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ESSAYS
-A N D
OBSERVATIONS,
PHYSICAL and LITERARY'.
Read before a Society in Edinburgh* and publijhed by them .
Volume L
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E D I N B U R G im¬ printed by G. Hamilton and J. Balfoub3 Printers to the Univerlity.
M,DCC,LIV.
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PREFACE.
AFTER the medical fociety of Edin¬ burgh had publiflhed thofe volumes of Effays, which have met with fo favourable a reception from the public, a propofal was made them to enlarge their plan, and to car¬ ry their difquifitions into other parts of na¬ ture, befide fuch as more immediately relate to the branches of medicine,, All the fci- ences are remarked to have a clofe connexion together ; but none more than thofe of me¬ dicine and natural philofophy : And the foci¬ ety foon obferved, that, fhould it turn its in¬ quiries into more general knowledge, it could reap the advantage of preferving all its old members, and needed but open its door to Gentlemen of other profeffions, who might enrich it with their obfervations and difco- veries.
Soon after the fociety had received a new form, feveral misfortunes happened, which retarded its progrefs, and have hitherto pre¬ vented it from communicating any thing to
the
IVo
PREFACE.
the public. The rebellion broke out in this country 5 and both fcattered the members for fome time, and engaged their attention to fubjedts, lefs agreeable and more intereft- ing, than general difquifitions into nature. No fooner were public affairs compofed, than we met with an irreparable lofs in the death of Mr. Maclaurin, one of our fecretaries. The great talents of that Gentleman are ge¬ nerally known and highly efteemed in the li¬ terary world ; but the fociety have, aifo, par¬ ticular reafon to regrete in him the lofs of thofe qualities, which form an excellent a- cademician. Indefatigable himlelf, he was a perpetual fpur to the induftry of others ; and was highly pleafed with the promotion of knowledge, from whatever hands it came. At the time of his death, a number of dis¬ coveries, fufficient to have formed a volume, had been communicated to him ; but, being mingled with his other papers, have been diffipated by various accidents 5 and the fo- dety could recover but few of them.
T HE
PREFACE,
The objed of this fociety is the fame with that of the other academies, which have been eftablifhed in different parts of Europe , the promoting of natural philofophy , and of literature , by communicating to the public fuch differtations as {hall be tranfmitted to them, either by their own members or by others. "Tis allowed, that thefe two branches of learning, efpecially the former, are more promoted by the obfervation of fads than by the mod ingenious reafonings and deputa¬ tions. To a diligent, and even fometimes to a carelefs inquirer, many valuable experi¬ ments, no doubt, occur ; and thefe would enrich our colledions, tho’ without this me¬ thod of conveyance, they would be intirely loft to the public. The united judgments too of men corred and confirm each other by communication, their frequent intercourfe excites emulation, and from the comnarifon
J i
of different phenomena, remarked by diffe¬ rent perfons, there often refult general truths* of which, from one of thefe fhceno?nena , no man of the greateft fagacity could entertain
any
P R E FA C E.
%
VI.
any fufpicion. Tho5 the collection of ex¬ periments feems continually, by means of the learned focieties, and the labours of in¬ dividuals, to be augmenting, we need not entertain any apprehenfions, that the world will ever be overwhelmed by the number of confufed and independent obfervations. The heap does not always go on, increafing in bulk and diforder, thro* every age. There arife, from time to time, bold and happy ge- niufes, who introduce method and fimplicity into particular branches of fcience ; and re¬ ducing the fcattered experiments to more general theorems, abridge the fcience of na¬ ture. Hints of this kind, we hope, may be able to pafs thro" our hands ; and at worft, our collections will be a fpecies of magazine, in which faCts and obfervations, the foie means of true induction, will be depofited for the purpofes of philofophy.
The fciences of theology, morals, and politics, the fociety are refolved intirely to exclude from their plan. However difficult the inferences in thefe fciences, the faCts, on
which
PREFACE.
Vile
which they are founded, are extremely obvi¬ ous ; and we could not hope, by our colledi- ons, to be, in this relped, of any fervice to the public. The great delicacy of the fub- jed, the imperfedions of human under- ftanding, the various attachments and incli¬ nations of mankind, will for ever propagate difputes with regard to thefe parts of erudi¬ tion. And ’tis the peculiar happinefs of geo¬ metry and phyfics, that, as they intereft lefs the paflions of men, they admit of more calm difquifition and inquiry.
It is not that the fociety exped or pro- pofe, that what they communicate will be intirely above doubt or difputation. The pa¬ pers, indeed, which they print, were all red before them, and they gave their confent to the inferting them in their colledions: But they pretend not to warrant the juftnefs of e- very reafoning, nor the accuracy of every obfervation. The author alone of each pa- peris anfwerable for the contents of it : And the fociety are as willing to infert what may ,)e communicated in oppolition to the fenti-
ments
vim PREFACE.
ments of any of its members, as in confir¬ mation of them.
The fociety are fenfible that it belongs a- lorre to the public to decide concerning the
value of any invention $ and all the merit to which they pretend, is that of exciting the induftry of the learned, and of conveying their productions to the notice of the world. They affume not fuch authority as to itamp their approbation on any performance, even thofe which they communicate, much lefs thofe which have barely been red before them. If ever their teftimony has been cited by any author in favour of his books, rea- fonings, or machines, they hereby declare, that this liberty has been ufed entirely with¬ out their confent or knowledge, and proceeded alone from the fond opinion, which the wri¬ ter had entertained of his own performance.
Whoever will favour the fociety with any difcourfe which it comprehends in its plan, may fend their papers to either of the fecretaries, Mr. Alexander monro Profefibr of Anato¬ my at Edinburgh , or Mr. David Hume Library-keeper to the faculty of Advocates,
CONTENTS.
Art. Pag.
I. QP the Laws of Motion ; by the Honour¬
able Henry Home, Efquire , one of the Senators of the College of JitJlice . i
II. Some Remarks on the Laws of Motion , and
the Inertia of Matter ; by John Stewart, M. D. Fellow of the Royal College of Phy - ficians , Prof e for oj Natural Philofo -
phy in the Univerfty of Edinburgh. 70
III. Pappi Alexandria! colleclionum mathema¬
tic arum libri quarti propoftio quart a genera- lior fadla , cui propoftiones aliquot eodem fpedl antes adjiciuntur\ auBore Mattheo Stewart, in Academia Edinenf Mathe- feos Profejfore. 14 1
IV. Of the Caufe of the Variation of the 0-
bliquity of the Ecliptic , by Colin Mc- Laurin, late Fellow of the Royal Society , and Profeffor of Mathematics in the Uni - verfuy of Edinburgh. 173
V. Concernhig the Judder and furprifing Chan¬
ges objerved in the Surface of Jupiter's Bo¬ dy 1 by the fame. 184
Art.
CONTENTS.
a
Art. Pag*
VI. Obfervations on 'Thunder and Electricity ,
by Ebenezer Mcfaxt, M. D. 189
VII. Some Phaenomena obfervable in foggy
Weather ; by the fame. 197
VIII. Of the Meajures of Scotland, compa¬
red with thofe of England, by James Gray. 200
IX. A Dijfertation on the Sexes of Plants ;
by Charles Alston, M. D. King s Bo - tanjft in Scotland, Fellow of the Royal College of Phyfcians , and Profeffor of Me¬ dicine and Botany in the Univerfty of E~ dinburgh. 20 if
X. Remarks on chemical Solutions and Preci¬
pitations 5 by Andrew Plummer, M.D* Fellow of the Royal College of Phyficians, and Profeffor of Medicine and Chemifry in the Univerfty of Edinburgh. 284
XL Experiments on Neutral Salts , compound¬ ed of different acid Liquors , and alcaline Salts , fixt and volatile ; by the fame, 315
XII. Experiments and Obfervations upon the
Hartfell Spaw, made at Moffat 1750 ; and an Account of its Medicinal Virtues , fo far as they have hitherto been difccvered
from
CONTENTS.
in
Art. Pag.
from Experience ; by William Horse- burgh, M. D. 341
XIII. Of the various Strength of different
Lime-waters , by Robert Whytt, M.D. F. R. S. Fellow of the Royal College of Phyjicians , and Profeffor of Medicine in the Univerfity of Edinburgh. 372
XIV. Of the anthelmintic Virtues cf the Root
of the Indian Pink, being Part cf a Let¬ ter from Dr . John Lining, Phyfician at Charleflown in South Carolina, to Dr . Robert Wiiytt, Profeffor of Medicine in the Univerfity of Edinburgh. 386
XV. The Hi/lory of a Cure performed by large Dofes of an alterative mercurial Medicine , communicated to Dr, Plum¬ mer ; by Mr, George Dennistoun,
Surgeon in Falkirk.
390
XVI. A Dejcription of the feminal Veffels ,
by Alexander Monro, Student cf Me¬ dicine in the Univerfty of Edinburgh . 396
XVII. The Df TeBion of a Woman with child , and Remarks on gravid uteri ; by Dr. Do¬ nald Monro, Phyfician at London. 403
XVIII. Additional Obfervations on gravid uteri, by Alexander Monro, Student
IV
CONTENTS.
Art. Pago
of Medicine in the Univerfty of Edin¬ burgh. 426
XIX. Of the Difference between Refpiration
and the Motion of the Hearty in feeping and waking Perfons ; by Robert Whytt, M. D. &c 436
XX. Remarks on the Inter cofal Mufcles ; by
Alexander Monro, F. R. S. Pro - feffor of Anatomy in the Univerfty of E- d Inburgh. 447
XXL Pke Cure of a fractured Tendo Achil¬ las ; by the fame. 430
XXII. An Account of the Dijeafe called Mill- Reek by the Miners at Leadhills, in a Let¬ ter from Mr. James Wilson, Surgeon at Durrifdeer, to Alexander Monro, P, A. 459
ESSAYS
ESSAYS
AND
Hi l
OBSERVATIONS
♦ 4
PHYSICAL and LITERARY.
Article I.
Of the Laws of Motion ; by the Honourable Henry Home, Ej quire , one of the Senators of the College of Jiftice.
NO thing has more perplexed philo- fophy, than an unlucky propenfity, which makes us grafp at principles, without due regard to facts and experiments, Tho’ fond of knowledge, we are willing to purchafe it at the eafieft rate ; and general principles delight us, becaufe they fhorten the read to knowledge- This bent of the mind is productive of manifold errors. Pre- pofleffed once by a favourite principle, we are no longer open to conviction. Every phe-
A nomenoi*
2 Essays and observations
nomenon mull be accommodated to that principle, and every oppofite fad:, however obftinate, inuft go for nothing. And thus we endeavour to mould nature to our wifh, inftead of defiring to know nature in her ge¬ nuine figure. •
We fee, then, that in fcience, as well as in adlion, appetite and inclination generally gain the afcendant. Even in natural philofophy, theory was introduced before experiment, and every philofopher urged his own notions, without regard to truth or reality. This produced a mafs of undigeited and contradi¬ ctory theory 5 which at length could not fail to bring on the difcovery, that the whole was little better than fancy and chimera. The difcovery had a remarkable good effed; ; which was, firft to make us doubt of every thing, and then to make us fearch after truth in the more painful road of induction. By this means, a greater number of im¬ portant truths have been brought to light within a century or two; than before that time from the beginning of the world.
But tho’ our only fore guides to truth are fads and experiments, it is however expedi¬ ent to keep the end in view. Fads and ex¬ periments
PHYSICAL and LITERARY. 3
periments are ufelefs lumber, if we are not to reafon about them, nor draw any confe- quences from them. In all our operations, we may have an eye to theory : nay we muft have it ; for fuch is the conftitution of our mind. Theory becomes only a fource of error, when we indulge in it too much, or attach ourfelves to it beyond what fadts and experiments can juftify. In fhort, theory is vain without ex¬ periments, and experiments are beft under- flood by applying them to theory.
Natural philofophy, it muft be acknow¬ ledged, is far from being ripe for firm and lafting theory. But we have fadts and expe¬ riments in great abundance, to be a founda¬ tion for theoretical {ketches ; which may be fafely indulged, provided they be done in fo flight a manner, as to leave the mind free from any wrong bias. Tho1 we have not ma¬ terials for a regular building, there is nothing to hinder us to venture upon a model.
Almost every author who treats of the laws of motion, has thought it incumbent up¬ on him to fet out with a definition of motion. And, in a thing fo Ample, it may appear ftrange to find fuch a variety of definitions : whence one thing may be gathered, that none
4 ESSAYS and OBSERVATIONS
of thofe definitions have been approved of by fucceeding authors. Epicurus defines motion to be tc a paflage from one place to another : ” and he might as well have defined it to be
S O
motion from one place to another ; becaufe pafTage in this fentence means nothing diiter- ent from motion. Sturmeus defines motion to be £t fuccejjiva rei motcz in diverfis locis ex- u iftentia f which is juftly blamed by Leib¬ nitz as defcribing the effedt of motion, rather than the formal nature of it. And yet Leib - nitz s own definition, cc Motus eft continua loci
mutatioP is not more fatisfadtory. But, of all definitions that ever were attempted, Art- jlotles definition of motion is the rnoft unin¬ telligible, cc Ac! us entis in potentra quateniis in -cc potential which Locke condemns as abfolute jargon ; and which, he fays, would puzzle any rational man, to whom it was not already known by its famous abfurdity, to guefs what word it could ever be fuppofed to be the ex¬ plication of.*
But it is no wonder thefe authors have not given fatisfadtion to each other, or to their readers, upon this fubject ; for they have attempted what is utterly impoffible,
viz.
f Locke concerning human undemanding, B. 3. ch. 4. §8.
PHYSICAL and LITERARY 5
* •
viz. to give a definition of a fimple idea. They might as well have attempted a defini¬ tion of colour or found, of pain or any other fimple feeling. It is to be regreted, that na¬ tural philofophers and mathematicians are not always well {killed in logics, and of this truth we {hall have but too often occaiion to give examples.
Scarce any author that I know has thought of giving a definition of reft; yet it is not a more fimple objedl than motion. I can guefs at the reafon, that reft is the more fa¬ miliar objedt; a greater number of things appearing to be in a qmefcent ftate than in motion. If every thing about us appeared to move, we fhould be furprifed the firft time we faw a body at reft, and probably would endeavour to explain the thing to o- thers : but both are equally incapable of a definition. They are fimple objedls of fight and perhaps of touch. Deprive us of thefe two fenfcs, and W'e could never have the leaft notion either of reft or motion.
When a being moves itfelf or moves, we conceive the being as adting ; and in this view motion is a fpecies of addon. But, when a body is moved by being adted upon,
we
6 ESSAYS and OBSERVATIONS.
we conceive the motion of the body as an effect produced by a proper caufe. In this cafe the body does not adt, but is adted up¬ on. This, tho’ an evident diftindtion, does not exclude felft motion from being alfo con- fidered as an effect in a certain light, viz* an effedt produced by a being upon itfelf.
Every thing which moves, and is not barely moved or adted upon, rnuft be endu¬ ed with a power of motion. For this power is involved in the very conception of felf- motion. And the term power may be equal¬ ly applied to animate and inanimate beings, fuppofing them to be equally felf-movers.
Wh ether matter in any cafe be endued with a power of motion, is a celebrated queftion, which is generally refolved in the negative : and, as this queftion cannot be o- verlooked in the prefent fpeculation, I fhall endeavour to examine it with all the accu¬ racy poflible.
Matter is generally reprefented as alto* gether unadtive and inert ; and indeed in a fuperficial view the fad appears to be fo. The bulk of the things about us feem to be at reft, and we lay our account that they will continue in that ftate, unlefs adted upon
PHYSICAL and LITERARY 7
by fome external force. If we lock up any moveable object, we truft to find it in the fame place ; and, if it be miffing, we afcribe our lofs to thieves, not to felf- motion in the body. Matter, fo far as we can difcover, is certainly not endued with thought or volun¬ tary motion; and yet, that it is endued with a power of motion in certain circumftances, appears to me an extreme clear point. Drop¬ ping a ftone from a high tower, it falls to the ground without any external impulfe, fo far as we can difcover. Plere is an effedt produced, which every one, who has not flu- died philofophy, will attribute to a power in the ftone itfelf. One would not hefitate to draw .this conclufion, ftiould the ftone move upwards ; and yet, fetting afide habit and cuftom, it muft be evident, that a ftone can as little move downwards as upwards with¬ out a vis motrix . And that this is a juft, as well as natural way of thinking, will appear by analogy. When a man is in motion, we readily afcribe the effedt produced to a power, which he poflfefles, to move his limbs. Why then do philofophers deny to the ftone, in the adf of falling, the power of beginning motion, a power which they fo readily afcribe to the
man ?
8
ESSAYS anp OBSERVATIONS*
man ? If it be objected that man is a being endued with a power of moving himfelf, and of moving other things, the plain an- fwer is, that thefe are fadts which we learn no other way than by experience ; and we have the fame experience for a voucher, that a Hone fet free in the air will move itfelf. And if it be farther urged, that man is a thinking being, the anfwer will readily oc¬ cur, that a power of beginning yifible mo-* lion is no more connected with a power of thinking, than it is with .any other property of matter or fpirit. Nay, Mr Loch holds, that matter may be endued with a power of thinking ; and, fuppoiing this power fuper- added to the other properties of matter, it cannot be maintained, that matter would be rendered thereby more or lefs capable of be¬ ginning or continuing vifible motion.
But this is not the only inftance in which we difcover an agency or adlive power in matter. A billiard ball ftruck upon the ground, re¬ bounds with a confiderable force. A bow bent by the hand, reftores itfelf with violence when the firing is let go. In both, there is an inftant* of reft betwixt the oppofite diredlions of the motion. The ball rebounds, and the bow
reftores
PHYSICAL and LITERARY.
feftores itfelf to its former fhape, without any external force, by an inherent power which is known by the name of elafticity. But we need not dwell upon particular in* Ranees. Chemiftry dife overs various powers in matter of the moft: aftive kind; and every man who is converfant with the operations of chemiftry, mud have a ftrong impreffion that matter is extremely active.
For the fake of iiluftration, let us fup- pofe a fubftance or thing having the follow¬ ing properties, that it makes no ref ftance to bodies impinging upon it; that when carried alone; in a man’s hand, even with the moil violent motion, it does not increafe the mo~ mentum of the hand, and that it flops fhort the inftant the hand ceafes to move. This would certainly be the mod inert of all con¬ ceivable things. And if fo, matter cannot he abfolutely inert or paffive, when its pro¬ perties differ fo widely from thefe deferibed. In many circumftances matter begins motion, and acts often with great violence. It has a conftant endeavour, when once fet in mo¬ tion, to preferve itfelf in the fame degree of motion, and, when at reft, is not put in motion without refiftance*
B But
10
ESSAYS and OBSERVATIONS
But it is maintained by the bulk of our philofophers, that matter is altogether inca¬ pable of aft ive powers ; that aftivity is con¬ fined to immaterial fubftances, and that in- ertnefs is implied in the very conception of matter. This moves them to afcribe to fome invifible agency, all that aftivity which we difcover in matter. In every one of the a- bove inflances, matter, they fay, does not aft, but is afted upon by the deity, who interpo- fes by general laws, to prefer ve the unifor¬ mity of nature. Thus, when a ftone falls, it is not the (tone which afts, but the deity. It is the continual action of the deity -which keeps the planets in elliptical orbits: and, when a plague infefts the world, it is the de¬ ity who fpreads the infection, and directs inert matter to ravage and deftroy. Arfenic is not of itfelf a poiion ; it is the immediate finger of God which makes it fo.
With regard to this whim fi cal doftrine, which declares war againft our fenfes, it may be observed, that natural philofophy is not mucli artefted by it, of whatever errors it may be productive in the more abftraft fciences. For it is admitted, that the deity, in afting upon matter, fubjefts himfelf to the fame
ft rift
PHYSICAL and LITERARY, u
ftridt and invariable laws which govern mat¬ ter, fuppofing it to have a power of motion. Therefore, the hifiory of nature will be the fame, upon either fuppofition. At the fame time, as this hypothecs not only contradicts common fenfe, but, in place of a beautiful chain of caufes and effedts, difcoverabie in the operations of matter, prefents a deform¬ ed and crude fcene, which detradts from the wifdom of the deity 5 I think it of confe- quence to bellow fome thoughts upon it: and, I am hopeful to make it evident, that this hypothecs is no better fupported by reafon than by experience.
To put an end to a good deal of loofe rea- foning upon this fubjedl, it will be neceffary to aicertain the meaning of the terms mate¬ rial and immaterial ; which, fo far as I know, has not been done with fufficient accuracy. All beings and exigences mud be either ma¬ terial or immaterial ; or, in other words, muft be matter or not matter : therefore, if we know what is matter, we cannot be at a lots about what is not matter. I take it for granted, that we have no conception of mat¬ ter but as fubftance or body, endued with co¬ lour, figure, extenfion, impenetrability, or
other
j 2 ESSAYS AND OBSERVATIONS.
other properties of fuch a nature as to be ob« jeds of our external fenfes. The dired op- polite, muft of courfe be an accurate defer i- ption of an immaterial fubftance, viz. that which has properties of fuch a nature, as not to lie open to any of our external fenfes, more than colour to one born without fight. Th us it comes out, that immateriality is merely a negative term, comprehending eve¬ ry thing that is not matter. And it is of con- fequence to be obferved, that the diftindion betwixt material and immaterial, not being founded on the nature of the things which are fo diftinguifhed, but on the limited na¬ ture of our external fenfes, has not the lead tendency to explain the nature or properties of immaterial fubftances, further than bare¬ ly, that thefe properties are of fuch a kind, as not to be the objeds of any external fenfe.
From thefe premifes, the following rea- foning will, it is hoped, be found entirely conclufive. Size, figure, motion, weight, &c. are qualities of matter which are percei¬ ved by pur external ienfes : but there is none fo foolith to maintain, that matter can have no qualities but what are objeds of an external Ccnlc, It would be the lame as to deny the
exigence
PHYSICAL and LITERARY 13
ex’ftence of immaterial fubftances becaufe thefe do not exhibit themfeives to our fenfes. Power is a property or quality, of which none of our external fences afford us the per¬ ception; and therefore our want of percepti¬ on of power, does not more conclude a nega¬ tion of power to matter, than to fpirit.- In general, we have no means to come at the knowledge of a caufe, but by the effeB pro¬ duced. We cannot, a priori , conclude* that animate beings are endued with any fort of powers, more than inanimate. Experience is here our only guide. We find by experi¬ ence man to be a reafoning being, endued with many powers and faculties: and, by the fame experience, we find matter to be endu¬ ed with certain powers and faculties. Both are difcovered by the effects produced ; and we have no other means to make a difcovery. We fee a Rone fall without any external im- pulfe. From that effect we have a juft foun¬ dation to conclude, that the ftone has a pow¬ er of moving itfelf. And, if we have not a juft foundation to make this conclufion, we have not a juft foundation to make this other conclufion, that a man has a power of felf- motion when we fee him walking. And af¬ ter
i4 ESSAYS and OBSERVATIONS.
after all, it mud appear extremely whimfi- cal to deny to matter a power of motion, merely becaufe matter difcovers itfelf to our external fenfes in part ; when, at the fame time, we are fo ready to attribute powers of every fort to immaterial fubftances, which cannot be reached by our external fenfes, ei¬ ther in whole or in part.
It is fuggefted above, that to endue mat¬ ter with a power of adling according to ge¬ neral and invariable laws, exhibits a more beautiful and compleat fyftem, than to leave it abfolutely inert, to require a continued in- terpofition of the deity. To illuflrate this point, I chafe to borrow the honourable Mr. Boyle s fentiment, whofe piety was not infe¬ rior to his knowledge. £C It feems manifeft cc enough, that whatfoever is done in the 6S world, at leaft where the rational foul in- tervenes not, is really effected by corporeal <c caufes and agents, according to the laws ££ fettled by the omnifcient author of things.’7 ^ And he obferves, cc That as it more recom- mends the (kill of an engineer to contrive C£ an elaborate engine, fo as that there need
f inquiry into the vulgar notion of nature, p. 60.
PHYSICAL and LITERARY 15
Ce nothing to reach his ends in it, but the cc contrivance of parts void of underftand- cc ing ; than if it were neceffary that, ever cc and anon, a difcreet fervant fhould be em- c< ployed to concur not ably to the operations “ of this or that part, or to hinder the en- “ gine from being out of order : fo, it more <c fets off the wild cm of God, in the fabric cc of the univerfe, that he can make fo vafta <c machine perform all thofe many things <c which he defigned it fhould, by the mere <c contrivance of brute- matter, managed by €C ce tain laws of motion, and upheld by his <c ordinary and general concourfe; than if he C£ employed, from time to time, an intern¬ ee gent overfeer to regulate and controul the <c motion of the parts fo'’ What maybe the ooinion of others, I cannot fay; but, to me, this argument is perfectly conclufive. Con- fidering this univerfe as a great machine, the workmanfhip of an intelligent caufe ; 1 can¬ not avoid thinking it is the more compleat, the lefs mending or interpolation it requires. The perfection of every piece of workman¬ fhip, human and divine, confifts in its an-
fwering
* Inquiry into the vulgar notion of nature. . p, 7.
i6 ESSAYS and OBSERVATIONS
fwering the defigned purpofe, without be- flowing further labour upon it. And there¬ fore, upon the whole, as we have no foun¬ dation, either in reafon or experience, to de¬ ny activity to matter; I conclude, that the doCtrine of the abfolute inertnefs of matter, is not only repugnant to truth, but tends, in an indirect manner, to arraign the deity of want of power or of wifdom, or of both.
Of the VIS I N S I T A or VIS
E R T I JE
AVING thus brought our fubieCt with¬ in bounds, by evincing that we have no occahon to fearch for any other im¬ mediate caufe of natural appearances than the activity of matter itfelf; I fhail proceed to ex¬ amine fome of the powers of matter, fuch of them as are productive of the moft remarkable effeCts: and (hall begin wuth the vis injita , or vis inertiae , that fignal property of matter, whereby, as philofophers teach, £C A body
always
PHYSICAL and LITERARY. 17
cc always perfeveres in its Rate of reft, or of cc uniform motion, in a right line, 'till, by cc fome external influence, it be made to cc change its Rate.” This property is han¬ dled by writers without any degree of accu¬ racy. The bulk of them refolve it into the inertnefs and paffive nature of matter ; and confider the prefent Rate of a piece of mat¬ ter, whether of motion or of reR, to be an effedt, which, once produced, muR conti¬ nue to exiR as it is, Rill it be changed or de- Rroyed by the operation of a new caufe. But, as this conception of the matter is liable to Rrong objections, which fliall by and by be mentioned, the moR rational waiters admit of a power in matter to prefer ve itfelf in its prefent Rate ; but then, confidering the per- feverence in reR and in motion, to be effedts of the fame kind, they, without making a- ny diRindtion, attribute both to the fame pow7er or caufe.
I cannot fubfcribe to either of thefe noti¬ ons. It is obvious to me, that the mere ne¬ gation of a caufe, tho’ it may account for the continuance of a body at reR, as it may ac¬ count for its prefer ving the fame figure or colour 5 yet can never account for the re-
C fifiance
1 8 ESSAYS and OBSERVATIONS
fiance made in the change from reft to mo¬ tion, or from motion to reft. And it is e- qually obvious, that a ftate of motion is very different from a ftate of reft ; and that the preferving a body in motion, muft be an o- peration of a different kind, from that of preferving it at reft.
In order to handle this fubjedt with fome degree of accuracy, I fhall endeavour to make out the three following propositions:
That motion is a continued addon, which muft infer fome power continually adding. Secondly , That as matter refifts a change from reft to motion, as well as from motion to reft, this refiftance is not to be accounted for by the mere negation of a caufe, but is a poft- tive effedl to require a caufe as much as mo¬ tion does. And, lajlly , after explaining the caufe of the continuance of motion, I fhall endeavour to fhow, that it is an effedt of a
y
different kind from the refiftance which mat¬ ter exerts againft any impuife which puts it in motion.
With regard to the flrft proposition, mo¬ tion evidently differs from the other proper¬ ties of matter. It is not like extenfion, fi¬ gure, and fuch like qualities effential to mat¬ ter.
PHYSICAL and LITERARY. 19
ter. Every body mu ft be of a certain fize and figure ; but it is eafv to feparate motion from body, by fuppofing it to be at reft. But what we have principally to confider in the prefent argument is, that the moulding of a body into a certain figure, or the giving it a certain colour, are not imperfedt, but compleated effedts ; which, once produced, muft continue invariably the fame, until fome power be exerted to make an alteration. This is involved in the very conception of colour and figure, and is fo Ample and clear a pro¬ position, as to be incapable of any illuftrati— on. The bare negation of a new caufe, is fufficient to account for the continuance of fuch effects. Reft is of the fame kind. It requires no adtion or operation to prefer ve a body at reft, more than to preferve its colour or figure. But motion, being the diredt op- pofite of reft, cannot be one of thofe corn- pleat effedts, which, once produced, muft continue invariably the fame. Motion, by the very conception of it, is action. While a body is in motion, it is in continual adtion; and, as adtion implies power, there muft be a power continually exerted to preferve a bo¬ dy in motion. Again, if motion be con fi¬ de red
20 ESSAYS AND OBSERVATIONS
dered as an effed, it can only be compared
to figure or colour, with regard to that part
of it which is paft : what part remains to be
performed, is fo far from a compleated effed:,
that it is not fo much as commenced ; and %
therefore muft neceffarily be conceived as a different e fifed, to the produdion of which there muft be a new exertion of power. Motion then is a continued effed, or rather a feries of different effeds, to require a caufe in continued adion. Accordingly, when we attend to our own perceptions, we do not inquire for a caufe, when a body ceafes to move. If the caufe of the motion ceafe, we feek no other reafon for the ceafing of the motion. If a thing fo evident can ad¬ mit of illuftration, let us figure an animal in motion. It never came into the mind of a~ ny perfon, that a man is paffive in the adion of walking or running. In this cafe we rea¬ fon juftly, that walking or running requires a continued exertion of power. It requires no exertion of power to put an end to thefe
motions. The man has but to forbear to ex¬ ert his power, and reft enfues. In this mat¬ ter there is no difference betwixt animate and inanimate beings ; not even tho’ it fhouid be
fuppofed
PHYSICAL and LITERARY. 21
fuppofed, that matter is altogether paffive. For, if matter itfelf has not a power of mo¬ tion, the fpirit which actuates matter, cannot other ways prefer ve it in motion, but by a continued exertion of potoer,
The fecond proposition is almoft felL evident. To account for continuance at reft, nothing is required except barely the nega¬ tion of a caufe. But matter at reft not only continues in that ftate, but plainly refills e- very force which tends to change its ftate from reft to motion. Matter makes no re- fiftance to any caufe which produces an alte¬ ration in its figure or colour. Refiftance is a pofitive effedl which requires a pofitive caufe. And this property of refiftance which all mat¬ ter is endued with, is a principle diredtly op- pofite to inertnefs or pafieity, if I may ufe that term. Refiftance is plainly aftion, which every man may readily perceive in himfelf, when an impulfe is made upon him : and, were matter abfolutely paffive and inert, it would make no refiftance, but be carried on by every impulfe, without diminifhing the force of the impelling body.
W ith regard to the third propofition, we cannot be at any lofs to affign a caufe for the
continuance
22 ESSAYS AND OBSERVATIONS,
continuance of that quantity of motion which is once given to a body. If the intervention of fpirit be rejedted as above, there is but an¬ other hypothefis to recur to, which is, That inanimate matter is endued with a power to preferve itfelf in motion, as well as animated matter is, without any other difference, but that the former having no will or feeling, adts blindly and invariably by an eftablifhed iaw« It has no fpontaneous motion, becaufe it has no will. Neither has it in every circumftance a power of beginning motion ; but, when once fet in motion, it has a power given it by the Author of nature to continue itfelf in mo¬ tion. And this is a law which regards all matter without exception.
And this power being once eftablifhed, it remains only to be made out, that it is of a different kind from that which refills a change from reft to motion, and from any degree of motion to a greater. The thing is obvious ; for, as caufes are beft diftinguifhed by their effedts, the caufe cannot be the fame of two effects diametrically oppofite, viz. preferving a body in motion, and oppofing motion. It may ferve to clear this matter, if we attend to the diftinction betwixt impulfe and refin¬ ance*
I
PHYSICAL and LITERARY.
23
\
ance. They are Ample ideas, and therefore incapable of a definition 5 but their difference will be obvious, by confidering a man in the aft of pushing againft an obftacle, and bare¬ ly refifting force applied againft him, without pushing again, or counterafting. The man, no doubt, is aftive in refifting, as well as in pushing y but the aftions are very different in their nature, and carefully to be diftinguiftied in accurate reafoning. In a word, the ten- dency of impulfe is, to produce motion ; the tendency of refiftance is, to prevent it. Thefe powers, therefore, fo oppofite to each other, fhall hereafter be diftinguiftied by different names. The vis injiia final 1 be appropriated to that power which is favourable to motion ; leaving the other power which refills motion to be denominated by the vis inertia?, or ra¬ ther vis reji ft entire.
Tho’ this vis inertia be a power, as obfer- ved, inherent in all matter, there are certain experiments which may appear to clafh with it, and which, upon that account, merit at¬ tention. If a round ball be laid upon a ho¬ rizontal table in vacuo , in which fituation there will be no counteraftion of gravity, it is certain, that the fmoother the ball and table
are.
£4 ESSAYS and OBSERVATIONS
are, the refiftance will be the lefs : and they may be made fmoother and fmoother, till the refiftance be quite infenfible. If the refift¬ ance do not vanifti altogether, it may be ow¬ ing to our want of art to make any furface abfolutely fmooth. There is no reafon, it may be thought, to afcribe the fmall remain¬ ing refiftance to a fuppofed vis inertia^ when it can be accounted for by other caufes > and that it is unphilofophicai to fuppofe the exift- ence of a caufe, when we cannot point out a tingle effedt that refults from it, and from no other caufe.
