a valley which run from South-weft to North-eaft: And, to the beftof my remem- brance, there was then but little wind, and that in the courfe of the fcorch ; but had there been" fome . other gentle wind, either North or South, 'tis not improbable but that the North wind gently blowing the volume of rinng wreak on the South fide of the ground, that fide might have been moft fcorched, and fo vice verfd.

As to particular fire-blafts, which fcorch here and there a few hop-vines, or one or two branches of a tree, without damaging the next adjoining; what Jljlronomers ob- ferve, may 'hint to us a no very improbable

caufe

Vegetable Staticks. 37

caufe of it; viz. they frequently obferve (efpecially with the reflecting Telefcopes ) fmall feparate portions of pellucid vapors floating in the air; which tho' not vifible to the naked eye, are yet confiderably denfer than the circumambient air : And vapors of fuch a degree of denfity may very proba- bly, either acquire fuch a fcalding heat from the Sun, as will fcorch what plants they touch, efpecially the more tender : an effect which the gardeners about London have too often found to their coft, when they have incautioufly put bell-glafTes- over their col- lyflowers early in a frofty morning, before the dew was evaporated off them; which dew being raifed by the Sun's warmth, and confined within the glafs, did there form a denfe tranfparent fcalding vapor, which burnt and killed the plants. Or perhaps, the up- per or lower furface of thefe tranfparent fe- parate flying volumes of vapors may, among the many forms they revolve into, fometimes approach fo near to a hemifphere, or hemi- cylinder, as thereby to make the Sun-beams converge enough, often to fcorch the more tender plants they fhall fall on : And fome- times alfo, parts of the more hardy plants

D 3 and

1 8 fegetabh Statkh.

and trees, in proportion to the greater or Iefs convergence of the Sun's rays.

The learned Boerhaave^ in his Theory of CkeTniftry, Dr. Shaw's Edition, p. 245. ob- ferves, " That thofe white clouds which ap- cc pear in fummer-time, are, as it were, fo 11 many mirrors, and occafion exceffive heat. }x Thefe cloudy mirrors are fometimes round, " fometimes concave, polygonous, &c. When cc the face of heaven is covered with fuch " white clouds, the Sun mining among C{ them, muft of neceffity produce a vehe- Ct ment heat; fincemany of his rays, which cc would otherwife, perhaps, never touch " our earth, are hereby reflected to us 5 thus* ci if the Sun be on one fide, and the clouds tc on the oppofue one, they will be perfect ci burning-glaiTe'S.

u I have fometimes (continues he) ob- ct fcrved a kind of hollow clouds, full of cx hail and fnow, during the continuance Ci of which the heat was extreme; fince by iC fuch condenfation they wrere enabled to <c reflect: much more ftrongly. After this cc came a fharp cold, and then the clouds <c difcharged their hail in great quantity; :< to which fucceeded a moderate warmth.

" Frozen

Vegetable Staticks. 39

" Frozen concave clouds therefore, by their " great reflections, produce a vigorous heat, " and the fame, when refolved, exceflive « cold/*

Whence we fee that blafts may be occa- fioned by the reflections of the clouds, as well as by the above mentioned refraction of denfe tranfparent vapors.

July 21. I obferved that at that feafon the top of the Sunflower being tender, and the flower near beginning to blow, if the Sun rife clear, the flower faces towards the Eaft ; and the Sun continuing to fhine, at noon it faces to the South ; and at fix in the evening to the Weft: And this not by turning round with the Sun, but by nuta- tion; the caufe of which is, that the fide of the ftem next the Sun perfpiring molt, it fhrinks, and this plant perfpires much.

I have obferved the fame in the tops of Jerufalem-artichokes, and of garden- beanss in very hot Sun-fhine.

Experiment X.

July 27. I fixed an Apple-branch, my 3 feet long, \ inch diameter, full of leaves, D 4 and

40 Vegetable Staticks.

and lateral {hoots to the tube /, 7 feet long, JL of an inch diameter, {Fig. 3.) I fil- led the tube with water, and then immerfed the whole branch as far as over the lower end of the tube, into the veflel uu full of water.

The water fubfided 6 inches the firft two hours, (being the firft filling of the fap-vef- fels) and 6 inches the following night, 4 inches the next day ; and 2 + ^ the following night.

The third day in the morning I took the branch out of the water, and hung it, with the tube affixed to it, in the open air; it im- bibed this day 27 +~ inches in 12 hours

This experiment fhews the great power of perfpiration; fince, when the branch was immerfed in the veflel of water, the 7 feet column of water in the tube, above the fur- face of the water, could drive very little thro' the leaves, till the branch was expofed to the open air.

This alfo proves, that the perfpiring mat- ter of trees is rather actuated by warmth, and 10 exhaled, than protruded by the force of the lap upwards.

And

Vegetable Statich. 41

And this holds true in animals, for the perfpiration in them is not always greateft in the greateft force of the blood ; but then often leaft of all, as in fevers.

I have fixed many other branches in the fame manner to long tubes, without immerf- ing them in water ; which tubes, being filled with water, I could fee precifely, by the defcent of the water in the tube /, how faft it perfpired off, and how very little perfpired in a rainy day, or when there were no leaves on the branches.

Experiment XI.

Aug. 17. At 1 1 a : m, I cemented to the tube ab (Fig. 4.) 9 feet long, and \ inch diameter, an Apple-branch d> 5 feet long, £ inch diameter 5 I poured water into the tube, \vhich it imbibed plentifully, at the rate of 3 feet length of the tube in an hour. At 1 o' clock I cut off the branch at c, 13 inches below the glafs tube. To the bottom of the remaining ftem I tied a glafs ciftern zy covered with ox-gut, to keep any of the water which dropped from the ftem cb, from evaporating. At the fame time I fet the

branch

4& Vegetable Staticks.

branch d r, which I had cut off in a known quantity of water, in the veffel x (Fig. 5.). The branch in the veffel x imbibed 18 ounces of water in 18 hours day and 12 hours night; in which time only 6 ounces of water had paffed thro' the (tern c by (Fig. 4.) which had a column of water 7 feet high, prefling upon it all the time.

This again fhews the great power of per- fpiration; to draw thrice as much water, in the fame time, through the long (lender parts of the branch r, (Fig. 5.) as was preffed thro' a larger (lem cb (Fig. 4.) of the fame branch; but 13 inches long, with 7 feet preffure of water upon it, in the tube a b.

I tried in the fame manner another Ap- ple-branch, which in 8 hours day imbibed 20 ounces, while only 8 ounces paffed thro' the item <rZ>, (Fig. 4.) which had the column of water on it.

The fame I tried with a quince branch, which in 4 hours day imbibed 2 ounces'-f-i., while but.*, ounce paffed thro' the (lem cb (Fig. 4.) which had 9 feet weight of water prelfmg on it.

Xcie, All thefe (under this experiment 11.) were made the firft day> before the

(lem

Vegetable Staticks. 45

ftem could be any thing faturate with water, or the fap-veflels fhrunk fo as to hinder its paffage.

Experiment XII.

I cut off from a dwarf Apple-tree e w the top of the branch /, (Ffg. 6.) which was an inch diameter, and fixed to the ftem /, the glafs tube lb: then I poured warer into the tube, which the branch would imbibe, at fuch a rate as to drink down 2 or 3 pints in a day, efpecially if I fucked with my mouth at the top of the tube /5, fo as that a few air- bubbles were drawn out of the ftem /-, then jthe water was imbibed fo faft, that if I im- mediately fcrewed on the mercurial gage, mryz, the mercury would be drawn up to r, 12 inches higher than in the other leg.

At another time I poured into the tube /, fixed to a golded Renate-tree, a quart of high rectified fpirit of wine camphorated, which quantity the ftem imbibed in 3 hours fpace ; this killed one half of the tree : this I did to try if I could give a flavour of cam- phire to the apples which were in great

plenty

44 Vegetable Statkks.

plenty on the branch. I could not perceive

any alteration in the tafte of the apples, tho'

they hung feveral weeks after; but the fmell

of the camphire was very ftrong in the ftalks

of the leaves, and in every part of the dead

branch.

I made the fame experiment on a vine, with ftrongly-fcented orange -flower- water; the event was the fame, it did not penetrate into the grapes, but very fenfibly into the wood and ftalks of the leaves.

I repeated the fame experiment on two diftant branches of a large Catharine pear- tree, with ftrong decoctions of Saffafrafs, and of Elder-flowers, about 30 days before the pears were ripe ; but I could not perceive any tafte of the decoctions in the pears.

Tho' in all thefe cafes the fap-veffels of the ftem were ftrongly impregnated with a good quantity of thefe liquors; yet the capil- lary fap-veflels near the fruit were fo fine, that they changed the texture of, and aflimi- lated to their own fubftance, thofe high-tafted and perfumed liquors; in the fame manner as grafts and buds change the very different fap of the ftock to that of their own fpecifick nature.

This

46 Vegetable Staticks.

it did not rife at all in the tube, tho' the top of the ftem was wet: I then filled the tube with water, but it paffed freely into the veflel x.

Experiment XV.

Sept. 10. 2+ jl feet from the ground, I cut off the top of a half ftandard Duke Cherry- tree againft a wall, and cemented on it the neck of a Florence flask fy (Fig. 8.) and to that flask neck a narrow tube g, five feet long, in order to catch any moifture that fhould arife out of the trunk y , but none arofe in four hours, except a little vapor that was on the flask's neck.

I then dug up the tree by the roots, and fet the root in water, with the glaffes affixed to the top of the ftem j after feveral hours nothing rofe but a little dew, which hung on the infide off, yet it is certain by many of the foregoing experiments, that if the top and leaves of this tree had been on, many ounces of water would in this time have palled thro' the trunk, and been eva- porated thro' the leaves.

I have

Vegetable Statlch. 4?

I have tried the fame experiment with feveral vine branches cut off, and fet in Water thus, but no water rofe into/.

Thefe three laft experiments all (hew, that tho' the capillary fap-veffels imbibe moifture plentifully; yet they have little power to protrude it farther, without the affiftance of the perfpiring leaves, which do greatly pro- mote its progrefs.

Experiment XVI.

In order to try whether any fap rofe in the winter, I took in January feveral par- cels of Filberd-fuckers, Vine-branches, green Jeflamine-branches, Philarea and Laurel- branches, with their leaves on them -, and dip- ped their tranfverfe cuts in melted cement, to prevent any moifture's evaporating thro' the wounds ; I tied them in feparate bundles, and weighed them.

The Filberd-fuckers decreafed in 8 days, (fome part of which were very wet, but the laft 3 or 4 days drying winds) the nth part of their whole weight.

The Vine-cuttings in the fame time the

rt Part-

The

i-

48 Vegetable Statich.

The JelTamine in the fame time the £ part.

The Philarea decreafed the \ part in five days.

The Laurel the ^part in 5 days, and more.

Here is a confiderable daily wafte of fap, which muft therefore neceffarily be fupplied from the root; whence ins plain, that fome fap rifes all the winter, to fupply this con- tinual wafte, tho' in much lefs quantity than in fummer.

Hence we fee good reafon why the Ilex and the Cedar of Libanus (which were graft- ed the firft on an Englijh Oak, the other on the Larix) were verdant all the winter, notwith- standing the Oak and Larix leaves were de- cayed and fallen off; for tho', when the win- ter came on, there did not fap enough rife to maintain the Oak and Larix leaves, yet by this prefent experiment we fee, that fome fap is continually rifing all the winter ; arid by experiment the 5th on the Limon-tree, and by feveral other the like experiments, on many forts of ever-greens, we find that they perfpiring little, live and thrive with little nourishment; the Ilex and Cedar might well therefore continue green all the win- ter, notwithstanding the leaves of the trees

they

Vegetable Stattch. 49

they were grafted on fell off. See the late curious and induftrious Mr. Fairchild's ac- count of thefe graftings in Mr. Millers Gardeners Didi.ionary ; vide Sap.

Experiment XVII.

Having by many evident proofs in the foregoing experiments feen the great quan- tities of liquor that were imbibed and per- fpired by trees, I was dcfirous to try if I could get any of this perfpiring matter ; and in order to it, I took feveral glafs chy- mical retorts, b a p ( Fig. 9. ) and put the boughs of feveral forts of trees, as they were growing with their leaves on, into the retorts, flopping up the mouth p of the retorts with bladder. By this means I got feveral ounces of the perfpiring matter of Vines, Fig-trees, Apple-trees, Cherry-trees, Apricot and Peach-trees ; Rue, Horfe-radilh, Rheubarb, Parfnip, and Cabbage leaves: the liquor of all of them was very clear, nor could I difcover any different tafte in the feveral liquors: But if the retort ftand expofed to the hot fun, the liquor will tafte of the clodded leaves. Its fpecifick gravity was nearly the fame with that of

E common

jo Vegetable Staticks.

common water; nor did I find many air- bubbles in it, when placed in the exhaufted receiver, which I expected to have found ; but when referved in open viols, it ftinks fooner than common water; an argument that it is not pure water ; but has fome he- terogeneous mixtures with it.

I put alfo a large Sun-flower full-blown, and as it was growing, into the head of a glafs-flill, and put its roftrum into a bottle, by which means there diftilled a good quan- tity of liquor into the bottle. It will be very eafy in the fame manner to colled: the perfpirations of fweet-fcented Flowers, tho* the liquor will not long retain its grateful odor, but ftink in few days.

Experiment XVIII.

In order to find out what ftores of moi- flure nature had provided in the earth, (againft the dry fummer feafon) that might anfwer this great expence of it, which is fo neceffary for the produ&ion and fupport of vegetables 3

July$ 1. *724- l dug up a cubick foot earth, in an alley which was very little trampled on; it weighed (after deducing the weight of the containing veffel ) 104

pounds

3*lA

/>. 5<?

J.C.

Vegetable Statich. 5 1

pounds 4 ounces + f. A cubick foot of water weighs nearly 62- pounds, which is little more than half the fpecifick gravity of earth. This was a dry feafon, with a mixture of fome few fhowers, fo that the grafs-plat adjoining was not burnt up.

At the fame time I dug up another cubick foot of earth, from the bottom of the for- mer; it weighed 106 pound 6 ounces -j- 4-.