But there is another experiment of the very eafteft operation, and which is liable to no ambiguity. Let a body of any determined weight be fufpended by a thread or rope fix’d to a hook in the ceiling : the leaft conceive- able force will put this body in motion. If any refiftance at all be felt, it ought to be at¬ tributed to the denfity of the air, not to the body. And indeed thefe experiments infer, no more than what is admitted by every phi- lofopher, that the fmalleft force is fufficient to move the greateft body. It is acknowled¬ ged, that, were the globe of the earth fuf¬ pended by a chain, there is not a force fo>
fmall.
PHYSICAL and LITERAL Y. 2§
finall which it would not yield to. Thefe* ■ and Rich like experiments, look as if matter had no attachment to reft, no vis rejijlentice , but that it readily yielded to motion. That a body is put in motion by the very fmalieft force, and yet that it refills a change from reft to motion, are propofitions which may appear not to be very confident : yet both are true in fact. And the difficulty will va- nifh, by attending to the power of the vis inertiae or refiftentiae , that it is not meafured merely by the fize or bulk of the body to which it belongs, but has a relation to the j momentum of the impingeing body. The leaft force will put the greateft body in motion 2 but from this it doe§ not follow, that matter does not refift a change from reft to motion. It only follows, that this refiftance is always lefs than the vis matrix . To calculate the proportion betwixt the vis matrix and the re¬ fiftance of a body at reft, (hall be the (abject of the next chapter.
D
Of
26 ESSAYS AND OBSERVATIONS
Of the COMMUNICATION
of MOTION.
H E Communication of motion from
r
A one body to another, has been ex¬ tremely puzling to metaphyficians ; tho’ not to practical philofophers, who make no dif¬ ficulty to fuppofe, that motion actually paffes out of one piece of matter into another. Let us figure one billiard ball at reft, and ano¬ ther dire&ed upon it with a certain velocity , It is under ftood that part of the motion of the impingeing ball paffes into that which is at reft, after which it proceeds to move with that degree of velocity which is communi¬ cated to it. This account of the matter ap¬ pears to me altogether abfurd. Motion can¬ not iubfift by i tie If to be' transferred from place to place, or from body to body. It is one of the qualities or properties of matter ; and it is; no lefs repugnant to the very conce¬ ption oi the thing, that the motion of one
PHYSICAL and LITERARY.
body can pafs from it to another, than that the figure of one body can pafs from it to an¬ other. In general, qualities, properties, and affedfrons, are infeparable from the particu¬ lar bodies to which they belong. They have no feparate exiflence, and therefore cannot be conveyed, even in the imagination, from one body to another. The green colour of this field, cannot be taken from it, and be¬ llowed upon another. All that can be done. Is to give the other a fimilar colour. My i- deas or feelings cannot be conveyed from me to any other perfon, tho’ fimilar feelings or ideas may be produced in that other per¬ fon. This is not a play about words; it leads to the explanation of a phoenomenon which natural philofophers have not been able to ex¬ plain with any fatisfadlion. When motion is produced in one body by the impuife of an¬ other, there is no neceffity to embrace fa ab- furd a dodlrine, as that motion pafies from the one to the other. The motion produced is eafily deducible, from the principles above laid down. The vis injit a and the vis reji - flentiae , are fufficient to account for all the effe<fts that proceed from the collifion of hard bodies which have no elailicity. If the re-
fiflance
28 ESSAYS AND OBSERVATIONS
fiftance of a body is always lefs than the im- preffed force, the refitting body, after its re- fiftance is overcome, muft neceftarily be car¬ ried along with the body which impinges up¬ on it. And, being once put in motion, its oven vis injita preferves it in the fame degree of motion. I am here putting the fimpleft cafe, that of a body in motion, impingeing upon one at reft $ and, for the eafe of the i- magination, I fhall fuppofe thefe two bodies equal. In this cafe it is afeertained by expe¬ riments, that the two bodies in contabl, go on with half the celerity which the impinge¬ ing body had before the collifion. For it is a general rule in the percuffion of hard bo¬ dies, that the momentum or force, dire died to the fame point, continues the fame after con¬ tact as before. There is no difficulty here : for after half of the force of the impingeing body is deftroyed, by the refiftance of the body at reft; the other half remains, with which the impingeing body moves, and car¬ ries along with it. the other body from reft to motion. When the refiftance of the body at reft is once deftroyed, it yields to the im- preiied force without any further oppofition;
and
PHYSICAL and LITERARY.
29
and, by its impenetrability, muft be carried along with the other.
But, in order to form an accurate notion of this operation of percuflion, two prelimi¬ nary points muft be fettled. The firft is, to determine the precife nature of the aCtion ex¬ erted by a body at reft when impelled by one in motion. Does the body at reft return ftroke for ftroke, or impulfe for impulfe ? Does it truly read, or does it barely refill ? That it refills only, and does not read, will be evident from a fingle confideration, which is, that motion is effential to impulfe, not at all to refiftance. Now, if the body at reft readts, by returning ftroke for ftroke; it muft rufh upon the impingeing body, and carry it backwards at lead for feme final 1 fpace : which cannot be ; becaufe, once admitting a retrograde motion, the vires inf it re of the two bodies muft carrv them on in the fame dire-
j
ction, which is contrary to fact. It is obvi¬ ous, then, that there can be no repercufiion or reaction of the body at reft. All the ob- ftrudtion it gives to the action of the impinge¬ ing body, muft be merely by refiftance. The other point to be fettled is, whether the ope¬ ration be inftantaneous, or whether it be per-
forpre$
ESSAYS and OBSERVATIONS
3°
formed in time ? That it is inftantaneous, will thus appear. A gradual change of mo¬ tion fuppofes, that the foremoil: body paffes through every degree velocity from reft, till it acquires its greateft velocity ; and that the motion of the impingeing body is gradually retarded in proportion. But this iuppofition is inconiiftent with a known faft, that the bo¬ dies continue conjoined after contadt $ whence it is evident, that both muft move with the fame velocity from the inftant ofcontadL These preliminary points being fettled, the operation may be eafily analyzed. Tho’ the whole is performed in an inftant, it may, however, be diftinguitlied into different fteps. The fir ft is, that, by a certain degree of re- fiftance, a proportion of the momentum or force of the impingeing body is deftroyed, and confequently of its velocity. The next ftep is, that, with the remaining force and velocity, an impulfe is made upon the body at reft, which now refifts no longer, where¬ by it begins to move with the remaining ve¬ locity of the impingeing body. And the laft ftep is, that it is carried on with the fame de¬ gree of velocity by its own vis injit a .
From
PHYSICAL and LITERARY. 31
From what is laid, it will be eafy to ad- juft the proportion betwixt the vis motrix , and the refiftance of a body at reft. For tho’ refiftance and impetus are fo effentially different, as not to admit of a comparifon be¬ twixt themfelves; yet, the effeds produced by them, are capable of a comparifon. Now, the force loft by the impingeing body is a juft meafure of the refiftance of the body at reft; and if the momentum , before and after im- pulfe, continue the fame ; it muft follow, that the momentum of the body which is put in motion, is equal to the momentum loft by the impingeing body. Therefore the momen¬ tum of the impingeing body, is to the refift¬ ance of the body at reft, as the quantity of matter of both bodies, is to the quantity of matter in the latter.
This power of refiftance in matter, which is never exerted but when an impulfe is made upon it, is of fo lingular a nature, as to lead us to fufped fome very artful contrivance. It is furprifing that writers have given very little attention to the laws of motion, con- lidered in the light of final caufes, tho’ it is a mod beautiful fpeculation. It would car¬ ry me too far from my prefent purpofe, to en¬ ter
52 ESSAYS AND OBSERVATIONS
ter profeffedly upon this theme. And there¬ fore I fhall barely touch upon It, fo far as concerns this property of refiftance. Gravi¬ ty; an Unlverfal law of matter, ferves the noblefi purpofes. In conjundtion with the vis infita , it preferves the folar fyftem in or¬ der. The vis injiia is ufeful in another re- fpedt ; becaufe, by its means, we can apply force greatly fuperior to our own. The re¬ finance of bodies again, is of admirable life to keep force within proper bounds. If the fmallefl: body, impingeing upon the greateft, had the effedt of communicating its own ve¬ locity, which it would do, were there no refiftance : the fmalleft force would be fuffi- dent to give a new violent motion to the earth, and to put the lives of all mankind in the power of every individual*
PHYSICAL and LITERARY, 3
Of ACTION and REACTION,
IT is laid down as an univerfal law of mat¬ ter, £C that readion is always contrary “ and equal to adion.” Or, C£ that the mutual <c adions of two bodies upon each other, are €C always equal, and with oppofite diredionsA And Sir Ijaac Newton , in illuftrating this law, gives particular inftances of its taking place in all the different adions of matter ; to wit, in impulfe, in preffure, and in refin¬ ance. For my part, I have always been puzled about this law, and am uncertain, after all, whether I have a juft conception of it. Are we to underftand it to be a pro¬ perty of matter in general, that when aded upon, it exerts an equal and contrary adion ? or only, that in thefe particular cafes where matter reads, the readion is always equal and contrary to the adion ? The former is Sir I- faacs fenfe of this lawq which is evident, from his placing it among the lav/s that go¬ vern all matter in general $ as well as from
E his
34 ESSAYS and OBSERVATIONS
his various inftances, importing that it holds In every cafe whatever. And now, taking the law in this fenfe, difficulties croud upon me ; of which I fhall mention a few, that
N
make the greateft figure. The fir ft is, that, according to this law, there cannot be in matter, fuch a thing as refiftahce without re¬ action ; a bold aflenion, which contradicts what appears to be the faCt in common ap- prehenfion ; and which therefore ought not to be admitted, without a very comp! eat in¬ duction of particular cafes *y more compleat, fo far as 1 can learn, than hitherto has been attempted. But, not to reft upon the nega¬ tive, it appears dear, that, in the collifion of hard bodies, there is refiftance without rea¬ ction : and I flatter myfelf with having made out above, that, were there reaction in this cafe, the effects of collifion would be very different from what they are in faCt. And this leads to another difficulty, that if rea¬ ction were, in every cafe, equal to aCtion, viz. in hard bodies as well as in elaftic; the effects of collifion behoved to be the fame in both. Two elaftic balls meeting in oppofite directi¬ ons, rebound ; becaufe, after their force is ipent by collifion, the fame force is reftored
to
PHYSICAL and LITERARY.
35
to each, by their mutual readtion ; and the fame mud happen to hard bodies, if they have the fame power of reaction. In a word,
I cannot didinguifh eladicity from a power of reaction ; and a hard body differs from an eladic only in this, that the former has no power of reaction, but only of reiidance.
A third difficulty is, that, in the bulk of the indances commonly given to illudrate this law, I cannot difcover an equality of adtion and reaction. And ladly, what appears the mod unfurmountable difficulty is, that, ex¬ cepting the cafe of eladicity now mentioned, and that of fluidity to be mentioned after¬ wards; I have not found a Angle indance of an effedt produced by the adtion of one body upon another, but what may be fairly explained by acknowledged principles, lay- * ing afide altogether this fuppofed equality of action and readtion. And if no fadt can be condefcended on, to prove the point with regard to hard bodies ; why ffiould we ad¬ apt this as an univerfal law of motion or of matter ? for fureiy it is irrational to admit of any law or principle without evidence.
These difficulties will be bed illudrated by going to particulars. And with regard to
Sir
go ESSAYS and OBSERVATIONS
Sir Jfaacs firft inftance, of a man’s prefling a flone with his hand; we mud diftinguilh betwixt a moveable and immoveable obftacle9
If a man prefs an immoveable obftacle with
N *
Ills hand, I cannot here difcover any thing but mere refiftance, which is not to be over¬ come by the force of the hand. This is an effed which mud follow from the impene¬ trability of matter, without neceffity of ta¬ king under confideration, any other of its pro¬ perties. I difcover here no reaction. There is no counter-achon or impulfe in the ftone, to correfpond to the addon or impulfe of the hand. There is nothing but refiftance, which is indeed an addon, but an addon which is not exerted upon the hand : the adion is exerted within the refilling body itfelf, to preferve it from motion. And, if this refift¬ ance ftiall be conceived as a couhter-adion, which it may be in a loofe way of thinking; 1 cannot however conceive any equality be¬ twixt the preflure of my hand and this flip- pqfed con nter~ addon of the ftohe. At this rate, the counter-addon of the ftone is equal to every degree of imprefled force, provided the imprefled force be not great enough to move the ftone; and fo it will be equal at
the
a
PHYSICAL and LITERARY. 37
the fame time to a thoufand different degrees of force. To talk cf the equality of addon and readtion in fuch a cafe, means really no¬ thing more than that the hand has not force enough to move the ftone.
Again, if the obftacle be moveable, it coincides with another inffance given, that of percuffion, or the collifion of hard bo¬ dies. Here indeed it is true, that there is as much force loft by the one body, as is gene¬ rated in the other. But then this is plainly the effedt of the vis refijlentiae as explained above 3 and therefore it is unphilofophical to introduce any other principle by which to ac¬ count for this phoenomenon. At the fame time, I cannot difcover any equality of add- on and readdon in this cafe 3 on the contrary, it is eftablifhed by infallible experiments, that the impreffed force or addon is always great¬ er in a determined proportion, than the re- fiftance or readdon. And it is this very pro¬ portion which produces the effedf of an equa¬ lity of motion before and after impulfe 3 or, in other words, the acquifition of as much force by the one, as is loft by the other.
Another inftance is of a horfe drawing a ftone by a rope 3 and it is faid, that the
ftone
3S ESSAYS AND OBSERVATIONS
ftone draws the horfe as much as the horfe the Hone. Were this To, there could be no motion. All I can difcover here, is mere re- fiftance in the ftone, occafioned partly by its vis rejijlentiae , and partly by fridion. And after this refiftance is overcome, which fpends or exhaufts fo much of the horfe’s ftrength; the ftone is drawn along with the horfe’s re¬ maining ftrength, without any further refift¬ ance.
With regard to gravitation, which is gi¬ ven as another inftance of the equality of a - dion and readion; it is very true, that there is an equal tendency in every particle of mat¬ ter to every particle 5 but I am at a lofs what further can be made of this, than that fuch is the law of gravitation. Why then fhouid we endeavour to account for this effed by a- ny feparate law ? I might add, that this at bevft is a doubtful inftance of the mutual a- dions of bodies upon each other. It will perhaps, upon examination, be found the more fafe opinion, that bodies ad not upon each other by the power of gravity. But of this afterwards.
KRILL , in explaining this law of na¬ ture, feems to confine it to the percuffion of
bodies ;
PHYSICAL and LITERARY. 39
bodies ; and refls it wholly upon this fadf, that equal changes of motion are produced upon colli fion; which is, in other words, that, whatever force is loft by the one body, an e- qual force is generated in the other. And indeed it appears probable, that the law has been invented chiefly to account for this ef¬ fect : if fo, it is extremely rafh in philofo- phers to apply it, as they do, in every cafe where there is the lead appearance of action and reaction, as if it were an univerfal law of nature that muft obtain in every cafe what¬ ever. It was not difcovered, it would feem, that the equality of motion before and after percuffion, is the genuine effedt of the vis rejiftentiae. Therefore, to account for this phoenomenon, a new law behoved to be in¬ vented; which, to difguife the matter, mull be confidered as a general law : for, had it been plainly fpoke out, what in effedt is faid by Dr. Keill , that this law' applies ’only to the percuffion of bodies; every perfon would be fenfible, that accounting for the law of per¬ cuffion in this manner, was doing no more than repeat ng the fadt itfelf in different words. For to lav that the adtions of two bodies
J
in percuffion are equal and in oppofite diredti-
ons,
40
ESSAYS and OBSERVATIONS
ons, is, in an obfcure and indiftind manner,, really faying no more, than that a force is generated in the one body, equal to that which is loft in the other.
N
In accounting for the preffure of fluids undequaque, Mufchenbroke reafons thus : he fuppofes the water in a veffel to be compofed of perpendicular columns of fpherical par¬ ticles, one refting upon another from the fur- face downwards, and all refting upon the bottom of the veffel. Thus the bottom of the veffel is preffed downwards with the weight of a column : and, becaufe adtion and readion muft be equal, therefore, fays our author, the bottom of the veffel muft prefs upwards with the fame force, i. e . with a force equal to the weight of the column 5 whence, fays he, the whole preffure up¬ wards, muft neceffarily be equal to the whole preffure downwards.
So far our author’s argument appears con- clufive, that, admitting the law of adion and readion, a preffure undequaque muft be the confequence : and as the law is not confined to fluids, but is fuppofed to be an univerfal law of matter; a preffure undequaque muft not only be the confequence in fluids, but in
folids
(
PHYSICAL and LITERARY. 41
folids equally. Here then is a fair dilemma . We muft either acknowledge a preffure un- dequaque in fand, powder, and indeed in all loofe bodies, as well as in fluids ; or confine this law of the equality of adion and readi- on to fluids. Can we remain a moment in doubt betwixt thefe oppofites ? We are cer¬ tain that a preffure undequaque is not a pro¬ perty of folids. The equality of adion and readion is but an affertion without evidence. What remains then, but that we adhere to the former, and rejed the latter, except as to fluids. And thus our author luckily, tho? without intention, has furnifhed a very con¬ vincing argument againft the univerfality of this fuppofed law of adion and readion. If an undequaque preffure is an effed of this law, it follows clearly, that this law takes not place in folids, at leaft not univerfaliy, as in fluids.
F
O F
l
42 ESSAYS AND OBSERVATIONS
Of G R A VI T Y. RAV1TY is one of the moft remark-
vl able properties that belong to matter. By this property, which is univerfal, every particle of matter tends to every other parti¬ cle ; whereby, if not obftrudted, all mat¬ ter would be gathered into one mafs. As e- very particle of matter has this tendency, the tendencies of any two bodies to a mutual union, mull be in proportion to their quanti¬ ties of matter. And it is obferved that the force, which, at different diftances, is exerted by two bodies in order to be conjoined, is in the reciprocal proportion of the fquares of thefe diflances. It is by this property that the heavenly bodies move round the fun, and are kept from flying off in a tangent : and it is by the fame property that bodies left free at any height, fall to the earth with an accelerated motion. When applied to the latter, it is commonly called gravi¬ ty 3 when to the former, attradlion . Sir
Ifaac
PHYSICAL and LITERARY. 43
f
Ifaac Newton , to whom the great difcovery Was referved, that the defcent of heavy bo- dies, and the curvilinear motion of the pla¬ nets, are efifefifs of the fame caufe, choofes to talk of this property of matter with great circumfpeftion and referve. He pretends on¬ ly, in his I rincipia, to have afcertained the facts, without venturing to point out the caufe. In the general cholium , which con¬ cludes that elaborate work, he fatisfi.es himfelf with having explained “ the motion of the “ celeftial bodies, and of the fea, by the force cc of gravity, without aligning the caufe of cc gravity.” He only observes, “ That gravi- C£ ty muft be the effiedt of fome caufe, whkh ‘ C£ penetrates into the very center of the fun cc and planets, and which afils not in propor- ec tion to the furfaces, but the fo'id quantity C£ of matter ; its adtion only decreafing in a £C duplicate ratio of the diflances.” And adds, tc That he has not been able to find <£ out from phoenomena, the reafon of thefe cc properties of gravity, and that he does not C£ choofe to deal in hypotnefes.” It need not be furpriting, that this great philofopher fihould be referved upon the caufe of a theo¬ ry fo extenfive and fo wonderful, when it
was
44 ESSAYS and OBSERVATIONS
was his own child. New difcoveries are ah ways received with fome degree of hefitati- on ; becaufe it is the effed of novelty to produce doubts as well as furprize. But now, that this theory is fully eftablifbed by habit, as well as by reasoning, and has got a firm hold of the mind; it is not obvious, why later phiiofophers mould affed the fame re- ferve, for my part, I cannot fee any diffi¬ culty of explaining the caufe of attraction or gravity, more than of explaining the caufe of a body’s continuing in the fame degree of motion with which it begins to move. And
o
this I fliall now attempt.
It is above eftablithed, that the continua¬ tion of motion in bodies muft be an effed of a power inherent in all matter, of preferving that degree of celerity which is once bellow¬ ed upon it. The body, by this power, is di- reded to move in a flreight line. But we perceive nothing in the nature of this power to confine its operation to a ftreight line, more than, a curve. And we may fuppofe the power ftill further varied, to make the body, inftead of moving in a ftreight line, or in a curve, to dired its equable motion towards any other given body, within a certain di-
ftanceo
PHYSICAL and LITERARY. 45
ftance. In general, as we have no means to difcover power in any being but by the effects produced; fo the nature and operation of the power are only to be difcovered by the fame means. There is nothing in our conception of any power to confine its operations to one law more than another. And this leads to the caufe of gravity or attradlion. If we admit of the vis injit a , the operations of which may be varied in a thoufand different ways ; it is equally eafy to conceive a power in matter by which every particle has a tendency to be u- nited with every other particle. JTis but va¬ rying the vis injit a in the two following parti¬ culars, to have an exadt defcription of gravity. Firft, That it have the effedt of beginning motion, as well as of continuing it; and, next, That it diredl the body to which it belongs, not in a ftreight line, but towards every body great and fmall within its fphere of activity.
The grand difficulty which puzzles foreign philofophers is, to admit of a power in a body to draw other bodies to it ; for this is their conception of attraction, fuggefted by the term itfelf. They obferve, that fuch a power is inconfiftent with a general maxim, that no being can adt where it is not ; which would
involve
46 ESSAYS and OBSERVATIONS
involve this evident abfurdity, to feparate the being from its aCtions. And, from thefe p e- mifes, they juftly conclude, that one body cannot aCt upon another at a diftance. It muft be confeffed, that attraction is an un¬ lucky term, fince it has led philofophers into the above miftake; tho’ Sir Ifaac Newton can¬ not be juftly blamed, who made ufe of a term invented to his hand. By varying the conception of attraction, and by confidering it as a power in matter not to draw other bo- dies to it, but to move itfelf towards other bo“ dies, the difficulty vanifhes.
But upon this idea of attraction or gravi¬ ty, it may be fuggefted, that there can be no reafon, why the power, in exerting itfelf, fhould keep pace with the diftance of the ob¬ ject towards which its force is directed. The diftance of the objeCt, it will be faid, can have no effeCt to diminifh the force, when, by the fuppofition, the aCtion of the one bo¬ dy is not exerted upon the other, but upon itfelf. This has the appearance of a difficulty, and no more but the appearance. If matter lias a power to aCt in any one care, its acti¬ ons may be varied by any affignable law. And in particular to imagine a power in a body
impelling
PHYSICAL and LITERARY. 47
impelling it towards a body at hand, with a greater force than towards one at a diftance9 is in reality not more difficult, than to ima¬ gine it exerting always the fame force, with¬ out regard to diftance.
It is not improbable, that the above men¬ tioned obiedtion, of a body’s adding where it is not, has led Leibnitz and other foreign philofophers, to adopt the vortices of Des Cartes , rather than Sir Ifaac Newtons theo¬ ry ; li ffile, according to their notion of it, to an infuperable ohjedtion. Yet there can¬ not be conceived a more whim deal hypothe¬ cs, than that of a fluid circulating about the fun, in which the planets are involved and carried alomr like a fhio in a torrent. The
O ' i
ingen ions Maoertuis , in his efiay upon attra¬ ction, moves feveral objedtions to it, even as new moulded by later writers. He objedts in the fir ft place, that the planets do not move in a circle, but* in an elipfe. In the next place, that they do not move with ce¬ lerities proportionable to their diftances from the fun ; which they behoved to do, if car¬ ried along in a vortex moving, like a wheel, equably round the fun. Thefe objedtions are juft; but, in my apprehenfion, he has over¬ looked
48 ESSAYS and OBSERVATIONS
looked the moft folid and weighty objection* Whatever caufe can be aligned for the moti¬ on of this fluid round the tun, will equally apply to the motion of the planets, without neceflity of introducing a new fund of mat¬ ter, of the exiftence of which we have no evidence. More particularly, motion is ob- vioufiy an effed which muft have iome caufe. This caufe mail: either be a continu¬ ed interpofition of a voluntary agent, or a power given to matter to continue itfelf in motion. A piece of matter cannot move in a ftreight line, without one or other of thefe caufes ; and as little in a circle. Therefore, to make this fuppofed fluid to circulate about the fun, one or other of thefe caufes muft operate 5 and one or other of thefe caufes is fufficient to account for the motion of the planets, without neceffiiy of inventing a fluid to produce the effect. Des Cartes therefore, and his followers, are guilty of the fame fort of abfurd reafomng, for which we juft- ly lairjh at the poor Indian , who was forced to invent an overgrown elephant to reft the earth upon, and an overgrown crab to be a footftool to the elephant.
Whether
PHYSICAL and LITERARY. 49
Whether the fame inconfiftency of a bo¬ dy adting where it is not, has moved our Britijh phiiofopher .to invent an aetherial medium much rarer than air, as the caufe of gravitation, I cannot fay. In the twenty firft query, at the end of his optics, he obferves, “ that this medium is much rarer within the <c denfe bodies of the fun, ftars, planets and <c comets, than in the empty celeftial fpaces cc between them. And, in pafling from them “ to great diftances, that it grows denfer and cc denfer perpetually; and thereby caufes the cc gravity of thofe great bodies towards one cc another, and of their parts towards the cc bodies; every body endeavouring to go <c from the denfer part of the medium towards “ the rarer.” I am not better fatisfied with this hypothecs than that of Des Cartes . For, without lofing time upon a minute enquiry into the very peculiar properties with which this fuppofed aether muft be endued, to pro¬ duce the effects affigned it; the fame obje¬ ction lies againft it, that is above urged a- gainft the vortices of Des Cartes , that it is a new fpecies of matter invented without evi¬ dence, and indeed without necefiity : for it is as eafy to endue the planets with a power
G which
5o ESSAYS and OBSERVATIONS
which impells them towards the fan, as to endue this fuppofed aether with a power which repells it from the fun. Therefore the argument which is juftly urged by this author himfelf again ft a plenum in the 28th query > at the end of his optics, may be ur¬ ged with equal fucce s again ft this fuppofed aether, t£ It is of no ufe; and, as there is no ct evidence for its exigence, it ought to be ct rejected.”
I Mu ft own, at the fame time, great re- luftance, to embrace a dodrine which over¬ turns, or fee ms to overturn, the moil; beau¬ tiful part of Sir Ifaac s own theory, and that which affords the ftrongeft conviction of its truth, m. the connexion, by a common, caufe, betwixt the curvilinear motion of the planets, and the defcent of bodies towards the center of this earth. Suppofing an ae- therial medium to he the caufe of the former, it cannot well alfo be the caufe of the latter. Among other reafons, this occurs, that the different denfities of the fuppofed aether, on the oppofite fides of a bit of matter left free in the air, muft be, quam pr oxime , no¬ thing. This muft be yielded 3 and the con- fequence is, that the bit of matter involved in
PHYSICAL and LITERARY, 51
a medium which prefles equally undequaque or quam proxime , will either remain at reft, or move with a very flow pace. But this is contrary to fact ; for the acce’eration of fal¬ ling bodies, within the leafl perceivable di- ftance, is perceivable.
The power of gravity has a Angular pro¬ perty not commonly attended to, that its force is not fpent by being exerted upon any Angle body. Its whole force is exerted upon a multitude of bodies, ail at the fame time. Thus the earth tends at once both to the fun and moon; and the whole force of its tend¬ ency is directed to each, juft as much as if the other were annihilated. Thus the fun is impelled towards the whole fyftem of pla¬ nets and comets ; and its total impulfe is di¬ rected upon every one of them at the fame inftant. It cannot fail to appear Angular and furpriflng, to And a force exerted in io many different and even oppofite directions at one time, without being diminifhed by di- viflon. Yet all this proceeds from one Angle property, that every particle of matter tends to every other particle; and confequently, by encreaAng the quantity of matter indeA- jiitely, the fum of the tendencies of any one
particle
52 ESSAYS AND OBSERVATIONS
particle of matter, may be greater than any affignable quantity. But nature is wonder¬ ful, as well as various, in her operations; and we ought to fubdue our incredulity, when, upon fearching into her works, we find fo many appearances different from wftat we are
accuftomed to in common life.
M \
Having thus eftablifhed, that there is a power inherent in matter, by which every particle tends to be united to every other par¬ ticle, and which power is in continual adtion without ever being fufpended but for a mo¬ ment; the curvilinear motion of the heaven¬ ly bodies, as well as the defcent of bodies towards the center of the earth, are obvi- oufly the effects of this power. With regard to any particular planet, the earth for exam¬ ple, we have only to fuppofe, that it is once fet in motion by the hand of the Almighty; it will endeavour to preferve itfeif in the fame degree of motion by the vis injita . Having like wife a tendency to the fun, theft two powers conftantly adting in different directi¬ ons, carry it round the fun. At the fame time, the proportion of theft two forces is fo adjufted, that the earth, as well as all the
other
PHYSICAL and LITERARY. 53
other planets, defcribe an elipfis, in one of the foci of which the fun is placed.
In the defcent of heavy bodies towards the center of the earth, the force of gravi¬ ty is fuppofed to be invariable. For, tho’ this force lefiens by diftance, yet the diftance of any two points, from which we have accels to drop a body, is fo inconfiderable in refped of the diftance of either from the center, that it is left out in all calculations as imper¬ ceptible. Hence the following queftion is readily fuggefted, How comes it, that the power of gravity which in this cafe is fuppo¬ fed invariable, has the effect of accelerating the motion,of a falling body? It fhould be thought, that the power of gravity, fuppo- fing it invariable, muft produce an equable motion downwards, without acceleration; juft as the vis injit a does, laying afide gravi¬ ty, in whatever diredion the body is thrown. For in general, as effeds muft always corre- fpond with their caufes, every force which is uniformly exerted without diminution or augmentation, muft produce an equable mo¬ tion, without acceleration or retardation : and, on the other fide, every varied effed
which
-* 4 *
54 ESSAYS and OBSERVATIONS
which is gradually diminifhed or augmented, mu ft proceed from a varied caufe.
This difficulty is endeavoured to be ex¬ plained in the following manner. Gravity, it is faid, has a remarkable property, ct That ee it afts with the fame force upon a body cc that is already in motion, as upon a body “ that is at reft, fo as to produce equal acce¬ lerations in falling bodies in equal times But this manner of conceiving the effedt of gravity, whatever obfcurity it may occafion, tends not to remove the difficulty. One thing is extremely clear, that we have no means afforded us, to eftimate the force of any power, other than the effedts produced by it; which holds in general, whether the power be internal or external. From the uniformity of the effedts, we conclude the vis infiia to be a uniform power ; and we have the fame foundation, from its varying effects, to con¬ clude gravity to be a varying power. In fhort, when acceleration is produced by an external caufe, it will be evident to every one, that the force of the impulfive caufe, muft be continually increaftng, to produce
fuch
f Mc Lanvin's account of Newton's philosophy, p . 248,
PHYSICAL and LITERARY. 55
fuch an effect ; and it will be a hard talk to affign any juft foundation for a difference in this particular, betwixt external and internal force.
We muft therefore yield to the difficulty, becaufe it is unfurmountable. It is very true, that a body has, quam proxime , the fame weight at the diftance of ten foot from the furface of the earth, as at the diftance of a hundred : and the farce of gravity is, quam proxime , the fame when a body is drcpt from the hand at thefe different diftances. But then, tho’ gravity is fuppofed invariable, where the difference of the diftances is fo fmall; yet this only holds where other cir- cumftances are the fame : that is, where the body is either at reft, or moves with the fame celerity, l or it is ext emely dear, that, in the perpendicular defcent of a body, the force of gravity varies every inftant, and turns greater in its progrefs downwards. And indeed gravity cannot otherways produce acceleration, more than the vis infita does. Nor is there any thing lingular in this pro¬ perty of gravity. The vis infita has a pro¬ perty fome what fimiiar : for, thoJ it conti¬ nues invariable after the body is fet in mo¬ tion,
56 ESSAYS and OBSERVATIONS
tion, yet it is not always the fame. It keeps pace with the imprelTed force, and is very dif¬ ferent, according to the different forces with which bodies are put in motion. In a word, fmce effedts muft always correfpond with their caufes, the gradual increafe of the force of a falling body, muft infer the gradual increafe of the power of gravity, which is the caufe of the motion. Or rather, confidering the matter in a different light, perhaps more ac¬ curately, the tendency or nifus of a body to¬ wards the center of the earth, which is great¬ er in motion than at reft, and which gradu¬ ally increafes with the velocity of the motion, being nothing elfe but the exertion of its power of gravity, makes it evident that the power of gravity is continually increafmg from the beginning, to the end of the mo¬ tion.
In accounting for this phoenomenon, I have negledted the vis inftta, tho’ it may pro¬ bably adt in conjundtion with gravity in the defcent of bodies towards the center of the earth, as well as in the curvilinear motion of the planets. For, if the force of gravity be fuppofed invariable, the addition of the vis
inftta , which is alfo an invariable force, will
only
PHYSICAL and LITERARY. 57
only bring out a greater invariable force, which can never produce an acceleration of motion. The acceleration therefore muft be attributed to gravity alone, the force of which, in the beginning of the motion, is fuppofed to be lefs than any affignable quan¬ tity, whereby a body, fet in motion by the force of gravity, paffes through every de¬ gree of velocity from reft, till it acquire that velocity which it has when it touches the ground.
I have dwelt the longer upon this proper¬ ty of gravity, becaufe there is connected with it another property, which is, that in mo¬ tion, the adion of gravity is not to be eon- ftdered as one adiori exerted through a length of time, but as a number of .different acti¬ ons exerted inceffantly. For, if the gravity of a body in motion continues not the fame any two fucceffive moments, but is continu¬ ally varying, the adion muft vary with the power 5 and confequently is not one, but a number of different addons. Gravity in a body at reft, is, like the vis in fit a , one in- varied power, which produces one in- varied a'dion exerted through a length of time. But, when once the body is put in
H motion.
58 ESSAYS and OBSERVATIONS
motion, we muft neceflarily admit, firft, that gravity is exerted by repeated impulfes 5 and next, that thefe impulfes, continually turn¬ ing fironger, form an increasing leries, hold¬ ing an exacd proportion with the growing ve¬ locity, of which thefe impulfes are the caufe.
And this leads us readily to conceive the operation of gravity in the afcent and defcent of bodies. A Rone, in its perpendicular mo¬ tion, is carried upwards by its vis infita coun-* ter- able d by gravity: in its return, it is carried down by gravity without any counter-addon. At firft view, the afcent will be confidered as the operation of two powers aching in op- pofite directions 5 the effed: of which com¬ monly is, to produce an equable motion with the difference of the forces. And, were the addon of gravity one uniform addon, like that of the vis infita ; fuch would truly be the effed:: but,, as gravity is exerted by re¬ peated impulfes, a different effed: muft fol¬ low. The very firft impulfe of gravity takes off* from the force of the vis infita ; what remains is leftened by the fecond impulfe; and io on, ^ till the vis infita , gradually de- creafing by the repeated counter-addons of gravity, be annihilated altogether. In the
return
PHYSICAL and LITERARY.
59
return downwards, gravity being exerted without an antagonift, every new impulfe produces an acceleration of motion ; and, thefe impulfes being repeated inceffantly, the acceleration goes on, till the ftone touch the ground.
It remains only to be obferved, that, as the force of gravity is accurately proportion¬ ed to the velocity, gravity rnuft produce the fame effedt, whether its force be exerted in the direction of the motion, or contrary to it ; and that the acceleration in the former cafe muft be equal to the retardation in the latter, in any two points where the velocities are equal. Thus, upon the whole, the gra¬ dual retardation of upward motion, is equal to the gradual acceleration of downward mo¬ tion. The fame feries of numbers repre- fents both ; a progrefs trom the (mailed to the greateft number being fimilar to accele¬ ration; the contrary progrefs, to retardation. And hence it is that thefe two contrary mo¬ tions are performed precifely in the fame time.
It is now eafy to account for the different velocities of a planet in the different points of its orbit. The motion of a planet may
be
6o ESSAYS and OBSERVATIONS
be iufliy reprefented by perpendicular afcent and defcent. A planet moving from the fun, refembles a ftone moving from the earth up¬ wards ; and, in its return towards the fun, refembles the fame ftone returning to the earth, after its upward motion is fpent. And, indeed, by prolonging the greater axis inde¬ finitely, an ellypfe coincides at laft with a ftreight line ^ and the motion in the former coincides with the motion in the latter. Con- fidering then that gravity and the vis injita are the two powers which govern motion in the curve as well as in the ftreight line ; it muft follow, that the law of motion is th§ fame in both.
PHYSICAL and LITERARY. 6t
Of the FORCE of BODIES in MOTION.
IN explaining the firft law of motion, that every body perfeveres, as much as in it lies, in its prefent ftate of reft or motion; I have touched at that remarkable power which all matter is endued with, of moving on with its original velocity ; and to which power I have chofen to confine the term vis in fit a . I now proceed to unfold fome fur¬ ther properties of this power. It appears clear, that the vis in fit a might have been fo ordered, as to produce an accelerated or re¬ tarded, inftead of an uniform motion. And it might have been fo ordered as to yield to the imalleft oppofing force, which is the cafe of the vis refiftentiae when the body is at reft. There is no difficulty to conceive a body en¬ dued with fuch a property, as to preferve it- felf in its original degree of motion, where there is no obftrudlion, and yet to yield to
the
62 ESSAYS AND OBSERVATIONS
the fmalleft refinance or oppofing force. But the vis injit a is plainly not of this nature. The body not only preferves itfelf in motion where there is no refiftance, but exerts a cer¬ tain force againft every thing that refills its progrefs. And it is with a view to this force exerted in motion, as well as with a view to the refiftance exerted at reft, that Sir Ifaac Newton , in his third definition, defcribes the vis infta to be u that power in matter, by *£ which every body, as much as in it lies, fi£ pe.rfeveres in its prefent ft ate of reft or mo- tionA The force, however exerted in motion, is effentially different from that ex¬ erted at reft. The latter is mere refiftance : the former is an impulfive force, by which the body endeavours, quantum in fe eft , to overcome every obftruction to its motion . The force of refiftance is above afcertained, and a rule laid down for eftimating it, about which all philofophers are agreed. They differ widely about the impulfive force of the vis in fit a: the Gerfnans holding it to be as the fquares of the velocities; the Englijh and French holding it to be Amply as the velocities. The difpute is fpun out to a great length : the parties, as is ufual, being more felici¬
tous
PHYSICAL and LITERARY.
tons to enforce their own arguments, than to give fair play to thofe advanced by their am* tagonifts. And, by profufion of writing, the point is rendered fo perplexed and intricate, that there appears not a better way to comeat tne truth, than neglecting the arguments on both (ides, to apply diredly to fads for a fo- lution, as one would do upon a point newly ftarted.
Con-sidering the matter abftr'adly, I can¬ not find that there is any inconfiftency in the German hypothefis. As we may conceive the vis infita to be exerted according to any a fig li¬ able law, fo we may conceive it to be exert¬ ed in any aflignable degree. When we con- fider the vis infita as employed in preferving the fame degree of velocity, it follows necef- farily, that its force, which is the caufe, mu ft be meafured by the velocity, which is the effed. But when we confider another branch or its operations, viz. its nifus to. overcome e- very obftrudion to the equable motion, we have no other means to eftimate this nifus, but its effeds ; for, however probable it may be, it does not necefiarily follow, that this ni(u$ muft aiio be meafured by the velocity, facts and experiments, then, are the only
means
64 ESSAYS and OBSERVATIONS
means by which we can determine this con- trove rfy ; and, when we look about for fads and experiments, there can be none lefs liable to exception than thofe, where the vis injita of one body is oppofed to the vis injita of an¬ other, by collifion and percuffion. It a pen¬ dulum of one pound weight be let down from fuch a height, as to acquire at the loweft point the velocity of 10, it will exadly ba¬ lance a pendulum of two pounds weight, let down from fuch a height as only to acquire the velocity of 5, and the two bodies will be at reft upon their collifion. The remaining at reft upon contad, is compleat evidence, that the forces of the two bodies are equal ; confequently that their forces are as their quantities of matter multiplied upon their ve¬ locities ; and therefore that the force of the fame body is always as its velocity,, A thou¬ sand different experiments of the fame kind, make it evident, that the force of every mo¬ ving body is in the precife ratio of its velo¬ city. And thofe experiments muft be abfo- lately unexceptionable, in which we compare the force of one body, with the force of ano¬ ther equal body moving with a different ve¬ locity ; for this is in effed comparing the dif¬ ferent!
1
PHYSICAL amd LITERARY. 65
ferent forces of the fame body moving with different velocities.
It being thus afcertained, that the force of a body moving by the vis injit a is always in proportion to its velocity, we have reafon to conclude, from analogy, that the fame rule holds where bodies move by the force of gra¬ vity. And accordingly this is alfo made evi¬ dent from a courfe.of unexceptionable expe¬ riments.
The German philofophers, in their experi¬ ments, have been milled, by afcribing to the force of the moving body, effects which ob¬ viously remit from other caufes. Not to lengthen out this paper too much, I fhall fa- tisfy my felt with giving an infcance or two. It is a fadt agreed upon, that a pendulum fwung upwards with a double velocity, will reach a quadruple height. Hence it is in¬ ferred by Leibnitz , and his followers, that the forces mu ft be as the fquares of the velo¬ cities ; feeing the effedts produced by the dif¬ ferent forces, viz. the fpaces gone through, are as the fquares of the velocities. And could it be juftly maintained, that the fpace run through is purely the effect of the mo¬ mentum or force, with which the body is thrown upwards, the argument would be
X con-
66 ESSAYS and OBSERVATIONS
cpnclufive. But it is not fo. Laying afide gravity, and the refinance of the air, a body thrown upwards with the final left force, will move on in infinitum < It is by the operation of gravity, and the refinance of the air, that motion ceafes, when the body arrives to a cer¬ tain height. The retardation, therefore, of motion, in bodies thrown up with different velocities, laying afide the refiftance of the air, may be a meafure of the force of gravity, of which it is the e fifed 5 but can never be a meafure of the force with which the body is thrown up, of which it is not the efifed. And, from the fad of a body’s arriving at four times the height with double the veloci¬
ty, to infer, that the momentum, at its out- fetting, muft be as the fquare of the velocity, is really not more juft, than to infer, when one body is let drop from four times the height of another body, that it muft acquire four times the force of the other body, tho? it acquire but double its velocity ; which does not af¬ ford the fhadow of an argument. When a body is thrown up with a double velocity, and confequently with a double force, the reafon why it afcends four times its former height, is plainly this, that the counteradion of gravity, while it has a double force to
ftruggle
PHYSICAL and LITERARY. €y
RruggR with, has but half the time in any given fpace to produce its effedt ; and there¬ fore this body, before its motion be totally fubdued, mu ft afcend four times the height that it afcends when thrown upwards with the Angle velocity and Angle force.
But the argument which the Leibnitfans truft moft to, is founded upon experiments of the falling of balls upon clay, or other loft body ; ‘ where it is eftablifhed, that the irn- preffions made, are in proportion to the heights from whence the balls are let fall, and confequently to the fquares of the velo¬ cities. From thefe experiments it is inferred, that the forces muft alfo be as the fquares of the velocities ; it being taken for granted, that the impreflions made upon the clay muft be the meafure of the forces or momenta, of which they are Laid to be the immediate and diredt effects. The error of this reafoning is of the fame kind with the former. The re¬ tardation of the motion of a body falling through a refilling medium, is not the effect of gravity, and therefore cannot be the mea- fure of its force. It is the meafure of the re- iiftance of the medium, becaufe it is the effedt o! that refiftance. All the world knows, that when bodies move through a fluid, or any
foft
68 ESSAYS and OBSERVATIONS
foft matter, a double force produces a qua¬ druple effect 3 which may be accounted for in the fame manner with the retardation which happens in the afcent of heavy bodies. A double force makes the body afcend four times the height before it be ftopt by the counteradtion of gravity. And it is equally reafonable to fuppofe, that when bodies fall into refilling mediums, a double force will carry the body a quadruple fpace downwards before the motion be quite ffopt by the refill- ance of the medium,
I fhall conclude this effay with the follow¬ ing obfervation, that the feveral powers I have afcrihed to matter, are in nothing fimilar to occult qualities. The error of thofe who dealt in the dodtrine of occult qualities was, in attributing every different effedt to feme quality or caufe confined to that Angle effedt 3 which was in reality faying no more, than, what all the world knows, that every effedt muff have a caufe. This was not advancing a fingle ftep in knowledge, but amufing one’s lelf with words in place of things. The powers I have attributed to matter, refolve into general laws, each of them productive pf 3 thoijfand different effedts. And we have
no
1 * ‘ i
PHYSICAL and LITERARY. %
no reafon to doubt that mere matter may be endued with various powers, as well as ani¬ mals are. When we fay, that feeing, hear¬ ing, tailing, touching, fmelling, proceed from fo many -different powers or fenfes, no perfon confiders this as afcribing effeds to occult caufes. Have we not the fame reafon to conclude, that there is a power in matter to continue itfelf in motion, another power to refill a change from reft to motion, and a third power to unite itfelf with every other piece of matter ; when we perceive effeds which as diredly refult from thefe powers, as feeing does from the fenfe of feeing. It may be true, for ought we know, that there is fome more general principle in matter, which is the foundation of all thefe powers. But ffcill it is gaining ground, and knowledge, to trace ef- feds to their caufes, and to difcover that many different effeds proceed from the fame caufe„ To be diffatisfied with fuch difcoveries, mere¬ ly becaufe of the poffibility of other caufes ftill more general, which lie hid from us, is in effed to be diffatisfied with all knowledge whatever ; becaufe, however far we pene¬ trate, we never can be certain, that we are arrived at our journey’s end,
Som&
jo ESSAYS and OBSERVATIONS
Article II.
Some Remarks on the Laws of Motion , and the Inertia oj Matter ; by John Stewart, M. D. Fellow of the Royal College of Phy - ficians , and Profejfor of Natural Philofo- phy in the Univerfity of Edinburgh.
Til E Laws of motion, as delivered by Sir Ifaac Newton , are all founded on the fuppofition, that body of it- felf is abfolutely inactive. And inactivity is now commonly afcr bed to matter as one of
j
its general properties 3 body being defined to be whatever is extended, impenetrable, divifible, moveable, and inactive. At the fame time, every one knows, that aCtive powers are continually employed through all the parts of nature. The life and motion of animals, the production and growth of vegetables, the attractions of gravitation and cohefion, with other inftances of the fame kind, are always prefent to our view*
Phi-
PHYSICAL and LITERARY.
71
Phi losophers who aflert the inactivity of matter, ought therefore to be able to give fome good reafon, why they refufe to allow it the free poffeffion of fuch powers in its own right ; and why it is only to be regarded as a paffive inftrument, under the direction, and fubjedt to the dominion, of fome fuperi- or being. But, in order to afcertain the true notion of the inertia of body, the proper method is to begin with the fimpleft cafe; and to confider body as a lifelefs inanimated mafs, without weight, attraction, repullion, or any tendency to begin motion, till added upon by fome foreign external caufe. And furely it would be fomewhat furprifing, if body, even in thefe circumftances, fhouid be found to difcover any activity.
It hath been imagined however, by fome people, tc That, if body were utterly unactive, cc the final left force would be fufficient to C£ move a great body and a little body, with <£ equal velocity : and that the fame power cc might communicate a great velocity or a “ fmall velocity to any body.*” Mr. De Mai - ran in Mem. de 1' Acad. 17 28, feems to enter-
* EiTa y I. p. 9. 21, 24,
tain
72 ESSAYS AND OBSERVATIONS
tain the fame opinion, when he afks, if the inertia of matter (which he explains to be that refinance which body makes to its being drawn out of reft, and receiving a determi¬ ned motion, and which is more or lefs in proportion to its mafs) may not be the effeft of fome motion ; and if it ought not to be conceived as an adtual force, acting by fome fecret mechanifm. And the author of an Ej- Jay on Spirit lately publifhed, maintains in like manner, that there is an active refiftance to the beginning of motion in every body ; tho’ indeed he attributes that activity to an immaterial caufe. And Meff. Bujfon and Needham too, who have carried the activity of matter to the higheft: pitch, have drawn one argument in fupport of their fyftem, from the refiftance of body to motion. Need - hams Obfervations. p.435.
To give the queftion a fair examination, we fhall, inftead of fpeaking about matter ' or body, fuppofe for once, a fubftance before us quite inactive of itfelf, which is extend- ed, impenetrable, finite, and confequently moveable. Let us try if any lefs refiftance to motion can be expe&ed here, than is actu¬ ally to be met with from common matter.
Place
PHYSICAL and LITERARY. ;3
i ’ *
Place any mafs of fuch a fubftance at reft, It cannot begin motion of itfelf by the fuppofiti- on. But an adtive animated being, as for exam¬ ple, a man, can move it. Some effort muft certainly be made, fome power exerted, to produce this effedt. It will never be pretend¬ ed, that the fame effort Can move the mafs ei¬ ther with a great velocity or a fmall velocity 5 that being as abfurd, as to fay that a great ve¬ locity and a fmall velocity are one and the fame thing. In like manner, it muft require one effort to move a fmall quantity of this fub- ftance with a certain velocity, and a differ¬ ent effort to move a great quantity with the fame velocity. The fame energy of the a- gent, will never ferve to move a given quan¬ tity of this fubftance, or double the quanti¬ ty of this fubftance, with the fame velocity % no more than it will move the fame fub¬ ftance with different velocities. By this ex¬ ertion of our own adtivky, we acquire the ideas of forces. The animated being (or the mind) is differently affected by different objects, whether of the ienfes or under- ftanding. And why {liquid it be affedted in the fame way, when a great fub-
K. ftancs
74 ESSAYS and OBSERVATIONS
ftance and a little fubftance are moved by it, or when a great velocity and a lit¬ tle velocity are imparted to the fame fub¬ ftance ? When we endeavour to communi¬ cate motion to fueh a fubftance, we muft be confcious of fome kind of fteeling ; and thefe feelings muft be different in different cafes. Thus the idea of ref ftance, as it is called, to motion, in the moil inactive fubftance we can imagine, would be fuggefted to us from thefe perceptions ; and is precifely the fame with what we experience daily in handling of matter* Nor does it feeiii poffible to con¬ ceive an extended, impenetrable fubftance, diverted of this kind of refiftance from iner¬ tia. The larger the fubftance is which we intend to move with a given velocity, the greater force muft be applied : and, could we fuppofe it actually infinite, no finite force could move it at all.
There is a very extraordinary paffage in Mr. M'dauriri s Account of Sir Ifaac Newton s Philofophy. p. 100. which, in refped of the high merit of the author, deferves our at¬ tention* It is there faid, cc That, for ought *c we know, matter may be of kinds fo dif- €C ferent from each other, that the folid ele¬ mentary
PHYSICAL and LITERARY. 75
mentary particles of the one, may have a cc greater inertia than equal folid elementary tc particles of the other kind.” This conje- diure, if true, would effectually overturn what hath been now advanced. But it ap¬ pears to be equally inconftftent with his own account of inertia , and occurs only in a poft- humous work. The inertia of body is a negative quality, or a negation of all pofitive power,, and therefore can admit of no de¬ grees of greater or lefs in a given quantity of matter. Two bodies, or two elementary particles of equal quantities of matter, if they are inert at all, mu ft have equal inertia , or require equal forces to move them with equal velocities. And, in every cafe, the inertia is proportional to the quantity of mat¬ ter.
If a body left at reft does not begin moti¬ on of itfelf, it is determined to remain in that ftate, not from any real repugnance to motion, which is as conformable to its na¬ ture as a ftate of reft : but becaufe nothing is done without a caufe. And, when adted upon by any external influence, it obeys without reludtance ; the motion produced being in exadt proportion to the moving
caufe.
76 ESSAYS and OBSERVATIONS
caufe. It has a conftant fufceptibility of mo¬ tion, and a per fed: facility in receiving it. Bat we may as well afk, why an inactive fubftance does not begin fome degree of mo¬ tion of itfelf? as, why different powers are requifite to produce different motions? When people talk of the refill mice of matter at reft, as of an aBive power > draggling againft any agent, and actively opppfing it, they farely frame to themfelves fome notion of force an¬ tecedent to all experience 5 and, they would do well to inform the world, in what man¬ ner this idea was fuggefted to them.
The pajjive nature of body is abundantly manifeft, from its yielding to the leaft con¬ ceivable adlion. The leg of a fly moves the whole globe of the earth. A man indeed cannot roll a tun fo faft as he can a tennis- ball : and we may find a horfe able to draw a loaded cart two miles in the hour, who cannot be prevailed upon to draw it four miles in the fame time. But are not fuch common phaenomena as thefe more natu-
a
rally accounted for, from the fluggifhnefs or Inactivity of matter, than from its fnppofed activity ? A great body fet in motion is one effedt 3 a little body moved with the fame
velocity
PHYSICAL and LITERARY.
//
velocity is another. A given body moved With a great velocity, is one effeCt; and, when moved with a lefs velocity, it is a different ei> fed:. The old principle feems to apply well enough in this cafe, that effects are proporti-* onal to their caufes.
It muft be confeffed, that authors in treating of the inertia of matter, and of its refinance to motion, are very apt to exprefs themfelves in terms that import a real activi¬ ty ; and which, if ftriCtly underftood, are inconfiftent with inertia . Thus, when a per- fon in a boat pulls a rope that is fattened to the fhore, it is commonly faid, that the man aCts upon the fhore in one direction, and that the fhore, by its reaction in the oppofite di¬ rection, pulls the man and boat towards it. Yet, notwithftanding fuch expreffions, will any one ferioufly maintain, that the ground has an active power to produce any fuch ef¬ fect?' It is evidently the force of the man extending himfelf, that draws the fhore with his hands one way, and at the fame time pu flies the veffel with equal force with his feet the oppofite way. In like manner, if a perfon handing in a boat, pufhes againft the ground with a pole, it is not really the rea-
78 ESSAYS and OBSERVATIONS
dtion of the ground that makes the boat re¬ cede; it is the force of the man that is the only moving power, adting equally upon both the boat and the ground. When a boat is rowed with oars, the oars are faid to adt up¬ on the water in one diredtion, and the water to readt upon the oars in the oppofite diredti¬ on, and to produce the motion of the boat* Yet it is plain, that the motion is intirely pro¬ duced by the rower, who, in fo far as he contributes to the motion of the boat, em¬ ploys the oar as a lever of the fecond kind* where the body to be moved, or the boat, is placed betwixt the moving power and the fulcrum .
In the common account of the progref- fion of animals, whether it be of walking, flying, or fwimming, Borelli and all other authors content themfelves with telling us. That the animal adts upon the ground, air, or water, in one diredtion, and that the rea¬ ction of the medium carries the animal for¬ wards in an oppofite direction. This is at belt but too concife, not to call it a falfe the¬ ory: feeing it mult be manifeft that the me¬ dium, by any readtion which takes place here, can only confume as much force as is
impreffed
PHYSICAL and LITERARY. 79
imprefied upon it, and is utterly incapable of producing any kind of motion. The only immediate caufe of the motion, being the active force of the animal which preffes the medium one way, and its own body the o- ther way, as might be particularly fhown in every kind of progreffion, if it were thought needful.
Thus, upon the moft attentive examina¬ tion into the Rate and condition of body at reft, we have found it to be perfectly inert or inadtive. Body in motion next demands our confederation. Suppofing a body once put in motion by fome agent or other, it behooves us to follow it out, and enquire what happens to it on this change of its ftate. An extend¬ ed, impenetrable, inactive fubftance has re¬ ceived a motion : Will it inftantly ftop when the immediate influence of the adlive power ceafes l or will it perfevere in its new ftate ?
From what commonly happens in the motions of bodies, their gradual lofs of force and returning to a ftate of reft ; people con¬ tract an early prepofleftion, and are ready to imagine, that reft is the proper ftate of body* But a diligent review of all the circumftan- ees, foon difcovers, that body is equally in¬ different
So ESSAYS and OBSERVATIONS
different to either Rate, of reft or motion * Body at reft does not change its Rate of itfelf* no more does body in motion. A body at reft requires no caufe of its continuance j as little does a body in motion, inis property of body, by which it perfeveres in its ftate of reft, or of uniform motion, in a (freight line, unlefs when forced to change it by fome external influence, is called the inertia of matter.
We know not how motion is originally communicated at all ; we know nothing of the nature of motion or force, but by expe¬ rience. We can define neither 5 the ideas being quite Ample. Natural philofophy however takes it for granted, that fuch a thifip- there is. Let a motion or force begin any way you pleafe, we never fee it ceafe till it be deftroyed. Why then fhould we imagine a body ought to (lop of itfelf ; and that, to preferve it in motion, a conftant exer¬ tion is neceffary, like that which produced it at firft ? What argument can lead us to a- feribe fuch an activity to body? What fhould determine the body to flop, if there be no¬ thing to oppofe its motion? Is there any experiment pointing that way ? yes, <c we,
mav
PHYSICAL and LITERARY- 81
sc may be defired to refied on what a perfon cc feels within hrmfelf in walking, during <c which a repeated adivity is exerted to con- 5f tinue the motion But this, furely, c^rt only be intended as an illuftration of what is meant by the fuppofed adivity of matter ill motion, and not as a proof of its reality. For* every day’s experience muft teach us on the contrary, that it requires a great adivity, fometimes more than we are mafters of, to flop a begun motion in our bodies. How doth it appear, that the fame effort is necef- fary to be continually exerted, which was employed at the beginning of the motion ? We find a certain effort neceffary to begin a motion in our own bodies 3 but, we fhould find no occafion for repeating it, were it not confumed or wafted upon other bodies. When we give ourfelves one pufh forwards upon a fmooth furface, fuch as ice for example, there is no need for a fecond immediately 5 and, were there no attrition nor refiftance
from the air, the motion would continue for
/
ever. If a body fet in motion, were to flop, retard, or any way change, its motion of it«
L felf ;
* Effay I. p.
82 ESSAYS AND OBSERVATIONS
felf; that would betray an inclination or ten¬ dency to one Hate preferably to another; it would no longer appear equally indifferent to either, in which alone paffivity confifts.
The mold general law of matter we dis¬ cover by experience is, that every effed con¬ tinues till deftroyed by fomething. Why then may not motion continue till it be deftroyed, as well as the magnitude, figure, colour, or any other property of body ? or even as well as the very exiftence of matter? “ Motion €C is indeed a mode of exiftence different cc from all others, nor can we compare it to cc any thing that is not motion ?*.” But that is no reafon why it fliould change of itfelf, any mbre than thefe other modes. If the conti¬ nuation of motion bore a nearer refemblance to the continuation of any other effed3 would that render it any plainer ? Motion is an effed fui generis but we have an infinite variety of examples of its continuance. An adive being preffes forwards a certain quantity of an impenetrable inadive fubftance : is there not feme effed produced here ? fomething then communicated to it ? The body is put
in
* EfTa y I. p. x8. 19.
PHYSICAL and LITERARY. 83
in motion : why ought that motion to ceafe without a caufe ? Adion is neceffary to the produdion of motion, and no wonder if no¬ thing can deflroy the effed of one adion but another adion. The trite maxim, fublata caufa , tollitur effeffius, is not to be fo literally interpreted, as that an effed may not conti¬ nue, after its caufe ceafes to ad.
As we know fo little of the nature of that influence by which one being puts another in motion, or by which it excites motion in itfelf ; with what reafon can we pofitively conclude its effeds to be- only momentary, when they every where appear to be fo per¬ manent ? When motion is begun in any body, we attribute it to a certain adion which we cannot poffibly explain ; when a body conti¬ nues in the motion which it has once recei¬ ved, it appears to be a neceffary confequence of that adion. We commonly indeed fay, that the body then moves on of itfelf; but the only queftion in debate is, W hether there be occafion for a continual recruit of force, new impreffions, new follicitations to motion, like to what were at firft exerted by the mo¬ ving power. '
Unless
V
*
84 ESSAYS and OBSERVATIONS
Unless this account of the continuation of motion can be fhewn to involve feme ab- furdity, why fhould we feek for any other caufe of it, than the force irnpreffed by the external agent ? We may be told perhaps,
C£ That motion is a continued addon and
*
therefore body continuing to move, is active* But is not this either a begging of the que- flion, or taking hold of the ambiguity of language to fupport it 3 inflead of explain¬ ing, why a motion once excited fhould ceafe of itfelf? No doubt, we commonly fay in the mechanical philofophy, that one body ads upon another by impulfe, and the other reads upon it. Nay, Sir Jfaac Newton him- felf fpeaks of matter ading by inertia , or f vis inertiae , which, tranilated literally, would feem to import an impotent power, or adive inadivky. Such terms cannot eaiily be avoid¬ ed, without introducing endlefs circumlocu¬ tions. If more accurate expreffions can con¬ veniently be fubftituted in their place, it would be no differvice done to philofophy. But we are not to difpute about words, when the meaning is clear ; or, to confound things entirely diftind, becaufe they happen fre¬ quently to be called by the fame name. The
true
PHYSICAL and LITERARY. 85
true diflincEtion between adive force, proper¬ ly fo called, and the vis inertiae , feems to con- hit in this, that feme beings can begin mo¬ tion where there was none before, either in themfelves, or in the body to be moved : in other beings, the motion, when begun from fome external caufc, is continued for want of a power to Rop it. The firft of thefe may be properly denominated active beings ; the other, even when in motion, have no proper activity of their own.
There can indeed be no action upon mat¬ ter without a production of motion, or at lead: a tendency to it. Rut it doth not there¬ fore follow, that motion and addon are fyno- nymous terms. Why may “not an adive be¬ ing communicate motion to matter, without moving itfelf ? Is not that every whit as eafy as felf-motion ? Rut, whether the agent moves itfelf or not, it muft have a poveer of ading, previous to all motion; otherways it would be impofiible for matter or any other being to begin motion of themfelves. A due attention to this remark, will afford a dired anfwer to what hath been fo much infilled on, £C That motion is adion.” Motion is not adion, but the efted of an adion.
• 1 1
Adiyity
$6 ESSAYS and OBSERVATIONS
Activity may be varioufly applied. An adl- on may be with-held by an oppofite and equal adion, as in the cafe of two contrary preflures: or, it may be employed in deftroying the ef¬ fect of fome former adion, as when it flops
\
or retards a moving body. But the genuine charaderiftic of an adive being, is a power of beginning motion either in itfelf or ano¬ ther, without the means of preceeding mo¬ tion Thus a man from a ftate of reft can begin a motion which fhall move another body : or he can begin a motion which fhall flop or retard another motion. And it will readily be admitted, that whatever adive be¬ ing can thus begin motion in another, without the means of previous motion, will of courfe be able to confume motion in another, with¬ out receiving any itfelf.
W hen one body ftrikes upon another and moves it, we commonly indeed call this an adion : yet there is no refemblance between this mechanical communication of motion,
and
* All mere mechanical communications of motion , are not properly adion, but mere pajji<venefs, both in the bodies that impel!, and that are impelled. Adion is the beginning of a motion where there was none before, from a principle of life or activity. Clarks Lett . to Leibnitz, p. 327.
PHYSICAL and LITERARY. 87
and the activity before defcribed. This is conceived to be an adion in a fecondary fenfe. It is only a confequence of the firft adion. A motion once produced continues, till it be deftroyed by an equal and oppofite motion, or an adion capable of having pro- duced it.
The effed produced by an agent is a cer¬ tain quantity of motion or force, which, like other efteds, continues without any tenden¬ cy to perifti of itfelf. This quantity of mo¬ tion, is always proportional to the real fpace defcribed by the whole quantity of matter ; and that fpace having length, breadth, and thidcnefs, is meafured by multiplying the quantity of matter, by the length of fpace defcribed by every particle, that is, by the velocity. If a body in motion ftrikes dired- ly upon another at reft, the two move on as one body after the ftroke. , They cannot move together with the fame velocity that the An¬ gle body had before the ftroke, for then there would be an increafe of quantity of motion. And whence fhould that proceed ? fuch an appearance as that, would difcover an adivi- ty in bodies indeed. Upon the fuppofition or perfed inadivity, the quantity of motion
mu ft
88 ESSAYS and OBSERVATIONS
muft remain unchanged : and we here abi- trail entirely from elafticity, whofe effects proceed from a real activity, and have no re¬ lation to what is called the vis inertiae. To find the length of the fpace defcribed by the impinging body, we divide the fpace by the quantity of matter, which is as it were the bale. And to have the length of the fecond fpace defcribed by the two bodies conjointly, we muft divide the fame fpace by the mafs of matter in both. As the divifor in- creafes, the quotient muft diminifh in the fame proportion.
Were we indeed to examine very minute¬ ly the gradual communication of motion from one body to another, we fhali find a real activity concerned in the operation ; but then it is not of that fort againft which we are now contending. It is that active force known by the name of the attraction of cohe - fion , which there takes place. When any part of a body is pulled or {truck upon by any moving power, it would neceffarily be feparated from the other parts, were there no cohefion. But, where there is a cohefion, that attractive force muft oppofe the moving power. And if either the cohefion be flrong,
or
PHYSICAL and LITERARY. 89
or the velocity of the moving power but fmall, this oppofition muft continue, till fuch time as all the parts of the body have acquired one common velocity. That part of the body which is immediately aCted up¬ on by the moving power, is firft put into motion; and, drawing the other parts alter it, gradually communicates motion to them, without ever getting beyond the reach of their attraction, or being broke afunder. Yet, it is ftill to the moving power that the motion of the whole body muft be aferibed ; became the attraction among the fmall particles be¬ ing mutual, will oppofe the motion one way, as much as it promotes it the other ; and fo can neither forward nor obftruCt the motion upon the whole. The attraction ferves only to conneCt and link the feveral parts together. The force loft by one body, is precifely c- qual to what is gained by the other 5 the whole effeCt or change, with regard to mo¬ tion being the fame, as if it had been in- ftantaneoufly produced. And there is no ar¬ gument to be drawn from hence, to prove the aCtive refiftance of one body at reft, to another in motion, or the tendency of any body in motion, to return to a ftate of reft.
M From
5TO ESSAYS AND OBSERVATIONS'
From the experiment of Mr. Poleni we learn, That fpheres of equal diameters falling upon foft clay, make equal imprefiions, when the prod lifts of the quantities of matter into the heights from which they fall, are equal * that is, when the quantities of matter multi¬ plied by the fquares of the velocities are e- qual. As it is much eafxer to determine when two imprefiions are equal, than when they differ in any proportion of magnitude; the velocities of the different bodies in this experiment, are fo admitted, in refpeft of the quantities of matter, as that the imprefiions may be equal. But, from thence we con¬ clude, that fueh imprefiions are always as the quantities of matter and fquares of the velo¬ cities conjointly ; and confequently, when the quantities of matter are equal, the im¬ prefiions will be as the fquares of the veloci¬ ties. The fame experiment may be (hewn •perhaps in a more Ample manner, by making pendulums of different quantities of matter, to ilrike with different velocities upon a fmooth fur face of foft clay ; the velocities being always afligned by help of a graduated arch, as is done in the common experiments of the collifion of bodies. In this manner, -
likewife.