I dug up alfo a third cubick foot of earth, at the bottom of the two former ; it weighed in pounds ~{~-j.

Thefe three feet depth were a good brick earth, next to which was gravel, in which at 2 feet depth, viz. 5 feet below the fur- face of the earth, the fprings did then run.

When the firft cubick foot of earth was fo dry and dufty, as to be unfit for vegeta- tion, I weighed it, and found it had loft 6 pounds ~j- n ounces, or 184 cubick in- ches of water, near -§• part of its bulk. '

Some days after, the fecond cubick foot being drier than either the firft or third, was decreafed in weight 10 pounds.

The third cubick foot, being very dry and dufty, had loft 8 pounds 8 ounces, of 247 cubick inches, viz. \ part of its bulk.

E 2 Now

54 Vegetable Staticks.

In a long dry fcafott, therefore, efpecially within the Tropicks, we muft have recourfe for fufficienc moifturc (to keep Plants and Trees alive) to the moift ftrata of earth, which lie next below that in which the roots are. Now moift bodies always com- municate of their moifturc to more dry adjoining bodies; but this flow motion of the afcent of moift u re is much accelerated by the Sun's heat to confiderable depths in the earth, as is probable from the following 20th Experiment.

Now 1 80 grains of Dew filling in one night, on a circle of a foot diameter, = 113 fquare inches; thefe 180 grains being equally fpread on this furface, its depth

will be 77 0 part of an inch =

r 113x254

I found the depth of Dew in a winter night to be the -^ part of an inch ; ib that, if we allow 159 nights for the extent of the fum- tner's Dew, it will in that time arife to one inch depth. And reckoning the remaining 206 nights for the extent of the winter's Dew, it will produce 2.28 inches depth, which makes the Dew of the whole year amount to 3.28 inches depth.

And the quantity which evaporated in a ftii ;•..;.. ;:ci's day frqm the fame furface, be- ing

Vegetable Statkks. 5 5

ing 1 ounce + 282 grains, gives ■£$ part of an inch depth for evaporation, which is four times as much as fell at night.

I found, by the fame means, the evapo- ration of a winter's day to be nearly the fame as in a fummer's day 5 for the earth being in winter more faturate with mos fture, that excels of moifture anfwers to the excefs of heat in fummer.

Nic. Cruquius, NQ 381 of the Philofo- phical Tranfadtions, found that 28 inches depth evaporated in a whole year from wa- ter, /. e. ~z °f an inch each day, at a mean rate ; but the earth in a fummer's day evapo- rates -|~ of an inch ; fo the evaporation of a furface of water, is to the evaporation of a furface of earth in fummer, as Tj to 7V .

The quantity of Rain which falls in a year is at a medium 22 inches: The quan- tity of the earth's evaporation in a year is at leaft 9.15 inches, fince that is the rate, at which it evaporates in a fummer 's day : From which 9.15 inches, are to be deduc- ed 3.39 inches for circulating daily Dew; there remain 5.76 inches, which 5.76 inches dedudled from the quantity of Rain which falls in a year, there remain at leaft 16.24

E 4 inches

5 6 Vegetable Staticls.

inches depth, to replenilh the earth with moiilure ior vegetation, and to fupply the Springs and Rivers.

In the cafe of the hop-ground, the eva- poration from the hops may be confidered only for three months atT£7 part of an inch each day, which will be T9o of an inch ; but before we allowed 5.76 inches vapour to evaporate from the furface of the ground, which added to T% inch, gives 6.66 inches which is the utmoft that can be evaporated from a furface of hop-ground in a year. So that of 22 inches depth of rain, there re- main 15.34 inches to fupply fprings; which are more or lefs exhausted, according to the drinefs or wetnefs of the year. Hence we find that 22 inches depth of rain in a year is fufficient for all the purpoles of na- ture, in fuch flat countries as this about tfeddington near Hampton-Court. But in the hill countries, as in Lancafiirc, there falls 42 inches depth of rain-water; from which deducting 6.66 inches for evaporation, there remains 35.34 inches depth of water for the fprings ; befides great fupplies from much more plemiful dews, than fall in plain countries: Which vail ftores feem fo abun- dantly fufficient to anfwer the great quantity

of

Vegetable Statuks. 57

of water, which is conveyed away, by fprings and rivers, from thofe hills, that we need not have recourfe, for fupplies, to the great Abyfs, whofe furface, at high water, is fur- mounted fome hundreds of feet by ordi- nary hills, and fome thoufands of feet by thofe vaft hills from whence the longeft and greateft rivers take their rife. See vol. II.

A *S7-

Experiment XX.

I provided me fix Thermometers, whofe items were of different lengths, viz. from 1 8 inches to 4 feet. I graduated them all by one proportional fcale, beginning from the freezing point ; which may well be fixed as the utmofl boundary of vegetation on the fide of cold, where the work of vegetation ceafes, the watry vehicle beginning then to condenfe and be fixed •, tho' many trees, and fome plants as grafs, mofs, &c. do furvive it ; yet they do not vegetate at that time.

The greateft degree of heat, which I at firft marked on my Thermometers, was equal to that of water, when heated to the great- eft degree that I could bear my hand in it, without ftirring it about. But finding by experience, that plants can endure, with- out

58 Vegetable Staticks.

out prejudice, a fomething greater heat than this, I have pitched upon the heat in which melted wax fwimming on hot water firft begins to coagulate ; for fince a greater heat than this will diflblve the wax, which is a vegetable fubftance, this may therefore well be fixed as the utmoft boundary of ve- getation, on the warm fide ; beyond which plants will rather fade than vegetate, fuch degree of heat feparating and difperfing, in- ftead of congregating and uniting the nu- tritive particles.

This fpace I divided into 100 degrees on all the Thermometers, beginning to num- ber from the freezing point. Sixty-four of thefe degrees are nearly equal to the heat of the blood of animals -y which I found by the rule given in the Philofophical Tranf- a&ions, Vol. II. p. 1. of Mr. Mottes Abridg- ment, which is fuppofed to be Sir Ifaac Nrwtotii eftimate ; viz. by placing one of the Thermometers in water heated to the greateft degree that I could bear my hand in it ftirring it about : And which I was further affured of, by placing the ball of my Thermometer in the flowing blood of an ex- piring Ox. The heat of the blood to that of boiling water is as 14.27 to 33.

. By

Vegetable Stattcks. 59

By placing the ball of one of thefe Ther- mometers in my bofom, and under an arm- fit, I found the external heat of the body 54 of thefe degrees. The heat of milk, as it comes from the Cow, is equal to 55 de- grees, which is nearly the fame with that for hatching of eggs -, the heat of urine 58 degrees. The common temperate point in thermometers is about 18 degrees.

The hotteft Sun-fhine in the year 1727 raifed the fpirit in the Thermometer expofed to it, 88 degrees j a heat 24 degrees greater than that of the blood of animals : And tho' plants endure this, and a confiderably greater heat within the Tropicks, for fome hours each day, yet the then hanging of the leaves of many of them fhews that they could not long fubfift under it, were they not frequently refreshed by the fucceeding evening and night.

The common noon-tide heat in the Sun in July is about 50 degrees : The heat of the air in the {hade in July is at a medium 38 degrees. The May and June heat is from 17 to 30 degrees: the mod genial heat for the generality of plants, in which they flou- rish moft, and make the greatefl progrefs in their growth. The autumnal and vernal

heat

60 Vegetable Staticks,

heat may be reckoned from 10 to 20 de- grees : The winter heat from the freezing point to 10 degrees.

The fcorching heat of a hot-bed of horfe- dung, when too hot for plants, is equal to 85 degrees and more; and hereabout is pro- bably the heat of blood in high fevers.

The due healthy heat of a hot-bed of horfe-dung, in the fine mold, where the roots of thriving Cucumber-plants were, in Feb. was equal to 56 degrees, which is nearly the bofom heat, and that for hatch- ing of eggs. The heat of the air under the glais-frame of this hot-bed was equal to 34 degrees; fo the roots had 26 degrees more heat than the plants above ground. The heat of the open air was then 17 de- grees.

It is now grown a common and very rea- fonable praclice, to regulate the heat of ftoves and green-houfes, by means of Ther- mometers hung up in them. And for greater accuracy, many have the names of fome of the principal exoticks written up- on their Tiber mometers^ over-againft the fe- veral degrees of hear, which are found by experience to be propereft for them. And I am informed that many of the moft cu- rious

Vegetable Staticks. 6\

rious Gardeners about London have agreed to make ufe of Thermometers of this fort ; which are made by Mr. John Fowler in Swithirfs- Alley, near the Royal-Exchange* which have the names of the following plants, oppofite to their refpeftive moft kindly degrees of heat ; which in my Ther- mometers anfwer nearly to the following de- grees of heat above the freezing point, viz. Melon-thiftle 31, Ananas 29, Piamento 26, Euphorbium 24, Cereus 2J-, Aloe 19, In- dian-fig i6~, Ficoides 14, Oranges 12^ Myr- tles 9.

Mr. Boyle, by placing a Thermometer in a cave, which was cut ftrait into the bot- tom of a cliff, fronting the Sea, to the depth of 130 feet, found the fpirit flood, both in winter and fummer, at a fmall divifion above temperate; the cave had 80 feet depth of earth above it. Boyle's Works, Vol. III. p. 54.

I marked my fix Thermometers numeri- cally, 1, 2, 3, 4, 5, 6. The Thermometer numb. 1, which was fhorteft, I placed with a South afpedt, in the open air; the ball of numb. 2, I fet two inches under ground ; that of numb. 3, four inches under ground; numb. 4, 8 inches; numb. 5,1 6 inches; and

numb,

6 i Vegetable Staticks.

numb. 6, 24 inches underground. And that the heat of the earth, at thefe feveral depths, may the more accurately be known, it is proper to place near each Thermometer a glafs-tube fealed at both ends, of the fame length with the ftems of the feveral Ther- mometers -, and with tinged fpirit of wine in them, to the fame height, as in each correfponding Thermometer ; the fcale of degrees, of each Thermometer ■, being mark- ed on a Aiding ruler, with an index at the back of it, pointing to the correfponding tube. When at any time an obfervation is to be made, by moving the index, to point to the top of that fpirit in the tube, an ac- curate allowance is hereby made, for the very different degrees of heat and cold, on the ftems of the Thermometers, at all depths ; by which means the fcale of degrees will fhew truly the degrees of heat in the balls of the Thermometers, and confequently, the refpe&ive heats of the earth at the feveral depths where they are placed. The ftems of thefe Thermometers, which were above ground, were fenced from weather and in- juries by fquare wooden tubes \ the ground they were placed in was a brick earth in the middle of my garden.

Vegetable Staticks. 63

July 30. I began to keep a regifter of their rife and fall. During the following month of Augujl, I obferved that when the fpirit in the thermometer, numb. 1, ( which was expofed in the Sun ) was about noon rifen to 48 degrees, then the fecond Thermometer was 45 degrees, the fifth 33, and the fixth 3 1 5 the third and fourth at intermediate degrees. The fifth and fixth Thermo??ieter kept nearly the fame degree of heat both night and day, till towards the latter end of the month ; when, as the days grew fhorter and cooler, and the nights longer and cooler, they then fell to 25 and 27 degrees.

Now, fo con fider able a heat of the Sun, at two feet depth, under the earth's furface, muft needs have a ftrong influence in rail- ing the moifture at that and greater depths ; whereby a very great and continual wreak muft always be afcending, during the warm fummer feafon, by night as well as day; for the heat at two feet depth is nearly the fame night and day, the impulfe of the Sun- beams giving the moifture of the earth a brifk undulating motion, which watery par- ticles, when feparated and rarefied by heat, do afcend in the form of vapour : And the

vigour

^4 Vegetable Staticks.

vigour of warm and confined vapour (fuch as is that which is i, 2, or 3 feet deep in the earth) muft be very confiderable, fo as to penetrate the roots with fome vigour; as we may reafonably fuppofe, from the vaft force of confined vapour in /Eolipiles, in the digefter of bones, and the engine to raife water by fire. See. Vol. II. p. 259.

If plants were not in this manner fup- plied with moifture, it were impoflible for them to fubfifl under the fcorching heats within the Tropicks, where they have no rain for many months together: For tho' the dews are much greater there, than in thefe more Northern climates ; yet doubtlefs, where the heat io much exceeds ours, the whole quantity evaporated in a day there, does as far exceed the quantity that falls by night in dew, as the quantity evaporat- ed here in a fummer's day, is found to ex- ceed the quantiry of dew which falls in the night. But the dew, which fidls in a hot fummer feafon, cannct poflibly be of any benefit to the roots of trees; becaufe it is remanded back from the earth by the fol- lowing day's heat, before {o fmall a quantity of moifture can have foaked to any con- fiderable depth. The great benefit there- fore

Vegetable Staticks. 6j

fore of dew, in hot weather, muft be, by being plentifully imbibed into vegetables ; thereby not only refrefhing them for the prefent, but alfo furnifhing them with a frefh fupply of moifture towards the great expences of the fucceeding day.

'Tis therefore probable, that the roots of trees and plants are thus, by means of the Sun's warmth, conftantly irrigated with frefh fupplies of moifture; which, by the fame means, infinuates itfelf with fome vigour into the roots. For, if the moifture of the earth were not thus actuated, the roots muft then receive all their nourifhment merely by imbibing the next adjoining moifture from the earth ; and confequently the fhell of earth, next the furface of the roots, would always be confiderably drier, the nearer it is to the root; which I have not obferved to be fo. And by Exper. 1 8, and 19, the roots would be very hard put to it to imbibe fufficient moifture in dry fum- mer weather, if it were not thus conveyed to them by the penetrating warmth of the Sun : Whence by the fame genial heat, in conjunction with the attraction of the ca- pillary fap-vefTels, it is carried up thro* the bodies and branches of vegetables; and F thence

66 Vegetable Staticks.

thence pa (Ting into the leaves, it is there moft vigoroufly acted upon, in thofe thin plates, and put into an undulating motion, by the Sun's warmth, whereby it is moft plentifully thrown off, and perfpired thro' their furface ; whence, as foon as it is dif- intangled, it mounts with great rapidity in the free air.