PHYSICAL and LITERARY. 91
like wife, the impreffions are found to he e- qual, when the products of the quantities of matter, by the fquares of the velocities, are equal. Thus, let a hollow ball, with a quantity of matter 1, move with a velocity 20, and make a certain impreffion. If you afterwards* inclofe as much lead within the fame ball, as to render it of double the mafs of matter; you mufl give it a velocity fome- what exceeding 14, before it make an im¬ preffion equal to the former one. If the bo¬ dy 2, receive only a velocity 10, the impref¬ fion will be remarkably lets. In the former method, the gravity or weight of the balls, continuing to ad after they touch the clay, may contribute fo me what in making the im¬ preffions; but, in the other way of proceed¬ ing, the impreffions muft be more exadly owing to the vis injit a , or force acquired by the bodies, in falling from the determined heights. This experiment can ealily be re¬ conciled with the old meafure of forces, ac¬ cording to which the forces of equal bod’es are to be eftimated from the velocities limply. But, in order to do this, we ought carefully to diftinguilh betwixt two very different kirn s
of refiftance, viz . that from the inertia of
the
92 ESSAYS AND OBSERVATIONS
the matter, and the other from the force of cohefion. When an impreffion is made by a ftroke, upon the forface of any yielding fuhftance, fuch as foft day ; the refiftance to be overcome in making that impreffion, pro¬ ceeds almoft entirely from the tenacity or co¬ hefion : any refiftance arifing from the inertia of the fmall quantity of matter difplaced in forming the pit or cavity, is quite inconfider- able. The force of cohefion or attraction amongft the feveral particles of any homoge¬ neous body, is equal and conftant; and there¬ fore, muft produce an uniform refiftance to the motion of any body applied to overcome it, or a refiftance proportional to the time of the aCtion. The continued refiftance of a few attracting particles in a flow motion, and the fucceffive refiftance of a greater number of particles in a quick motion, will equally diminifh the force of a given fpherical body, in an equal time. If then the force of any ball, moving with a certain velocity, be con- fumed by the refiftance from cohefion in a gi¬ ven time; the force of the fame ball moving with double velocity, will be confumed in a double time ; if the velocity be triple, the time will likewife be triple 5 and the veloci¬ ty
PHYSICAL and LITERARY.
9 3
ties muft always be proportional to the times in which they are deftroyed. From whence it is manifeft, that a ball finking with a velo- city as 2, muft make an impreffion fourfold of what it makes with a velocity as i • be- caufe it continues likewife for double the time. In uniform motions, a double veloci¬ ty and a double time, muft always give a fourfold fpace : and the fame thing muft ob¬ tain in equably retarded motions 3 the fpaces defcribed being exadtly the half of what would have been defcribed by the uniform motions. But, tho* the impreffion be four¬ fold, the real effeft, by which the force ought to be meafured, is only double ; for it has on¬ ly undergone a double refiftance. For the fame reafon, triple the velocity makes a nine¬ fold impreffion. And, in general, the fmall impreffions made upon the furface of loft clay, (or even upon marble) by bodies lin¬ king upon it, muft, caeteris paribus , be, as the fquares of the velocities. Thefe impref¬ fions, made in oppofition to the uniform re¬ fiftance of cohefion, are no better meafures of forces, than the heights to which bodies are thrown near the earth, in oppofition to the uniform power of gravity. The
Jieightg
94 ESSAYS and OBSERVATIONS
heights are known to be, as the fquares of the velocities. When the velocities are, as 2 to i, ah heights are, , as 4 to 1. But the forces ire Hill to be eftimated, as 2 to 1 5 fince the times which the uniform a&ion of gravity tafes to deftroy them, are in that proportion. With a double velocity, and in a double time, the body arives at a fourfold height.
What hath been here remarked, con¬ cerning the meafure of forces, is not fo much intended for the inftruftion of thofe who have had leifure to attend to this cele¬ brated controverfy, as to enable every one who has the fmalleft acquaintance with thefe matters, to lodge for themfelves; whether the common arguments, when rightly underftood, be fufficient for the decifion of the queftion P or, whether there be ftill occafion for a new folution of the difficulties ? The debate has been clofed long ago ; after being managed by the ableft advocates on both fides : and the fubjedt is generally thought to be exhaufted, though no formal reconciliation hath hitherto been declared arnoneft the parties. We are now told, C£ That by a profufion of writing,
the point is rendered fo perplexed and in¬ tricate.
PHYSICAL an d LITERARY, 95
“ tricate, that there appears not a better way ct to come at the truth, than, neglecting the <c arguments on both (ides, to appV, direCtly “ to faCts for a lolution, as one would do up« “ on a point newly darted,” With this pom¬ pous introduction, or preamble, is ufhered in a new projeCt for a treaty of peace amongd the Englijh , French , and German philofophers* No mention is made of the Italians , the Dutch , and others, tho’ they were pretty deeply engaged in the quarrel. The reafon for which omiflion may poffibly be this, that the philofophers in Italy y Holland and elfe- where, chufe rather to preferve the appear¬ ance of neutrality, and aCt as mediators, A preliminary article being fird fettled, name¬ ly, to confider the feveral pretenlions of the contending powers, as (o many points newly Jlarted , and that without any regard to their refpeclive memorials ; there arofe a neceffity in the next place, in order to render the ne¬ gotiation the more confident with itfelf, for Jlarting new faCts like wife, or at lead of new- modelling the old ones. The method in which the whole affair hath been conduc¬ ed, and the jarring and oppofite intereds ad- juded, will bed appear by an indance or
9 6 ESSAYS and OBSERVATIONS
two. It is faid, That when a body is thrown up with a double velocity, and confequently with a double force* the rea- fon why it afcends four times its former C£ height, is plainly this, that the counter- sc adfcion of gravity, while it has a double €€ force to ftruggle with, has but half the “ time, in any given fpace, to produce its ef- C£ fedt.” The natural meaning of which is, that if a body, thrown up with" any velocity, riles to a certain height in a given time * a body thrown up with double the velocity, ought to afcend to an equal height in half that time. This indeed would hold true, if the upward motions could be fuppofed u- niform : but, as a body thrown up, happens always to be equably retarded, the real fadt comes out to be very different. The body thrown, up with the double velocity, rifes to triple the height of the firft body in an equal time, and to f of that height in half the time. Let the height to which the firft bo¬ dy rifes in any time, be called i yard * the height to which the fecond body afcends in half that time, is i yard and f. The for** mer pofition however, as it was only taking a retarded motion for an uniform one, was
pretty
PHYSICAL and LITERARY. 97
pretty plauiible, and good enough to pafs up- ' on Germans and other foreigners 5 efpecially if they were ftrangers to the Englijh language,, Another allowable artifice to deceive the ad- verfaries, is in endeavouring to make them believe, that “ all the world knows, that u when bodies move through a fluid, or <c any foft matter, a double force produces a “ quadruple effedt.” If the word effeffi were taken in its mcft proper fenfe, for the force communicated to the fluid or foft matter, by the moving body, this could never exceed the force of the body. A double force could never produce any more than a double effedt in its own direction. All the world indeed may know, that when a body ftrikes upon clay or other fuch foft matter, a double force may produce a quadruple impreffion. But then, this can only happen in fuch cafes, where no other refiftance is worth the mind¬ ing, but that arifing from the cohefion of the matter, in the manner above explained. When a ball moves through a fluid, the re¬ fiftance proceeds, almoft entirely, from the denfity or inertia \ and, the denfity being gi¬ ven, this refiftance muft increafe as the fquares of the velocity. In this cafe, it would be a » N vain
9 S’ ESSAYS and OBSERVATIONS
vain attempt, to affign any meafure of the ini- preffions; hecaufe, it follows clearly from the demonflrations of Sir Jfaac Newton that the body would go on for ever. And furely, it requires not much abflradt reafoning to prove, that meer inertia , without the help of feme adlive power, like gravity, or the attraction of cohefion, could never totally confume any motion, or reduce a body from a Rate of motion to a Rate of abfolute refl. Yet, after all, as every one has heard, that the reflflance of a perfeft and incompreffible fluid, was in the duplicate ratio of the velo¬ cities; this was foundation enough for a lover
»
of peace, to aflfert roundly, that the impref- iions made in a fluid, were in that ratio like- wife. Greater Rretches might well be per¬ mitted for the accomplifhment of fo defirable an end, as a compleat union and harmony a- mongfl philofopliers.
When one body Rrikes upon another with a great velocity, the parts immediately im¬ pelled, are fometimes broken off or driven away beyond the reach of attraction, before they have time to draw the other parts after them with any obfervable force ; and the
force
* Princip. Lib. II. Prop, v, et cor.
99
PHYSICAL and LITERARY.
force of cohefion, having oppofed the im¬ pinging body for fo fhort a time, makes no fenfible refiftance to it. The attraction of cohefion ading without interruption ; any refiftance made, or any motion communica¬ ted by it, mult be gradually produced; and confequently, in a very frnall time, the ef- fed will be proportionally frnall. Of this we have many examples. Let us fuppofe a board fet nearly upright on its end, and fo flightly fupported, that a bullet thrown againft it, out of a man’s hand, will tumble it over ; if the fame bullet be difeharged from a gun, it will go through the board without moving it out of its place. In the fame way, a bullet has been known to go through a man’s body, an arm has been taken off by a cannon ball, or even by the fail of a wind-mill, without any vifible motion produced in the other parts of the body; though a much lefs force would be fufficient to drag the whole body forwards. The better to illuftrate the manner in which thefe effeds are performed ; let it be obfer- ved, that by means, of a frnall thread or a load-ftone, a confiderable mafs of matter may be gently pulled alongft a table: where¬ as, if a fudden tug be given, or a greater
force
100 ESSAYS AND OBSERVATIONS
force applied; the thread breaks, or the load- Rone feparates, without feeming at all to move the body. The nature of inertia and -refiftan.ee has been fo much mifunderftood, or mifreprefented, that it was neceffary to explain thefe phaenomena from their true prin¬ ciples. In particular it might be thought, confidently with the falfe notions advanced concerning the refiftance of matter, that the reafon why a body did not move forwards when a part of it was broke off by a great force, was this, that the inertia or refiftance to motion in that cafe, became ftronger than the power of cohefiom Philosophers have fondly perplexed them- felves, with many fubtile queftions con¬ cerning the communication of motion; and have perfifted, with the utmoft anxiety, in a a very fuitlefs enquiry, how motion can pafs out of one body into another : as if motion was fomething that could be feparated from the moving body, and infufed from one into the other, like water poured into a phial. But, notwithftanding all the intricacy of this affair, it would appear to be ftill a greater myftery, if one body in motion were not to ?nove another lying freely at reft. It is in¬ deed
PHYSICAL and LITERARY, ioi
deed only by experience that we learn the laws of the communication of motion. For who ever fuppofed, that either the general or particular properties of matter could be dif- covered in any other way? Flow could it be known, whether body was penetrable or im¬ penetrable, diviflble or indivifible, elaftic or non-elaftic, animated or inanimated, but by trial? Suppoftng however, that we were in¬ formed before-hand, that the body at reft was impenetrable, utterly inactive and foft, and had neither impediment nor tendency to motion ; what would hinder us to foretell exactly every circumftance that happens, when another body of the fame kind ftrikes upon it * ?
When a body in motion ftrikes upon ano¬ ther at reft; the one lofes as much motion, as the other gains, in the fame diredion. This is ordinarily faid to proceed from a readion of the body that acquires the motion. The effed is indeed the fame upon the percutient body; there is the fame change of its ftate, as if it had adually received an impulfe in the contrary diredion. This, for the fake of
fhortnefs,
* r
•* Phi!of. Effay?t
i
102
ESSAYS AND OBSERVATIONS
ihortnefs, we may, and always do call, the ejfeSi of r eaSt ion ; but we can never imagine that there is any real adive oppofition of the bo¬ dy at reft to the motion of the other. The great difficulty complained of, is in concei¬ ving;, how the one body has its motion dimi- nifhcd by the ftroke as much as the other is increafed, while there is no adive repugnan¬ cy allowed in the one to tne other. It would be ridiculous enough to fancy, that the mo¬ tion of the one was a pait oi tne motion or the other ; and that the very fame motion could be transferred from the one into the other. “ As well might the magnitude, fi- « gUre, or colour, of one body be imparted <t t0 another.” But this we may venture to fay, that, for ought appears to the contrary, it follows from the nature of a paffive, ex¬ tended and impenetrable fubftance, that mo¬ tion is loft in one by producing it in another. It will eafily be admitted, that one motion may deftroy an oppoftte motion, and by that means loie oi its own. r Cl tneie is no leis difficulty here, than in the communication of motion. If two pieces of clay oppofing each other with equal forces, had any real a- divitv of .their own, it might be expected.
PHYSICAL and LITERARY. 103
that, tho’ they both ftopt at their firft meetings this was only done by fufpending the effedt of each other’s adtion ; and that they would relume their former degree of motion, upon being feparated by a man’s hand. We find however, that the motion of both bodies is irrecoverably loft by fuch a collifion. If then the force of one body is loft or confumed by deftroying force in another ; why may not one body as well lofe force by producing it in another. Befides, were there any real a- dlive oppoiition in the body at reft, to the body in motion 5 part of the force ought to be loft on that account, and the fum of the motions after the ftroke, would be lefs than the motion before it.
Vv hen a horfe pulls a ftone forwards, it is commonly faid, that the ftone pulls the horfe back, with a force equal to that with which the horfe pulls the ftone forwards. But no¬ thing more can poftibly be meant, than that the horie lofes as much force as the ftone gains : and that, with refpedt to the horfe, the effedt is the fame, as if there was no ftone tied behind him, but that he was pufh- ed back with a force equal to that acquired by the ftone. The adlive force of the horfe’s
limbs
J04 ESSAYS and OBSERVATIONS
limbs prefles forwards both the horfe and the ftone; what is called the reaction of the ftone, is not equal to the whole force exerted by the horfe ; for then indeed there could be no progreffion : it is only equal to what is im-
prefled upon the ftone.
The equality of aftion and reaftion in the cafe of preffures, is to be underitood in the fame manner. When a finger is prefifed a- gainft any body, the body is (aid to react upon the finger, as much as the finger is made to aft upon the body. If the weight of the body be fuftained by the prefiure of the fineer, there will be an aftive refinance
o '
from the power of gravity. And, if the fi¬ gure of the body be violently kept in a bent or compreffed Rate, there will be an aftive refiftance from the caufe cf cohefion. But if the finger be applied fo as to communicate an equal motion to all the parts of the body, and without oppofing its gravity; there will be no occafion for imagining, that the body really reafts, or aftively bears againft the fin¬ ger. The effeft indeed upon the finger is the fame, as if the body aftually prefled up¬ on it; but that e fie ft can eafiiy be accounted for, without having recourfe to inch a fup*
pofltion.
PHYSICAL and LITERARY. 105
pofition. The furface of a foft body, like that of the finger preffed againft a hard body, muft undergo a change of figure, and receive the fame impreffion, as if the hard body was preffed againft it ; becaufe, when the parts that come fir ft into contaCt with the body have their motion retarded, the other parts will advance farther forwards.
If there was any contradiction or abfurdity in the common opinion of the communica¬ tion of motion, this would be a fufficient rea- fon for rejecting it, tho’ it were ever fo a - greeable to the natural appearances of things. But fhall we maintain, that every particular body can only be moved by a power of its own 1 and fhall we deny, that motion is com¬ municated by one body to another, meerly becaufe we do not underftand the precife manner in which motion is either conveyed or preferved ? Why do we not, for the fame reafon, deny, that motion is begun at the command of any animated being ? Or do we better conceive how any being or body moves itfelf, than how it moves another ?
xYn appeal has been offered to the com¬ mon fenfe of mankind, as ready to declare in favour of the a&ivity of matter. If the facts
O be
to6 ESSAY'S and OBSERVATIONS
be fully reprefen ted, the public judgment need not be declined. Whatever obfcurity the learned may find in this fubjed of the communication of motion, a vulgar obferver will be very little perplexed about the matter. When a ftone is thrown out of the hand, and continues to move when left to itfelf ; there is no fear, but tc every perfon, who has not C£ ft u died philosophy,5’ will rather attribute this to a force fome how imp Defied upon the ftone, than to any adion or operation of the lifelefs ftone. It will never enter into his head, that the ftone flies away with wings of its own. Such a perfon, judging from firft appearances that all motion lan- guifhes and decays, may, likely enough, be inclined to think that body rather affeds a flats of reft than a ftate of motion ; and that the imprdfed force would not remain for e- ver : but he will never entertain the fmalleft doubt, but, that as long as the motion con¬ tinues, it is only an effied of the firft impulfci And, h aving once granted that motion can continue one moment as an effed after the adion of the moving power is over, the fame reafon muft remain for its continuance the next moment of nme, and fo on forever.
When
PHYSICAL and LITERARY. 107
When we fee a body continuing to move with the felf-fame velocity which is received from the hand, is it not more natural to fay, that it does fo for want of a power or adiivity to flop itself, or to deftroy this motion, than to imagine the body to be no way de¬ termined by the impulfe, but to be carried on with an equal force by a power of its own continually exerted after the impulfe. Such obfequious complaifance of the ftone, in imi¬ tating fo exactly the motion of the hand, muft appear extremely curious 3 efpecially if we confider what a violent oppofition it is fuppofed to have made, before it yielded to the motion at firft. It brings to remem¬ brance the man in the parable, who faid , he would not go, hut went : or perhaps it may be likened to a young fellow learning to dance, who bends his limbs but aukwardly at firft fetdng out, till being led about for a while in the mafter’s hand, he can afterwards con¬ tinue the ftep of himfelf. If, in the collifion of bodies, the one body could thus adapt and conform itfelf in all cafes to the motion of the other 3 it feems to be the higheft in- juftice to refufe it the power of fenfation and cpnfcioufnefs.
From
'toS ESSAYS and OBSERVATIONS
From experience and obfervation we learn 5 that body is equally indifferent to motion and reft. And this indifference appears to be the natural confequence of the moft abfolute Inactivity. Body muft exift either in the one ftate or the other. But, fuppofmg it once ex- Ifting in a moving ftate, the continuance of the motion implies no activity in the body, any more than it requires aftivity to preferve a quiefcent body in a ftate of reft. And we may, with equal reafon, enquire for the caufe of the continuation of reft, as for a caufe of the continuation of motion.
Philosophers have indeed entertained various opinions concerning the continuation of motion. Arijiotle endeavoured to explain It by means of a vehicle or the circumpulfion pf fluid matter, hereby only evading the queftion, as the fame difficulty returned, how the motion of this fluid continued. And many of the moderns have imagined reft to be the proper ftate of ina&ive matter, to which it naturally tended 5 and have af- cribed the continuance of motion to the con- ftant and immediate agency of the Deity, or of feme delegated intelligent power.
How
PHYSICAL and LITERARY. 109
How far the concurrence of the Deity is . neceffary to the fupport of created beings in general, is perhaps impoffible for us to de¬ termine: but, unlefs fome continual influ¬ ence of that fort be requifite, there appears to be no occafion for any fpecial concurrence, in order to account for the continuance of motion. If however, it could be demon- fixated, that body cannot continue to move on in a {freight line, by virtue of the fir ft impulfe ; what more rational folution will be found, than to have recourfe to the efficiency pf an intelligent principle? For tho1 it fhould be granted, that the continuation of motion, and the communication of it from one body to another, cannot proceed from the inertia pf matter; will it therefore follow, that every atom of unintelligent and undefigning matter is endued with an aftivity capable of moving it with the greateft order and regularity, avS well as variety and diverfity; conforming it- felf to the motion of other atoms with which it is connected ; and adapting itfelf often to the will and intention of man ? Why fhould we not rather rank this power of the preferT vation of motion, with thofe other a&ive powers employed upon matter, tho’ not eft
feudally
xio ESSAYS AND OBSERVATIONS
fentially belonging to it (fuch as gravity, at¬ tractions and repulfions of various kinds, &c.) and refer them all to an intelligent caufe, if there be herein difcovered the fame figna- tures of thought and defign?
This leads us to another fource of objecti¬ ons againft the inactivity of matter. As the very refiftance which matter makes to an ex¬ ternal force, and its prefervation of the mo¬ tion received, have been taken for fymptoms of activity j we need wonder the lefs to find an activity fufpeCted in matter from its gravi¬ tation, and thefe other inftances where mo¬ tion begins in bodies, without any vifible caufe.
' It may be objected, £C That a {tone falls to the ground without any external im- pulfe, fo far as we can difcover ; and there- fore dead matter begins motion of itfelf.” Such manner of reafoning would make fhort work of natural philofophy, Becaufe there are a variety of motions, changes and trans¬ formations, produced every day amongft in¬ animate bodies 5 is it ftraight way to be con¬ cluded, that thefe bodies move themfelves ? The contrary of this appears in fo many in¬ ftances, as gives good reafon to believe it ne-
PHYSICAL and LITERARY, nt
Ver happens in any cafe. We fee for certain, many motions begun by animated beings; we obferve many bodies moved by the im- pulfe of other bodies ; and the mechanical caufes of fome motions, have through time been difcovered, which were not formerly perceived. Once in a day, it was found phi- lofophy to maintain that fmoak and vapour mounted upwards of themfelves by a princi¬ ple of levity, tho’ now one might as well af- fert that cork rifes up of itfelf in water. Ma¬ ny phenomena were explained from an ab¬ horrence of a void, which was fully as rea- fonable a paffion in a dead body, as the love of a center, or an inclination to meet with o- ther bodies. The rife of water in pumps was afcribed to a felf-moving power in the water, and the pulfation of the arteries to a power they had of dilating themfelves. The power of magnetifm bears fome refemblance to that of gravity ; the theory of it is Rill imper¬ fect : yet there are a multitude of fads which indicate a mecbanifm by means of fome ef¬ fluvia ; particularly the new method of ma¬ king artificial magnets by attrition, and the •well known experiment, in which an iron rod is preiented to a magnetic needle, the
fame
$12 ESSAYS and OBSERVATIONS
fame end being made to attract, fometimes one pole and fometimes another, by only changing the pofition of the rod, or invert¬ ing it up fide down; and much more by lin¬ king upon it with a hammer, or beating it a- gainft the ground. Electricity is another more palpable inftance of the fame fort. That a fluid is concerned in producing the apparent attractions and repulflons, and other more a- fton idling effeCts of the eleCtric globe, can hardly be doubted, however difficult it may ft ill be to defcribe the laws to which it is fub- jeCted in its operations. Why then ffiould it be accounted <c whimfical” or unphilolophi- cal to demand a caufe for the attractive power of gravity? Tho’ all the mechanical accounts, hitherto given of the caufe of gravity, fhould be found unfatisfaCtory ; may it not Hill be owing to fome unknown mechanifm, or the intervention of matter, moving other mat¬ ter ? Or, tho’ it were fhown to be impraCtk* cable by any mechanifm whatever, as is not improbably the cafe; why may we not attri¬ bute it to the immediate agency of an intel¬ ligent aCtive being ?
It may be urged further by way of ob*» jedion, “ That a power of beginning vifible
motion
PHYSICAL and LITERARY. 113
u motion is no more connected with a power of thinking, than it is with any other pro- perty of matter or fpirit.” This may' poftibly be admitted in a certain fenfe, viz. that there may, for ought we know, exiit fome fpecies of thinking beings, deftitute of the power of motion altogether. Oifters have very little of it. Rut however this be, we know, with all the certainty attainable in phyfics, th^t many thinking beings have fuch a power ; we fee them begin motion, a relative motion on the ground. When that motion is loft, they renew it and vary it again at every ftep. They not only begin new motion, but deftroy old motion, at pleafure i whereas no experience can ever tell us, that the beginning of the vifible motions of dead matter is original and underived. And there is this wide difference (which hath been often remarked by authors on this fuLedt) betwixt animated and inanimated beings, with ref-bed; to motion, namely, that the thinking being can determine the direction and quantity of its motion : wrhich is a power incompatible with dead matter ; and confequently it will of itfelf remain for ever incapable of the Is aft motion. Thus far therefore there is a con-
P
nexion
*i4 ESSAYS and OBSERVATIONS
\
nexion betwixt motion and thinking, that a power of beginning motion feems neceffarily to infer a power of thinking; tho’ we cannot affirm inverfely, that a power of thinking mu ft infer a power of beginning motion.
But if the bare beginning of motion feems to require an intelligent caufe, the power of gra¬ vity, furely, has the higheft title to lay claim, to that origin. The motions arifing from gra¬ vity are evidently of fuch a fort, as cannot, without the greateft violence to reafon, be afcribed to any blind tendency betwixt the attracting bodies. This will beft appear up¬ on ftating fome of its known effects. A ftone is drawn towards the earth in Europe and in America ; it changes its direction in different places, pointing always nearly to the center of the earth, (or exactly in a line per¬ pendicular to the level furface) in the fame manner as iron does' towards the loadftone, or a feather to the eleCtric tube. The attractive force of a ftone d'iminifhes, the farther it is removed from the earth, according to a fixed rule, or as the fquare of the diftance encreafes. A body placed by itfelf would move no way ; but two bodies run together. A given body is more attracted to a large
quantity
PHYSICAL aktd LITERARY. 115
quantity of matter than to a leffer. Is it then conceivable, that an unthinking being (bould be endued with an adivity which it regulates and varies in proportion to the fituation, di- ftance, and magnitude of another body, whilft it is fuppofed to be not in the lead in¬ fluenced or aded upon by that other body, or any other being whatfoever ? If this {hall be maintained, another queftion will arife. By what adions, or what ftronger language than this, can any man convince his neighbour of his own reafon or underftanding ? It is pre¬ fumed, that a higher degree of evidence will hardly be required in phyficai matters, than what we have for the life and exigence of one another : the voice of nature as loudly declares the origin of gravity, that ruling principle which binds the parts of the fyftem together. From the circumftances obfer- vable in the apparent mutual tendency of bo¬ dies, we are naturally led to conclude, that gravitation is the effed of the continued and regular operation of fome other being upon matter ; and that bodies are either drawn or preffed together by fomething ex¬ ternal. A power fo conftant, fo regular, and withal fo uniformly varied and diverfi-
fied
ii 6 ESSAYS and OBSERVATIONS
fied according to different circumftances, can proceed from nothing but an intelligent caufe, either mediately or immediately exert¬ ed upon bodies.
When motion is obferved to begin in any body, it mud be afcribed to one or other of thefe four caufes; i. Some external animated being ; 2. An external inansmated being ; 3. A felf-moving animated faculty 3 and 4. A felf-moving inanimate faculty. Of the for¬ mer three, there are a variety of manifeft examples. Of the laft there can be no certain example at all 5 and confequently we fhould make a bad choice, in preferring it to the o- thers : fuch a fuppofition, namely the produ¬ ction of motion from an internal inanimate principle, is intirely without foundation *, and feems to be much the fame thing as to allow, that motion may begin without any caufe at all.
That fomething may begin to exift, or ftart into being without a caufe, hath indeed been advanced in a very ingenious and pro¬ found
PHYSICAL and LITERARY, uy
found fyftem of the fceptical philofophy*} but hath not yet been adopted by any of the focieties for improvement of natural know¬ ledge. Such fublime conceptions are far above the reach of an ordinary genius ; and could not have entered into the head of the greateft phyfiologift on earth. The man who believes that a perception may fubfift without a perci¬ pient mind or a perceiver, may well compre¬ hend, that an addon may be performed with¬ out any agent, or a thing produced without any caufe of the production. And the au¬ thor of this new and wonderful dodtrine in¬ forms the world, that, when he looked into his own mind, he could difcover nothing but a series of fleeting perceptions ; and that from thence he concluded, that he himfelf was nothing but a bundle of fuch perceptions.
Mr. Baxter , in his Inquiry into the Nature of the Human foul , and likewife in his Ma-, tbo, endeavours to prove, that gravity cannot
be
* Ereatije on Hyman Nature , 3. vols. o&avo. This is the fyftem at large, a work fuited only to the comprehenfion of Adepts. An excellent compend or fummary whereof, for the benefit of vulgar capacities, we of this nation enjoy in the P hilojaphical EJjays , and the EJjays Moral and Political \ And to thefe may be added, as a farther help, that ufcfu! commentary, the EJjays on Morality a?id natural Religion ,
Jig ESSAYS and observations
be a property inherent in matter ; from this confideration, that, if body had an adtual ten¬ dency to fall down, it could not at the fame time refill; the downward motion by its iner ia. Which reafoning plainly fuppofes, that there is a real aftive refinance arifmg from inertia. And indeed, tho’ he exprefsly intends to de¬ ny the fmalleft activity in matter, yet he eve- ry where fpeaks of as a coudtus or ten^
dency effential to matter, by which it makes a violent oppofition to the power of gravity, and other aftive powers. This being a que- flion of the utmoft importance, it may not be amifs to offer an amendment upon that ar® gument, which will free it rrom any incon- fiftency, and place it on its true bottom, on which alone it can Hand its ground. To prove then that gravity does not proceed from any internal active force of any kind, either in the earth or fuch bodies as fall towards it ; it is on-3 ly neceffary to affume one axiom, that no fub- ftance can actively tend to move to two oppo- ‘ fite fides, at the fame time. It is eafy to conceive that a body may be puffed or drawn to oppofite fides, by two contrary external for¬ ces : in which cafe, if they are equal, the body
will remain at reftj, if unequal, it will be mo¬ ved
i
PHYSICAL and LITERARY. n9
ved to one fide, by the difference of the twa forces. Thus, every part of a ffagnating fluid is * prefled equally in every direction. But if a body actively tend to one fide, it cannot a- ^lively tend to the other at the fame time 5 that being a contradiction in terms. And in fa£t, we fhali find it impoflible, to make two fuch efforts in our own bodies, to move them wholly to two oppofite fides. This be- ing granted, it follows, that if the waters of the fea gravitate towards the earth by an a- Ctive force, they cannot, at the fame time* gravitate by their own activity towards the moon, fo as to produce the tides. And there¬ fore, the gravitation in one or both cafes, is owing to an external influence. The fame argument, if it fhali be found conclufive* may be applied to the attraction of the moon towards the earth and fun, in the conjuncti¬ ons, and other fuch like cafes. The attra¬ ctions betwixt fmall corpufcles, will be fhown to proceed from an external caufe, in the fame manner. And hence it will follow* that elafticity and the chymical effervefcen- cies, are not the refult of the activity of at¬ tracting particles. And for the fame reafon, a body thrown upwards, cannot move up by » an
no ESSAYS and OBSERVATIONS
an active force of its own ; for that would be oppofite to the adtive force of gravita¬ tion.
If, in order to evade the foregoing argu¬ ment, it fhould be faid, that a body never tends to two oppofite bodies at the fame time; but tends only to one fide with the dif¬ ference of the forces with which it would tend to each of thefe bodies taken fepafately : this will at leaft afford another remarkable Inflance of that exadt regularity with which the power of gravity is varied and adapted to the different fituations of bodies ; and which it is quite inconceivable that blind matter fhould perform without the fuperintendance of an intelligent being.
It has indeed been frequently afferted, that bodies move towards each other by vir¬ tue of a law originally eftablifhed. But law, that is to fay, a mere abftradt name or com- plex notion, which is no real being, cannot impel a ftone, and caufe it to begin to move. Law by itfelf, with fubmiffion be it fpoken, will avail nothing, unlefs either the fubjedts of it have under (banding to yield a wil¬ ling obedience, or they be compelled to it by external force.
If''
PHYSICAL and LITERARY. 121
If the firft appearances of things are to be trufted, there is full as good reafon to affert, that the earth draws the ftone, or the mag¬ net the iron, as that the (tone or iron move of their own accord. Yet the fuppoiition of one body drawing another body at a diftance, without the intervention of other matter, is univerfally rejected ; and that merely becaufe of the natural impoffibility of the thing. That a being cannot a &. where it is not, any more than when it is not, is an axiom or principle of reafon and common fenfe, and not a leffon of experience. And is it not e- qually felf-evident, that dead matter can ne¬ ver begin motion of itfelf 3 far lefs regulate its motions according to a law? If bodies are not fenfible of the neighbourhood of other bodies, of their quantities of matter, and of their precife diftance from them 5 is it to be imagined that they will move themfelves with fuch determined degrees of force, correfpond- ing to the different quantities of matter and different diftances?
The adtive powers both of attraction and repulfion are of fuch a fort, as could not be exercifed by the bodies themfelves, without ei¬ ther diftindt perceptions of their own fit unions
and
i.aa ESSAYS and OBSERVATIONS
and magnitudes with refpeft to other bodies, or a regular fucceffion of fame kind of clear perceptions, correfponding to every variety of fituation and magnitude, and all this accompa¬ nied with a memory and a power of comparing part with prefent perceptions. It would there¬ fore, make nothing to the prefent purpofe to have recourfe to that extraordinary fubterfugc, made ufe of by Mr. Hobbs on a like occafion. That all matter is endued with an obfcure fenfe and perception, and wants only the or¬ gans and memory of animals. And it hath never yet been alledged, that all matter is ef- jentially endued with a clear and diftind fen- iation or confcioufnefs. If it fhould, we need be at no lofs for an anfwer. For, were that the cafe, why have we no perception of this activity that is fuppofed to be exerted by our own bodies in falling: to the ground ?
Dr. Clark , Wollajlon , and others, have fo fully proved that matter is incapable of any degree of thinking, that it is impoffible to confute their arguments, but by fcornfully denying the force, of all raetaphyfical demon- ilrations whatever. If matter thinks, then either thinking is effential to all matter, or it arifes from the modification, magnitude, fi-
gure
PHYSICAL and LITERARY. 122
gure or motion of certain parcels of matter, •But what can be more ridiculous than to i~ magine, that matter is as effentially con- fcious, as it is extended ! Will it not follow* from that fuppofition, that every piece of matter, being made up of endlefsly feparable parts, (that is, of parts which are as really dlftind beings, notwithftanding their conti¬ guity, as if they had been at the greateft diftance one from another) is made up alfo of innumerable confcioufnefles and infinite confufion ? And farther, if every part of matter be felf-confcious, it would be a con- trad idion to fuppofe that any lyftem could he fo. The refulting fenfation or confciouf- nefs at laft being but one diftind fenfation or confcioufnefs, (as is that of a man) the fenfa¬ tion or confcioufnefs of every one of the conftituent particles, would be the individual fenfation or confcioufnefs of all and each of the reft. In the next place, the faculty of thinking cannot arife from the fize, figure, texture, or motion of body: nor can be de- ftroyed by any alteration of thefe qualities : becaufe bodies, by any change of thefe, only become greater or lefs, round or fquare, rare or denfe, tranflated from one place to another,
224 ESSAYS AND OBSERVATIONS
with this or that new diredion, or velocity 3 or the like. All which ideas are quite diffe¬ rent from that of thinking 3 there can be no relation between them.
This fort of reafoning defer ves at lead fame dired anfwer, and is not to be over¬ thrown by any criticifm on the meaning of the word immateriality . This, as is learned¬ ly obferved, mod certainly £C comes out to £c be merely a negative term, comprehending cc every thing that is not matter.” And it is not to be doubted that if other terms, fuch as immortality and infinity , were but examined with the fame cc fufficient accuracy,” the one might come out to be merely a negative term, comprehending every thing that is not mortal, and the other a negative term com¬ prehending every thing that is not finite. Such premiffes as thefe are undeniably true 3 the only difficulty lies in difcerning the ufe and importance of them. But if the rea-* foiling fubjoined to. thefe premiffes cc be found €C entirely conclufive,” the confequence mud be, that, in judging of the qualities of mat¬ ter, we are in every cafe to rely upon the report of our external fenfes, and never to employ our reafon in comparing one thing
with
PHYSICAL and LITER ARY. 125
with another, in order to corredt our firft imprefiions. 'Epicurus is to be applauded for believing on the credit of his eye -fight, that the fun and moon were no bigger than a cart¬ wheel or a cheefe. The peafant, who thinks that the fun moves from eaft to weft every day, is wifer in that refpedl, than the great- eft philofopher \ and Copernicus is to be re¬ garded as a common enemy to mankind, <c for declaring war againft our fenfes.5’
The grand queftion to be refolved in this controveffy, is not whether we have clearer conceptions of material or immaterial fub- ftances, as we are equally ignorant of both ; but whether the power of thinking, which is a known faculty of fame fuhftance, be not absolutely indivifible ? and as fuch, incom¬ patible with the known properties of matter ? The moft plaufible objection that can well be made againft this argument, arifes from the late obfervations made concerning the poly¬ pus, and other living creatures of that kind. Yet thefe, when duly considered, will be found entirely conftftent with the indivisibi¬ lity and unity of thinking fuhftance. They do indeed exhibite a remarkable peculiarity in the manner of the propagation of thefe
animals 3
i<i6 ESSAYS and OBSERVATIONS
animals ; and perhaps give fome ground for conjecturing, that a number of animals, or a fyftem of thinking beings, may probably be conjoined together, under the form of one animal. We were formerly acquainted with inftances of two or more animals connected or adhering together, as in worms of differ¬ ent kinds, tho* they do not grow or extend themfelves to any larger dimen (ions upon re¬ paration. Other animals were known, which, upon loiing a limb, had it regenerated again, as is the cafe of craw-fifh and lobfters. May it not then be fuppofed, that, in the polypus, both thefe cafes concur together ?
He who allows, that the fyftem of the u- niverfe may proceed at prefent without any guidance or direction, will find it difficult to afiign to himfelf any good reafon, why it might not always, or from eternity, have done the fame. The excellency and perfe¬ ction of the material world, can be no evi¬ dence to him of an original architect or con¬ triver of all things : ffnce the higheft excel¬ lencies and perfections are acknowledged, e- ven by every Theift, to exift without a caufe. But the inftances of a wife adminiftration and fuperintendence, prefented every moment to
our
PHYSICAL and LITERARY. 127
our view, ftrike the mind in the moft forci¬ ble manner. We are eye-witneffes of pro¬ vidence, but not of creation. The contem¬ plation of every part of nature, furnifhes us with irrefiftible proofs of intelligence, coun- fel and defign, ftill employed in actuating, moving, conducing and governing the uni- verfe. Nihil eft enim , quod rati one, et nume - ro moveri poffit fine conjilio , in quo nihil efi te- meranum , nihil varium , nihil fortuitum . Or- do autem Jiderum et conjlaniia , ncque naturam fignificat ; g/? enim plena rationis : neque for - tunam , arnica v arietati confiantiatn re -
//av/. yav vide at, non impie folum ,
indocle faciat , fi Deos effe neget # multnm inter efi, utrum id neget , an eos omni procuration , add i one privet:
mihi enim , yof wL/ agit , ^ omnino non vide - fur. Cic. de Nat. Deor. lib. II. cap. 16.
We obferve indeed, in various inftances, a fubordination of natural caufes and effedts, ana a dependence of one thing upon another. To inveftigate thefe, is the proper province of natural philofophy. The philofopher’s buhnefs ss, to learn the confutation of things as they really are 3 and to Larch out the laws and
order
I2S ESSAYS AND OBSERVATIONS
order eftablifhed in the material world, and by which it is conducted. The mod fuccefs- ful enquirers into nature, have feen moft rea- fon to refolve all things finally, into an incor¬ poreal, intelligent, and powerful fir ft caufe: and have rejoiced in the perfuafion, that they themfelves, and all parts of the univerfe, are the offspring, and under the adminiftra- tion, of the fame great, wife, and benefi¬ cent parent. But they are not follicitous in limiting the number of fecond caufes, far lefs in excluding them altogether, as fome over zealous friends to religion have done. Plutarch in recommending the philofophy of Anaxagoras , obferves, that fuperftition proceeds from ignorance of caules, and want of experience ; but that natural philofophy banifhes all fuperftition, and begets in the mind a well grounded piety, with comfort¬ able hopes*
Many
^ &si<rt$ou[Aovi& 7 rgo$ ret, fxsncc^ix, S'.ccyJvO; sgy&Qrott OCVTOOV T£ TOVTM CCiTlGC; CCyVGXdi. 0 (pVdlKOq A 0- yas T7iv K<T<p<x,\vi pzr zXtti^oov ccy&^tt]/ svreGsiotv mgyxty- Vit. p£RICL.
PHYSICAL and LITERARY. 129
Many fruitlefs attempts have formerly • been made to explain ail the phaenomena of nature, on mechanical principles alone. But it is exceedingly furprifmg, that, in the prefent age, fo eminent an aftronomer as M. Mau~ pertuis ^ fhould again revive exploded notions 5 and fuggeft, that the planets may poffibly be retained in their orbits, by the motion of a circumambient fluid, as an ultimate caufe* There is nothing more demonftrably certain, than that gravity cannot arife from the pref- fure of a whirlpool, or vortex of a denfe flu¬ id, once put in motion, and continuing to move round of itfelf, as M. Des Cartes ima¬ gined. And it is needlefs at prefent to exa¬ mine, whether it can be better explained by means of a rare elaftic aether. If Sir Ifaac Newton endeavours in that manner to account for gravity, the attraction of cohefion, the reflexion and refraCtion of light, &c* it is only with a view to point out fome more ge¬ neral mechanical caufe, upon which all thefe powers may poffibly depend. He never could believe that his aether was poffeffed of a real activity of its own. The elaidicity of that
R fluid
Co/ma logic.
i%o ESSAYS AMD OBSERVATIONS
fluid, mu ft itfelf either proceed from fome higher mechanical caufe, or flow immediate- ly from fome vita! intelligent principle, which muft he im mechanical. The mutual repul- lions betwixt one particle and another of the fluid, and betwixt the fluid and the bodies fwimming in it, difcover as much variety and regularity, as were before obferved in the phenomena of gravity; and muft confequently be regarded as the continual effeds of thought and delign.
It feems to have been far from Sir Ifaacs intention, to afcribe adivity to matter in any fhape ; tho’ his meaning has been fometimes miftaken To do fo, would be a manifeft contradidion to the primary laws of motion.
i - *
delivered by hinlfeif in the beginning of his
Principia.
According to Spinoza, one piece of mat¬ ter is moved by another, and that by a third ; and thus there is a progreffion of caufes and effeds, in infinitum , all ading blindly, with¬ out intelligence and deflgn. Not to repeat here, the metaph deal argument againft the poffibility of an endlefs feries of dependent
caufes
® Ph'ilofophical EJJays. p. no.
PHYSICAL and LITERARY.
I3I
eaufes of any kind, it will be a fufficient . confutation of this fcheme to obferve, that it fuppofes that an infinite number of undefir.n- ing beings can continually produce the greateft order, regularity and harmony: which is no better fen fe than to fay, that, tho’ one Angle cypher be of no value, yet an infinite num¬ ber of nothings can amount to a real quan¬ tity. There is no other poffible method whereby to judge of the intelligence or wif- dom of any being, but by it’s fenfible effedts; and we may as eafily fuppofe one fingle life— lefs being to produce by itfelf the ordinary ef¬ fects of wifdom, as that they can re-uk from the fucceflive adtion of an infinite number of them.
Because the world is often compared to a machine, it hath been imagined, that, when once let a going, it may continue its motions without any further interposition of the Au¬ thor of nature, or any other being. If we attend however to any machines of huirrn contrivance, we only learn, that all their mo¬ tions depend upon certain adtive powers, as gravity and elafiicity. Thefe are employed by ingenious artifts, fuch as they find them, to many ufeful purpofes in life. But it is by
. confiuering
j3z ESSAYS and OBSERVATIONS
confidering the effects of thefe powers in ge¬ neral, and without regard to any particular application, of them, that we muft determine CQncerning their nature. And it hath been already attempted to fhew, that they are all probably derived from an adtive intelligence, either immediately or mediately exercifed up« on matter, A connexion manifeftly appears amongft different parts of the fyftem of the world; and many bodies in it, tho’ dead and inanimated, are not only moved and agitated themfelves, but communicate motion to each other, according to a certain fixed and efta- blifhed order, which is called the courfe of nature. But there is no foundation in me¬ chanics for imagining, that a lifelefs body, in confequence of a lav/ promulgated feme thoufands of years ago, can move itfelf with as much regularity and variety, as if it was adtually endued with thought and reflexion. This, to moil people, will appear an im- ppffibility, as much, as to make a blind man . to fee, whilfl he continues blind. And there are few, but will at ieaft acknowledge the contrary opinion to be fupported with fa high a degree of probability, as juftly to de¬ fence
PHYSICAL and LITERARY. 133
ferve the preference. Haec quidcm , fi non ve¬ na y faltem verifimiliima videtur.
<c It is alledged, that the fyftem of the cc world would difcover more contrivance, if it went on of itfelf, without any concur- <c rence of the Deity.” That Mr. Boyle gives any countenance to this opinion, cannot be pofitiveiy concluded from his words. Pie does not fay, that brute matter moves itfelf^ but that £C it is managed by certain laws, and cc upheld by God’s ordinary and general con- cc courfe.” The lefs power is exerted to pro¬ duce a given effedt, the mec^anifm may juft- ly indeed be efteemed the more perfedt. Rut a machine going on without a moving power at all, is a thing quite unheard of. And where would be the beauty of every body3 every wheel moving itfelf, wdthout a depend¬ ence of one part upon another ? There would then be no mechanifm at all. Let the ma¬ chine be as grand and perfedt as poiilble \ it muft ftand in need of a firft mover, not on¬ ly to begin the motion, but to preferve it. If every part lpontaneoufly moved itfelf, it is then no machine ; fome other name muft be found ior fuch an arrangement or fyftem pf things* If all the motions and changes
of
334 ESSAYS and OBSERVATIONS
of bodies are performed immediately by the e bodies themfelves, without the influence of other matter, or any other power; there is an end of all enquiries intocauies and effects; philoSophy muft be degraded to a bare know¬ ledge of fads, a hiftory of nature.
There is an argument, in the form of a reduStio ad. abfurdum, brought againft the re¬ ceived opinion of the equality of action and readion, which had almoft been overlooked. The fubftance of it is this, that as the preffure undequaque, is a confequence of the law of equal adion and reaction in fluids; lo the fame fort of preffure ought to be a property of folid bodies likewife, if the fame law be univerfally extended to all bodies, fobds as well as fluids. For a ready anfwer to this ob- jedion, we need only recoiled the definition of a fluid, as diftinguifhed from a folid body. An undequaque preffure cannot obtain in a folid body, unlefs the particles of it did yield to any force exercifed upon them ; and, in yielding, were eafily put in motion amongfl themfelves ; or in other words, unieis the folid body was converted into a fluid. A parcel of dry fand may bear feme (mail re- femblance to a fluid; its particles may be men
PHYSICAL and LITERARY. 135
ved more eafily amongft one another, than thefe of a firm body, whofe parts are clofsiy united by attraction : yet dill there muft be a confiderable adhefion of the particles of land, on account of their irregular figures, and the inequalities on their furfaces. When a man applies his hand to a hole in the fide * of a veffel of water, he fu (tains a preffure from the tendency of the particles to Hide down and make their efcape : but, when his hand is laid on the fide of a fand bank, there is no fuch preffure to be felt ; becaufe the particles are intangled together, and fup- port one another. Thus a body laid upon a rough inclined plain, may remain fixt, by the refiftance from attrition alone ; whereas, if the plain be fmooth, fome other power becomes neceffary to hinder the defcent of the body.
The mechanical action and reaction of matter, or the changes with regard to moti¬ on and reff, which take place in the collifi- ons of non-eladic bodies, have been already confidered; and were found to be entirely confident with the mod abfolute inertia . But that real actions and equal oppofite reactions, obtain in the active powers of attraction and
repulfion.
j36 ESSAYS and OBSERVATIONS
repulfion, is agreeable to perpetual experience; and is no lefs certain, than that thefe powers themfelves are eftablifhed in nature. We find the loadftone attrads iron, and that iron attrads the loadftone, with equal force ; and, becaufe they attrad each other equally, they remain at reft when they come into con tad. If a mountain, by its gravity, preffed upon the earth, and the earth did not read equal¬ ly on the mountain ; then the mountain would neceffarily carry the earth before it, by its preffure, with a motion accelerated in tn~ jinitum . The fame is to be faid of a ftone, or the leaft part of the earth, as well as of a mountain. A mutual attradion too is ob- ferved amongft the diftant bodies of the io- lar fyftem.
When a heavy body lies upon a table, and confequently ads upon it with its whole ■ weight; there muft be an equal readion from the power of cohefion of the parts of the table, in order to fupport the burden. In the fame manner, if the bottom of any vei- fel fuftains the weight of a certain quantity of fand, it muft read with a force equal to that weight; otherways it muft break or give way. The power of cohefion may indeed greatly
exceed
PHYSICAL and LITERARY. 137
exceed the particular weight which it hap¬ pens to counteract at any time : and the fame table, at different times, may fupport very different degrees of weight. Rut ftill it is true, that the force exerted by this power upon the body, can neither be greater nor lefs than its weight, fince the reaction bare- ' ly fupports the body without beginning mo¬ tion in it. If this needs any illuftration, we may furpofe a man to have a weight hanging at his hand, w'hile at the fame time he pref- fes that hand upwards againft any fix’d body $ the force with which the hand adheres to, or is preffed againft the body, may be greater 01 lefs at pleafure 5 but the force employed againft the weight, or that which diredly op- poles and counterads it, muft exadly be e-
qua! to the weight itfelf.
The argument againft the law of adion and
reaction may be made to conclude with equal force againft the law of gravity itfelf j and, if it proves any thing at all, will even prove it impoffible that all terreftriai bodies fhould be endued with weight. Mutatis mutandis , the reasoning proceeds thus. Admitting the law of gravity, a fmooth level furface muft be the confequence. And as the law is not con-
S fined
2^8 ESSAYS AND OBSERVATIONS"
fined to fluids, but is fuppofed to be an uni- verfal law of matter ; a fmooth level furface mud not only be the copfequence in fluids, but in folids, equally. Here then is a fair dilemma. We muft either acknowledge a fmooth level furface to be always found in land, powder, and indeed in all loofe bodies, as well as in fluids ; or confine this law of gravity to fluids. Can we remain a moment in doubt betwixt thefe two oppofites ? we are certain that a fmooth level furface is not a necefiary property of folids. The gravity of a whole hill of fand, is but an alTertion without evidence. What remains then, but that we adhere to the former, and reject the latter, except as to fluids ? And thus our author luckily, tho’ without intention, has furnifhed a very convincing argument againfl: the univerfality of this fuppofed law of gravi¬ tation. If a fmooth level furface is an effedt of this law, it follows clearly, that this law takes not place in folids, at leaf! not univer- fally, as in fluids.
It hath been judged a fubjecft worthy cc to tc be regreted that natural philofophers and 6£ mathematicians are not always well flailed 6£ in logics.5' A fair comparifon alone can
fhow*
PHYSICAL and LITERARY, 139
fhow, whether they be more obnoxious to this cenfure than other people, and who are the moft guilty of fallacious reafoning, and in particular of that fpecies of it commonly cal¬ led Ignorantia Elenchi or Ingotyl It mu ft indeed be avowed, that few of the mathe¬ matical philofophers have teftified any high admiration of thofe fpacious openings and en¬ largements lately ftruck out by certain bold and enterprizing undertakers in the dialectic art. Nor can it reafonably be expe&ed that they fhould entertain the moft favourable o- pinion of fuch performances. Men who puzzle themfelves with felf-evident axioms, and ftumble at the plained: demonftrations* raife a fhrewrd fufpicion that they may be li¬ able to like human infirmities in other mat¬ ters, and can have no pretentions to be recei¬ ved as infallible guides. The fartheft that complaifance can go, is to transfer the com¬ pliment, and to regrete, that thefe univer - fal philofophers are not always well {killed in the elements of mathematics and natural philofophy. * If their end in view be really
the
* MefT. Hobbs , Poland and Collins 9 have made little other ufeofthe mathematical philofophy, than as a touch done for difcovering their own metal. Witnefs Elementa Phyficae , Let¬ ters to Serena , and Reflexions on Mr. Clarke s fecond defence. p.$6
j4o ESSAYS AND OBSERVATIONS
the inveftigation of truth, as it is to be wi fil¬ ed ; a little more converfation and familiari- ty with Euclid and other geometricians, might be of good fervice to them, by aecuftoming their minds to the fteady purfuit of real knowledge : but if their higheft aim in life be vain difputation, and an ofientatious dis¬ play of their abilities, in attempting to in¬ volve the cleared: truths in doubt and uncer¬ tainty, better were it for them to throw away the rule and compafs altogether, and to ex- ercife their faculties on other fubjeds, where there may be more room for fubtile evafions, and where miftakes, tho’ equally remote from truth, and perhaps of more pernici¬ ous confequence to mankind, cannot, from the nature of the thing, be fo eafily detect¬ ed.
Art.
PHYSICAL and LITERARY. 141
Art. III.
Pappi Alexandrini colleBiomim mathematica- rum libri quarti propojiiio quarto, genera H or faSia, cui propojitiones aliquot eodem fpetfantes adjiciuntur 5 auclore Mattheo
Stewart, m Academia Edinenji Mathefeof ProJeJJore,
PROP. IV. Lib. 4. ColleSt, Math. Pappi Alexandria.
Sit \Tab. 1 Fig. i.J circulus ABC, cujus centrum E, diameter BC, et recta linea contingens AD, quae cum BC in pundto D conveniat. Ducatur autem DF, et juncta AE, producatur ad G, et FKG et GLH jungantur. Dico KE ipfi EL ae- qualem e(Te.
Tadtum jam fit, et ipfi KL parallel duca- tur IIXM. Ergo MX eft aequalis XH ; du- catur etiam a punfto £ ad FH perpendicularis
142 ESSAYS AND OBSERVATIONS
EN : aequalis igitur eft FN ipfi NH : erat autem et MX aequalis XH : ergo NX ipfi FM eft parallela 5 et angulus PINX aequalis eft angulo NFM, hoc eft, angulo HAX, et in circulo funt punfta A, N, X, FI 5 eft igitur angulus ANH aequalis angulo AXH, videlicet angulo AEL : et propterea in circulo funt pun 6t a A, E, N, D ; recftus eft enim uterque •angulorum EAD, END.
Componetur autem fic, Quoniam uterque angulorum EAD, END eft recftus, puntfta A, D, E, N in circulo erunt. Aequalis igitur eft angulus AND angulo AED. Sed angulus AED eft aequalis angulo AXH, propterea quod parallelae funt ED, XH : ergo in circu-* lo funt A,N,X, H puntfta : et angulus HAX
angulo HNX eft aequalis : angulus autem FI AX aequalis eft angulo FIFM : ergo FM ip ft. NX eft parallela ; et eft FN aequalis NH: quare et MX ipfi XH aequalis erit ; eftque ut XG ad GE, et ita XM ad EK, et HX ad IE : ut igitur XM ad EK, ita HX ad LE : ct, permutando, aequalis autem eft MX ipfi XH : ergo et KE ipfi EL eft aequalis.
Perpendcnti autem hanc propojitionem , ejufque pulcherrimam refolutionem et compofitionem Jlatim
rt
mihi
PHYSICAL and LITERARY. 143
mihi occurrit veram ejfe, etfi redia BC non ft ■diameter • ft vcro lifeSia fit in punSlo E, et iif- demfere verbis quibus utitur Pappus ofenditur , ope jequentis Lemmatis.
L E MM A. Tab. 1. Fig. 2. 3,
Suit duae rcctae AR, CD circulo in- lcriptae, fibi mutuo occurrentes
a
in pundto E extra circulum, et bi~ fariam fecentur rcctae AB, CD in F, G punctis, a pundio E ducatur EH circulum contingens in H, e- runt puncta E, F, G, H in circulo.
Et, ilfdem manentibus, fi lit pundtum H in circumferentia, atque puncta
E, F, G, H in circulo, con tinge t juncta EH circulum in H.
Cas. i. Si una {Fig. 2.] redtarum AB, CD,
puta recta AB, FH.
fit diameter ; jungantur FG,
Quoniam redta CD bifedta eft in G, et eft F centrum circuii quoniam diameter AB bi- fefta eft in F ; redtus erit angulus FGE ;
redtus
144 ESSAYS and OBSERVATIONS
redus autem eft angulus FHE, quoniam con- tingit EH circulum in H, quare erit angulus FGE aequalis angalo FHE : in circulo igi- lur funt panda E, F, G, H.
Et, iifdem manentibus, ft fit pundum H in eircumferentia, aque pun da E, F, G, H in circulo, continget junda EH circulum in H.
Quoniam AB diameter bifeda eft in F, erit F centrum circuli 5 et quoniam re da CD bi¬ feda eft in G5 redus erit angulus FGE ; eft autem angulus FHE aeqtialis angulo FGE, quoniam in circulo funt panda E,F,G,H 3 redus igitur eft angulus FFIE ; quare con tin- get EH circulum in pundo H.
Cas. 2. Si neutra [Fig, 3.] redarum AB, CD fit diameter, fit K centrum circuli, et jungantur KF, KG, RH, FH, GH et KE.
Quoniam redae AB, CD bifedae funt in F, G pundis, erunt anguli KFE, KGE redi* et quoniam contingit EH circulum in II, re¬ ctus erit angu'us EHK. Quoniam redi funt anguli KGE, KHE in circulo funt panda E, K, G, H 3 quare erit angulus FGH aequa- !;s angulo EKH ; et quoniam redi funt an¬ guli EFK, EHK in circulo funt panda E, F* K, IT * quare erit angulus EFH aequalis an-
gula
PHYSICAL and LITERARY.
1 45
gulo EKH, hoc eft, angulo EGH : in circu¬ it) igitur funt punda E, F, G, IT.
Et, iifdem manentibus, ft fit pundum H in circumferentia, atque punda E, F, G, H in circulo, continget junda EH circulum in
H. /
Quoniam redae AB, CD bifedae funt in F, G, et eft K centrum circuli, erunt angu- li El K, EGK redi ; quare in circulo funt punda E, F, G, K ; in circulo igitur funt punda E,JF, K, G, H ; quare erit arigulus EHK aequaiis angulo EGK ; redus autem eft angulus EGK ; redus igitur eft angulus EHK ; quare contingit EH circulum in H.
Propofitio Peippi alt ter enunciari potefc hoc mo do.
P R O P» Pah, i. Fig „ i«
Sit circulus ABC et recta BC circulo occurrcns in B, C; fitque re£la AD circulum contingens in A, et reclae BC occurrens in D , bifariam fece- turBCinE, et occurrat juncta AE
T circulo
I4S ESSAYS AND OBSERVATIONS
circulo in G; per punctum D du- catur quaevis re&a circulo occur- rens in F, H; et GF, GH, jungan- tur reftae BC occurrentes in K, L ; erit EK aequalis ipli EL.
Fadum jam fit, et ipfi KL parallela duca- tur HM redis GF, GAoccurrens in M, X; et bifariam fecetur FH in N, et jungantur NE, NX, NA et AH.
Quoniam eft EK aequalis ipfi EL, erit et MX aequalis ipfi XH ; eft autem FN ae¬ qualis ipfi NH 5 parallelae igitur funt redae NX, FM ; quare erit angulus HNX aequalis angulo HFM, hoe eft, angulo HAX ; in eir- culo igitur funt punda A, N, X, H : eft igitur angulus ANH aequalis angulo AXH, hoc eft, angulo AEL ; quare in circulo funt pun¬ da A, E, N, D ; contingit igitur AD cireu- lum [per Lem. praec.] in A, quod quidem. ita fe habet.
Componetur autem fic. Quoniam contin¬ git DA circulum in A, in circulo funt pun- da A, E, N, D [per Lem. praec.] ; quare e- rit angulus AND aequalis angulo AED, hoc eft angulo AXH 5 in circulo igitur funt pund-
da
PHYSICAL and LI TER R Y.
*47
€ta A, N, X, H ; quare erit angulus HNX aequalis angulo HAX, hoc eft, angulo HFM; parallelae igitur funt reftae NX, FM ; et quo- niam eft FN equalis ipfi Nil, erit et MX ae¬ qualis ipft XH, quare erit et EK aequalis ipft EL. E. D.
Alias quoque propofi tones hide fpeblantes ex- cogitavi> quarum aliquot huic Jubjicere mfum ejl.
PROP. I. Tab. i. Fig. 4.
Sit circulus ABC, et re<5ia AB circulo occurrens in A, B; et fit C pundtum in circumferentia circuli ; jungan- tur CA, CB, fitque redta DE paral- lela redtae AC, redlis AB, CB oc¬ currens in D, E ; per pundtum D clucatur quaevis recta circulo oc¬ currens in F, G ; et CF, CG jun- eantur redtae DE occurrentes in
O
H, K ; erit redtangulum HEK ae- quale redtangulo CEB.
Factum
s48 ESSAYS and OBSERVATIONS
Factum jam fit, et jungantur BH, BF? Quoniam eft redtangulum HEK aequaie re- dtangulo CEB, in circulo funt pundta K, H, C, B 3 qaare erit anguius BHD aequalis an¬ gulo BCG, hoc eft, angulo BED: in circu¬ lo igitur funt pundta B, H, F, D3 aequalis igi- tur eft anguius ADH angulo CFB, hoc eft, angulo CAB 3 quare erit DE parallela redtae ACe Quod quidem ita fe liabet.
Componetur autem fic. Quoniam eft re- fta DE parallela redtae AC, erit anguius ADH aequalis angulo CAB, hoc eft, angulo CFB: in circulo igitur funt pun din B, H, F, D 3 quare erit anguius BHD aequalis angu¬ lo BFD, hoc eft, • angulo BCG : in circulo igitur funt pundta K, H, C, B3 quare erit re¬ dtangulum HEK aequaie redtangulo CEB* Q_ E? Do
L E M M A.
Sint recdae A, B. C, D ; E,F, G, H ; Ur- quo ut A ad B, ita C ad D, et ut E ad F, ita G ad H ; erit reUangulum - A iri E ad reUangulum B in F, ut
rectangulum
PHYSICAL and LITERARY. 143
rectangulum G in G ad rectangulmn DinH. ,
it *
Efi: enim redtangulum A in E ad redtangu- lum B in E, ut A ad B, hoc eft, ut C ad^D, hoc eft, ut rectangulum C in G ad redtangu- lum D in G 5 et eft redtangulum B in E ad redtangulum B in F, ut E ad F, hoc eft, ut G ad H, hoc eft, ut redtangulum D in G ad redtangulum D in FI : quare, ex aequo, erit redtangulum A in E ad redtangulum B in F, ut redtangulum C in G ad redtangulum D in FL Q^E. Do
P R O P. IL Fig. 5. Tab. 1.
Sit circulus ABC, et re<5fca AB circa- lo occurrens in A, B; et fit C pun- &.um in circumferentia circuit, et CA, CB jungantur, et fit puii&um D in refta AB, fitqire BE ad BC ut BD ad DA ; per pun Pram D ducatur quaevis redta circulo occurrens in F, G; et CF, CG jungantur rectae AB occiirrentes in H, K; erit rectangu-?
KC • luni
i5o ESSAYS AND OBSERVATIONS
lum HAK ad re&angulum HBK, ut quadratum ex AC ad redlangu- lum CBE,
Faftum jam fit, et ducatur DL parallels reftae AC reftis CB, CF, CG occurrens in L, M, N ; et per punftum L ducatur parallels reftae AB reftis CF, CG occurrens in O, P.
Quoniam eft reftangulum HAK ad reftan- gulum HBK, ut quadratum ex AC ad re¬ ftangulum CBE, erit, alternando, reftangu- lum HAK ad quadratum ex AC, ut reftan¬ gulum HBK ad reftangulum C^iV. Quoni¬ am vero eft OL ad LM, ut HA ad AC, et PL ad LN, ut KA ad AC ; erit [per Lem. praec.] reftangulum OLP ad reftangulum MLN, ut reftangulum HAK ad quadratum ex AC, hoc eft, ut reftangulum HBK ad re¬ ftangulum CBE ; et, invertendo, erit reftan- gulum MLN ad reftangulum OLP, ut re¬ ftangulum CBE ad reftangulum HBK; eft autem reftangulum OLP ad quadratum ex CL, ut reftangulum HBK ad quadratum ex BC ; quare erit reftangulum MLN ad qua¬ dratum ex CL, ut reftangulum CBE ad qua¬ dratum ex BC, hoc eft, ut Be, ad BC ; et quoniam eft BE ad BC, ut BD aa DA, hoc
PHYSICAL and LITERARY.
1 53
eft, ut EL ad LC, hoc eft, ut redangulum CLB ad quadratum ex CL ; erit redangu- lum MLN ad quadratum ex CL, ut redan- gulum CLB ad quadratum ex CL : eft igitur redangulum MLN aequale redangulo CLB. Quod quidem [per Prop . praec.] ita fe habet, Componetur autem fie. Quoniam eft re- dangulum MLN, aequale redangulo CLB, erit redangulum MLN ad quadratum ex CL, ut redangulum C.LB, ad quadratum ex CL, hoc eft, ut BL ad LC ; et quoniam eft: BL ad LC, ut BD ad DA, hoc eft, ut BE ad BC, hoc eft, ut redangulum CBE ad quadratum ex BC, erit redangulum MLN ad quadratum ex CL, ut redangulum CBE ad quadratum ex BC : eft autem quadratum ex CL ad redangulum OLP, ut quadratum ex BC ad redangulum HBK ; quare erit re¬ dangulum MLN ad redangulum OLP, ut redangulum CBE ad redangulum HBK ; et, invertendo, erit redangulum OLP ad redan¬ gulum MLN, ut redangulum HBK ad re¬ dangulum CBE. Quoniam vero eft HA ad AC, ut OL ad LM, et KA ad AC, ut PL ad LN, erit [per Lem. praec.] redangulum HAK ad quadratum ex AC, ut redangulum OLP ad redangulum MLN, hoc eft, ut redan-
gulum
j 5 2 ESSAYS AND OBSERVATIONS
o-ulum HBK ad retdanaiulum CBE, et, al- ternando, erit reclangulum HAK ad redan- gulum HBK, ut quadratum ex AC ad re- dtangulum CBE. CE E. D.
PROP. III. "Tab. i. Fig. 6.
Sit circulus ABC et recta AB circuit? occurrens in A, B ; et fit C pundium in eircumferentia circuit ; e i. CA, CB jungantur, et fit pundtum D in redta AB, fitque quaevis redta EF rectis CA, CB occurrens in E, F ; et fit FG ad CF, ut DB ad DA. ; per pundtum D ducatur quaevis recta circulo occurrens in H, K ; et CH, CK jungantur redtae EF occur- rentes in L, M ; erit redtangulum LEM ad reclangulum LFM, ut quadratum ex EC ad reclangulum
CFG.