But when, towards the latter end of Oflober, the vigour of the Sun's influence is fo much abated, that the firft Thermometer was fallen to 3 degrees above the freezing point, the fecond to 10 degrees, the fifth to 14 degrees, and the fixth Thermometer to 16 degrees j then the brisk undulations of the moifture of the earth, and alfo of the afcending fap, much abating, the leaves faded and fell off.

The greateft degree of cold, in the fol- lowing winter, was in the firft 12 days of November ; during which time, the fpirit in the firft Thermometer was fallen 4 degrees below the freezing point, the deepeft Ther- mometer 10 degrees, the ice on ponds was an inch thick. The Sun's greateft warmth, at the winter folftice, in a very ferene, calm, frofty-day, was, againft a South afpedl of a wall, 19 degrees and in a free open air, but

11 de-

Vegetable Staticks. 67

1 1 degrees above the freezing point. From the 10th of January to the 29th of March was a very dry feafon ; when the green Wheat was generally the fineft that was ever remembred. But from the 29th of March J 72 5, to the 29th of September fol- lowing, it rained more or lefs almoft every day, except ten or twelve days about the beginning of July, and that whole feafon continued fo very cool, that the fpirit in the firft Thermometer rofe but to 24 degrees > except now and then in a fhort interval of Sunfhine ; the fecond only to 20 degrees ; the fifth and fixth to 24 and 23 degrees, with very little variation: So that during this whole fummer, thofe parts of roots which were two feet under ground, had three or four degrees more warmth than thofe which were but two inches under ground : And at a medium the general degree of heat thro* this whole fummer, both above and under ground, was not greater than the heat of the middle of the preceding September.

The year 1725 having been, both in this ifland, and in the neighbouring nations, moft remarkably wet and cold; and the year J723, in the other extreme, as remarkably dry, as ha« ever been known ; it may not Fa be

68 Vegetable Statich.

be improper here to give a fhort account of*

them, and the influence they had on their

productions.

Mr. Miller, in the account which he took of the year 1723, obferved, " That the <c winter was mild and dry, except that in " February it rained almoft every day, which " kept the fpring backward. March, April, " May, June, to the middle of July, proved " extremely dry, the wind North-eaft moft " part of the time. The fruits were for- <c ward, and pretty good ; but kitchen-ftuflf, <c efpecially Beans and Peas, failed much. <c The latter half of July the weather proved " very wet, which caufed the fruits to C£ grow fo faft, that many of them rotted " on the trees; fo that the autumn fruits " were not good. There were great plenty cc of Melons, very large, but not well tailed. " Great plenty of Apples -, many kinds of " fruits bloffomed in Augujl, which pro- <c duced many fmall Apples and Pears in c< October, as alfo Strawberries and Rafp- <c berries in great plenty. Wheat was good, " little Barley, much of which was very un- €C equally ripe, fome not at all, becaufe fown <c late, and no timely rain to fetch it up. £ There were innumerable Wafps -, how it

" fared

Vegetable Staticks. 69

" fared with the hops this dry year, is men- 'f tioned under Exper. 9.

" The following winter, 1724, proved " very mild ; the fpring was forward in Ja- " nuary, fo that the Snow-drops, Crocus's, " Polyanthus's, Hepaticas, and Narcijfuss, C{ were in flower. And it was remarkable, cc that moft of the Colliflower-plants were ■•" deftroyed by the mildew, of which there u was more, all this winter, than had been " known in the memory of man. In Fe- cc bruary we had cold fharp weather, which " did fome damage to the early crops, and " it continued variable till April, fo that " much of the early Wall-fruit was cut off: ct And again the 6th of May was a very <c (harp froft, which much injured tender c< plants and fruits. The fummer in general fcC was moderately dry, the common fruits cc proved pretty good, but late: Melons c< and Cucumbers were good for little; *' Kitchenrftuff was in great plenty in the €c markets/'

In the very wet and cold year 1725, moft things were a full month backwarder than ufual. Not half the Wheat in by the 24th of Augujl, in the Southern parts of England-. very few Melons or Cucumbers, and thofe

F 3 no£

?o Vegetable Staticks.

not good. The tender Exoticks fared but ill; fcarce any grapes, thofe fmall, and of very unequal fizes, on the fame bunch, not ripe ; Apples and Pears green and infipid ; no fruit nor products of the ground good, but crude: Pretty good plenty of Wheat, tho' coarfe, and long ftraw ; Barley coarfe, but plenty of it in the uplands. Beans and Peas mod flourifhing and plentiful ; few Wafps or other infects, except Flies on hops. Hops were very bad thro' the whole kingdom. Mr. Aujlin of Canterbury fent me the following particular account, how it fared with them there \ where they had more than at Farnham, and moft other places, viz.

Cl At mid- April not half the fhoots ap- << peared above ground ; fo that the plant- <c ers knew not how to pole them to the " beft advantage. This defect of the flioot, «c upon opening the hills, was found to be " owing to the multitude and variety of " vermin that lay preying upon the root; <c the increafe of which was imputed to <c the long and almoft uninterrupted feries <c of dry weather, for three months pafl : <c Towards the end of April, many of the ?c hop-vines were infefted with the Flies. * About the 20th of May there was a

« very

Vegetable Statich. 71

u very unequal crop, fome Vines being " run feven feet, others not above three or " four feet -> fome juft tied to the poles, and <c fome not vifible : And this difpropor- li tionate inequality in their lize continued " through the whole time of their growth. u The Flies now appeared upon the leaves (< of the forwarded Vines, but not in fuch '* numbers here, as they did in moft other '* places, About the middle of Juney the u Flies increafed, yet not fo as to endanger *c the crop 5 but in diftant plantations they *c were exceedingly multiplied, fo as to a fwarm towards the end of the month. ** June 27th fome fpecks of Fen appeared : " From this day to the 9th of July, was " very fine dry weather. At this time, " when it was faid that the Hops in moft u ocher parts of the kingdom looked black " and fickly, and feemed pail: recovery, ours *f held it out pretty well, in the opinion IC of the moft skilful planters. The great " leaves were indeed difcoloured, and a lit- M tie withered, and the Fen was fomewhat " increafed, From the 9th of July to the cc 23d the Fen increafed a good deal, but <c the Flies and Lice decreafed, it raining M daily much : In a week more the Fen, F 4 " which

71 Vegetable Staticks.

" which feemed to be almoft at a (land, u was confiderably increafed, efpecially in M thofe grounds where it firft appeared. u About the middle of Augtijl, the Vines <: had done growing, both in ftem and " branch ; and the forwarded began to be *' in Hop, the reft in Bloom : The Fen " continued fpreading, where it was not €t before perceived, and not only the leaves, t% but many of die Burs alfo were tainted cz with it. About the 20th of Aiigujl, u fome of the Hops were infected with the " Fen, and whole branches corrupted by it. u Half the Plantations had hitherto pretty " well efcaped, and from this time the Fen " increafed but little: But feveral days vio- <c lent wind and rain, in the following cc week, fo difordered them, that many of (i them began to dwindle, and at laft came c: to nothing 5 and of thofe that then re. 11 mained in bloom, fome never turned to 11 Hops; and of the reft which did, many " of them were fo fmall, that they very iC little exceeded the bignefs of a good lc thriving Bur. We did not begin to pick " till the eighth of September, which was " eighteen days later than we began the 'f year before. The crop was little above

" two

Vegetable Statich. 7$

« two hundred on an acre round, and not " good." The beft Hops fold this year at Way -Hill Fair for fixteen pounds the hundred.

The almoft uninterrupted wetnefs and coldnefs of the year 1725, very much af- fe&ed the produce of the Vines the enfu- ing year ; and we have fufficient proof from the obfervations that the four or five laft years afford us, that the moifture or drinefs of the preceding year has a confiderable in- fluence on the productions of the Vine the following year. Thus in the year 1722, there was a dry feafon, from the beginning of Augujl thro' the following autumn and winter, and the next fummer there was good plenty of Grapes. The year 1723 was a remarkably dry year, and in the following year 1724, ihere was an unufual plenty of Grapes. The year 1724 was moderately dry, and the following fpring the Vines produced a fufficient quantity of bunches; but by reafon of the wetnefs and coldnefs of the year T725, they proved abortive, and produced hardly any Grapes. This very wet year had an ill effect, not only upon its own productions, but alfo on thofe of the following year: For notwithftanding there

,was

74 Vegetable Staticks.

was a kindly fpring, and blooming feafon, in the year 1726, yet there were few bunches produced, except here and there in fome very dry foils. This many Gardeners fore- faw early, when, upon pruning of the Vines, they obferved the bearing (hoots to be crude and immature j which was the reafon why they were not fruitful. The firft crop thus failing in many places, the Vines produced a fecond, which had not time to come to maturity before the cold weather came on.

Mr. Miller fent me the following ac-r count of the long and fevere winter in the year 1728; and of the effedl it had on the plants and trees in this and the neighbour- ing countries, 'viz.

" The autumn began with cold North H and Eaft winds, and early in November " the nights were generally frofty ; tho' the " froft did not enter the ground deeper than " the fucceeding days thaw'd. But towards " the end of November the winds blew ex- " tremely cold from the North, which was c< fucceeded by a great fnow, which fell in M fuch quantities in one night, as to break <c off large arms and tops of many ever-green " trees, on which it lodged.

« After

Vegetable Stathks. 75

*c After the fnow was down, it began to <c freeze again, the wind continuing to « blow from the North ; the days were " dark and cloudy for fome time, bucaf- " terwards it cleared up, and the Sun ap* cc peared almoft every day, which melted ■" the fnow where expofed to it, whereby P the froft penetrated the deeper into the ic ground. It was pbfervable, that during " thefe clear days, a great mift or vapour " appeared in the evenings, floating near " the furface of the ground, till the cold P* of the night came on, when it was fud- " denly condenfed and difappeared ; the P nights now began to be extreme fharp. <c The fpirit in the Thermometer was 18 de- " grees below the freezing point, (as mark- " ed upon Mr. Fowler's Thermometers) and *c it was at this time that vaft quantities of " Lauriiftimis'sy Phyllyreas, Alaternuss^ Rofe- " wary, and other tender plants began to P fufferj efpecially fuch as were trimm'd " up to naked items, or had been clipp'd " late in the fummer. At this time alfo P there were great numbers of trees diC- " barked, fome of which were of a confi- M derable bulk ; particularly two Weft-India U Plane Trees^ in the Phyfick Garden at

P Chelfea,

7 6 Vegetable Statich.

<< Chelfea, which are near forty feet high. <c and a fathom in circumference, were dif- " barked almoft from the bottom to the " top, on the weft fide of the trees. And " in a nurfery belonging to Mr. Francis il Hurji, great numbers of large Pear-trees <c were all of them disbarked on the Weft or « South-Weft fides of 'em. And in feveral « other places I obferved the like accident, " and foun^ it was conftantly on the fame M fide of the trees.

<( About the middle of December the " froft abated of its intenfenefs, and feemed << to be at a Hand, till the 23d of the month, «c when the wind blew extreme fharp and «' cold from the Eaft, and the froft continued " very hard to the 28th day, at which time lt it began to abate again, and feemed to be H going off, the wind changing to rhe Scuih ; " but it did not continue long id this point, " before it changed to the Eaft again, and " the froft returned, tho' not fo violent as <•' before.

iC Thus the weather continued for the cc moft part frofty, till me middle of March, " with a fevy intervals of mild weather, li which brought forward fome of the early u flowers i but the cold returning, foon de-

a ftroyed

Vegetable Staticks* 77

ct ftroyed them ; io that thofe plants which " ufually flower in January and February, ci did not this year appear till the latter end " of March) or the beginning of April \ as " the Crocus's, Hepaticas6 Perfian Iris's, " Black Hellebores, Polyanthus's, Mezereons, u and many others.

u The Colliflower - plants which were ct planted out during the intervals between " the froft, were moft of them deftroyed, " or fo much pinched, as to lofe the great- " eft part of their leaves 5 whereas thofe " which had been planted out in Ottober cc efcaped very well. The early Beans and " Peas were moft of them deftroyed ; and " great quantities of timber and fruit-trees, " which had been lately removed, were quite " killed.

" The lofs was very great in moft cu- " rious collections of plants ; there being " a great deftru&ion made of many trees, " fhrubs, and plants, which had endured " the open air many years, wichout being " the leaft hurt by cold; as the Granadilla " or Paffion-flowe?\ Arbutus or Straw- l£ berry Tree, Cork Tree, with moft of the <c Aromatick Plants, as Rofemary, Laven- €i ' der, Stcechas, Sage, Maftick, Mar urn,

" and

7% Vegetable Staticks.

H and many others, which were deftroyed u to the ground, and were by many people " pulled up and thrown away ; but in warm '■• dry foils, where they were fuffered to re- <c main undifturbed, many of them broke u out from the root again, tho' it was very u late in the fummer before they fhewed any cc figns of recovery.

u The plants in the confervatories fuffered <c very much by being fo long (hut up clofe ; e< for the days being for the moft part cloudy, *c and the wind blowing very ftiarp, the <c windows of the green-houfes could not be <c with fafety opened, which occafioned a <c noxious damp in the houfes, whereby the c£ plants became fickly, languifhed and de- €< cayed foon after.

" Nor was the froft more fevere with us " than in other parts of Europe, but on " the contrary in comparifon favourable -, l< for in the Southern parts of France the <£ Olives, Myrtles , Ci/luss, and other trees " and fhrubs, which grow there almoft c< fpontaneoufly, were deftroyed ; and in the <c Northern parts of France, as about Paris, " &c. the buds of many kinds of fruit-trees u were deftroyed, although clofed, fo that c< many of them never opened, but decayed

" and

Vegetable Statuks. 79

*< and perifhed; and the Fig-trees which " were expofed to the open air, were alfo ic deftroyed.

" In Holland the Pines, Firs, and other " hardy refinous trees, were moft of them cl killed, altho' many of them are natives <c of the Alps, and other mountainous cold " countries ; but this I apprehend to be ow- " ing to the lownefs of their fituation and " foil, whereby their roots eafily ran down " into the water, which is more injurious to 11 thefe trees than froft.

<c But it was obferved, that the trees and " fhrubs which are natives of Virginia and a Carolina, efcaped well in Holland-, when " almoft all thofe which were b/ought from " Italy, Spain, or the South parts of France, <c were intirely deftroyed. Which will greatly <c inhance the value of the former trees, ef- " pecially fuch of them as are either proper " for ufe or beauty.

" In Germany the winter was fo fevere as * to deftroy almoft all their plants and flowers, <c which were not either removed into the " green - houfes, or protedled by coverings u from the froft, as I was informed by letters u from thence.

« And

8o Vegetable Statich.

" And in Scotland the froft and fnow did " great damage, fome of the particulars of €i which I fhall tranfcribe from a letter, <l which I received from a gentleman living " near Edinburgh who is a curious ob- u ferver.

" About the 20th of November, he fay9, cc they had much fnow, which lay ten days, <c and then went off very pleafantly without " rain 5 and from that time till the middle " of December, we had very good winter ct weather, when a great fnow fell, which " was attended with a ftorm from the North- <c eaft -, which fnow lay very thick upon the " ground till the 12th day of January, du- " ring which time there was a very intenfe " froft: After which the cold abated, and cc the fnow went off gradually •, and about " the end of January, I obferved in my cc green- houfe the flowers and young fhoots " of the Orange and other exotick trees did " begin to appear, and all of them began to " prepare for vegetation. In the open ground " we had Spring Cyclamens, Primrofes, Win- " ter Aconites, Snowdrops, Hellebores, Poly- " anthuss, Glajlenbury Thorn, Winter Hya- c cinths, and Mezereons in flowv \

But

cc

Vegetable Staticks. 81

u But before I proceed to give a farther cc account of the weather, I fhail offer you <c my thoughts upon the reafon of this ve- cc gecation fo early, whilft the cold was fo " intenfe with you. Firft, it is to be obferved, " that our ftorms of fnow at that feafon " came on before the froft had entered the " ground; fo that the fnow kept the ground " warm and fecure from the froft, which " only crufted the top of the fnow : Du- " ring this feafon the wind blew from the (c Eafr, which coming off the fea, (from <c which we are but eight miles diftant) was <c not attended with fo much cold as if it " had blown over the land, which was cc covered with fnow, where there is no cc fea for two hundred miles. Till the fifth li of February we enjoyed this weather \ at <c which time we had a violent fnow with <c a ftorm from the South-w7eft, and the <c froft having entered the ground before it " fell, checked our early flowers from ap- " pearing : During this fnow, which con- " tinued moft part of February, we had a " great deal of fun-mine, which contributed ■ very much to our early crops of Cu- " cumbers and Melons ; but during the nights " it froze very hard, which deftroyed great G " numbers

8 1 Vegetable Statieks.

" numbers of plants that were not fhel- " tered.

" Every thing was now at a ftand ; the iC Apricot and Peac h bloflbms continued tur- " gid; but not being opened, they fuffered " very little; the Laurujlinuss fuffered u extremely by this laft fevere feafon, efpe- " cially where the (how had been melted from cl their roots.

" This fnow went off with a violent

<c South-well wind, which was very bleak

<£ and cold ; and where the fun had no ac-

" cefs, the fnow lay till the 12th of Marchy

" at which time we had for fix days very

M mild weather, which occafioned our put-

if ting abroad our Carnatiojis, thereby we

* loft moft of them. The wind continued

" cold, varying from the South-weft to the

c< North-weft, and fometimes North-eaft>

" and upon the 23d day it was very cold,

« the wind at North-weft and by North;

" in the evening the fun was clouded, and

<•' the wind abated, the Mercurv in the Ba-

¥ rometer fell at night; at two o' clock the

<f next morning a violent hurricane at

" North-eaft brought a fnow in many

" places, 6, 10, and 12 feet deep, with a

" moft piercing cold; the fnow continued

•' to

Vegetable Staticks. 83

«« to fall till ten o' clock in the morning, " when the wind chopped about to the u North-weft with incredible fiercenefs, « and extreme cold. Now it was that in- " numerable fheep and other cattle were <c loft in the mountains of fnow; and many cc poor people going that morning to <c look after their cattle, the remembrance " of which is terrible, were equally fuf- " ferers with them, being buried in the cc fnow.

" The Apricots and Peaches v/hich were <c now in bloffom upon warm walls, were u all deftroyed, and not only the bloflbms, " but the trees alfo, their bark burfting »■ off."

I have often obferved from thefe Ther- mometers, when that kind of hovering lam- bent fog arifes, ( either mornings or even- ings) which frequently betokens fair wea- ther, that the air which in the preceding day was much warmer, has upon the ab- fence of the fun become many degrees cooler than the furface of the earth ; which being near 1500 times denfer than the air, cannot be fo foon affected with the alter- nates of hot and cold ; whence 'tis pro- bable, that thole vapours which are raifed

G 2 by

84 Vegetable Staticks.

by the warmth of the earth, are by the cooler air foon condenfed into a vifible form. And I have obferved the fame dif- ference between the coolnefs of the air, and the warmth of water in a pond, by putting my Thermometer, which hung all night in' the open air in fummer time, into the water, juft before the rifing of the fun, when the like wreak or fog was rifing on the furface of the water.

CHAP. II.

Experiment ls> whereby to find out the force with which trees imbibe moijlure.

HAving in the firft chapter fecn many proofs of the great quantities of li- quor imbibed and perfpired by vegetables, I propofe in this, to inquire with what force they do imbibe moifture.

Tho' vegetables (which are inanimate) have not an engine, which, by its alternate dilatations and contractions, does in animals forcibly drive the blood through the arte- ries and veins; yet has nature wonderfully

contrived

Vegetable Staticks. 85

contrived other means, moft powerfully to raife and keep in motion the fap, as will in fome meafure appear by the experiments in this and the following chapter.

I (hall begin with an experiment upon roots, which nature has providently taken care to cover with a very fine thick ftrainer ; that nothing (hall be admitted into them, but what can readily be carried off by perfpiration, vege- tables having no other provifion for difcharg- ing their recrement.

Experiment XXI.

Auguft 13. in the very dry year 1723, I dug down 2 + ~ feet deep to the root of a thriving baking Pear-tree, and laid bare a root ~ inch diameter n (Fig. 10.) I cut off the end of the root at i3 and put the remaining ftump i n into the glafs tube dr, which was 1 inch diameter, and 8 inches long, cementing it faft at r; the lower part of the tube d z was 1 8 inches long, and \ inch diameter in bore.

Then I turned the lower end of the tube

z uppermoft, and filled it full of water, and

then immediately immerfedthe fmall end z

into the ciftern of mercury x ; taking away

G 3 my

86 Vegetable Staticks.

my finger, which flopped up the end of the tube z.

The root imbibed the water with fo much vigour, that in 6 minutes time the mercury was railed up the tube d z as high as zy viz. 8 inches.

The next morning at 8 o' clock, the mer- cury was fallen to 2 inches height, and z inches of the end of the root i were yet im- meried in water. As the root imbibed the water, innumerable air-bubbles hTued out at /, which occupied the upper part of the tube at r3 as the water left it.

Experiment XXII.

The eleventh experiment mews, with what great force branches imbibe water, where a branch with leaves imbibed much more than a column of 7 feet height of water could in the fame time drive through 13 inches length of the biggeft part of its item. And in the following experiments wc fhali find a farther proof of their ftrpng imbibing power.

MiiX 25, I cut off a branch of a young thriving yi/^/t'-Zra? b, (Fig. 11.) about 3 feet long, with lateral branches ; the diameter of ti.e tranfverfe cut /, where it was cut off,

was

Vegetable Staticks. 87

was \ of an inch : The great end of this branch I put into the cylindrical glafs e r, which was an inch diameter within, and eight inches long.

I then cemented faft the joint r, firfl fold- ing a ftrap of fheeps-skin round the Hem, fo as to make it fit well to the tube at r ; then I cemented faft the joint with a mixture of Bees-wax and Turpentine melted together in fuch a proportion, as to make a very ftiff clammy pafte when cold, and over the cement I folded feveral times wet bladders, binding it firm with packthread.

At the lower end of the large tube e was cemented, on a lefier tube z e, {■ inch dia- meter in bore, and 1 8 inches long : The fub- ftance of this tube ought to be full f of an inch thick, elfe it will too eafily break in making this experiment

Thefe two tubes were cemented together at ey firft with common hard brick-duft ce- ment to keep the tubes firm to each other ; but this hard cement would, both by being long moift, and by the different dilatations and contractions of the glafs and cement, feparate from the glafs in hot weather, fo as to let in air ; to prevent which incon- venience, I further fecured the joint with

G 4 the

8 8 Vegetable Statkks.

the cement of Bees-wax and Turpentine, binding a wet bladder over all. If the hard cement be made of powder'd chalk inftead of brick-duft, it is more binding, and is not fo apt to be loofened by water.

When the branch was thus fixed, I turned it downwards, and the glafs tube upwards, and then filled both tubes full of water ; upon which I immediately applied the end of my finger to clofe up the end of the fmall tube, and immerfed it as faftaslcould into the glafs ciflern x, which was full of mercury and water.

When the branch was now uppermoft, and placed as in this figure, then the lower end of the branch was immerfed 6 inches in water, viz. from r to i.

Which water was imbibed by the branch, at its tranfverfe cut /; and as the water af- cended up the fap-veffels of the branch, fo the mercury afcended up the tube e z from the cittern x ; fo as in half an hour's time the mercury was rifen 5 inches and | high up to z.

And this height of the mercury did in feme meafure ihew the force with which the fa p was imbibed, tho' not near the whole force; for while the water was imbibing,

(he

Vegetable Staticks. 89

the tranfverfe cut of the branch was covered with innumerable little hemifpheres of air, and many air-bubbles iffued out of the fap- veffels, which air did in part fill the tube e r, as the water was drawn out of it 5 fo that the height of the mercury could only be proportionable to the excefs of the quantity of water drawn off, above the quantity of air which iffued out of the wood.

And if the quantity of air, which iffued from the wood into the tube, had been equal to the quantity of water imbibed, then the mercury would not rife at all •> becaufe there would be no room for it in the tube.

But if 9 parts in 1 2 of the water be im- bibed by the branch, and in the mean time but three fuch parts of air iffueinto the tube, then the mercury muft needs rife near 6 inches, and fo proportionably in different cafes.

I obferved in this, and moft of the follow- ing experiments of this fort, that the mer- cury rofe higheft, when the fun was very clear and warm; and towards evening it would fubfide 3 or 4 inches, and rife again the next day as it grew warm, but feldom to the fame height it did at firft. For I have always found the fap-veffels grow every day,

after

90 Vegetable Staticks.

after cutting, lefs pervious, not only for water, but alio for the fap of the vine, which never paries to and fro fo freely thro' the tranfverfe cut, after it has been cut 3 or 4 days, as at firft ; probably, becaufe the cut capillary veffels are fhrunk, the veficles alfo, and in- terfaces between them, being faturate and dilated with extravafated fap, much more than they are in a natural ftate.

If I cut an inch or two off the lower part of the ftem, which has been much fa- turated by Handing in water, then the branch will imbibe water again afrefh ; tho' not alto- gether fo freely, as when the branch was firft cut off the tree.

I repeated the fame experiment as this 2 2d, upon a great variety of branches of feveral fizes and of different kinds of trees, fome of the principal of which are as fol- low, viz.

Experiment XXIII.

July 6th and 8th, I repeated the fame experiment with feveral green fhoots of the Viney of this year's growth, each of them full two yards long.

The mercury rofe much more leifurely in thefe experiments, than with the Apple-tree

branch -,

Vegetable Statkks. 91

branch ; the more the fun was upon it, the fafter and higher the mercury rofe, but the Vine-branches could not draw it above 4 inches the firft day, and 2 inches the third day.

And as the fun fet, the mercury fometimes fubfided wholly, and would rife again the next day, as the fun came on the Vine- branch.

And I obfei'ved, that where fome of thefe Vine-branches were fix'd on the North-fide of the large trunk of a Pear-tree, the mer- cury then rofe mod in the evening about 6 o* clock, as the fun came on the Vine-branch.

Experiment XXIV.

Auguft 9, at 10 ante Merid. (very hot funftiine) I fixed in the fame manner as Ex. 22. a Non-pareil branch, which had 20 Apples on it ; it was 2 feet high, with lateral branches, its tranfverfe cut £ inch diameter : It imme- diately began to raife the mercury moft vigo- roufly, fo as in 7 minutes it was got up to z 12 inches high.

Mercury being 13 | times fpecifically heavier than water, it may eafily be eftima- ted to what height the feveral branches in

thefe

$> i Vegetable Staticks.

thefe experiments would raife water; for if any branch can raife mercury 12 inches, it will raife water 13 feet 8 inches: A fur- ther allowance being alfo made for the per- pendicular height of the water in the tubes, between r and z the top of the column of mercury ; for that column of water is lifted np by the mercury, be it more or lefs.

At the fame time, I tried a Golden Re- nate branch 6 feet long ; the mercury rofe but 4 inches, it rifing higher or lower in branches nearly of the fame fize and of the fame kind of tree, according as the air iffued thro' the ftem, more or lefs freely. In the preceding experiment on the Nonpareil branch, I had fucked a little with my mouth at the fmall end of the tube, to ge£ fome air-bub- bles out of it, before I immerfed it in the mercury $ (but thefe air-bubbles are beft got out by a fmall wire run to and fro in the tube) and this faction made air-bubbles arife out of the tranfverfe cut of the branch : but tho* the quantity of thofe air-bubbles thus fucked out, was but fmall ; yet in this and many other "experiments, I found, that after fuch faction, the water was imbibed by the branch much more greedily, and in much greater quantity, than the bulk of the air was,

which

Vegetable Stathks, <?j

which was fucked our. Probably therefore, thefe air-bubbles, when in the fap-veffels, do flop the free afcent of the water, as is the cafe of little portions of air got between the water in capillary glafs tubes.

When the mercury is raifed to its great- eft height, by precedent fudtion with the mouth, (which height it reaches fometimes in 7 minutes, fometimes in half an hour or an hour) then from that time it begins to fall, and continues fo to do, till it is fallen 5 or 6 inches, the height the branch would have drawn it to, without fucking with the mouth.