Factum jam fit, et ducatur DN parallels reftae AC reftis CB, CH, CK occurrens in
N,0>
PHYSICAL and LITERARY,
N, O, P; et per pundtum N ducatur parallels, redtae EF, redtis CO, CP occurrens in Q. R3 Qooniam eft redtangulum LEM ad re¬ dtangulum LFM, ut quadratum ex EC ad redtangulum CFG, erit redtangulum LEM ad quadratum ex EC, ut redtangulum LFM ad redtangulum CFG. Quoniam vero eft QN ad NO ut LE ad EC, et RN ad NP ut ME ad EC ; erit [per Lem. ad Prop. 2,1 redtangulum QNR ad redtangulum ONP, ut redtangulum LEM ad quadratum ex EC, hoc eft, ut redtangulum LFM ad redtangulum CFG : et, invertendo, erit re¬ dtangulum ONP ad redtangulum QNR, ut redtangulum CFG ad redtangulum LFM: eft aufem redlangiilum QNR ad quadratum ex CN, ut redtangulum LFM ad quadratum ex CF ; quare erit redtangulum ONP ad qua¬ dratum ex CN, ut redtangulum CFG ad qua¬ dratum ex CF, hoc eft, ut FG ad CF : et quoniam eft FG ad CF ut DB ad DA, hoc eft, ut BN ad NC, hoc eft., ut redtangulum CNB ad quadratum ex CN ; erit redtangu¬ lum ONP ad quadratum ex CN, ut redtan¬ gulum CNB ad quadratum ex CN : eft igi- tur redtangulum ONP aequale redtangulo CNB. Quod quidem [per Prop . i.J ita fc habet* U Componetur
I
i £4 ESSAYS and OBSERVATIONS
t
Componetur autem fie. Quoniam eft re¬ danguium ONP aequale redangulo CNBy erit redanguium ONP ad quadratum ex CN, ot redanguium CNB ad quadratum ex CN, hoc eft, ut BN ad NC : et quoniam eft BN ad NC ut BD ad DA, hoc eft, ut GF ad FC, hoc eft, et redanguium CFG ad qua¬ dratum ex CF ; erit redanguium ONP ad quadratum ex CN ut redanguium CFG ad quadratum ex CF : eft autem quadratum ex CN ad redanguium QNR, ut quadratum ex CF ad redanguium LFM ; quare erit redan¬ guium ONP ad redanguium QNR, ut re¬ danguium CFG ad redanguium LFM : et, invertendo, erit redanguium QNR ad re¬ danguium ONP, ut redanguium LFM ad redanguium CFG. Quoniam vero eft LE ad EC ut QN ad NO, et ME ad EC ut RN ad NP ; erit [per Lem. ad Prop. 2.] redangu- lum LEM ad quadratum ex EC, ut redan- gulum QNR ad redanguium ONP, hoc eft, ut redanguium LFM ad redanguium CFG : et, alternando, erit redanguium LEM ad re¬ danguium LFM, ut quadratum ex EC ad redanguium CFG. Q^E. D.
Corollarium*
I
PHYSICAL and LITERRY. 155
Corrolarium. Sit circulus ABC (Tab. 1. Fig. 6.) et redta AB circulo occurrens in A, B3 et fit C pundtum in circumferentia cireuli, et CA, CB jungantur; fitque redta EF redtis CA, CB occurrens in E, F; in AB produdbi fumatur pundtum D, ut fit DB ad Dx4, ut quadratum ex CE ad quadratum ex CF; bi- fariam fecetur EF in T, et per pundtum D ducatur quaevis redta circulo occurrens in H, K, et CH, CK jungantur redtae EF occurren- tes in L, M3 erit LT aequalis ipfi TM.
Sit FG ad FC ut DB ad DA. Quoniam eft redtangulum CFG ad quadratum ex CF, utFGadFC, hoc eft, utDBadDA; et eft DB ad DA ut quadratum ex CE ad quadra- :um ex CF : erit redtangulum Ch G ad quadra¬ tum ex CF ut quadratum ex CE ad quadra¬ tum ex CF : eft igitur quadratum ex CE ae- quale redtangulo CFG 3 eft autem [per P?*op. praec.] redtangulum LEM ad redtangulum. LFM ut quadratum ex CE ad redtangulum CFG 3 quare erit redtangulum LEM aequa- le redtangulo LFM : erit igitur EL ad LF ut FM ad ME, et, componendo, erit EF ad FL ut EF ad EM 3 aequalis igitur eft EM ipfi FL: et quoniam eft ET aequalis ipfi TF, erit LT aequalis ipfi TM, Q^E, D.
PROP.
jij 6 ESSAYS and OBSERVATIONS
PROP. IV. Tab. i. Fig. 7.
Sit re&a AB circulo occurrens in A, B ; et fmt rectae AC, BC eirculum contingentes in A, B ; et per quod-? vis punctum D in AB ducatur DE parallela re£tae AC, rectae BC occur¬ rens in E. Si per punctum D ducatur quaevis redta circulo occurrens in F , G; et CF, CG jungantur, rectae DE occurrentes in Id, K; erit redtangu- lum HEK aequale quadrato ex DE,
Fadtum jam fit. Jungantur CD ; et oc- currat recta DF re£tis AC, EC in L, M; per M ducatur re 61 a reftis AC, DE parallela) pccurratque reftis CH, CE, CD, et AD, in N, O, P et pundtis.
Quoniam eft redlangulum HEK aequale quadrato ex DE, et eft reGangulum NMO ad quadratum ex MP ut reGangulum HEK gd quadratum exDE) erit reGangulum NMO aequale quadrato ex MP: et eft reGangulum
FMG'
(t ' -w *• -S
PHYSICAL and LITERARY. 157
FMG aequale quadrato ex MB ; quare erit reGangulum FMG ad reGangulum NMO, ut quadratum ex MB ad quadratum ex MP: et quoniam eft FL ad LC ut FM ad MN, et GL ad LC ut GM ad MO; erit [per Lem. ad prop. 2.] reGangulum FLG, hoc eft, qua¬ dratum ex AL, ad quadratum ex LC, ut re- Gan gul uni FMG ad reGangulum NMO, hoc eft, ut quadratum ex MB ad quadratum ex MP : eft autem quadratum ex MQ^ad qua¬ dratum ex MP, ut quadratum ex AL ad qua¬ dratum ex LC, hoc eft, ut quadratum ex MB ad quadratum ex MP ; quare erit MQaequa-
lis reGae MB: eft autem AC ad CB, ut MQ _
ad MB; aequalis igitur eft reGa AC reGae CB. Quod quidem verum eft, quoniam reGae AC, BC circulum contingunt in A, B punGis.
Componetur autem lie. Quoniam reGae AC, BC circulum contingunt in A, B punGis, e- rit reGa AC aequalis reGae BC : et eft MQ ad MB ut AC ad CB; quare erit MQ^ aequa¬ lis reGae MB; eft igitur quadratum ex MQae- quale quadrato ex MB, hoc eft reGangulo FMG; quare erit reGangulum FMG ad re- Gangulum NMO ut quadratum ex MQjid reGangulum NMO: et quoniam eft FL ad LC ut FM ad MN, et GL ad LC ut GM ad
MO;
?58 ESSAYS and OBSERVATIONS
MO; erit reftangulum FLG, hoc eft, qua¬ dratum ex AL ad quadratum ex LC ut re- dtangulum FMG ad rettangulum NMO, hoc eft, ut quadratum ex MQ^ ad reftangulum NMO: eft autem quadratum ex MQjid qua¬ dratum ex MP ut quadratum ex AL ad qua¬ dratum ex LC, hoc eft, ut quadratum ex MQ^ ad redtangulum NMO; aequale igitureft re^> Qangulum NMO quadrato ex MP : et quo- niam eft reclangulum HEK ad quadratum ex DE ut redtanguium NMO ad quadratum ex MP, erit redtangulum HEK aequale quadra¬ to ex DE. E. D.
PROP. V. Tab. i. Fig. 8.
»
Bit recta AB circulo occurrens in A, B, et lint rectae AC, BC circulum contingentes in A, B; per pundtum quod vis D in AB ducatur re£ta cir¬ culo occurrens in F, G; et CF, CG jungantur, redtae AB occurrentes in H, K ; erit reclangulum HAK ad reclangulum HBK, ut quadratum ex AD ad quadratum ex DB.
Fadtum
PHYSICAL and LITERARY. i59
Fadum jam fit. Et ducatur DL parallela r’edae AC, redis CB, CF, CG occurrens in L, M, N; et ducatur LO parallela redae AB, redlis CF, CG occurrens in O, P.
Quoniam eft redangulum HAK ad redan- gulum HBK, ut quadraturn ex AD ad qua- dratum ex DB, hoc eft, ut quadraturn ex CL ad quadraturn ex LB ; et efi: redangu¬ lum IT B f v ad redangulum GLP, ut quadra- turn ex CB ad quadraturn ex CL ; ent re¬ dangulum HAK ad redangulum OLP, ut quadraturn ex CB vel AC ad quadraturn ex BL: et, alternando, erit redangulum HAK ad quadraturn ex AC, ut redangulum OLP ad quadraturn ex BL. Rurfus, quoniam eft OL ad LM ut El A ad AC, et PL ad LN ut KA ad AC; erit [Lem. ad prop. 2.] redan¬ gulum OLP ad redangulum MLN, ut re¬ dangulum EIAK ad quadraturn ex AC, hoc eft, ut redangulum OLP ad quadraturn ex BL. Eft igitur redangulum MLN aequale quadiato ex BL, hoc eft, quadrato ex DL. Quod quidem [Prop, praec.] verum eft.
Componetur autem fic. Quoniam eft re- ftangulum MLN aequale [Prep, praec.] qua¬ drato ex DL, hoc eft, quadrato ex BL, erit redangulum OLP ad redangulum MLN
ut
360 ESSAYS a d OBSERVATIONS
ut redan gulum OLP ad quadratum ex BL 2 quoniam vero eft HA ad AC ut OL ad LivI, et K A ad AC ut PL ad LN ; erit redangulum [per Lem. ad prop. 2.] HAK ad quadratum ex AC, ut redangulum OLP ad redangu- lam MLN, hoc eft, ut redangulum OLP ad quadratum ex BL : et alternando, erit dangulum HAK ad redangulum OLi , ut quadratum ex AC vel BC ad quadratum ex BL : eft autem redan gulum OLP ad re dan - gulum HBK, ut quadratum ex CL au qua¬ dratum ex CB 5 quare erit redangulum HAK ad redangulum HBK, ut quadratum ex CL ad quadratum ex BL, hoc eft, ut quadratum ex AD ad quadratum ex DB. QHE. D*
P Pv O P. VL Tab. 1. Fig. 9.
Sint dime reftae AC, BC, circulurrt contingentes in A, B, et fit D pun- ctura in recta AB; fit recta EF, re¬ als AC, BC occurrens in E, F, et junUa CD in G : fi per punttum D ducatur quaevis recta circulo occur¬ rens in H, K, et CR, CK jungen- tur, re£iae EF occurrences in L, M-j
PHYSICAL and LITERARY. i6i
erit: reciangulum LEM ad redtangii- lam LFM, ut quadratum ex GE ad quadratum ex GF0
Factum jam fit. Per pundum D ducatur reda parallela redae AC, redis CB, CH CK occurrens in N, O, P ; per pundum N ducatur reda parallela redae EF, redis CH, CK occurrens in CQ R ; et per pundum F ducatur FS parallela redae AC, redae CD occurrens in S.
Quoniam eft redangulum LEM ad redan- gulum LFM, ut quadratum ex EC ad qua¬ dratum ex FG, hoc eft, ut quadratum ex EC ad quadratum ex FS ; erit, aiternando, redangulum LEM ad quadratum ex EC, ut redangulum LFM ad quadratum ex FS: quo¬ niam eft redangulum QJNR ad quadratum ex CN, ut redangulum LFM ad quadratum ex CF, et eft quadratum ex CN ad quadra¬ tum ex ND, ut quadratum ex CF, ad qua¬ dratum ex FS; erit redangulum QNR ad quadratum ex ND, ut redangulum LFM ad quadratum ex FS, hoc eft, ut redangu¬ lum LEM ad quadratum ex EC. Quoniam vero eft LE ad EC ut QN ad NO, et ME
X ad
' 162 ESSAYS and OBSERVATIONS
ad EC ut RN ad NP, erit [per Lem ad prop. 2.] reftangulum LEM ad quadratum ex EC, ut redlangulum QNR ad redtangulum ONP ; quare erit reftangulum QNR ad re&angulum ONP, ut redtangulum QNR ad quadratum ex ND : eft igitur reftangulum ONP ae qua¬ le quadrato ex ND. Quod quidem [per Prop . 4.] verum eft.
Componetur autem fic. Quoniam eft re- dtangulum ONP aequale quadrato ex ND, erit redtangulum QJSTR ad redtangulum ONP ut redtangulum QNR ad quadratum ex ND; et quoniam eft LE ad EC ut QN ad NO, et ME ad EC ut RN ad NP, erit reftangulum LEM ad quadratum ex EC, ut recftangulum QNR ad redtangulurn ONP, hoc eft, ut reftangulum QNR ad quadratum ex ND. Quoniam vero eft redtangulum QNR ad qua¬ dratum ex CN, ut reftangulum LFM ad qua¬ dratum ex CF, et eft quadratum ex CN ad quadratum ex ND, ut quadratum ex CF ad quadratum ex FS ; erit redtangulum QNR ad quadratum ex ND, ut redtangulum LFM ad quadratum ex FS; quare erit redangulum LEM ad quadratum ex EC, ut redlangulum LFM ad quadratum ex FS : et, alternando, erit reftangulum LEM ad redlangulumLFM,
ut
PHYSICAL and LITERARY. 163
ut quadratum ex EC ad quadratum ex FS, hoc eft, ut quadratum ex EG ad quadratum ex FG. Q^E. D.
PROP. VII. Tab. 2. Fig. 10.
Sit refta AB circulo occurrens in A, B, et in ipla lumatur pundtum C, et ducatur CD circuio occurrens in D, E,/ et AD, BE jungantur fibi mutuo occurrentes in F ; ducatur CG parallela redtae AF, redtae BF occurrens in G : ii per pundtum C ducatur quaevis redta circulo occur¬ rens in H, K, et FH, FK jungantur, redtae CG occurrentes in L, M; erit rectangulum LGM aequale quadra- to ex CG.
Fadtum jam fit. Jungantur CF, et oc- currat redta CH redtis AF, BF in N, O; per pundtum O ducatur redta parallela redtae CG, vel AF, redtis FL, I'M, FC occurrens in P, Q, R, et redtis AB, DE in S, T.
Quoniani
1 64 ESSAYS and OBSERVATIONS
Quoniam eft redangulum LGM aequale quadrate ex CG, et eft redangulum POQ^ad quadratum ex OR, ut redangulum LGM ad quadratum ex CG; erit redangulum POQ_ aequale quadrato ex OR : et eft redangulum HOK aequale redangulo EOB ; quare erit redangulum HOK ad redangulum POQ, lit redangulum EOB ad quadratum ex OR : et, quoniam eft PIN ad NF ut PIO ad OP3 et KN ad NF ut KO ad O Qj erit j per Lem 0 pd prop, 2) redangulum HNK ad quadra¬ tum ex FN, ut redangulum XTOK ad redan¬ gulum PQQ^ hoc eft, ut redangulum EOB ad quadratum ex OR : eft autem quadratum ex FN. ad redangulum AND, ut quadratum ex OR ad redangulum SOT ; quare erit re¬ dangulum HNK ad redangulum AND, ut redangulum EOB ad redangulum SOT : et quoniam eft redangulum HNK aequale re- dangulo AND, erit redangulum EOB ae¬ quale redangulo SOT; quare erit OB ad OS ut QT ad OE, hoc eft, erit BG ad GC ut GC ad GE : eft igitur angulus GEC aequalis angulo GCB, hoc eft, angulo BAD ; quod quidem ye rum eft, quoniam punda A,B,E,D fppt in drculo,
Componetur
Jr . .
PHYSICAL and LITERARY. 165
Componetur autem fie. Quoniam punfia A> B, E, D iunt in circulo, erit angulus GEC aequalis angulo BAD, hoc eft, angulo GCB; quare erit EG ad GC ut GC ad GE, hoc eft, ent OB ad OS ut OT ad OE : eft igitur re- Aangulum SOT aequale reftangulo EOB, hoc eft, redanguloHOK; quare erit redtangu- lumEIOK ad quadratum ex OR, ut redtangu- lum SOT ad quadratum ex OR, hoc eft, ut rectangulum AND, velHNK, ad quadratum ex FN. Quoniam vero eft FIN ad NF ut HO ad OP, et KN ad NF ut KO ad OQ, erit redtangulum HNK ad quadratum ex FN, ut redtangulum HOK ad re&angulum POQj quare erit redtangulum HOK ad redtangulum POQ ut redtangulum HOK ad quadratum ex OR ; eft igitur redtangulum POQ^aequa- le quadrate ex OR : et quoniam eft redtan¬ gulum LGM ad quadratum ex GC, ut re¬ dtangulum POQ^ ad quadratum ex OR, erit redtangulum LGM aequale quadrato ex GC. QJE. D.
PROP. VIII. rak2.Fig.1u
Sit recta AB circulo occurrens in A} B, et in AB fumatur punctum C,
ducatur
,66 ESSAYS and OBSERVATIONS
ducatur CD circulo occurrens in D, E, et jungantur AD, BE, fibi mu- tuo occurrentes in F ; per pun- dfcum C ducatur quaevis recta cir¬ culo occurrens in G, H, et FG, FH jungantur, re£tae AB occurren- tes in K, L; erit reftangulum KAL ad re&angulum KBL, ut quadrature ex AC ad quadraturn ex BC\
Fad am jam fit. Ducatur CM parrallela redae AF, redis FB, FK,FL occurrens in M, N, O 5 et per pundum M ducatur parallela redae AB, redis FK, FL occurrens in P. Ch Quoniam eft redanguium KAL ad redan- gulum KBL, ut quadraturn ex AC ad qua- dratum ex BC, hoc eft, ut quadraturn ex FM ad quadraturn ex BM et eft redangu- lum KBL ad redanguium PMQ^S ut quadra- turn ex FB ad quadraturn ex FM ; erit re? dangulum KAL ad redanguium PMQ^, ut quadraturn ex FB ad quadraturn ex BM, hoc eft, ut quadraturn ex AF ad quadraturn ex CM : et. alternando, erit redanguium KAL
PHYSICAL and LITERARY. 167
ad quadratum ex AF, ut redtangulum PMQ ad quadratum ex MC. Quoniam vero eft PM ad MN ut KA ad AF, et Q_M ad MO ut LA ad AF ; erit [per Lem. ad prop. 2.] re¬ dtangulum PMQjid redtangulum NMO, ut redtangulum KAL ad quadratum ex AF, hoc eft, ut redtangulum PMQjid quadratum ex CM : eft igitur redtangulum NMO aequale quadrato ex CM. Quod quidem [per Prop . praec.] verum eft.
Componetur autem fie. Quoniam eft re¬ dtangulum NMO aequale quadrato ex MC, erit redtangulum PMQad redtangulum NMO ut redtangulum PMQ^ad quadratum ex MC ; quoniam vero eft KA ad AF ut PM ad MN, ct LA ad AF ut QM ad MO ; erit redtangu¬ lum KAL ad quadratum ex AF, ut redtan¬ gulum PMQjjd redtangulum NMO, hoc eft, ut redtangulum PMQjid quadratum ex MC; et, alternando, erit redtangulum KAL ad re¬ dtangulum PMQ^ ut quadratum ex AF ad quadratum ex MC, hoc eft, ut quadratum ex FB ad quadratum ex BM: et eft redtangu¬ lum PMQ^ ad redtangulum KBL, ut quadra¬ tum ex i' M ad quadratum ex FB ; quare erit redtangulum KAL ad redtangulum KBL ut
eft
i68 ESSAYS and OBSERVATIONS
quadratum ex FM ad quadratum ex BM, hoc eft ut quadratum ex AC ad quadratum ex BC.
E. D.
PROP. IX. Tab. 2. Fig. 12.
Sit recta AB circulo occufrens in A. B, et in AB fumatur punctum C ; per C ducatur redta circulo occurrens in D,E; et AD, BE jungantur, fibi mutuo occurrentes in puncto F ; et fit recta GH reefs AF, BF occur¬ rens in G, H, et junbta FC in K : fi per punftum C ducatur quaevis recta circulo occurrens in L, M, et FL, FM jungantur, rectae GH oc¬ currentes in N, O; erit rectangulum OGN ad rectangulum OHN, ut quadratum ex GK ad quadratum- ex HK.
Fadtum jam fit. Ducatur per pundtum C parallela redtae AF redtis FB, FL, FM oc¬ currens in P, Q^Rj et per pundtum P du-
catuf
PHYSICAL and LITERARY. 169
catur parallela redae GPI redis F.L, FM 00 currens in S, T, et ducatur HV parallela re¬ dae PC redae FC occurrens in V.
Quoniam eft redangulum OGN ad redan- gulum OHN, ut quadratum ex GK, ad qua¬ dratum ex HK, hoc eft, ut quadratum ex PG ad quadratum ex HV 5 erit, alternando* redangulum OGN ad quadratum ex FG, ut redangulum OHN ad quadratum ex HV : quoniam eft redangulum SPT ad quadratum ex PF, ut redangulum OHN ad quadratum ex FIF, et eft quadratum ex PF ad quadratum ex PC, ut quadratum ex HF ad quadratum ex PIV <y erit redangulum SPT ad quadratum ex PC, ut redangulum OHN ad quadratum ex HV, hoc eft, ut redan gulum OGN ad quadratum ex FG. Quoniam vero eft NG ad GF ut SP ad PQ^ et OG ad GF ut TP ad PR, erit [per Lem . ad prop. 2.] redan gulum OGN ad quadratum ex FG, ut rectangulum SPT ad redan gulum QPR ; quare erit re¬ dan gulum SPT ad redangulum QPR, ut redangulum SPT ad quadratum ex PC. Eft igitur redangulum QPR aequale quadrate ex PC. Quod quidem [per Prop . 7.] verum eft,
Componetur autem fic. Quoniam eft re¬ dangulum QPR aequale quadrate ex PC3 erit
Y Redangulum
ESSAYS and OBSERVATIONS
redangulum SPT ad redangulum QPR, ut redangulum SPT ad quad rat u in ex PC : et quoniam eft NG ad PG ut SP ad PQ , et OG ad GF ut TP ad PR, erit redangulum OGN ad quadratum ex FG, ut reftangulum SPT ad redangulum QPR, hoc eft, ut redangu- lum SPT ad quadratum ex PC. Quoniam vero eft redanguium SPT ad quadratum ex PF, ut redangulumvOHN ad quadratum ex HF, et eft quadratum ex FP ad quadratum ex PC, ut quadratum ex HF ad quadratum ex HV 3 erit redangulum SPT ad quadratum ex PC, ut recftangulum OHN ad quadratum ex HV : quare erit reftangulum OGN ad quadratum ex FG, ut redangulum OHN ad quadratum ex HV : e£, alternando, erit re- dangulum OGN ad redangulum OHN, ut quadratum ex FG ad quadratum ex HV, hoc eft, ut quadratum ex GK ad quadratum ex HK. Q^E. D,
SCHOLIU Mo .
Prcpo/itiones ante diciae in Jediionibus quoque comas obtinento Idque reput anti fequentia ob- fervata funt theoremata , a quibus aha etiarn multa dednci pojjunt .
Theor.
PHYSICAL and LITERRY. 171
Theor. 1. Sint [Tab. 2. Fig. 13.] duae re~ . diae AB, CD, fedhonem conicam contingentes in A, C; et A,C jungantur ; Jit quaevis redla, redlis AB, CD, AC occurrens in B, D, E, et fedlioni in F, G pundlis ; erit redlangulum BFD ad reciangidum BGD, ut quadratum ex EF ad quadratnm ex EG.
Theor. 2. Sit [Tab. 2. Fig. 14.] retta AB fedlionem conicam contingens in A, et reel a CD fedhom occurrens in C, D pundlis ; et jungan- iur AC, AD ; occurratque quaevis redla redlis AB, CD, AC, AD in E, F, G, H, et fedlioni in K, L pundlis ; erit redlangulum EKF ad rediangulum ELF, ut reciangidum GKH ad redlangulum GLH.
Theor. 3. hi [Tab. 2. Fig. 13.] fedlione conica infer ibantur duae redlae AB, CD; et jungantur AC, BD; occurratque quaevis redla redlis AB, CD, AC, BD, in E, F, G, H, et fe¬ dlioni in K, L pundlis ; erit redlangulum EKF ad redlangulum ELF, ut redlangulum GKH ad redlangulum GLH.
Ex hifee patet fequens theorema .
Si in fedlione conica infer ibatur quaevis fi- gura quadrilatera^ cue us tria la era per data pundla in redla tranfeunt ; reliquum latus , vel
ad
,72 ESSAY'S and OBSERVATIONS
ad datum punBum verget, vel parallelum erit pe¬ tit tone data.
Ut finem fact am ; theorema mum tantum fubjiciam , obfervatione quidem baud indignum ; et quod etiam in feBionibus conicis, paululum mu- tatum , obtinet ; unde aha, a nullis, quod fciarn, Jcriptoribus geometricis obfervata , deriventur,
Sit AB diameter circuit [Tab. 2. big. 16.17.] pofitione dati, occurratque reBa CD ipfmor- fnalis in dato punBo C ; non fit autem C cen¬ trum circuit, et datum Jit punBum D m i,Ba CD ; fitque quadratum ex CD majus rcBangulo ACB,/ fit punBum C intra circulum ; fi vero extra, fit quadratum ex CD minus reBangulo ACB ; producatur DC ad E, ut fit CE ae- qualis ipfi CD ; dabuntur duo puvBa F , G ex¬ tra reBam DE, ut, fi ab ipfis wfieBantur reBas EH, GH ad punBum quodvis H in circulo, reBae DE occur rentes vn K,L, erit fumma quadratoruin ex DK, EK ad reBanguhm DLE in rations
data.
*
/
■
/
PHYSICAL and LITERARY. 173
Art. IV.
Of the Caufe of the Variation of the Obliquity of the Ecliptic, by Colin McLaurxn, late Fellow of the Royal Society , and ProfeJJor of Mathematics in the Univerf ty of Edinburgh,
Til E French aftronomers in Peru , and Dr* Bevis at London , and others elfe- where, have endeavoured to determine the
1
obliquity of the ecliptic with greater accu¬ racy than former aftronomers had attained to. The refult of their obfervations makes it to be now about 230 29^ 28"^. It had been for fome time reckoned 230 29' 29" 3 and before
that, 230 29" 30'" ; and, by fome antient aftro¬ nomers, 19 or 20 minutes greater. Meff. Cab - fmi and Bradley had found it to vary a little : and this has given occalion to a notion, that it is decreafing continually ; that there was a time when the axis of the earth lay in the plane of the earth’s orbit ; that it has been gradually riling, till now it contains an angle
with this plane of 66° 30' 3 if 5 and that, in
a
174 ESSAYS AND OBSERVATIONS
a long period of time, it will become perpen¬ dicular to this plane ; when we fhall have everywhere a continual spring throughout the year. The Chevalier de Louville and M. Godin pretend even to compute the pe¬ riod of this motion ; the former having gone to Marfeitles to meafure the variation of this obliquity from the time when Piiheas meafu- red it at the fame place 2000 years ago ; he found it diminifhed by 20", and thence efti- mates the period of this motion to be above 2 millions of years. M. Godin has fince found, that, from the year 165510 1734, it decreafed 55", by comparing an obfervation of old M. Cajjinis with his own ; and thence deduces the period to be 1944000 years. And hence fome authors have endeavoured to explain feveralold Egyptian and Babylonijh traditions, concerning the fun’s having rifen twice in the weft ; and have taken occafion to indulge themfelves in feveral {peculations,
1 have formerly feen a piece that was printed many years ago, but never, I think, publiftied ^ containing a fyftem and a kind of liturgy for the Pantheifts or Spinofifts $ wherein the author warmly efpoufed this no¬ tion, concerning the variation of the obliqui¬ ty
PHYSICAL and LITERARY.
l7$
ty of the ecliptic, and endeavoured to improve it, for fupporting his favourite principle of equality ; imagining, that, in the compafs of this period, the Rate and phenomena of all places on the earth would be upon the whole equal ; an opinion that feems to fuit the pa¬ trons of a biind and abfolute neceffity : but, whatever be thought of this continual and regular diminution of the angle in which the ecliptic and equator interfed each other, it is certain that fuch an equality would not be the confequence of it. Places of the earth would Rill have their peculiarities : the peo¬ ple at the equator would have their days and nights conRantly equal, how great or fmall foever the obliquity of the ecliptic were ; for this is a neceffary confequence of their de- fcribing a great circle of the earth by the di¬ urnal motion, that is always bifedted by the boundary of light and darknefs, which is like wife a great circle in confequence of a ne- cefiary truth. The poles would have their fix months day and fix months night, as now i with this further Angularity, that, when the axis lay in the plane of the ecliptic, the heat mult have been far more intolerable at the poles than is now known in any part of the
t earth5
i7G ESSAYS and OBSERVATIONS
earth, or could be known in any other part of it, during this long period : for the fun mud: have then continued ten days toge¬ ther within 5° degrees of the zenith of the poles, without any intermiffion of night, or a- batement from a leffer elevation, at which al¬ titude he never continues above 40' in the equinoctial days at the equator ; a peculiarity as Angular as it would have been fatal to the polar regions. The prefent obliquity of the ecliptic gives evidently great relief to the e- quatoreal regions ; as by it the fun is carried to both fides of the zenith during the year, and is not permitted to dart conftantly per¬ pendicular rays upon them. It is to it like- ways the more northern countries owe their fummer and harveft; which we are told is o- ver with them in two months, or very little more, while the fun's almoft continued and inceffant acftion ripens fruits which the heat of our fun, much lefs theirs, on the 10th of March , the equinoctial day, could never be able to accomplifh. Thus it ferves for dimi- nifhing, their heat at the equator where it was ufeful to leffen it, and for increa- fing it towards the polar regions where it was proper to ftrengthen it. But a regular
and
PHYSICAL and LITERARY. 177
and continued variation of the obliquity of the ecliptic would ruin fome parts of the world, and dilWb an order well eftablifhed in nature, without ferving the purpofe of the Pantheifts.
I would not take up your time in ma¬ king remarks on what is brought to fupport this dodtrine, from old fables of Egyptian or Babylonijh priefls delivered to Herodotus , that feem to have flown from their vanity. What is fhewn by Dr. Shaw , in his travels, con¬ cerning the gradual riling of the furface of the land of Egypt , from the annual fediments of the Nile , leems to afford a much better ar¬ gument againlt their boa fled antiquity in Egypt , than any thing can be drawn from aflronomical obfervations, to fupport a va¬ nity fo univerfal, that we need not go very far from home to find abfurd enough in- fiances of it. As for what is (aid of Pitheas and other antients, their wrong notions con¬ cerning the refractions and the imperfecti¬ on of their inftruments, render any conclu- lions on fo nice a fubjedt, drawn from their obfervations, dubious. We ought to fhew* more regard to the modern obfervations brought for this dodtrine, than to reprefent
Z fihens
i;8 ESSAYS and OBSERVATIONS
them in a level with the fables vented by the priefts of Egypt . According to feverai modern obfervations, the obliquity of the ec¬ liptic varies : but we are to remember, that even the noble Tycho Brache committed an error of 18', in drawing his meridian in his ifland of Teraniburgum 5 and, from his errone¬ ous opinions concerning the refraction of the atmofphere, made the mean diftance of the moon lefs by 4 femidiameters of the earth than it really is. It is true, Mr. GaJJim s ob- fervation in 1655, compared with late ones9 makes it vary at the rate of 55" in 79 years. Let us therefore fee, if a variation, fuch as that arifes from Meff Caffini’s and Godins obfervations, be not a confequence of prin¬ ciples already eftablifhed in the folar fyftem ; and offer fome hints of a method by which it may be afcertained whether this be the juft folution of this queftion, and how, from a proper feries of obfervations, made with great exaCtnefs, an improvement and correction in geography and navigation may be deduced from this inquiry, by bringing the theory of the earth's motion in her orbit, and particu¬ larly what relates to the declination of the fun to greater perfection. This will be the
more
PHYSICAL and LITERARY. 179
more ufeful, that the ufual methods of ta¬ king the latitude of places by the fun’s me¬ ridian altitudes, fuppofes the tables of his de¬ clination to be perfectly juft ; whereas there is ground to doubt of their precifenefs.
Mathematical inftruments in general^ and fuch particularly as ferve for aftronomi- cal purpofes, have been, of late, brought to an exadlnefs never known in former times. Hence fome minute motions, or inequalities of motions, in the heavens, may be difcovered, that have hitherto efcaped the mod diligent obfervers. They had difcovered indeed lome motions that are very minute or flow, fuch as the preceflion of the equinoxes ; but this was owing to the continual increafe of the effedls of thofe very minute motions, which, tho’ infenfible in one revolution, become ve¬ ry manifeft in many revolutions. Motons of this kind are eafily found, and are accu¬ rately determined, by comparing diftant ob- fervations. But there are other minute mo¬ tions which are hard to be difcovered : thefe which do not grow up to be fenflble in a number of revolutions ; their effedt in one part deftroying their eflfedt in another part of a revolution. Of this kind is the mo¬
tion
jSo ESSAYS and OBSERVATIONS
I •
lion lately difcovered by Mr. Bradley , which, on this account, lay fo long concealed from aftronomers. Of the fame kind is the moti¬ on of the fixed flars, that ought to arife trom the parallax of the earth’s orbit. And of this kind I fufpedt the variation of the obliquity pf the ecliptic to be.
To proceed therefore to what I take to be the caiife of this motion, Sir ifaac Newton has found, that the fun and planets gravitate all towards each other mutually ; that it is neither the fun (according to the Coper ni* - can fyflem), nor the earth (according to Pto- Jomy ), that is the center of the fyflem, or fixed point ; but the center of gravity of the whole fyflem. That the fun therefore moves about this center : and that when Jupiter and Saturn , the two biggeft planets, are in the fame right line, on the fame fide of the fun ; the center of the fun will be, almofl a diameter of the fun, diflant from this fixed point. Hence, tho’ we fuppofe the earth to move always in the fame plane, the fun will appear to have different declinations at the time of the fold ice : and, as the obliquity of the ecliptic is determined always from the declination of the fun at the foiflice, it will
therefore
PHYSICAL and LITERARY. 18$
therefore appear to vary, but not in a manner that will accrefce and produce any fenfibie change in our ieafons ; but it will increafe and decreafe a little within fmalj limits, and its variation will principally depend on the pofition of Jupiter and Saturn to the fun and earth, and will nearly return to the fame ma¬ gnitude when thefe return to the fame pofi- tion, with refped; to one another, and to the foiftice. Jupiter has mo ft effect in produ¬ cing this variation ; and, if it be found to have a connexion or dependence on his pofition to the fun and earth, it will be an indication that this is the true caufe of the phenome¬ non.