But when, in a very warm day, the mer- cury is drawn up 5 or 6 inches, (without precedent fudtion with the mouth) then it will ufually hold up to that height for feve- ral hours, viz. during the vigorous warmth of the fun; becaufe the fun is all that time ftrongly exhaling moifture from the branch thro1 the leaves -y on which account it muft therefore imbibe water the more greedily, as is evident by many experiments in the firft chapter.

When a branch is fixed to a glafs tube fet in mercury, and the mercury fubfides at night, it will not rife the next morning,

(as

9 4 J' e get able Staticks.

(as the warmth of the fun increafes upon it) unlefs you fill the tube fir ft full of water: For if half or I of the large tube cr be full of air, that air will be rarefied by the fun ; which rarefaction will deprefs the water in the tube, and confequently the mercury can- not rife.

But where little water is imbibed the firft day, (as in the cafe of the green fhoots of the Vine, Exper. XXIII.) then the mercury will rife the fecond and third day, as the warmth of the fun comes on, without refilling the little water that was imbibed.

Exper iment XXV.

In order to make the like experiment on larger branches, (when I expected the mer- cury would have rifen much higher than in fmall ones) I caufed glafilrs to be blown of the fh ape of this here defcribed (Fig. 12.) of feveral dimenfions at r, from two to five inches diameter, with a proportionably large cavity c; the ftem z as near i_ inch diameter as could be, the length of the ftem 16 inches.

I cemented one of thefe glafs veffels to a large fmooth barked thriving branch of an

Apple-

9 6 Vegetable Statkks.

the glafs tube z r, to the remaining branch i r> and then filling the tube with water, fet its lower end in the mercury x -y fo that now the branch was placed with its top i down- wards in the water, in the Aqueomercurial

gage.

It imbibed the water with fuch ftrength, as to raife the mercury with an almoft equable progreffion 1 1 + 4 inches by 3 o' clock (the fun mining then very warm) 3 at which time the water in the tube r i being all imbibed, fo that the end i of the branch was out of the water, then the air-bubbles paffing more freely down to /, and no water being imbibed, the mercury fubfided 2 or 3 inches in an hour.

At a quarter pad 4 o' clock, I refilled the gage with water ; upon which the mercury rofe afrefh from the ciftern, viz. 6 inches the firft ^ of an hour, and in an hour more the mercury reached the fame height as be- fore, viz. 1 1 + \ inches. And in an hour and \ more, it rofe -J. inch more than at firft ; but in half an hour after this it began gently to fubfide; viz. becaufe the fun declining and fetting, the perfpiration of the leaves decreafed, and confequently the imbibing of the water at i abated, for the end i was then an inch in water,

July

Vegetable Staticks. 97

July 3 lft, it raining all this day, the mer- cury rofe but 3 inches, which height it flood at all the next night. Aitguft ift, fair fun-mine ; this day the mercury rofe to 8 in- ches : This mews again the influence of the fun, in raifing the mercury.

This Experiment proves that branches will ftrongly imbibe from the fmall end immer- fed in water to the great end; as well as from the great end immerfed in water to the fmall end; and of this we mall have further proof in the fourth chapter.

Experiment XXVII.

In order to try whether branches would imbibe with the like force with the bark off, I took two branches, which I call M and N\ I fixed M in the fame manner as the branch in the foregoing Experiment, with its top downwards, but firft I took off all the bark from i to r. Then fix'dl in the /

fame manner the branch N> but with its great end downwards, having alfo taken off all the bark from / to r- both the branches drew the mercury up to z, 8 inches; fo they imbibed with equal ftrength at either end, and that without bark.

H Expe-

Vegetable Statichi 99

tube : And if thefe wounds (thro* which the air always iflued plentifully) were well co- vered with fheeps gut, bound over with packthread, it would in a good meafure prevent the inconvenience : But I always found that my experiments of this kind fucceeded beft, when that part of the branch which was to enter the tube r i9 was clear of all knots or wounds j for when there were no knots, the liquor paiTed moil free- ly, and lefs air iffued out.

The fame day I fixed in the fame man- ner a gage to an Apricot-tree ; it raifed the mercury three inches; and tho' all the water was foon imbibed, yet the mercury role every day an inch, for many days, and fub- fided at night j fo that the branch muft daily imbibe thus much air, and remit it at night.

Experiment XXX.

We have a further proof of the influence of the leaves in raifing the fap in this fol- lowing Experiment.

Auguft 6th, I cut off a large Ruffet Pippin a, (Fig. 15.) with a ftalk 1 ~f \ inch long, and 12 adjoining leaves g growing to it.

H 2 I ce-

ioo Vegetable Staticks.

I cemented the flalk faft into the upper end of the tube d, which tube was 6 inches long, and \ inch diameter -y as the ftalk im- bibed the water, it raifed the mercury to z> four inches high.

I fixed another Apple of the fame fizeand tree in the fame manner, but firft pulled off the leaves ; it raifed the mercury but I Inch. I fixed in the fame manner a like bearing twig with 12 leaves on it. but no apple; it raifed the mercury 3 inches.

I then took a like bearing twig, without either leaves or apple; it raifed the mercury

I inch

o a twig with an apple and leaves raif- ed the mercury 4 inches, one with leaves only 3 inches, one with an apple without leaves 1 inch.

A Quince which had two leaves, juft at the twig's infertion into it, raifed the mer- cury 2 + \ inches, and held it up a confi- derable time.

A fprig of Mint fix'd in the fame manner, raifed the mercury 3 -j- \ inch, equal to 4 feet 5 inches height of water.

Expe-

Vegetable Staticks. 101

Experiment XXXI.

I tried alfo the imbibing force of a great variety of trees, by fixing Aqueo-mercuriai gages to branches of them cut off, as in Ex- periment 22.

The Pear, Quince, Cherry, Walnut, Peach, Apricot, Plum, Black-thorn, White-thorn, Goofeberry, Water-elder, Sycamore, raifed the mercury from 6 to 3 inches high : Thofe which imbibed water moft freely, in the Ex- periments of the firft chapter, raifed the mercury higheft in thefe Experiments, ex- cept the Horfe-Chefnut, which, though it imbibed water moft freely, yet raifed the mercury but one inch, becaufe the air paf- fed very fait through its fap-veffels into the

gage.

The following raifed the mercury but 1 or 2 inches, viz. the Elm, Oak, Horfe- Chefnut, Filberd, Fig, Mulberry, Willow, Sallow, Ofier, Am, Lynden, Currans.

The Ever-greens, and following trees and plants, did not raife it at all ; the Laurel, Rofemary, Lauruftinus, Phyllyrea, Fuz, Rue, Berberry, Jeffamine, Cucumber-branch, Pum- kin, Jerufalem Artichoke.

H 3 Expe-

102 Vegetable Staticks.

EXPERIMEN T XXXII.

We have a further proof of the great force with which vegetables imbibe moi- fture, in the following Experiment, viz. I filled near full with Peas and Water, the iron Pot ( Fig. 37.) and laid on the Peas a leaden cover, between which and the fides of the Pot, there was room for the air which came from the Peas to pafs freely. I then laid 184 pounds weight on them, which (as the Peas dilated by imbibing the water) they lifted up. The dilatation of the Peas is always equal to the quantity of Water they imbibe : For if a few Peas be put in- to a VeiTel, and that Veffel be filled full of water, tho' the Peas dilate to near double their natural fize, yet the water will not flow over the veiTel, or at moll very incon- fiderably, on account of the expanfion of little air-bubbles, which are hTuing from the Peas.

Being defiious to try whether they would raife a much greater weight, by means of a lever with weights at the end of it, I com- preffed feveral frefh parcels of Peas in the fame Pot, with a force equal to 1600, 800, and 400 pounds> in which Experiments, tho'

the

Vegetable Statich. i o ;

the Peas dilated, yet they did not raife the lever, becaufe what they increafed in bulk was, by the great incumbent weight, prefled into the interfaces of the Peas, which they adequately filled up, being thereby formed into pretty regular Dodecahedrons.

We fee in this Experiment the vaft force with which fwelling Peas expand ; and 'tis doubtlefs a confiderable part of the fame force which is exerted, not only in pufhing the Plume upwards into the air, but alfo in enabling the firft (hooting radicle of the Pea, and all its fubfequent tender Fibres, to pene- trate and moot into the earth.

Experiment XXXIII.

We fee, in the Experiments of this chap- ter, many inftances of the great efficacy of attraction; that univerfal principle which is fo operative in all the very different works of nature; and is moft eminently fo in vegetables, all whofe minuteft parts are curioufly ranged in fuch order, as is bcfl adapted, by their united force, to attract pro- per nourishment.

And we mall find in the following Ex- periment, that the diflevered particles of vegetables, and of other bodies, have a

H 4 ftrong

1 04 Vegetable Staticks.

flrong attractive power when they lie con- fjfed.

That the panicles of wood are fpecifical- ly heavier than water, ( and can therefore flrongly attract it ) is evident, becaufe feveral forts of wood fink immediately; others (even cork) when their fnterftfceS are well foaked, and filled with water: As Dr. Def- aguliers informed me, he found a cork which had been fealed up in a tube with water for 4 years, to be then fpecifically heavier than water; others (as the Peruvian Bark) fink when very finely pulverized, be- caufe all their cavities which made them ivvim, are thereby deltroyed.

In order to try the imbibing power of common wood allies, I filled a elafs tube c r i> 3 feet long, and | of an inch diameter, (Fig. 16.) with well dried and fiftcd wood aihc?, prefiing them clofe with a rammer; I tied a piece of linen over the end of the tube at /, to keep the allies from falling out ; I then cemented the tube c h(l at r to the Aqueo-mercurial gage r z ; and when I had filled the £a<:e full of water, I immerfed it iti the ciftern of mercury x ; the 1 to the upper end of the tube c7 ac oa I fcrewed on the mercurial gzge a t.

The

Vegetable Stattcks. 105

The afhes, as they imbibed the water, drew the mercury up 3 or 4 inches in a few hours towards z -, but the three following days it role but 1 inch, •£• inch, and •£, and fo lefs «nd lefs, fo that in 5 or 6 days it ceafed rifing : The higheft it rofe was 7 inches, which was equal to raifing water 8 feet high.

This had very little effect on the mer- cury in the gage a b, unlefs it were, that it would rife a little, viz. an inch or little more in the gage at a, as it were by the fuc- tion of the afhes, to fupply fome of the air- bubbles which are drawn out at i.

But when I feparated the tube c 0 from the gage r z, and fet the end i in water, then the moifture (being not reftrained as before) rofe fafter.and higher in the afhes c 0, and deprefled the mercury at a, fo as to be 3 inches lower than in the leg by by driving the air upwards, which was inter- mixed with the afhes.

I filled another tube 8 feet long, and ~ inch diameter, with red lead 5 and affixed it in the place, of c 0 10 the gages a b, r z, The mercury rofe gradually 8 inches to z.

In both thefe Experiments, the end i was covered with innumerable air-bubbles, many

of

1 06 Vegetable Staticks.

of which continually patted off, and were fucceeded by others, as at the tranfverfe ctm in the Experiments of this chapter. And as there, fo in thefe, the quantity of air-bub- bles decreafed every day, fo as at laft to have* very few : The part i immerfed in the wa- ter, being become fo fatarate therewith, as to leave no room for air to pafs.

After 20 days I picked the minium' out of the tube, and found the water had rifen 3 feet 7 inches, and would no doubt have rifen higher, if it had not been clogged by the mercury in the gage z. For which reafon the moifture rofe but 20 inches in the afhes, where it would otherwife have rifen 30 or 40 inches.

And as Sir Ifaac Newton (in his Op- tkks, query 31.) obferves, lt The water rifes " up to this height, by the aftion only of " thofe particles of the afhes which are up- " on the furface of the elevated water ; the " particles which are within the water, at- " tradting or repelling it as much down- ,f wards as upwards ; and therefore the ac- " tidn of the particles is very flrong : But " the particles of the allies being not fo" " denfe and clofe together as thofe of glafs, H their adion is not fo flrong as that of

!c glafs*

Vegetable Statkks. 107

4< glafs, which keeps quick-filver fufpended " to the height of 60 or 70 inches, and cc therefore ads with a force, which would " keep water fufpended to the height of " above 60 feet.

" By the fame principle, a fponge fucks <c in water; and the glands in the bodies of " animals, according to their feveral natures te and difpoiitions, fuck in various juices " from the blood."

And by the fame principle it is, that we fee, in the preceding Experiments, plants im- bibe moifture fo vigoroufly up their fine ca- pillary veflets; which moifture, as it is car* ried off in perfpiration, ( by the action of warmth) thereby gives the fap-veflels liber- ty to be almoft continually attracting of frefli fupplies ; which they could not do, if they were full faturate with moifture : For without perfpiration the fap muft neceflarily ftagnate, notwithstanding the fap-veffels are fo curioufly adapted by their exceeding fine- nefs, to raife the fap to great heights, in a reciprocal proportion to their very minute diameters.

C H A 1\

io8 Vegetable Statich.

CHAP. IIL

Experiments, jhewing the force of the jap in the Vine in the bleeding feafon.

HAVING in the firft chapter (hewn many inflances of the great quanti- ties imbibed and perfpired by trees, and in the fecond chapter feen the force with which they do imbibe moiflure -y I propofe next to give an account of thofe Experi- ments, which will prove with what great force the fap of the Vine is pufhed forth, in the bleeding feafon.

Experiment XXXIV.

March 30th at 3 p. m. I cut off a Vine on a weflern afpe<ft, within feven inches of the ground ; the remaining flump c (Fig. 17.) had no lateral branches : It was 4 or 5 years old, and -| inch diameter. I fix'd to the top of the flump, by means of the brafs collar hy the glafs tube b f\ feven feet long, and -J inch diameter ; I fecured the joint b with fliff cement made of melted Bees- wax and Turpentine, and bound it fafl over with fe- veral folds of wet bladder and packthread :

I then

Vegetable Staticks. lop

I then fcrewed a fecond tube/g to the firft, and then a third g ay to 25 feet height.

The ftem not bleeding into the tube, I filled the tube two feet high with water; the water was imbibed by the ftem within 3 inches of the bottom, by 8 o' clock thac evening. In the night it rained a fmall Ihower. The next morning at 6 and ~, the water was rifen three inches above what it was fallen to laft night at eight o' clock. The thermometer which hung in my porch was 1 1 degrees above the freezing point. March 3 1 from 6 and \ a, m. to id p. m. the fap rofe 8 -j- \ inches. April ift, at 6 a. m. T'hermofneter 3 degrees above the freezing point, and a white hoar froft, the fap rofe from ten o' clock laft night 3 + \ inches more ; and fo continued riling daily till it was above 21 feet high, and would very probably have rifen higher, if the joint b had not feveral times leaked: After flop- ping of which it would rife fometimes at the rate of an inch in 3 minutes, fo as to rife 10 feet or more in a day. In the chief bleeding feafon it would continue rifing night and day ; but much more in the day than night, and moft of all in the greateft heat of the day ; and what little finking it

had

1 1 o Vegetable Staticks.

had of 2 or 3 inches was always after fun- fet; which I fufpecl was principally occa- fioned by the fhrinking and contraction of the cement at b, as it grew cool.

When the fori fhined hot upon the Vine, there was always a continued feries of air- bubbles, conftantly afcending from the ftem thro' the fap in the tube, in fo great plenty as to make a large froth on the top of the fap, which mews the great quantity of air which is drawn in thro" the roots and ftem.

From this Experiment we find a confide- rable energy in the root to pufh up fap in the bleeding feafon.

This put me upon trying, whether I could find any proof of fuch an energy, when the bleeding feafon was over. In or- der to which,

Experiment XXXV.

July 4th, at noon, I cut off within 3 in- ches of the ground, another Vine on a fouth afpecl, and fixed to it a tube 7 feet high, as in the foregoing Experiment: I filled the tube with water, which was im- bibed by the root the firft day, at the rate of a foot in an hour, but the next day much more (lowly ; yet it was continually finking,

fo

Vegetable St Micks. i 1 1

fe that at noon day I could not fee it fo much as ftationary.

Yet by Experiment the 3d, on the Vine in the garden pot, it is plain, that a very confiderable quantity of fap was daily pref- fing thro' this ftem, to fupply the perfpira- tion of the leaves, before I cut the Vine off. And if this great quantity were carried up by pulfion or trufion, it muft needs have rifen out of the ftem into the tube.

Now, fince this flow of fap ceafesat once, as foon as the Vine was cut off the ftem, the principal caufe of its rife muft at the fame time be taken away, viz. the great perfpiration of the leaves.

For tho' it is plain by many Experiments, that the fap enters the fap-veflels of plants with much vigour, and is probably carried up to great heights in thofe veflels, by the vigorous undulations of the fun's warmth, which may reciprocally caufe vibrations in the veficles and fap-veflels, and thereby make them dilate and contract a little ; yet it feems as plain, (from many Experiments, as parti- cularly Exper. 13, 14, 15, and Exper. 43. where, tho' we are allured that a great quan- tity of water pafled by the notch cut 2 or 3 feet above the end of the ftem 5 yet was the

notch

! 1 1 Vegetable Statkks.

notch very dry, becaufe the attraction of the perfpiring leaves was much greater than the force of trufion from the column of water: From thefe Experiments, I fay, it feems evident) that the capillary fap-vefiels, out of the bleeding feafon, have little power to pro- trude fap in any plenty beyond their ori- fices ; but as any fap is evaporated off, they can by their ftrong attraction ( affifted by the genial warmth of the fun) fupply the great quantities of fap drawn off by perfpi- ration.

Experiment XXXVI.

April 6th, at 9. a. m. rain the evening be- fore, I cut off a Vine on a Southern afpecl, at a, (Fig. 18.) two feet nine inches from the ground ; the remaining ftem a b had no lateral branches ; it was \ inch diameter ; I fixed on it the mercurial gage ay. At 1 1 a. m. the mercury was rifen to z, 15 inches higher than the leg xy being pufhed down at x, by the force of the fap which came out of the ftem at a.

At /[.p.m. it was funk an inch in the leg zy.

April 7th at 8 a. ;;;. rifen very little, a fog : at 1 1 a. 777 . 'tis 17 inches high, and the fog gone.

April

Vegetable Statich. 1 1 j

April ioth, at 7 a. #;. mercury 18 inches high; I then added more mercury, fo as to make the furface z 23 inches higher than x; the fip retreated very little into the ftem, upon this additional weight, which fhews with what an abfolute force it advances: at noon it was funk one inch.

April 1 ith, at 7 a. m. 24 -p | inches high, fun-mine: at 7 p. m> 18 inches high.

April 14th, at 7 a. m. 20+1 inches high, at 9 a.m. 22 ~f"a> fine warm fun-mine ; here we fee that the warm morning fun gives a frefti vigour to the fap. At 1 1 a. m. the fame day i6~-f-~, the great perfpiration of the Hem makes it fink.

April 1 6th at 6 a. m. 19 -j- 4 rain. At 4 p. m. 13 inches. The fap (in the foregoing experiment, numb. 34.) rifen this day fince noon 2 inches, while this funk by the perfpi- ration of the ftem ; which there was little room for, in the very fhort ftem of the other. April 17th, at 1 1 a. m. 24 + \ incrl high, rain and warm; at yp. m. 29 + ~, finewarm rainy weather, which made the fap rife all day, there being little perfpiration by reafon of the rain.

April 1 8th, at 7 a. m. 32 -J- \ inches high, and would have rifen higher, if there had

I been

1 1 4. Vegetable Staticks.

been more mercury in the gage; it being all forced into the leg y z. From this time to May 5th, the force gradually decreafed.

The greateft height of the mercury being 32 -f- i inches; the force of the fap was then equal to 36 feet 5 + -j inches height of water.

Here the force of the riling fap in the morning is plainly owing to the energy of the root and ftem. In another like mercurial gage, (fixed near the bottom of a Vine, which run 20 feet high) the mercury was raifed by the force of the fap 38 inches equal to 43 feet -f- 3 inches + ~ height of water.

Which force is near five times greater than the force of the blood in the great crural ar- tery of a Horfe ; fevtn times greater than the force of the blood in the like artery of a Dog; and eight times greater than the blood's force in the fame artery of a fallow Doe: Which different forces I found by tying thofe feveral animals down alive upon their backs ; and then laying open the great left crural artery, where it firft enters the thigh, I fixed to it (by means of two brafs pipes, which run one into the other) a glafs tube of above ten feet long, and i- of an inch diameter in bore: In which tube the

blood

Vegetable StaUcks. 1 i 5

blood of one Horfe rofe eight feet three inches, and the blood of another Horfe eight feet nine inches. The blood of a little Dog fix feet and half high : In a large Spaniel feven feet high. The blood of the fallow Doe mounted five feet feven inches.

Experiment XXXVII.

April 4th, I fixed three mercurial gages, (Fig. 19.) A, B, C, to a Vine, on a South- eaft afpecl, which was 50 feet long, from the root to the end ru. The top of the wall was 1 1 -jf | feet high ; from i to k, 8 feet 5 from k to e, 6 feet + i. ; from e to A, 1 foot 10 inches ; from e to 0, 7 feet ; from 0 to B, 5 + 4 feet; from 0 to C, 22 feet 9 inches; from 0 to u, 32 feet 9 inches.

The branches to which A and C were fixed, were thriving moots two years old, but the branch 0 B was much older.

When I firft fixed them, the mercury was pufhed by the force of the fap, in- all the gages down the legs 4, 5, 13, fo as to rife nine inches higher in the other legs.

The next morning at 7 a. m. the mercury in A was pufhed 14 -f- \ inches high, in B 12 -f-i, in Cj3 -p-i.

I 2 The

i ! 6 Vegetable Statich.

The grcateft height to which they puttied the fap feverally, was ^2 1 inches, £26 inches, C 26 inches.

The mercury conftantly fubfided by the retreat of the fap about 9 or 10 in the morn- ing, when the fun grew hot; but in a very moift foggy morning the fap was later before it retreated, viz. till noon, or fome time after the fog was gone.

About 4 or 5 o' clock in the afternoon, when the fun went off the Vine, the fap be- gan to pufli afrefh into the gages, fo as to make the mercury rife in the open legs ; but it always rofe faftefl from fun-rife till 9 or 10 in the morning.

The fap in Z? (the oldefl flem) play'd the mod freely to and fro, and was therefore fooneft affected with the changes from hot to cool , or from wet to dry, and vice verfd.

And April 10, toward the end of the bleeding feafon, B began firft to fuck up the mercury from 6 to 5, fo as to be 4 inches higher in that leg than the other. But April 24, after a night's rain, B puihed the mercury 4 inches up the other leg; A did not begin to fuck till April 29, viz. 9 days after B > C did not begin to fuck till May 3, viz. 13 days after B> and 4 days after A\ May 5,

at

Vegetable Statich. 1 1 7

at 7 a. ?n. A pufhed 1 inch, Ci+Ij but to- wards noon they all three fucked.

I have frequently obferved the fame dif- ference in other Vines, where the like gages have been fixed at the fame time, to old and young branches of the fame Vine, viz, the oldefl began firft to fuck.

In this experiment we fee the great force of the fap, at 44 feet 3 inches diftance from the root, equal to the force of a column of water 30 feet 11 inches ~j~l high.

From this experiment we fee too, that this force is nor from the root only, but muft alfo proceed from fome power in the ftem and branches : For the branch B was much fooner influenced by changes from warm to cool, or dry to wer, and vice verfa% than the other two branches A or C -, and B was in an imbibing flare, 9 days before Ay which was all that time in a ftate of pufhingfap; and C pufhed 13 days after B had ceafed pufhing, and was in an imbibing ftate.

Which imbibing ftate Vines and Applet trees continue in, all the fummer, in every branch, as I have found by fixing the like, gages to the, m in July.

I 3 Expe-

1 1 8 Vegetable Staticls.

Experiment XXXVIII.

March io, at the beginning of the bleed- ing feafon, (which is many days fooner or later, according to the coldnefs or warmth, inoifture or drinefs of the feafon) I then cut off a branch of a vine bfcg at b, (Fig. 20.) which was 3 or 4 years old, and cemented faft on it a brafs-collar, with a fcrew in it; to that I fcrewed another brafs collar, which was cemented faft to the glafs tube zy 7 feet long and - inch diam. (which I find to be the propereft diam.) to that I fcrewed ethers, to 38 feet height. Thefe tubes were fattened and fecured in long wcoden tubes, 3 inches fquare, one fide of which was a door opening upon hinges ; the ufe of thofe wooden tubes was to preferve the glafs tubes from being broke by the freezing of the fap in them in the night. But when the danger of hard frofts was pretty well over, as at the beginning of April, then I ufually nVd the glaffes without the wooden tubes, fattening them to fcaffold poles, or two long ironfpikes drove into the wall.

Before I proceed to give an account of the rife and fall of the fap in the tubes, I

will

Vegetable Staticks. i 1 9

will firft defcribe the manner of cementing on the brafs collar b, to the ftem of the Vine, in which I have been often difappointed, and have met with difficulties ; it mud there- fore be done with great care.

Where I defign to cut the ftem, I firft pick off all the rough ftringy bark carefully with my nails to avoid making any wound thro' the green inner bark 5 then I cut ojk^ the branch at /, (Fig. 21.) and immediately draw over the ftem a piece of dried fheeps- gut, which I tie faft, as near the end of the ftem as I can, fo that no fap can get by it, the fap being confined in the gut if: Then I wipe the ftem at i very dry with a warm cloth, and tie round the ftem a ftiff paper funnel x i> binding it faft at x to the ftem , and pinning clofe the folds of the paper from x to i : Then I Aide the brafs collar r ever the gut, and immediately pour into the pa- per funnel melted chalk cement, and then fet the brafs collar into it ; which collar is warmed, and dipped before in the cement, that it may the better now adhere : When the cement is cold, I pull away the gut, and fcrew on the glafs tubes.

Buc finding fome inconvenience in this

hot cement, (becaufe its heat kills the fap-

I 4 vefTels

\ 20 Vegetable Staticks.

vefTels near the bark, as is evident by their being difcoloured) I have fince made ufe of the cold cement of Bees-wax and Turpentine, binding it faft over with wet bladder and pack- thread, as in Exper. 34.

Inftead of brafs-collars, which fcrewed into each other, I often (efpecially with the Syphons in Exper. 36, and 37.) made life ^f two brafs collars, which were turned a little tapering, fo that one entered and exactly fitted the other.

This joining of the two collars was ef- fectually fecured from leaking, by firft anointing them with a foft cement ; and they were fecured from being disjoined, by the force of the afcending fap, by twilling packthread round the protuberant knobs on the fides of the collars. When I would feparate the collars, I found it neceflary (except in hot fun-fliine) to melt the foft cement by applying hot irons on the out- fide of the collars.

It is needful to made all the cemented joints from the fun with loofe folds of pa- per, elfe its heat will often melt them, and fo dilate the cement, as to make it be drove forcibly up the tube., which defeats the ex- periment

The

Vegetable Staticks. ! 1 1

The Vines to which the tubes in this ex- periment were fixed, were 20 feet high from the roots to their top; and the glafs tubes fixed at feveral heights b from the ground, from 6 to 2 feet.

The fap would rife in the tube the firft day, according to the different vigour of the bleeding ftate of the Vine, either 1, 2, 5, 12, 15, or 25 feet; but when ic had got to its greateft height for that day, if it was in the morning, it would conftantly begin to fubfide towards noon.

If the weather was very cool about the middle of the day, it would fubfide only from 11 or 12 to 2 in the afternoon; but if it were very hot weather, the fap would begin to fubfide at 9 or 10 oV clock, and continue fubfiding till 4, 5, or 6 in the even- ing, and from that time it would continue ftationary for an hour or two ; after which it would begin to rife a little, but not much in the night, nor till after the fun was up in the morning, at which time ic rofe fafteft.

The frefher the cut of the Vine was, and the warmer the weather, the more the fap would rife, and fubfide in a day, us 4 or 6 feet.

But

121 Vegetable Statich.

But if it were 5 or 6 days fince the Vine was cut, it would rife or fubfide but little ; the fap-vefTels at the tranfverfe cue being faturate and contracted.

But if I cut off a joint or two off the Hem, and new fixed the tube, the fap would then rife and fubfide vigoroufly.

Moifture and warmth made the fap mod vigorous.