Was the orbit of the earth perpendicular to the orbit of Jupiter , this variation would be much more confiderable than it is, and might amount to above half a degree, or a diameter of the fun. Suppofe [Tab. 2. Fig. 1 8.] RET to reprefent the orbit of the earth in fuch a cafe, C the common center of gra¬ vity of the fun and Jupiter , which we may confider as the center of the earth's orbit, be- caufe of the minutenefs of the earth compa¬ red with thefe, T the folftitial point, PTp the axis of the earth, IS the right line join-
i8z ESSAYS and OBSERVATIONS
ing the centers of the fun and Jupiter, which we funpofe perpendicular to the orbit of the earth, while the earth is in the lolftice T. Then, if Jupiter be at I, and the fun at S ; the angle PTS will be the complement of the fun’s greateft declination, or of the angle contained by the ecliptic and equator : but, if Jupiter be at i, and the fun at J ; the angle PT/ will be the complement of this declina¬ tion, and thefe would differ by the angle ST J, which, (becaufe CS is nearly equal to a femidiameter of the fun) might amount to 32'*
But, becaufe the angle contained by the orbits of Jupiter and the earth is fmall, the right line CS is feen very obliquely from the earth, and the variation of the obliquity thence arifing is fmall. The angle CTS is nearly to the inclination of Jupiter’s plane to the eclip¬ tic, as the femidiameter of the fun to the di- ftance of the earth from the fun : or the angle CTS is about of that inclination ; there¬ fore ST f, which is equal to 2CTS, may be fomewhat more than a minute. And this may be fufficient to account for any variation that is yet aifcovered by aftronomers. But, fince it may exceed one minute, it appears
PHYSICAL and LITERARY. 1 83
that it is of moment to have this theory pro- fecuted farther and afcertained : for an error of a minute, in a matter of fuch moment as the declination of the fun, which is an ele¬ ment in moft queftions in aftronomy, geogra¬ phy, and navigation, is not to be defpifed ; efpecially now when fo great exadlnefs in thefe matters is defired, and, I believe, may be obtained. Such a variation, however, can have no fenfible effect on our feafons ; and there feems to be no ground to apprehend, that our year will degenerate into a perpe¬ tual fpring in any period of time ; which, after all, would be far from being an advan¬ tage to us, or to the inhabitants of the earth in general.
A R T,
$84 ESSAYS and OBSERVATIONS
A R To V*
Concerning the fudden and furprifing Changes obferved in the Surface of JupiterV Body y
by the fame*
THERE have been mere fudden and furprifing changes obferved Gn the furface of Jupiter s body, than on any other planet in the fyftem. Cafjini has obferved feveral belts rife on his body in one hour’s time 3 and fpots, in very different forms, are often feen upon him. I could wifh that the Doiition of his fatellites were well confidered
a
when thofe changes happen : for, fince Ju¬ piter has four moons, fome of which are much nearer to him than our moon is to the earth 3 when they are all in conjunction or oppofition to one another, very great tides muft be produced in the ocean there, if there' be any 3 and there is ground to fufpedt that thefe ludden and great changes on his fur- face are owing to tides analogous to thofe we
call
v / n^- . IS. 03
. *• .r
4b
*
> i
'
/
*■
> ,/ '
- j ' *
*
PHYSICAL and LITERARY. 185
call fpring tides. Farther, the velocity with which Jupiter revolves on his axis, and the greatnefs of his body, mu ft contribute to the greatnefs of thele tides, and of the inunda¬ tions produced by them.
In Jupiter s fyftem, the theory of gravity difcovers itfelf in feme particulars more ma- nifeftiy than in any other part of the general fyftem. Jupiter is the only body that is, to fenfe, fpheroidical ; the axis being lefs than the diameter of the equator by Poftibly we may, by farther obfervations, difeoverthe effects of the tides likewife 5 or rather may learn, that effects already viftble and known proceed from them.
The a&ion of the fatellites upon one an¬ other produces fome irregularities in their motions ; and from this it is fuppofed that their eclipfes do not anfwer accurately to the times computed f om the tables. But there is another fource, I believe, of their irregu¬ larities. Jupiter s figure differs confiderably from a fphere ; and the gravitation towards him is not inverfely as the fquare of the di- ftance from his center. Nov/ this variation from the regular courfe of gravity may pro¬ duce fome inequalities in their motions. And,
A a in
i S 6 ESSAYS AND OBSERVATIONS
in order to judge of thefe, I have computed the law of gravity towards fuch a fpheroid as Jupiter ; and will fubjoin fome theorems on this fubjeft.
It feems fomewhat extraordinary, that in 130 years, fince Jupiter s fatellites were difcovered by Galileo , no eclipfe of any of thefe fatellites by one another has been ob- ferved. Such an eclipfe could hold but for a fmall time : but, as it is not difficult to com¬ pute nearly the time when they ought to hap¬ pen, it would be worth while to look for them ; fince this might contribute to render their theory more perfect; which is of io much ufe in afcertaining the longitudes of places. If it be found to be a phenomenon that paflfes over quickly, becaufe of their fwift motions 3 it may be the more ufeful, providing it can be feen.
No phenomenon feems more extraordi¬ nary, relating to Jupiter , than that, according to CaJJini , fome of his fpots revolve in lefs time than others ; the difference amounting to 4 . This is a phenomenon, of that kind, of which it is perhaps beft not to attempt any explication, till the fame be confirmed by more obfer various*
It
PHYSICAL and LITERRY. 187
It is worthy of our notice, that, from fe¬ deral phenomena, aftronomers conclude the Satellites to revolve on their axis, in the fame time that they revolve around their prima¬ ries ; by which means the exceeding great tides that would be produced in them are avoided. Thole arifing from their various di- ftances from the primaries, in their apfldes , may be fufficient for agitating their waters. The tides that would be produced in our moon, from this circumftance alone, ought to be confi derably greater than the tides pro¬ duced in our ocean ; and poffibly, by a care¬ ful attention to the limits of thofe black parts of the moon which formerly were confider- ed as feas, but, becaufe of cavities difcovered in them, with better telefcopes, are ill i peel¬ ed by many to be only large planes, fome decifion of this queftion might be obtained. Water is of too great importance, in natural operations, to fuppofe haftily any planet to be deprived of it ; tho’ we muft alfo allow that the variety of nature is not to be limited by our conceptions.
Theor.
i88 PHYSICAL and LITERARY.
* ' » •
Theor. I.
The gravity towards an oblate fpheroid in the axis produced, decreafes in a lefs proportion than that in which the fquare of the dihance from the center increafes : but the gravity in the plane of the equator de¬ creafes in a higher proportion than that in which the fquare of the dihance increafes.
The or. II.
Let b denote the femidiameter of the e* quator, c the dihance of the focus of the ge¬ nerating elhpfe from the center, d the di¬ hance of any body from the center of the fpheroid in the plane of the equator 3 and the gravity at the dihance d, will be to the gra- at the dihance b, as £2 ^ 9C 4
^ ' • x
to I + — - , &c. * * *
&c.
so h“ ’ 56 b*
A R T.
PHYSICAL and LITERARY. 189
Art. VI.
Obfervations on Thunder and Electricity , by Ebenezer McFait M. D.
Hj^HE experiment propofedby Mr. Frank- X liny to prove that lightning and the e- leetrical fire are the fame, has often been re¬ peated with fuccefs both in England and a- broad ; fo that the moil: noted ele&rical ex¬ periments have been performed by fire drawn from the clouds.
Mr. Franklin alfo firft difcovered, that fharp points attract and difcharge the eleftri- cal matter mofi: copioully ; and from thence fuppofes, that a very (harp pointed rod, fixed to the extremity of the top 'mail of a fhip, with a wire conduced down from the foot of the rod round one of the fhrouds, and over the {hip’s fide into the fea, would filent- lv lead oft the eledrical fire, and fave the fhip from thunder in hot countries ; and that, by a fimilar method, buildings might be pre- feryed.
I90 ESSAYS AND OBSERVATIONS
So ufeful a propofal deferves to be exa¬ mined : variety of experiments may give hints for new improvements. For this reafon the following obfervations are communicated, tho* not fo compleat as might be wifhed, being the refult of one trial only.
It feldom thunders in this northern clime. In June 1752, there feemed to be fome thun¬ der at a diflance from Edinburgh 5 but, from the beginning of July to the beginning of OBober , we had nothing almoft but conti¬ nual rains. The lafl fummer was uncom¬ monly warm and dry ; and yet we had only a few claps of thunder at Edinburgh , one e- vening : and my attempts for making any of thofe experiments were entirely unfuccefsful till Saturdays night September 15. when we had a very great ftorm.
I used around iron rod, two tenths of an Inch diameter, about eleven feet long, fharp- ened at one end ; the other end was inferted Into a glafs-tube ; and that tube flood in a common glafs-bottle, which I held in my hand.
I used alio another rod about three feet long, fharpened in like manner, at one end ; which flood with the other end in a glafs-
tube3
igi ESSAYS and OBSERVATIONS
tube, which was ftuck in the ground. 1 began upon the Calton-hill.
The lightning and fire in the air abound¬ ed greatly ; and yet it was fome time before any thing elfe appeared. At laft, fome rain began to fall, and the air turned moifter ; then fire appeared upon the extremities of each of the rods in a fmall pretty blaze : very like the fire which is difcharged from the point of a fword in the dark, when the perfon that holds it is electrified, and hands upon glafs or rofin ; or like that which appears upon any (harp point, when prefented to an ele¬ ctrified gun-barrel, but in greater quantity. I touched the long rod with my finger ; but had no fparks from it. The (hort rod was accidentally taken out of its tube, and yet continued to burn and blaze as formerly. In like manner the flame continued upon the end of the long rod, tho’ I took hold of it any where at pleafure above the glaffes, till I moved my hand or finger along, within a few inches of the flame ; then it was attract¬ ed by my hand, and vanished.
I went from the Calton-hill to the Cajlle - hill , at the other end of the town ; and, in pafiing thro’ the ftreets, no fire appeared up-
i92 ESSAYS and OBSERVATIONS
> »•
on either of the rods : but almoft immedi¬ ately when I got clear of the houfes, upon the open hill, the point of the longer iron rod took lire. In the dark, I had loft the tube belonging to the fhorter rod ; and the point of it did not catch fire when the long¬ er one was kindled. Perhaps I did not wait long enough for a proper trial ; for I foon touched the flame upon the long rod with the fharp point of the fhort one, and then it alfo took flame and continued burning, as before, without any further dependence up¬ on the longer one.
I held the fhorter rod by the fharp end, and approached the blunt end of it to the flame, upon the point of the longer rod ; then this blunt end catched the fire, and the flame upon the points of the two rods conti¬ nued rather ftronger, than on the Angle one before, fo long as I kept them in contadt, and the fires within three or four inches of one another : but, when I drew them far¬ ther afunder, the flame upon the extremity of the blunt rod vanifhed. This happened as often as I tried it ; and it is evident, that in like manner, I could have got the fire to fix upon the points of a great many rods, and
fo.
PHYSICAL and LITERARY. i93
. fo have had them all flaming together. Once . or twice, a flafh of lightning feemed to dart di- reftly againfi: the point of the rod ; then the fire, as I thought, expanded itfelf and united with the lightning , hut it immediately began to fhine again, when the lightning was paft.
Tho’ it rained much in time of thefe ob~ fervations, yet the fire upon the ends of the rods did not go out until it became fo heavy., as if it were pouring down out of funnels.
After this I went home for fome time, refolving to come abroad again when the ftorm was more tolerable ; but it continued to rain all night, fo violently, that I was obliged, with regret, to leave feveral expe¬ riments to the chance of fome future oppor¬ tunity.
j
For example, I fufpefted that the glafs- tubes had not been of great ufe on this oc~ cafion ; and wanted to have tried, whether I fhould have had the fame appearances by u- fing the rods alone, without any other ap-» far at us. This is very probable ; as alfo, that the glaffes, by being wet, allowed the eledtri-
cal fire to flow off as it was attracted.
1 beg leave to add a few remarks relative to this fubjedt.
B b It
i94 ESSAYS and OBSERVATIONS
It would feem that experiments of this kind may be made without danger, when the thunder is at a moderate diftance.
The lightning expands itfelf, as it flies ; and, by expanfion, lofes its vigor.
Perhaps there is one Ample and eafy way of protecting marts and fpires from thunder, viz. to fix horizontally, upon the higheft parts of them, a flat round piece of wood, of a foot diameter, or more, in order to prevent thofe blazing fires from fixing upon them, and accumulating.
This ftorm pafled diredly over Edin - burgh , and came on from the fouth by weft, as nearly as could be eftimated. There was a great deal of lightning, that night, above fixtv miles to the weftward : but no thunder heard. At Glafgow , there was very much lightning, and a few diftant faint claps of thunder. On the road from Belford or Ber¬ wick , it lightened incefiantly ; but two claps of thunder only were heard, and thofe very faint : fo that there is reafon to think, that the fire of this ftorm fpread over the breadth of 130 miles, at leaft. I wifh I could alfo give fome account where this thunder began, and how far it run before it was extinguifhed.
On
PHYSICAL and LITERARY. 195
On September 3. there were a great deal of ftreamers, which rofe nearly from the fame point that the thunder afterwards came from ; and gradually worked north, till they defcended below the horizon. The air had a thunder-like appearance, for feveral days before this ftorm ; and for fome nights after it, the ftreamery vapour appeared equally dif- fufed, muddy, inert and languid, and not vibrating any variety of colours ; as if the more volatile parts had been confumed. It is highly probable that lightning and the au¬ rora borealis are of the fame materials. In hot countries ftreamers are not feen, or but rarely ; becaufe they are kindled into thun¬ der and flafhes of lightning: in cold coun¬ tries ftreamers abound, and it feldom thun¬ ders. The ftreamers have ferved to pre¬ dict thunder to follow next day, in fummer and they have been alfo feen to break out into flafhes of lightning. Thunder difturbs the motion of the magnetic needle ; and it has been lately found in Sweden, that ftream¬ ers do the fame. Thus thunder, electri¬ city, magnetifm, and the aurora borealis , appear all wonderfully related 3 and many
things
ic)G ESSAYS and OBSERVATIONS
things remain undifcovered in this vaft fields which is but juft newly opened.
As it is probable that the height which fomephilofophers have affigned fortheftream- ers in the atmofphere, is by feveral hundreds pf miles too much ; it were to be wifhed that people in various latitudes would care¬ fully obferve their altitude, at different times of the night ; that, by comparing fi mul tan e- ous obfervations, this matter may be deter¬ mined with more certainty.
Art.
PHYSICAL and LITERARY.
*97
Art. VII.
Some Phenomena obfervable in foggy Weather 5 by the fame.
ONE may often meet with opportunities of making obfervations : but he may not always have leifure enough to judge of their importance, and make a proper ufe of them. This is the cafe at prefent, with re- fped: to what follows.
I have frequently obferved, in foggy wea¬ ther, during froft, that, when the fun was come to a proper altitude, there was a bow formed in the mift, of a white colour , and the altitude of the bow feemed to fubtend an angle equal to the elevation of the fun above the horizon, and formed a femicircle.
This kind of mift comes from the ocean* with a flow north-eafterly wind 5 and over- fpreads all the lower grounds : but, in a country like ours, fo much diverfified with long ridges of hills, and interjacent plains and valleys, one may often emerge out of the
mift
293 ESSAYS AND OBSERVATIONS
mid by g°ing UP f°me neighbouring hill ; then he will fometimes fee the whole coun¬ try around, as it were, buried under a vaft deluge ; and nothing but the tops of diftant hills, appearing here and there above the flood ; and he will think of diving down a- gain into it, with a kind of horror. The air at that time, in thefe regions, is very pure, ferene, and agreeable to breathe in.
In this, or a fimilar fituation, there is a phenomenon obfervable, which I have feen many years ago ; namely, a rainbow formed round one’s fhadow in the mift. The French Gentlemen who went to Peru, with a view to determine the figure of the earth ; having* among many other difficulties, the emba- raffment of tedious and very frequent fogs to ftruggle with ; had often occafion to ob- ferve this phenomenon. It feemed alfo worth mentioning here, that any one who has the curiofity may fatisfy himfelf concerning it.
I had occafion to fee it again on the 23d of QBober laft, in travelling from Glafgow 2 northward. When I had afcended a very little out of the fog, fo that my fhadow was projedled amongft it ; the fun being behind, and almoft on a level with me $ there was a
double
I
PHYSICAL and LITERARY. 19-9
double range of colours, like thofe of the rainbow, formed round the fhadow. The colours of the outermoft range were broad and very diftinCt, and about two feet diftant from the fhadow every where 3 then there Was a darkifh interval, and after that another narrower range of colours, clofely furround¬ ing the fhadow, which was very much con¬ tracted.
It is remarkable, that there is a ring of light, brighter than ordinary, that furrounds the fhadows of all bodies 3 occafioned by the inflexion of the rays of light, as they pafs by the furfaces of thofe bodies. But I dure not proceed to offer my conjeflures in what manner this inflexion of the rays con¬ tributes to the formation of thofe ranges of colours.
Art.
200 ESSAYS AND OBSERVATIONS
A R t. VIII.
< - ' • • i
Of the Meafures of Scotland, compared with thofe of England, by James Gray.
5 HE ftandard pint jug in the cuftody of the burgh of Sterlings is made of brafs, in form of a frufirum of a cone ; it weighs near fixteen Averdupois pounds.
It appears, by its make, to be very old, and has two fhields in relievo up¬ on its fide, with rude fi¬ gures upon them, as re- pr dented in the margin.
Its dimenfions, as near as could be taken from a veflel of fuch rude work¬ man (hip, are, viz.
Mean
PHYSICAL and LITERARY. 201
« * ' ' |
Inches . » |
Mean diameter of its mouth, |
|
Mean diameter of the bottom. |
5 hr |
Mean depth, |
6 |
It was five times carefully filled with clear river water, which was each time accurately weighed by a nice beam, that would turn* with lefs than a grain, when 100 ounces were in each fcale ; and its content of water, at a medium of thefe trials, which did differ but a few grains from one another, was found to Weigh 26180 troy grains.
At the fame time, a veffel which was made to contain accurately, one hundred cu¬ bic inches, was fifed with the fame water: and after feveral trials, which did not differ one grain from one another ; its content in wa"er was found to weigh 25318 troy grains.
The ftandard pint jug therefore contains cuhic inches; and each cubic inch
of water with which the jug was filled, weighs 253II-6 tr°y grains.
The ffandard Sterling jug, in the cuffody of the Dean of Gild of Edinburgh , likewife made of brafs, and weighing about 2o f A- *, verdupois pounds, having the arms of Scot¬ land and of Sterling marked in relievo upon
C c its
202 ESSAYS and OBSERVATIONS
its fide, was in the fame manner filled with water; and its content was found not to differ from that in the cuftody of the burgh of Sterlings above a fiftieth part of a cubic inch. Perhaps it may not be improper to obferve, that notwithftanding the nicety of the beam, and the fmall furface of the mouth of the veffel, which contained 100 cubic inches; no difference was perceptible in the weight of its content of water, tho’ the heat of this fluid was feveral degrees both above and below temperate in the thermometer; and that no difference was to be found between fpring and river water; nor even between river wa¬ ter when clear, and when fomewhat difco- loured after a fpeat.
By a£t. pari, of 19. February 16 1 8. anent fettling the meafures and weights of Scotland \ it is ftatute and ordained, that the wheat fir- lot fhall contain 21^- of the Sterling jug ; and that the bear firlot fhall contain 3 1 of the fame.
The Englijh wine gallon contains, accor¬ ding to the Guild-hall ftandard, 224 cu¬ bic inches ; but, according to ftatute, 23 1 cu¬ bic inches. The Englijh ale gallon, both according to the Exchequer ftandard and ftatute, contains 282 cubic inches. The Win~
chejler
PHYSICAL and LITERRY. 203
chefler bufhel, according to ad: of parliament, 1697, and ratified in the firft year of Q. Anne^ contains 2150^- cubic inches. Therefore
Cubic Inches.
The Scotch pint contains - i03tt
The Englijh wine pint, accor¬ ding to ftatute, contains - 28|-
The Englijh ale pint contains - 35^
The wheat firlot contains - 2197-^^-
The bear firlot contains - 3205-^-^
The Wincbeft ^rbufhel contains 2 1 50— 7^
According to ad pari, of 19th February
1618 above mentioned, the Scotch pint jug
►
contains, of the clear running water of Leith , three pounds and feven ounces of French Froas weight, ordained to be the weight of Scotland ; whence the Scotch pound is equal to 7616 Froy grains, or 15^ ounces Troy.
By an accurate comparifon of ftandard weights made at London , [yid. Philofoph.Franf- aB. N° 470.) the Averdupois pound was found equal to 7000 Troy grains. Therefore
The
204 ESSAYS AND OBSERVATIONS
Troy Grains •
T he Troy ounce being equal to 48o The Scotch ounce is equal to 476 The Averdupois ounce is 43 7t
Englijh Inches .
The Scotch foot is - 12rf
The Englijh foot is - 12
The. Scotch ell, according to the ftandard of Edinburgh, is equal
to - 37tt
The Englijh ell is - “45
The Englijh yard is - - 36
The Scotch mile contains The Englijh mile contains The Scotch acre The Englijh acre contains
Englijh Feet.
5952
5280
55353tt Square. 43360 fquare*
PHYSICAL and LITERARY. 205
Art. IX.
A Differtation on the Sexes of Plants ; by Charles Alston, M. D. King’s Botanifl in Scotland, Fellow of the Rcyal College of Phyficians, and ProfeJJor oj Medicine and Botany in the Umverfty of Edinburgh.
THE fmalleft, and apparently moft defpi- cable produ&ions of nature, are not lb barren, but that they are capable, both to in¬ vite our fpeculations, and to recompencethem. Even Pliny could fay, “ rerum natura nuf- “ quam magis quam in minimis tota eft”, (a) For how much foever the celeftial bodies de¬ clare magnificence, and immenfity of power ; yet do they not by far afford us fo clear and cogent arguments of wifdom and defign, as do the bodies of animals and plants. And for my part, fays the great Boyle, I am apt to tnink, that the eye of a fly is a more cu¬ rious piece of workmanfhip than the body
of
(a) L» xi. 2,
*0 6 ESSAYS AND OBSERVATIONS
of the fun, at lead as far as appears to us (b). Hence
The exquifite ftrudure of flowers, e- fpecially of the mod minute, and fcarcely vi- fible dud of the apices, commonly the fport of the winds, has engaged the attention of the learned, both of this and the preceeding age : and yet, no body has been able to de¬ termine, with any certainty, whether it is abfolutely neceffary to the fecundity of the feeds, or excrementitious only ; which is the fubjed of the following inquiry.
Animals and .vegetables reiemble one another in fo many things, that not only fome of the antients, but even of the moderns al¬ io, feem to be at a lofs how to didinguifh them, or fix the limits of each of thefe king¬ doms (*:) ; yea, and to reckon analogy a dif¬ fident proof, that fuch properties as are ge¬ nerally obfervable in the one, do belong to the other alfo. Thus Empedocles and Anaxa¬ goras feem to have reafoned, when they main¬ tained, that both fexes were conjoined in plants; that they were animated, yea and fen-
tient
(&) Vid. Boyle’s works, fol. edit. vol. i. p. & yol. iv. p.523.
(c) Vid. Tyrocin bot. p. 3.
PHYSICAL and LITERARY. 207
tient beings, capable of pleafure and pain, defire and averfion, &c. ( d )
I shall follow the philofophers no fur¬ ther ; my defign being only to inquire into the rife and progrefs of the doctrine concern¬ ing the fexes of vegetables among botanifts ;
and
[d) £t Vita et in animalibus et in plantis efle deprehenfa efti Anaxagoras itaque et Empedocles deftderio plantas duci aiunt ; fentire item, ac triftitia voluptateque affici affirmant. Et Anaxagoras quidem, animalia i~ pfas effie, et voluptate ac dolore moveri, docuit ; e foliorum fcilicet defluvio, et ex incremento, iftud colligens. Em¬ pedocles vero fexum his admiftum efte arbitratus eft. Eo» dem modo Plato quoque appetitu folom illas duel* “ ob vehementem fcilicet facultatis altricis neceffitatem, affir- mabat Quod ft conftec plantas voluptate ac dolore affici, turn .entire quoque rationi erit confentaneum : et ubi hoc conftiterit, turn appetitu quoque duci ; ft quidem fomno reficiuntur, et vigiliis excitantur, rationi confentaneum erit. Ad eundem modum ft quaeramus, an fpiritum ducant, e£ fexuum miftionem habeant, an contra ftt ; multam fuper hoc ambiguitatem, et quaeftionem prolixam excitabimus.— • Cum in plantis reperiatur, quod unaquaeque fpecies maf- culum genus habeat et femellum, et omnino quod mafeu- “ lum eft afperius ac durius rigidiufque, femellum debilius et foecundius ; quaerendum rurfus eft, inveniaturne haec “ duo genera ftmulcommifta in plantis effe, utEMPEDOQLEs “ dicit. Id quod ego fane ita habere non arbitror,” Thus Aristotle de plantis, lib. i. c. i. et 2. See alfo Frag ■=■
mentum Galenj in Platonis Timaeum, c. 2. Et li-
brum de hiftoria philofophica Galeno adferiptum fub nem.
*08 ESSAYS and OBSERVATIONS
and whether it is fupportalbe by experiments., or a mere hypothefis ?
Sect. I.
* Theophrastus, the greateft, as well as the eldeft, of the Greek botaniffs whore works have been preferved, can beft explain, why fome plants of the fame kind were called fe¬ males, and others males, by them. I know fome reckon Grateva more antient, and co¬ temporary to Hippocrates , on the authority ot fome epiftles fathered on the old man, and annexed to his works. But the learned have proven thefe letters to be fpurious $ and that Grateva lived not before Mithridates , whom he complimented with the name of a plant, as Pliny (?) informs us. As for Hippocrates himfeif, I find in him a conyza femino , but no other plant called either male or female.
2. But Theophraftus , who fucceeded Ari~ flotle in his fchool, in the 1 14. olympiad, ve¬ ry frequently mentions the fexes of plants. Thus part & t iveg3 fays he, x) ruv 'opotoyem 1/, ra r jtAEv ai/Gstv, tqc h s', &c, tx But it is faid, that fit oi plants of the fame kind, fome flower,
“ others
(e) lib. 25. c. 6.
PHYSICAL and LITERARY. 209
a thers not ; as of the palm-trees , that the £C male bloffoms, not the female, which a- ££ bout the fame time puts out the fruit, ££ Plants therefore of the fame kind, are thus “ differenced, as alfo all iuch as cannot perfedi ££ the fruit.” ( / ) And elfewhere, (g) ££ the C£ moil: common diftinftion of trees, is into “ female and male, whereof the one is fer- “ tile, but the other barren, in fome. Bu ££ when both are fertile, the female carries £C the faired: fruit, un’efs fuch be called males3 “ for fo fome call them.” And aimoft all the plants which he diftinguifhes into male and female, are equally fertile in both fexes, as abies, filix , cornus , tHia, cupreffus , cijlus 5 conyza , &c» Even palm-trees he divides in¬ to frudtiferous and barren 3 and the fructife¬ rous again into female and male ( h ): fo feems not much to have regarded analogy, in the diftinftion of fexes, except it be in one fpecies of the palm-tree .
, D d 3« But
(f) Hift. lib. c. 22. (£) Hift. lib. 3. c. 9, (h) Hift. lib. %, e< S.
2io ESSAYS and OBSERVATIONS
3. But of this famous tree he fays, (/) um lefs the fpatha be cut from the male, and, while it retains the down, flowers and duff, (k) be fhaken over the fruit of the female; It will never ripen, but fall off: which this fprinkling prevents. ££ For the male, adds C£ he, of both the fig-tree and th t palm-tree y £C is of ufe to the female, ^ oiov
&t r\ $s xur cZxxou TgoTTov, but in the one (7) there £t is, quaji coitus ; in the other it happens af- €C ter a different manner.” And elfewhere, €£ [m) That the fruit will not continue on the C£ female palm-tree, unlefs the flower of the ££ male with the be fhaken over it,
e£ as fome affirm, is certainly Angular : for cc tho5 there is an evident reafon for caprifica- e£ tion, which it fomewhat refembles; yet ££ none can be afilgned for the effedl of this cc fptdnkling.” And leaf! it fhould hence be Inferred in general, that female trees were of themfelves infufficient for fructification, without the affiflance of the males; he ob- ferves, that in order to fuch a concluflon, this
ought
(7) Hift. lib. 2. c. 9.
[k) K ovioproc.
(/) to, Palm-tree.
(m) Cauf. Plant, lib. 3. c. 23.
PHYSICAL and LITERARY. 211
ought to appear, not in one or two inftances . («), but in all, or the greateft part of the females, t r,v y&g (pwiv htw Kgivopev rS ysi/S?. Of this tree more afterwards.
4. D iosc or ides, who lived under Nero, has a male and female mandr agora, ahrotonum , mer curtain , anagallis , arijhlochia , ciftus , fUix , peeonia , polygonum , tithymalus , verb a [cum, and an arundo fee min a : but, without any regard to analogy, or to their fertility or barrenefs, does he call them fo 3 for his curialis-mas carries the feed, and the faemhia is barren ; and the male of all the reft, equal¬ ly fertile with the female. The fame may be faid of Galen and the fucceeding Greeks ; none of them, fo far as I have obferved, men¬ tioning the fexes of the palm-tree.
5. Pliny, who flourifhed under Vefpa - Jian , fays indeed, £C Arboribus, imo potius
“ omnibus quae terra gignit, herbifque etiam, <c utrumque fexum efle, diligentiffimi naturae “ tradunt : nullis tamen arboribus (palma) cc manifeftius. Mas in palmite floret, fae- cc mina citra florem germinat tantum, fpicae
“ modo.” (0) But when he comes to mention
particular
(») As here in the fig-tree and palm-tree,
[°) L 13* c. 4*
%i% ESSAYS and OBSERVATIONS
particular plants, excepting what he has from T ’beopkrajius of the palm-tree , he tranfgreffes analogy as much as DioJ'corides: his mercurialis mafculus being the feed-bearing one ; and his other male and female plants the fame with thofe of Theopbrajlus and Diofcorides . Hence it appears that the palm-tree is the only in- ftance, among the antients, where fexes are attributed to particular plants, on account of fertility or barrennefs : other plants being cal¬ led male or female, on various and very different accounts, and for diftinctions fake only*
6. In a word, from Theopbrajlus down to Cafalpinus , who died at Rome in 1603, the analogy between plants and animals, with regard to fexes, feems to. have been intirely neglefted. But Cafalpinus [p) fays exprefsly, cc FruSum ferunt, non vero florent oxycae- 4£ drus, taxus ; in genere herbaceo mercuria- lis, urtica, cannabis : quorum, omnium fie- riles mares vocant, faeminas a u tern frii- cc ftiferas. In eo tamen genere faeminas • e melius provenire et foecundiores fieri aiunt, p fi juxta mares ferantur ; ut in palms eft a-
nimadverfurn ;
1 I [ s l i ? i
ip) Be plantis, 1. z . c. 2,
PHYSICAL and LITERARY, 213
u nimadverfum : quafi halites quidam, ex “ mare efflans, debilem faeminae calorem ex- cc pleat ad frudtincandum.”
Sect. II.
7. But of late it has been maintained by not a few, that there is as real a diverfity of fexes in every fpecies of plants, as in every fpecies of animals 5 and, firfl of all by the celebrated natural!!! Dr. N. Grew , to whom therefore the honour of the invention is of right due. For this great man, in his anatomy of flowers, read before the Royb¬ al Society November 9. 1676, after noticing the fecondary ufes of the duft of the apices y which he calls globulets or fmall particles with¬ in the the ere of the attire ; he adds, ££ But the <c primary and chief ufe is fuch as has refpedi <c to the plant itfelf, and fo appears to be ve- <c ry great and neceffary ; becaufe even thofe “ plants which have no flower or foliature, are yet fome way or other attired ; fo "£ that it feems to perform its fervice to the cc feed, as the foliature to the fruit. In dif- cc courfe hereof with our learned Savilian pro- <£ fe.iTor, Sir Thomas Millington , he told me,
€C hs
214 ESSAYS AND OBSERVATIONS
cc he conceived that the attire doth ferve as C£ the male for the generation of the feed. <LC I immediately, replied, that 1 was of the C£ fame opinion ; gave him fome reafons for “ it, and anfwered fome objections that might ce oppofe them.”
Whether, as fome pretend, this com¬ pliment paid to Sir 'Thomas Millington , fhows him to have been of this opinion before our author, I leave to the learned to determine 5 for my part, I think the words cannot bear it. And Mr. Ray (q) gives it for Dr. Grew , without naming Sir Thomas .
8. Dr. Grew then proceeds to give the fum of his thoughts concerning this matter ; and plainly afferts, as his opinion, that when the attire or apices break, or open, the glo¬ bules or duft fails down on the feed-cafe or uterus , and touches it with a prolific virtue % not by entering bodily, or as to its grofs fub- ftance, but only by communicating to it fome fubtle and vivific effluvia (r),
9. Among the firft who adopted this do¬ ctrine, was Mr. John Ray , that great natu¬ ral hiPcorian ; at firft indeed only as probable
(0.
{q) Hilt p. 17.
(r) See Grew’s anat. fol. p. 17s.
PHYSICAL and LITERARY. 215
CO* but afterwards as proven by many argu¬ ments, which are collected in the preface to
his jylloge Jhrpium Europearum extra Britan- mas nafcentium , printed at London 1694, in : whether thefe arguments fufficiently prove the doctrine will be confidered below.