If the beginning or middle of the bleed- ing feafon, being very kindly, had made the motion of the fap vigorous, that vigour would immediately be greatly abated by coldeafterly winds.

If in the morning, while the fap is in a rifmg ftate, there was a cold wind with a mixture of fun-fhine and cloud ; when the fun was clouded, the fap would immediately viiibly fubfide, at the rate of an inch in a minute for feveral inches, if the fun con- tinued fo long clouded: But as foon as the fun-beams broke out again, the fap would immediately return to its then rifing ftate, juft as any liquor in a thermometer rifes and falls with the alternacies of heat and cold 5 whence 'tis probable, that the plentiful rife of the fap in the Vine in the bleeding feafon, is effected in the fame manner,

When

Vegetable Statkks. 123

When three tubes were fixed at the fame time to Vines on an eaftern, a fouthern, and a weftern afpedt, round my porch, the fap would begin to rife in the morning firft in the eaftern tube, next in the fouthern, and laft in the weftern tube : And towards noon it would accordingly begin to fubfide, firft in the eaftern tube, next in the fouthern, and laft in the weftern tube.

Where two branches arofc from the fame old weftern trunk, 15 inches from the ground; and one of thefe branches was fpread on a fouthern, and the other on a weftern afpedt ; and glafs tubes were at the fame time fixed to each of them 5 the fap would in the morning, as the fun came on, rife firft in the fouthern, then in the weftern tube; and would begin to fub- fide, firft in the fouthern, then in the weftern tube.

Rain and warmth, after cold and dry, wrou!d make the fap rife all the next day, without fubfiding, tho' ic would rife then flowed about noon; becaufe in this cafe the quantity imbibed by the root, and raifed from it, exceeded the quantity per- fpired.

The

H4 Vegetable Statich.

The fap begins to rife fooner in the morn- ing in cool weather, than after hot days; the reafon of which may be, becaufe in hot weather much being evaporated, it is not fo foon fupplied by the roots as in cool wea- ther, when lefs is evaporated.

In a prime bleeding feafon I fix'd a tube 25 feet long to a thriving branch two years old, and two feet from the ground, where it was cut off; the fap flowed fo briskly, as in two hours to flow over the top of the tube, which was feven feet above the top of the Vine ; and doubtlefs would have rifen higher, if I had been prepared to lengthen the tube.

When at the diftance of four or five days, tubes were affixed to two different branches, which came from the fame ftem, the fap would rife higheft in that which was laft fixed; yet if in the fixing the fecond tube there was much fap loft, the fap would fub- fide in the firft tube; but they would not afterwards have their fap in equilibrio; i. e. the furface of the fap in each was at very unequal heights ; the reafon of which is, be- caufe of the difficulty with which the fap paffes thro* the almoft faturate and contracled capillaries of the firfl-cut ftem,

la

Vegetable Stattch. i x 5

In very hot weather many air-bubbles would rife, fo as to make a froth an inch deep, oil the top of the fap in the tube.

I fix'd a fmall air-pump to the top of a long tube, which had 12 feet height of fap in it 5 when I pumped, great plenty of bubbles arofe* tho* the fap did not rife, but fall a little, after I had done pumping.

In Experiment 34. (where a tube was fixed to a very {hort ftump of a Vine, with- out any lateral branches) we find the fap rofe all day, and fafteft of all in the greateft heat of the day : But by many obfervations under the 37th and this 38th Experiments, we find the fap in the tubes conftantly fub- fided as the warmth came on towards the middle of the day, and fafteft in the greateft heat of the day. Whence .we may reafon- ably conclude, (confidering the great perfpi- rations of trees, fhewn in the firft chapter) that the fall of the fap in thefe fap-gages, in the middle of the day, efpecially in the warmer days, is owing to the then greater perfpiration of the branches, which perfpi- ration decreafes, as the heat decreafes towards evening, and probably wholly ceafes when the dews fall.

But

\l6 Vegetable Staticks.

But when towards the latter end of Jlprtl the fpring advances, and many young fhoots are come forth, and the furface of the Vine is greatly increafed and inlarged by the ex- panfion of feveral leaves, whereby the per- fpiration is much increafed, and the fap more plentifully exhaufted, it then ceafes to flow in a vifible manner, till the return of the following fpring. *

And as in the Vine, To is the cafe the fame in all the bleeding trees, which ceafe bleeding as foon as the young leaves begin to expand enough to perfpire plentifully, and to draw off the redundant fap. Thus the bark of Oaks, and many other trees, mod: eafily feparates, while it is lubricated with plenty of fap : But as foon as the leaves expand fufficiently to perfpire off plenty of fap, the bark will then no longer run, (as they term it) but adheres rnoft firmly to the wood.

Experiment XXXIX.

Jn order to try if I could perceive the flem of the Vine dilate and contract with heat or cold, wet or dry, a bleeding or not bleeding feaibn, fome time in February y I hVd to the

ftem

Vegetable Statich. 117

ftem of a Vine an inftrument in fuch a man- ner, that if the ftem had dilated or contracted but the one hundredth part of an inch, it would have made the end of the inftrument (which was a piece of ftrong brafs-wire, 18 inches long) rife or fall very fenfibly about one tenth of an inch ; but I could not per- ceive the inftrument to move, either by heat or cold, a bleeding or not bleeding feafon. Yet whenever it rained, the ftem dilated fo as to raife the end of the inftrument or lever -^ of an inch; and when the ftem was dry, it fubfided as much.

This Experiment fhews, that the fap (even in the bleeding feafon) is confined in its proper veflels, and that it does not confufedly per- vade every interftice of the ftem, as the rain does, which entering at the peripiring pores* foaks into the interftices, and tfeereby dilates the ftem.

CHAP.

iiB Vegetable Stattch. CHAP. IV.

Experiments, Jhcwing the ready lateral mo- tion oj the fapy and confequently- the late- ral communication of the fap-vejjels. The free fajjage of it fro?n the f mall branches towards the ft em y as well as from the ft em to the branches. With an account of fome Experiments, relating to the circulation or non-circulation of the jap.

Experiment XL.

IN order to find whether there was any lateral communication of the fap and fap- veiTels, as there is of the blood in animals, by means of the ramifications, and lateral communications of their vefTels ;

Augufl 15th, I took a young Oak-branch Y inches diameter, at its tranfverfe cut, fix feet high, and full of leaves. Seven inches from the bottom, I cut a large gap to the pith, an inch long, and of an equal depth the whole length ; and four inches above that, on the oppofite fide, I cut fuch ano- ther gaps I let the great end of the ftem in water : It imbibed and perfpired in two nights and two days thirteen ounces, while

another j

Vegetable Statkks. 129

another like Oak-branch, fomewhat bigger than this, but with no notch cat in its ftem, imbibed 25 ounces of water.

At the fame time I tried the like experi- ment with a Duke-cherry-branch 5 it imbibed and penpired 23 ounces in 9 hours the fxrft day, and the next day 15 ounces.

At the fame time I took another Duke- cherry '-branch, and cut 4 fuch fquare gaps to the pith, 4 inches above each other; the i& North, 2d Eajl, 3d South, /phWeft: It had a long (lender ftem, 4 feet length, with- out any branches, only at the very top ; yet it imbibed in 7 hours day 9 ounces, and in two days and two nights 24 ounces.

We fee in thefe experiments a moil free lateral comuunication of the fap and fap-vef- fels, thefe great quantities of liquor having paffed laterally by the gaps ; for by Experiment 13, 14, 15, (on cylinders of wood) little evaporated at the gaps.

And in order to try whether it would not be the fame in branches as they grew on trees, I cut 2 fuch oppofite gaps in a 'Duke-cherry- branch, 3 inches diftant from each other: The leaves of this branch continued green, within 8 or 1 o days, as long as the leaves on the other branches of the fame tree.

K The

i}o Vegetable Staticks.

The fame day, viz* Aug. 15th, I cut two fuch oppofite gaps four inches diftant, in an horizontal young thriving Oak-branch -, it was one inch diameter, eighteen days after many of the leaves begun to turn yellow, which none of the leaves of other boughs did then.

The fame day I cut off the bark for one inch length, quite round a like branch of the fame Oak; eighteen days after the leaves were as green as any on the fame tree ; but the leaves fell off this and the foregoing branch early in the winter ; yet continued on all the reft of the boughs of the tree (except the top ones) all the winter.

The fame day I cut four fuch gaps, two inches wide, and nine inches diftant from each other, in the upright arm of a Golden- renate - tree -> the diameter of the branch was 2 -f-i inch, the gaps faced the four cardinal points of the compafs; the apples and leaves on this branch flourifhed as well as thofe on other branches of the fame tree.

Here again we fee the very free lateral paffage of the fap, where the direft paflage is feveral times intercepted. See Vol II. p.

262.

Expe-

Vegetable Staticks. 1 3 1

Experiment XLI.

Aug. 13th, at noon I took a large branch of an Apple-tree, (Fig. 22.) and cemented up the tranfverfe cut, at the great end x9 and tied a wet bladder over it : I then cut off the main top branch at b ; where it was -| inch diameter, and fet it thus inverted into the bottle of water b.

In three days and two nights it imbibed and perfpired four pounds two ounces ~j- - of water, and the leaves continued green ; the leaves of a bough cut off the fame tree at the fame time with this, and not fet in water, had been withered forty hours be- fore. This, as well as the great quantities imbibed and perfpired, mews, that the wa- ter was drawn from b moft freely to e, fy g, b, and from thence down their refpeclive branches, and fo perfpired off by the leaves.

This experiment may ferve to explain the reafon, why the branch b, (Fig. 23.) which grows out of the root c xy thrives very well, notwithftanding the root c x is here fuppofed to be cut off at cy and to, be out of the ground : For by many expe- riments in the firft and fecond chapters, it K 2 is

ip Vegetable Statkks.

is evident, that the branch b attradts fap at x with great force: And by this pre- fent experiment, 'tis as evident, that fap will be drawn as freely downwards from the tree to x, as from c to x, in cafe the end c of the root were in the ground ; whence 'tis no wonder, that the branch b thrives well, tho' there be no circulation of the fap.

This Experiment 41, and Experiment 26, do alfo fhew the reafon why, where three trees ( Fig. 24. ) are inarched, and thereby incorporated at x and z, the middle tree will then grow, tho' it be cut off from its roots, or the root be dug out of the ground, and fufpended in the air; viz. becaufe the middle tree b attracts nourifliment ftrongly at x and z, from the adjoining trees a cy in the fame manner as we fee the inverted boughs imbibed water in thefe Exper. 26, and 41.

And from the fame reafon it is that Elders, Sallows, Willows, Briars, Vines, and mod Shrubs, will grow in an inverted ftate, wTidi their tops downwards in the earth.

Exp e-

Vegetable Staticks. 133

Experiment XLII.

July 27th, I repeated Monfieur Peraulfs Experiment ; viz. I took Duke-cherry, Ap- ple and Curran- boughs, with two branches each, one of which a c (Fig. 25.) I immer- fed in the large veilel of water e dy the other branch hanging in the open air: I hung on a rail, at the fame time, other branches of the fame forts, which were then cut off. After three days, thofe on the rails were very much withered and dead, but the branches b were very green ; in eight days the branch b of the Duke-cherry was much withered : but the Curram and Apple-branch b did not fade till the eleventh day: Whence 'tis plain, by the quantities that muftbeper- fpired in eleven days, to keep the leaves b green fo long, and by the wafte of the water out of the veffel, that thefe boughs b muft have drawn much water from and through the other boughs and leaves c, which were immerfed in the veffel of water.

I repeated the like experiment on the branches of Vines and Apple-trees, by run- ning their boughs, as they grew, into large glafs chymical retorts full of water3 where K 3 the

1 54 Vegetable Staticks. the leaves continued green for feveral weeks, and imbibed confiderable quantities of water.

This mews how very probable it is, that rain and dew is imbibed by vegetables, efpe- cially in dry feafons.

Which is further confirmed by experi- ments lately made on new -planted trees; where, by frequently warning the bodies of the moft unpromifing, they have out-ftrip- ped the other trees of the fame plantation. And Mr. Miller advifes, « Now and then " in an evening to water the head, and with €C a brufh to wafh and fupple the bark all " round the trunk, which (fays he) I have ci often found very ferviceable."

Experiment XLIII.

Aiiguji 20th, at i p. ?n. I took an Apple- branch b, (Fig. 26. ) nine feet long, 1 -j^ I inch diameter, with proportional lateral branches ; I cemented it faft to the tube ay by means of the leaden fyphon /: But firft I cut away the bark, and laft year's ringlet of wood, for three inches length to r. I then filled the rube with water, which was twelve feet long, and \ inch diameter, having firft

cut

PL -12

p- 13 +

S.G.

Vegetable Statich. i 5 5

cut a gap at y through the bark, and laft year's wood, twelve inches from the lower end of the ftem : the water was very freely imbibed, viz. at the rate of three -j- \ inches in a minute. In half an hour's time I could plainly perceive the lower part of the gap y to be moifter than before ; when at the fame time the upper part of the wound looked white and dry.

Now in this cafe the water muft necef- farily afcend from the tube, thro' the inner- most wood, becaufe the laft year's wood was cut away, for 3 inches length, all round the ftem ; and confequently, if the fap in its natural courfe defcended by the laft year's ringlet of wood, and between that and the bark, (as many have thought) the water fhould have defcended by the laft year's wood, or the bark, and fo have firft moiftened the upper part of the gap y -, but on the con- trary, the lower part was moiftened, and not the upper part.

I repeated this experiment with a large Duke- cherry -branchy but could not perceive more moifture at the upper than the lower part of the gap -y which ought to have been, if the fap defcends by the laft year's wood, or the bark.

K 4 It

\]6 Vegetable Staticks.

It was the fame in a Quince- branch as the Duke- cherry.

N. B. When I cut a notch in either of thefe branches, 3 feet above r, at qy I could neither fee nor feel any moifture, notwith- flanding there was at the fame time a great quantity of water paffing by ; for the branch imbibed at the rate of 4^ 3, or 2 inches per minute, of a column of water which was half inch diameter.

The reafon of which drinefs of the notch q is evident from Experiment 11, viz. be- caufe the upper part of the branch above the notch imbibed and perfpired three or four times more water, than a column of kvtn feet height of water in the tube could im- pel from the bottom of the ftem to q, which was three feet length of ftem ; and confe- quently, the notch muft neceflarily be dry, notwithftanding lb large a ftream of water was pafling by j viz. becaufe the branch and ftem above the notch was in a ftrongly im- bibing ftate, in order to fupply the great per- foration of the leaves.

ExpEr

Vegetable Staticks. \ 3 7

Experiment XLIV.

Augufl 9th, at 10 a. m. I fix'd in the fame manner (as in the foregoing experiment) a Duke-cherry-branch five feet high, and one inch diameter, but did not cut away any of the bark or wood at the great end ; I filled the tube with water, and then cut a flice off the bark an inch long, 3 inches above the great end ; it bled at the lower part mod freely, while the upper part continued dry.

The fame day I tried the fame experi- ment on an Apple- branch, and it had the fame efFecl.

From thefe experiments 'tis probable, that the fap afcends between the bark and wood, as well as by other parts.

And fince by other experiments it is found that the greateft part of the fap is raifed by the warmth of the fun on the leaves, which feem to be made broad and thin for that purpofe ; for the fame reafon, it's moft probable, it fhould rife alfo in thofe parts which are moft expofed to the fun, as the bark is.

And when we confider, that the fajp-vcf- fels are fo very fine as to reduce the fap almoft

to

138 Vegetable Staticks.

to a vapour, before it can enter them, the

fun's warmth on the bark fhould moft eafily

difpofe fuch rarefied fap to afcend, inftead of

defcending.

Experiment XLV.

July 27th, I took feveral branches of Cur- ram, Vines, Cherry, Apple, Pear and Plum- tree^ and fet the great ends of each in veffels of water x (Fig. 31.) 5 but firft took the bark for an inch off one of the branches, as at z, to try whether the leaves above z at b would continue green longer than the leaves of any of the other branches a, c, d-, but I could find no difference, the leaves withering all at the fame time : Now, if the return of the fap was flopped at z, then it would be expected, that the leaves at b fhould continue green lon- ger than thofe on the other branches; which did not happen, neither was there any moi- fture at z.

Experiment XL VI.

In Aitgujl, I cut off the bark for an inch round, of a young thriving Oak -branch, on the North -weft fide of the tree. The

leaves

Vegetable Staticks. 1 3 9

leaves of this and another branch, which had the bark cut at the fame time, fell early, viz. about the latter end of OBobery when the leaves of all the other branches of the fame tree, except thofe at the very top of the tree, continued on all the winter,

This is a further proof, that lefs fap goes to branches which have the bark cut off, than to others.

The 19th of April following, the buds of this branch were 5 or 7 days forwarder than thofe of other branches of the fame tree ; the reafon of which may probably be, be- caufe lefs frefli crude fap coming to this branch than the others, and the perfpira- tions in all branches being, cceteris paribus, nearly equal, the lefler quantity of fap in this branch muft fooner be infpiffated into a glutinous fubftance, fit for new produc- tions, than the fap of other branches, that abounded with a greater plenty of frefh thin fap.

The fame is the reafon why Apples, Pears, and many other fruits, which have fome of their great fap-veffels eaten afun- der by infects bred in them, are ripe many days before the reft of the fruit on the fame trees y as alfo that fruit which is ga- thered

140 Vegetable Staticks. thered fome time before it is ripe, will ri- pen fooner than if it had hung on the tree, tho* it will not be fo good ; becaufe in thefe cafes the worm- eaten fruit is deprived of part of its nourishment, and the green-gathered fruit of all.

And for the fame reafon fome fruits are fooner ripe towards the tops of the trees, tlian the other fruit on the fame tree; viz. not only becaufc they are more expofed to the fun ; but alfo, becaufe being at a greater diftance from the root, they have fomewhat lefs nourishment.

And this is, doubtlefs, one reafon why plants and fruits are forwarder in dry, fandy, or gravelly foils, than in moifter foils; viz. not only, becaufe thofe foils are warmer, on account of their drinefs; but alfo, be- caufe lefs plenty of moifture is conveyed up the plants; which plenty of moifture, tho' it promotes their growth, yet retards their coming to maturity. And for the fame rea- fon, the uncovering the roots of trees for fome time, will make the fruit be confiderably the forwarder.

And on the other hand, where trees abound with too great a plenty of frefh-drawn fap, as is the cafe cf trees whofe roots are planted

too

Vegetable Staticks. 141

too deep in cold moift earth, as alfo of too luxuriant Peach and other wall trees; or, which comes almoft to the fame, where the fap cannot be perfpired off in a due pro- portion; as in orchards, where trees ftand too near each other, fo as to hinder perfpiration, whereby the fap is kept in too thin and crude a ftate ; in all thefe cafes little or no fruit is produced.

Hence alfo, in moderately dry fummers, cateris paribus, there is ufually greateft plenty of fruit; becaufe the fap in the bearing twigs and buds is more digefted, and brought to a better confidence, for {hooting out with vigour and firmnefs, than it is in cool moift fummers : And this obfervation has been verified in the years 1723, 1724, and 1725. See an account of them under it, Exper. 20.

But to return to the fubjedl of the mo- tion of the fap: When the fap has firftpaffed thro' that thick and fine ftrainer, the bark of the root, we then find it in greateft quan- tities, in the moft lax part, between the bark and wood, and that the fame thro* the whole tree. And if in the early fpring, the Oak and feveral other trees were to be examined near the top and bottom, when the fap firft

begins

141 Vegetable Staticks.

begins to move, (o as to make the bark eafily run, or peel off, I believe it would be found, that the lower bark is firft moiftened ; whereas the bark of the top branches ought firft to be moiftened, if the fap defcends by the bark : As to the Vine, I am pretry well affured that the lower bark is firft moiftened. See Vol II. p. 264.

We fee in many of the foregoing expe- riments, what quantities of rnoifture trees do daily imbibe and perfpire : Now the ce- lerity of the fap muft be very great, if that quantity of rnoifture muft, moft of it, afcend to the top of the tree, then defcend, and afcend again, before it is carried oft by per- fpiration.

The defect of a circulation in vegetables feems in fome meafure to be iupplied by the much greater quantity of liquor, which the vegetable takes in, than the animal, whereby its motion is accelerated; for by Experiment 1. we find the fun-flower, bulk for bulk, imbibes and perfpires feventeen times more frefh liquor than a man, every 24 hours.

Befides, nature's great aim in vegetables being only that the vegetable life be carried on attd maintained, there was no occafion

to

Vegetable Stathks. 145

to give its fap the rapid motion which was necefTary for the blood of animals.

In animals, it is the heart which fets the blood in motion, and makes it continually circulate ; but in vegetables we can difco- ver no other caufe of the fap's motion, but the ftrong attraction of the capillary fap- veflels, affifted by the brisk undulations and vibrations, caufed by the fun's warmth, whereby the fap is carried up to the top of the talleft trees, and is there perfpired oft thro' the leaves : But when the furface of the tree is greatly diminished by the lofs of its leaves, then alfo the perfpiration and motion of the fap is proportionably dimi- nifhed, as is plain from many of the fore- going experiments : So that the afcending velocity of the fap is principally accelerated by the plentiful perfpiration of the leaves, thereby making room for the fine capillary veffels to exert their vaftly attracting power, which perfpiration is effected by the brisk rarefying vibrations of warmth : A power that does not feem to be any ways well adapted to make the fap defcend from the tops of vegetables by different veflels to the root.

If

144 Vegetable Stathh.

If the fap circulated, it muft needs have been feen defcending from the upper part of large games cut in branches fet in wa- ter, and with columns of water prefling on their bottoms in long glafs tubes, in Ex- periment 43, and 44. In both which cafes, it is certain that great quantities of water paffed thro' the ftem, fo that it muft needs have been feen defcending, if the return of the fap downwards were by trufion or pul- fion, whereby the blood in animals is re- turned thro* the veins to the heart: And that pulfion, if there were any, muft necef- farily be exerted with prodigious force, to be able to drive the fap thro* the finer capil- laries. So that, if there be a return of rhe fap downwards, it muft be by attraction, and that a very powerful one, as we may fee by many of thefe experiments, and par- ticularly by Experiment 11. But it is hard to conceive, what and where that power is, which can be equivalent to that provifion nature has made for the afcent of the fap in confequence of the great perfpiration of the leaves.

The inftances of the JefTamine tree, and of the Paflion tree, have been looked upon as ftrong proofs of the circulation of the

ftp.

Vegetable Stathks. 145

lap, becaufe their branches, which were far below the inoculated Bud, were gilded: But we have many vifible proofs in the Vine, and other bleeding trees, of the Tap's recede- ing back, and pufhing forwards alternately, at different times of the day and night. And there is great reafon to think, that the fap of all other trees has fuch an alternate^ receding and progreffive motion, occafioned by the alternacies of day and night, warm and cool, moift and dry.

For the fap in all vegetables does proba^ bly recede in fome meafure from the tops of branches, as the fun leaves them ; be- caufe its rarefying power then ceafing, the greatly rarefied fap, and air mixt with it, will condenfe, and take up lefs room than they did, and the dew and rain will then be ftrongly imbibed by the leaves, as is pro- bable from Exper. 42. and feveral others; whereby the body and branches of the ve- getable which have been much exhaufted by the great evaporation of the day, may at night imbibe fap and dew from the leaves; for by feveral Experiments in the firft chap- ter, plants were found to increafe consider- ably in weight, in dewy and moift nights. And by other experiments on the Vine in

L the

\<\6 Vegetable Staticks.

the third chapter, ic was found, that the trunk and branches of Vines were always in an imbibing ftate, caufed by the great perfpirarion of the leaves, except in the bleeding feafon ; but when at night that perfpiring power ceaies, then the contrary imbibing power will prevail, and draw the fap and dew from the leaves, as well as moifture from the roots.

And we have a farther proof of this in Experiment 12, where, by fixing mercurial gages to the ftems of feveral trees, which do not bleed, it is found that they are al- ways in a ftrongly imbibing ftate, by draw- ing up the mercury feveral inches: whence it is eafy to conceive, how fome of the particles of the gilded Bud, in the inocu- lated JefTamine, may be abforbed by it, and thereby communicate their gilding Miafma to the fap of other branches; efpe- cially when fome months after the inocu- lation, the ftock of the inoculated JefTa- mine is cut off a little above the Bud; whereby the ftock, which was the counter- acting part to the ftem, being taken away, the ftem attracts more vigoroufly from the Bud.

Another

Vegetable Statich. 147

Another argument for the circulation of the fap, is that fome forts of graffs will infect and canker the flocks they are grafted on : But by Exper. 12, and 37, where mer- curial gages were fixed to frefh cut flems of trees, it is evident that thofe flems were in a flrongly imbibing flate ; and confe- quently the cankered flocks might very like- ly draw fap from the graft, as well as the graff alternately from the flock; jufl in the fame manner as jeaves and branches do from each other, in the viciffitudes of day and night. And this imbibing power of the flock is fo great, where only fome of the branches of a tree are grafted, that the remaining branches of the flock will, by their ftrong attraction, flarve thofe graffs; for which reafon it is ufual to cut off the greatefl part of the branches of the flock, leaving only a few fmall ones to draw up the fap. See. Vol. II, ^.265,

The inflance of the Ilex grafted upon the Englijh Oak, feems to afford a very confi- derable argument againfl a circulation. For, if there were a free uniform circulation of the fap thro' the Oak and Ilex, why fhould the leaves of the Oak fall in winter, and not thofe of the Ilex ?

L 2 Another

148 Vegetable Stattch.

Another argument againft an uniform cir- culation of the fap in trees, as in animals, may be drawn from Exper. $j. where ic was found by the three mercurial gages fix'd to the fame Vine, rhat while fome of its branches changed their flate of protrude- ing fap into a ftate of imbibing, others con- tinued protruding fap, one nine, and the other thirteen days longer.

In the fecond Vol. of Mr. Lowthorp's Abridgment of the Philof. T^ranfaB, p. 708. is recited an Experiment of Mr. Brother- tons -, viz. A young Hazel n (Fig. 27.) was cut into the body at x z with a deep gam ; the parts of the body below at z> and above at x> were cleft upwards and down- wards, and the fplinters x z by wedges were kept off from touching each other, or the reft of the body. The following year, the upper fplinter x was grown very much, but the lower fplinter x did not grow 3 but the reft of the body grew, as if there had been no gafh made: I have not yet fucceeded in making this Experiment, the wind having broken at x z all the trees I prepared for it : But if there was a Bud at x which (hot out leaves, and none at z, then, by Experi- ment 41, 'tis plain that thofe leaves might

draw

Vegetable Staticks. 149

draw muchnourifhment thro'/ x, and there- by make it grow -> and I believe, if, vice verfa, there were a leaf-bearing Bud at z> and none at x, that then the fpl inter z would grow more than x.

The reafon of my conjecture I ground upon this Experiment, viz. I chofe two thriving moots of a dwarf Pear-tree, 1 1 a ay Fig. 28, 29. At three quarters of an inch diftance I took half an inch breadth of bark off each of them, in feveral places, viz, 2,4, 6, 8, and at 10, 12, 14. Every one of the remaining ringlets of bark had a leaf- bearing bud, which produced leaves the following fummer, except the ringlet 13, which had no fuch Bud. The ringlet 9 and 11 of a a grew and fwelled at their bottoms till Augujl, but the ringlet 13 did not increafe at all, and in Auguft the whole moot a a withered and died ; but the (hoot / / lives and thrives well, each of its ringlets fwelling much at the bottom: Whch fwel- lings at their bottoms muft be attributed to fome other caufe than the floppage of the fap in its return downwards, becaufe in the (hoot //, its return downwards is in- tercepted three feveral times by cutting away the bark at 2, 4, 6. The larger and L 3 mors

1 5 o Vegetable Statich.

more thriving the leaf-bearing Bud was, and the more leaves it had on ir, fo much the more did the adjoining bark fwell at the bottom.

Fig. 30. reprefents the profile of one of the divifions in Fig. 28. fplit in halves; in which may be feen the manner of the growth of the lafl; year's ringlet of wood mooting a little upwards at x x -, and moot- ing downwards and fwelling much more at z z 5 where we may obferve, that what is fhot end-ways is plai