10. In 1695, Rudolphus Jacobus Camera- rnts 5 profeiTor of botany and medicine at ‘Tu¬ bingen, publi flaed there an epijlola de fexu plan¬ tar um^ in 1 2 mo (/) : this I have not feen, but on¬ ly an ab ft rad of it in the appendix to Mifcel. nat. cur. Dec. 3. an. 3. for 1695, an^ 1696* by M. B. Talent ini . Here the generation of
plants to be analogous to that of animals, he endeavours to fhew in eight particulars • the lan of wnich lie calls the palmarium and ponderojijjimum argumentum: and it is this, Cer- turn eft, fays he, ad animalium generation <c nem copulam utriufque fexus exigi : quae in plantis adeo quoque neceftaria eft, ut ft vel maris apices, vel faemmarum fly li, vel utraque deficiant, nulla proles fequi poffit ;
“ ut in frumento turcico, cuijuba praemature refecatur, et mercuriali mare, a faemina fe- * Parata> conftat.” But then he propofes
three
(J) Vid. R. Hid. p. ig.
(0 Reprinted Francofurti,
1 ' Oi, in 4(0 Lin. bib.bot. 273*
216 ESSAYS and OBSERVATIONS
three ob'edions againft his own dodrine, which are ftronger than all his arguments for it ; yea, the third plainly confutes it : and they are thefe, as Valentini delivers them ; “ \mo, Plantae dantur apicibus copiofis, aft « nullo ftylo praeditae; adeoque mares fine • - faeminis, ut in equifeto, lycopodio, &c. « 2 do Vidctur e contrario fibi obfervaflfe faemi- “ ninum fine pretenfo virili iemine. fiio, Ader- curialis, fpinachiae, et cannabis femelias fo- « litario, abfque vicini maris contagio excul- t£ tas, plurima granula feminaque foecunda 5t obtinuiffe vidit : et haec in cauia erant, cur “ haec omnia cum aliquali oppofiti formidine “ proponat.”
ii. In 1703, Mr. Samuel Morland laid be¬ fore the Royal Society, fome new obfervations on the parts and ufe of the flower in plants («)} here he fays, “ Dr. Grew falls fhort, in that « he fuppofes the farina only to drop upon “ the outfide of the uterus, and to impregnate st the included feed by fome fpintuous etna * t£ nations, or energetical imprefs.” bo he pa* raphrafes prolific virtue and fubtle vivfic efflu¬ via. He then propofes a more probable hy¬ po thefis, as he thinks, viz. “ that th & farina
S£ is
(«) Philof, Tranfaft, No 287*
PHYSICAL and LITERARY. 217
1
€C is a congeries of feminal plants ; one of . £C which mu ft be conveyed into every ovum or feed, betore it can become prolific.” He has the honour, I believe, of being the in¬ ventor of this hypothefis ; but is o far from making it probable, that the ftrudure and po- fition of the parts of fome of the flowers he inftances, which are all the arguments ad¬ vanced by him for it, fufficiently confute it ; e. g. corona imperialism For allowing for once, which however cannot be allowed, that the Jiylus is always hollow, and that rain, might w^afh the duft, or wind fhake it down this cavity, into the heart of the feed in eredt flowrers ; what muft become of pendulous flowers, fuch as the crown imperial ? here the farina muft be waftied or fhaken upwards.
12. As for JValdfchmidii dijfertatio de fexu plant arum , Kiliae 1705, 4/0, and Gakenholzii dijfertatio de vegetal) ilium indole cognojcent!a> Helmjladii 1706, in 4 '0, mentioned by the learned Heijlerus , in his praejatio in epijlolam Burckhardi ’, Helmjladii 1750, in 8 vo ; I know nothing about them : but I have no reafon to think, that they have been more fuccefsful in demonftrating the lexes of plants than Ca¬ mera ri us, <c qui, omnium planillime, fexum
E e plantarum
2 1 8 ESSAYS AND OBSERVATIONS
cc plantarum expofuitf’ as the fame profeffor Heifter (x) teftifies.
13. In 17 1 1, Mr. Gecffroy prefented the Royal Academy at Paris , with cc obfervati- ons on the ftrudture and ufe of the princi- cc pal parts of flowers wherein he attempts to prove, that the duft of the apices really Impregnates the feed. And after advancing a! mo ft ail that had been faid on this fubjedt by Grew , Ray , Camerarius, Mori and, without mentioning them ; he afferts, 1 mo, That the arerm is never to be feen in the feed till the
O \ V
apices died their duft. And, 2 do. That, if the /lamina be cut out before the apices open, the feed will either not ripen, or be barren if it ripens : in proof whereof he gives two experiments that he made, one on the mays, by cutting off all the jiamina before the apices opened ; and the other on the mercurialis , by training up feparately fome of the feed¬ bearing plants by themfelves. The confe- quence was, fome of the ears of the mays aborted altogether 5 others ripened a few feeds; as did aifo the mercurialis plants : both which feemed to be foecund. £C Perhaps, fays he, st the duft of the apices , brought from fome
<£ other
(at) Pref., p. 70.
PHYSICAL and LITERRY.
219
cc other place by the wind, fertilized thefe few “ feeds : that this is not impoffible, we have €£ a fine infiance in Jovianus Pont anus , precep- C£ tor to Alphonfus King of Naples , who, in a cc poem, tells us, that in his time, there were C£ two palm-trees, a male cultivated at Brindes , “ and a female in the woods of Otranto , which cc carried no fruit for many years. But at <£ length being elevated above the other trees cc of the forefi, fo that it could fee the male cc palm-tree of Brundujium , it then began to <£ bear good fruit in abundance. No doubt, C£ becaufe then it began to receive the dufi: €C of the /lamina , carried by the wind from ££ the male palm-tree > over the other trees of <£ the wood (y)d A very fine ftory indeed !
I fiiall only further obferve, concerning this learned author, that tho’ he has added nothing new, of confequence, on this fubjedl, yet he feems to claim the honour of being the inventor of all ; for after giving his con¬ jectures, with relation to the manner how th ib dufi impregnates tire teed, and as his own too, tho’ the one be Crew’s and the o- ther Morland' s, he thus concludes,
cc But
(y) Yid. Mem, Acad. 1711.
220 ESSAYS and OBSERVATIONS
<c But whichfoever of thefe conjedlures ec be pitched on, it remains always certain, C£ by my obfervations , that the dud of the a - cc pices, which has been hitherto negleded, C£ as vile excrements, which in a manner C£ disfigured the flowers, are neverthelefs parts cc effentia!, and neceflfary to the foecundity of cc plants/’ The pains however he has been at, in examining and defcribing the dud of the apices , of a confiderable number of plants, if accurately performed, might have procured him better treatment, than he met with from feme of his countrymen.
14. In 1717, M. Vaillant, at the opening of the Royal garden, intertained his audience with a difcourfe on the drudlure of flowers, and the ufe of their parts ; which was print¬ ed in French and Latin at Leiden in 1718, in 4/0 : and thus he begins , ££ Since the flowers ££ are, without controverfy, the mod effential ££ parts of plants, it is very fit that I intertain £C you, in the fird place, with them ; and ££ the rather becaufe every botanid hitherto, has given only confufed ideas of them. The ££ language perhaps which I am to make ufe of, may appear fomewhat new in botany : ?■ but, as it will abound in terms altogether ' fuitabje
PHYSICAL and LITERARY. 221
ec fuitable to the ufe of the parts which I am cc to explain ; I believe it will be much bet- €C ter underftood, than the old one, which “ being fluffed with improper and equivocal
words, more apt to perplex than illuflrate cc the matter, precipitate into error tbofe, 6£ whole clouded imagination has no right “ notion of the functions of thefe parts. The u flowers, ftridily fpeaking, are nothing elfe *c but the organs which conftitute the differ- “ ent fexes of plants, &c.5’ I fliall notice only two or three things concerning this dif- courfe. 17710, That, according to it, the a~ pices of barren flowers fhed their dull: all at once, by a kind of explofion : but fertile flowers, flowly and by degrees, and common¬ ly before they open, or expand their covers $ but he gives only the parieiaria for an in- fiance.
2 do. That he has demonflrated that the dull: of the apices cannot enter the feeds ; be- caufe the ftylus is not always hollow, but of¬ ten folid : and, although it were hollow or tu¬ bular into the feed-veffel, it could not thus convey the dud into the feeds, without pe¬ netrating their proper covers or fin ells. Be¬ sides, he afferts, and that truly too, that this
duft
%%1 ESSAYS AND OBSERVATIONS
daft does not enter even the cavity of the fruit; as may be feen by opening the heads of the pa- pavcr orientale hirfutijfimum flore magno, T. Cor. p. 17. when the flower is fully blown. For, fho’ the upper part of the heads, are then co¬ vered with the purple dufl of the apices ; yet the feeds, partitions to which they adhere, and all within the fruit, continue perfe&ly white. I might add, that the dufl: of the a- pices is fometimes in fo large grains, as to be vifible to the naked eye : as in fome of the maU *vaceae , while no conduits are difcoverable, by magnifying glaffes, in the Jlylus , whofe dia¬ meter does not much exceed that of the grains of the dufl:, which refembling prickly balls, mu ft be very unfit to enter a ftrait paf- fage. And,
3 tio. That the volatile fpirit, or vapour of the dufl:, may be conveyed to the feed, in this manner ; it may enter the air veflfels of the jlylus , pafs through them into the placenta , thence into the Junes umbihcales , and fo into the ova or feeds, along with the nutritive juices. But I cannot omit a remark¬ able paffage in this difcourfe, as it anfwers an afiertion of Mr. Geoffrey , and on other accounts which take in the tranflators words,
cc Tubas
PHYSICAL and LITERARY, 22$
Tubae igitur hae, quas fallopianis compa¬ re), quod ad ova deferant, non exigua ipfa “ ilia pulveris foecundi grana, quae apices fu- per ilias ejaculantur, aut in ip fa rum excu- u tiunt infundibulum, ut feftator Leeuwe n- hoehanorum atque 11 artfoekeri anorum phan- cc tafmatum voluit; fed halitum modo, aut fpiritum volatilem, qui pulvere hoc fe ex^ :c pedit, ovaque ipfa foecundat. Credo eniin :c auditores, perfuafum certumque habendum, :t non materiam mafeulinam, nec vermiculos :c fuppofititios, vel animalcula feminalia efie, :c quae impregnationem in femella abfolvant: :c quia Malpighius , narrante anatomico recen- u te (z) agnovit foetum reperiri in ovis rana- c rum et gallinarum ante copulam : ut et c certiftimum eft germen adefie in feminibus c plantarum quae non fuerunt impregnata, c quorumque parenchyma facit cum germi- c ne ipfo continuum corpus. Non poterit :c ideo efle aliud quid, preter volatilem hunc c fpiritum, cui craffior materies vehiculi mo- c do vicem praeftat fimplicis. Natura vero c femper eafdem fe eft ante leges, conciudere c opportets id quod hac occafione in anima-
cc libus
{*) M. Diohis edit. 1715. p. 392,
224 ESSAYS AND OBSERVATIONS
C£ libus contingit, idem et vegetantihus acci- « dere (a)." Upon the whole, it is evident that Mr. Vaillant affnmes more the air of an original writer on this (uhjedt than belongs to him. Fie never mentions Grew , Ray, or Carrier arias*, and quotes only fome pafleges from Geoff roy, for the pleafure of cornu-
ting them.
15. I fhall pafs a variety of later authors who have treated on this fubjedt ; and come to the mod ftrenuous defender of the fexes of plants, who has collected all the arguments for it that perhaps can be advanced, and pre¬ tends to have demonftrated it fully : I mean the famous and very learned Carolus Lmneus , profeffor of medicine and botany in the uni- verfity of Upsal , fellow of a great many phi- lofophical focietles ; and certainly one of the greateft botanifts of this age. For this great man thus writes, “ Antheras et ffigmata (b) €C conftituere fexum plantarum, a palmicolis, cc Millingtono , Grewio , Rayo , Carrier ario , Go - £c dofredo , Morlando , Vaillantio , Blairio , juj*
cc ffevio, Bradley 0, Royeno , Logano , &c. de-
“ tedium;
[a) Vid. p. 57.
(b } that is, the apices, and extremity of the flylus.
PHYSICAL and LITERARY. 225
detedium, defcriptum, et pro infallibili af- cc fumptum: nec ullum, apertis oculis confi- cc derantem cujufcunque plantae Acres, latere tc poteft 3 quod demonftrattum in fponfalibus <c plant arum ^ Upfaliae 1746, in 4to (c)” And elfewhere (d) “ Generationem v’egetabilium “ fieri, mediante pollinis antherarum illapfu c< fupra ftigmata nuda, quo rumpitur pollen* “ efflatque auram feminalem , quae abforbetur “ ab humore ftigmatis; quod confirmat ocu- cc lus, proportio, locus, tempus, pluviae, pal- Ci micolae, Acres nutantes, fubmerfi, fynge- <c nefia 3 immo omnium florum genuina con-* 4c fideratio.”
Yet I cannot help thinking this doctrine not capable of demonftration, far lefs that the genuina conjideratio of any Aower can make it probable : Camerarius himfelf doubt¬ ed of it 3 Tournejort difbelieved it 3 and Pon- tedera (e) ufes many arguments to refute it* It remains therefore only, that the argu^ mentsr for and againft the fexes of plants, as under Aood by the moderns, efpecially the de-
F f fervedly*
(d Syftema naturae, edit. Lipfiae 1748. in 8vo, p. 216.
[cf] Philofoph. Botan. edit. Stockholm. 1751, in 8vo. p. 9s 4 {e) Anthol. 1. 2. p. 107 — 185.
226 ESSAYS AND OBSERVATIONS
fervedly much commended Carolus Linnaeus ■, be fairly Rated .
Sect. III.
26. The Rate of the controverfy is briefly this ; Whether the influence of the duR of the apices , is abfolutely neceffary to the foe- cundity of the feeds, or not : or, Whether good and fertile feeds can be produced, when the duR of the apices has no accefs to the Jlyli or Jligmata of the plants that carry them. Now, there being feveral fpecies of vege¬ tables, which bear flowers on one plant, and feeds on another, as fpmacia , mercurialisy cannabis , &c.; I know no way, to determine the queflion fo certainly, as by training up one or more of thefe feed-bearing plants, at a fufficient diffance from fuch as carry the flowers, and obferving the confequence: for,
17. If a feed-bearing or female fpinacia , mercurialisy or cannabis , ftanding at a di¬ flance from any of the flowering or male plants, can produce fertile feeds ; then the in¬ fluence of their duR is not neceffary to the fertility of thefe feeds: but, cc foemellam fpi- naciae, mercurialis, cannabis, abfque vici-
cc ni
PHYSICAL and LITERARY. 227
cc ni maris contagio excultam, femina foe- cc cunda producere vidit Camerarius •” ergo the duft of the apices is not neceffary to the foecundity of all feeds. Although this tefti- mony of Camerarius is beyond all exception 5 yet, in confirmation of it, and to prevent ca¬ villing, I fhall relate the experiments I made with the fame plants.
1. In the Spring 1737, I tranfplanted three fets of the common fpinage , long be¬ fore it could be known, whether they were flowering or feed-bearing plants, from a little bed on which they were raifed, into a place of the garden, full 80 yards diflant, and al- moft directly South 5 there being two haw¬ thorn and three holly hedges, all pretty thick and tall, between them and their feed-bed $ and no other fpinage in the garden, nor fo near them by far : all the three proved fer¬ tile plants, and ripened plenty of feeds. I fowedthem, they grew, and profpered as well as any fpinage feed poffibly could do. This, I own, made me, at firft, call in queftion the fexes of plants, which I formerly too impli¬ citly believed.
2. The fame year, a few plants of the
common hemp> which I had raifed for a fpe-
cimen
228 ESSAYS AND OBSERVATIONS
cimen from the. feed, being accidentally de- ftroyed when very young; and finding after¬ wards, about the end of June, a pretty ftrong but late plant of hemp* growing in the inclo- fure to the eaft of Holyrood-houfe , commonly called the Bowling-green, by itfelf : I caufed great care to be taken of it ; there not being that year any hemp raifed within a mile of it, that I could find. This plant grew luxuri¬ antly ; and, tho’ bad weather in the Autumn made me pluck it up a little too foon, yet I got about thirty good feeds from it, which the fucceeding Spring produced as thriving male and female plants, as if the mother hemp had flood unrounded with males. And, 3. In the Spring 1741, I carried two young feedling plants of the French mercury , long before there was any in flower, from the City Phyfic-garden, the only place where it was then to be found in this country, to the King's Garden at the Abbey, which are more than 700 yards diftant from one ano¬ ther, with many high houfes, trees, hedges, and part of a hill between them : and planted one of them in one inclofure, where it was ihaded from the fun the greateft part of the day; and the other, in another, 25 yards di¬ ftant.
i • i
PHYSICAL and LITERARY. 229
Rant, expofed to the South and Weft. Both plants ripened fertile feeds; and the laft lhed them fo plentifully, that it proved a trou- blefom weed for feveral years : tho’ none of the fpecies was to be found in that garden, for more than twenty years preceeding.
Hence the duft of the apices of thefe three fpecies of plants, cannot, on any ac¬ count, be called their genitura. And the fame may be faid of the lupulus , according to Mr. Tourneforf s obfervation, (/) of the bryonia, as noticed by Mr. Miller (g), yea of Mr. Geoff¬ rey's mays mentioned above.
18. The learned Valentini (h) attempts to remove Gamer arius' s doubts two . ways. 1 , Perhaps, fays he, there may be found latent ftyli among the apices of the equifeium ; and 2. The wind may carry the pollen feminale, (or duft of the apices) to as great a diftance, as the mercurialis , vel frumenti Turcici feminina, can be feparated from their proper males.
That the wind could have this effedt, even on the fpinage male duft, is far from being probable : for, to fay nothing of the
globular
(/) Page 69.
(g) Card. Di£t. abridg,
\b) German, ephemer. 1. c.
230 ESSAYS and O B S E R V AT IONS
globular figure or fpecific gravity of this duft, a north wind only could drive it to¬ ward the females, which coming over the Caltonhilly muft rather have driven it into the ground, orinto the intervening hedges. Andin- deed thisfuppofitionis fo evidently extravagant, that I find not any notice taken of it, by the moft ftrenuous defenders of the fexual fcheme.
19. But the other fuppofition of the la¬ tent Jlyli , inequifeto &c. feems to have given occafion to another as extraordinary, viz. of latent Jiamina , in cannabis , lupuli, &c. foe- mellis £C Accidit interdum, fays Mr. W ahlbom^ cc or rather Mr. Linnaeus , ( i ) ut cannabis fe- <c minifera, unum alterumve ferat florem “ ftaminiferum, quo nonnullae feminae im- cc pregnari pofiint ; quod Camerarium lu° “ fit.” Granting this fhould happen fome- times, and that thefe Gentlemen have feen it, (which, however, is not here afierted) ; yet, 3 may fay, that I believe they are the firft that ever faw it 5 and that this is not enough to re¬ move Camerarius s doubt, nor to weaken the
argument
(z) Amaen. Acad. vol. 1. edit. Lug, Bat, 2749.
P- 99*
PHYSICAL and LITERARY. 23*
argument drawn from the above experiments* unlefs they can fay, that the feed-bearing hemp carries always one or more fuch ftami- niferous flowers ; or that the cannabis of Ga- tner arias , and the other abovementioned, had really fuch flowers on it, which they cannot aflert. For my part, I can declare, that, tho’ I fearched very carefully for the feed of the hemp plant, (k) I could fee no¬ thing like ftamina on it ; neither on the feed¬ bearing plants of the fpinacia , mercurialise bryonia , either before or fince I read Mr. Wahlbom s Sponfalia Plant arum,
20. Hence I think the pofition of that learned botanift Julius Pontedera, viz, cc A- <c picum liquorem embryonis foecundationi €C in omnibus plantis non efle neceffarium,” to be a demonftrable truth, which neither authorities nor arguments can refute. How¬ ever to clear up further this controverfy, I fhall conlider the arguments advanced by the moft famous fexualifls, as they are fummed up by the very learned Carolus Linnaeus , in his Fundament a Botanic a ; explained by Jo, Gef-
nerus
(k) Exp. 2,
232 ESSAYS AND OBSERVATIONS
items (/), and demonftrated, they fay, by Jo. Wahlbom {m)y and Car, Linnaeus himfelf (n)« 2i. Generationem vegetabilium fieri, me» diante pollinis antherarum, &c. ut fupra, N° 2 5. confirmat (or, as in former editions, di£li- tat) i.oculus , P. B. § 145. How the eye fhews or confirms the generation of vegeta¬ bles, to be thus effected, is explained three different ways. For,
1. “ Ipfa autopfia (fays J. Gefner) hunc ££ generationis adtum edocet. Primus qui ££ florum connubia vidit, cel. D. Seb. Vaillant £S ( 0) tam eleganter defcribit, ut nemini de £C hac re dubium fupereffe poffit. Ita autem £C cl. Vaillant, £C Quoties acciderit, ut in ea- ££ dem ftirpe flores gerantur fimul, quorum £C hi foeminiria tantum, illi autem mafculina £c et foeminina conjundta organa cingunt, ar- ££ redtio tumorque organorum mafculi norum in his tam fubito eontingit, ut lobuli gem-
£C mse
(/) Differtationes Phyficae de Vegetabilibus, Lugd. Bat. 3743. 8vo conjunctum cum C. Linnaei oratione de necefiitats peregrinationum. Explicant elementa botanica Linnaei. Lin. bib. vol. p. 1 74.
[m) In the Sponfalia Plantarum, Amaen. Acad. vol. t. p, 61. ad 109.
{#) In Phil. Botan.
(c) In lib. de ftru&ura florum. . .
PHYSICAL and LITERARY. 233
c* mas flofculofas cedant illorum impetui, at- <c que hincinde femet expandant, mirabili me- 4£ hercle velocitate, et extemplo quam vio- lentiffime fcecundam explodant, omnem- <c que uno impetu ejaculentur genituram, *c diffufa nimirurn pulverulenta nubecula, <c Ipargente quaquaverfum foecondationem cc arvi genitalis. Vix venereus hie Indus ab- C£ folutus eil, quin illico florum labia, aut lo- “ buii, ad fe invicem accedant eodem qui- dem, quo a fe mutuo recefierant, celeri** ££ tatis impetu, veteremque ita formam fta- ,c tiin renovent. Apparatum hunc artificio- u fum facile fpedtare datur in parietaria . Sed u accedas opportet hora facra veneri, aurora eft quae favet his congreflibus ; ubi vero agere lenuunt fatis opportune, aciculae a- :c Pice> leniter modo, flimules. In herma- ,£ phroditis, ubi duo fexus conjundti haben- lUi, muitum aoeit ut tanto impetu explo- dj.Lur. Pierique enim fiores, praecipue “ nutantes, in quibus piftillurn obliquum iiAia ftamina pontum habet, adum gene- 1 at i on is floribus claufis exercent, dum ftig- ma adhuc intra medias antheras contine- tur.;J Thus Mr. Gefner. (p)
G
(/>} Ditr. p. 86.
or
22. Allow
234 ESSAYS and OBSERVATIONS
22. Allow me here to chferve, in the firft place, that this artificial apparatus ( q ) was feen and defer ibed by John Bauhinus , long before Vaillant was born (r), and tranferibed botn by Morifon and Ray in their hiftories of plants, tho’ Vaillant mentions none of them : and, fecondly, that this feems to afford a ftrong argument againft the impregnating virtue of the d nil of the apices . For, according to Linneus himfelf, “ parietariae hermaphroditic €C flores duo continentur involucro piano hex- « aphyllo. Calyx monophyllus, magnitude « ne involucri dimidiati. Stamina filamenta « quatuor calyce longiora, iliumque expan¬ se dentia. Faemineus flos unus, inter hernia¬ s' phroditos ambos, intra involucrum ; cum
calyce ut hermaphroditi (/).” Now, fince the (lamina of the hermaphrodite flowers,
as well as the germen of the female flower
betwixt
(q) Tout, cette mechanique, Vaill.
(r) 44 Parietariae flofculi conferti circa caulem ex foliorum fiC alls, floccos coccinei ferici imitantur, primulum e nodulo « emicantes : poll fe ilamina oftendunt obfeure, exalbo pur- 44 purafeentibus apiculis, involuta, quae fi ftylo evolvere co- et neris, fubfultim excuffo pulvere cum impetu, fpedlaculo 44 jucundo, fe expandunt repanda, in medio ieminis rudimen- 44 turn circundantia.11 I. B» 2. p. 976.
(/) Gen. pi. p. 494.
PHYSICAL and LITERARY. 235
betwixt them, are contained, in one common involucrum , and the apices do not ejeft their duft, until, by the ftraightning, or ftretching out of the formerly crooked Jlamtna , the common involucrum is burft open, and the a- pices raifed in the air ; fince no fooner do they find themfelves free, and eredted high enough above the involucrum , than immedi¬ ately, by a fort of explofion, all the duft is entirely, with great violence, thrown out ; and fince the leaves of the involucrum clofe up again, as quickly, and with as much force as they feparated, and refume their former figure (t) ; does not all this fhew, that the duft is not by nature defigned to impregnate the feed, but to be carried away by the winds, left it fhould infedt it, by falling on the ftig- mata ; and that autopfia teaches the quite con¬ trary to what Mr. Gefner alledges.
23. <c It a
(*) “ Ita quidem, (adds Mr. Vaillant), lit difficillimum “ foret credere, flores hofce ullarn vim paffos efle, nifi vel ipfe aftum hunc vidifiet oculus.vel adhuc cerneret caduca fcele- “ ta magnanimorum heroum, aliquumdiu eredla in campo “ confli&us, ubi apluftrium inllar, jocularios experiuntur lufus yolitantis zephyri.’*
236 ESSAYS and OBSERVATIONS
23. ec It a fefe in plantis habere, (fays €t M. Wahlbom) didlitat primo oculus. Flo- cc re florefcente, et polline antherarum vo- cc litante, quod ftigmati pollen inhaereat, pri- £C raa fronte obvium eft (u)L But it is not at all obvious, far lefs does the eye fee, that ge¬ neration is thus accomplifhed ; for this duft as often befpatters thzpetala, &c. Neither does what he adds concerning the florefcentia molae triccloris , gratiolae , iridisy campanulae et fyngenefianim , in the leaft favour him. For, tho’ all he fays were true, thefe make but a very inconfiderable part of the vege¬ table kingdom. Yet they feem rather to make againft him. For in thefe compound flowers, which he calls fyngenejiae , the ' anther ae font lineares, eredtae, lateribus cc coalitae in cylindrum tubulatum. Stylus filiformis eredlus ftaminum longitudine, £C antherarum cylindrum perforans. Jligma c‘ bipartitum, laciniis revolutis, patentibusA Lin , Gen. pL p. 370. To which if we add,
that thefe anther ae fplit, and emit their duft, on the outfide, not in fide, of this cylinder , while the Jligma is commonly pretty far a-
bove
/ . ,
{y) Amaen Acad. 1. p. 90*
PHYSICAL and LITERARY. 237
bove it ; what can reafonably be inferred from this ftrudture, but that Nature deligned this duft fhould be thrown away as ufelefs^ if not hurtful to the Jlylus ?
Again, the Jlylus of the campanula is com¬ monly much longer than the Jlajnina , and briftly a little above them, as it were to hin¬ der their accefs to the Jligma . The Jlamina of the iris are hid under the outhde of the fegments of the jligma , the depreffed petala being frequently bearded or hairy under them. So no plants could be here more improperly alledged 5 for, by the firucture of their flowers, it is evident, that the pollinis il- lapfus fupra Jligmata nuda is impoffible : nor can Mr. Wahlbom deny it ; cc campanula , (fays *c he) a caeteris in eo differt, quod pulvis la- cc teri hifpidi ftyli adfigatur, et exinde per cc certos canales iligmati communicetur. I- “ ris particularem nobis oftendit ftrudturam ; “ ftigmata enim fefe dilatantia, antheras om- <c nino operiunt ; ilium tamen ad petala re- cc ferunt fitum, ut, aura fubeunte ftigmata* <c pollen per rimas iilorum afcendat.” What eye ever faw thefe canales , or rimae , with the pollen rifing in them ? how, or why ri {q to th t Jligma thus fituated ?
A§
238 ESSAYS AND OBSERVATIONS
As for his obfervations on the viola tricolor , I pafs them, becaufe nothing to the purpofe 3 and alfo too fmutty for BritiJfj ears. But let us hear what the great Linnaeus by himfelf fays:
24. “ Generationem vegetabilium fieri, <£ &c. (fays he) confirmat oculus . Pollinem C£ intrare germina credidit Morilandus 3 ejuf- <c dem eflentiam extrahi, mediante ftigmate cc madido, ftatuit Vaillant 3 pollinem aceris cc rumpi in humore vidit Bern. JuJjiaeus 3 om- tc nem pollinem in humore explodere auram 4c feminalem, confirmat Needham (#).” But Norland? s opinion is fully confuted by Vaillant, who maintains only that the vapour, or vola¬ tile fpirit of the male duft, enters the trachiae of the Jlylus 3 but not a word can I find in his difcourfey concerning the extraction of the effence of the duft by means of the moift fligma : and, aitho' it ftiould all burft in moifture, I do not fee how it thence follows, that it thus fends out an aura Jetninalis 3 e- fpecially, fince it does not appear, that the Jligmata muft necefiarily be moift in or¬ der to fertility : and it is obferved by Mr,
Wahlbom
(x) PliiL 9E0
PHYSICAL and LITERARY. 239
Wahlbom (y), That, “ In omnibus fere flo- £C ribus confpicitur, quomodo, aere humido,
<c flofculos complicant, ne aqua pollen attin- cc gatT By no means, therefore, can the eye be faid to confirm the fexual fcheme.
25. The fecond argument for this fcheme is taken from the proportion which the an¬ ther ae bear to the flylus .
cc Ex proportione quoque, (fays Gefnerns) u (#), verofimiliter judicamus, cum, pro cc magnitudine et numero feminum, ipfa quo- cc que (lamina maiora fint vel numerofiora.” But that this is evidently a miflake, will ap¬ pear to any one that will take the pains, to compare Linnaei monandriae with his poly- andriae ; or the cannacorus with the prunus , and other (loned fruits : the fyngenefiae have five Jlamina for one feed, and that, not feldom, a very (mail one : the umbelliferae , as many for two feeds, &c.
cc Ita lefe in plantis habere diddtat fecun- ic do proportio : plerumque (lamina et piftilla
eandem ferunt altitudinem, ut eo melius €C ad fligma pollen, mediante vento, accedat 3
£< in
(y) Amaen Acad, i, p. 95.
(z) DiiTert. p. 91.
24o ESSAYS AND OBSERVATIONS
cc in quibufdam vero non, ubi fingularis ob- £C fervatur proceffus foecundationis (a)” But plerumque diditat nihil, efpecially lince there are a great many genera , where no fuch pro¬ portion or lingular procefs takes place, as in almofl all the flofculoji , Jemi flofculoji , radiati , liliaceiy caryophyllrei , and of the iix
plants inftanced as lingular, in three* viz. dianthus , ntgella , and pajjiflora ; the pi/tilla, any curvature notwithftanding, continue high above the flamina (b)>
This argument is thus explained by £/;z- £C Property: lligmata fefe fledere'ad “ antheras, dein exferi ex diantho , pajjiflora , 4C ntgella , patet. Piftillum ubi breviffimum, “ connivent antherae. fupra lligmata : y&V- cc frag a, parnajjia. Connivent dum efHant pol-
Jinem antherae in celofla. Comprimit corolla cc digitis antheras ad lligmata in Teucrio (e).” Here not a word of proportion confirming his fcheme 5 no inltance of it ; but only rea- fons for inequality. No matter, therefore, whether it be fo in thefe or not.
26. The
(a) Wahlbom, Amaen. acad. 1. p. 90.
(b) See Pontedera for more inftances. AnthoL 3,2, c 8.
(c) Phil. Bot. p. 91.)
PHYSICAL and LITERARY. 241
26. The third argt is, cc Ex loco ftaminum et piftilli, non leve argumentum petere pof- <c famus j nam in plerifque plantis, floribus hermaphroditicis preditis, {lamina ambiunt cc ovarium, et ea ratione ut maxima pars ge~ c< niturae ad ftigma accedat.” Gefnerus (c). Can the / lamina furround the ovarium , in the monandriae , diandriae , &c ? but this needs no anfwer; neither what he adds concerning the pijlilli fabrica, and anther arum mater icsy which is nothing to the purpofe.
tc Tettio, locus. Etenim ftamiiia plerumque <c piftillum ambiunt, ut ventorum ope femper <c quidquam pulveris attingat ftigma.” Wahl- horn (d). But the learned author cannot but know, that the Jlamina {landing round the piftillum can never prove the neceffity of the duffs falling on the Jligma of every plant, in order to its foecundity 5 efpeciall'y when this is not always their filiation. He adds, ££ Mo- <c neciae fores mafculi plerumque fupra flo- <c res foemineos collocantur, ut pollen eo me- £C lius in piftillum decidat and inftances ricinus among others: but, fure I am, the ricinus vulgaris B. p. has all its female flowers
H h above
(c) Differt. p. g,
{d) Amaen. Acad, i. p. 91,
242 ESSAYS AND OBSERVATIONS
above the male flowers ; the jiigma of the upper mo ft being commonly feme inches a- bovethe neareft f lamina .
fC Locus. Nunquam piftilliferae fponte *£ nafcuntur fine ftaminiferis in eadem terra; C£ prodeunt ex eodem femine ambaeA Lin¬ naeus (e). But this cannot be proven. Yea, Gamer arius afTerts the contrary (/). But2 granting it true, it proves nothing, confirms nothing,
2 y. Argument 4th, C£ Ex tempore quoque sc vegetationis harum parti urn concludere “ datum eft : namque in antheris, flam in a C£ farinam foecundantem eo tempore conti- nent, quo piftillum viget, deinde, excuflb ££ pulvere peradta foecundatione, perit ft a men; g£ fuccus copiofior in piftillum devolutus, ef- fCficit ut frudlum maturefcat,” Gefnerus (g). But the (lamina fpinaciae , mercuriality canna¬ bis s mays, ] uni peri, violae martiae , &c. Hied their duft commonly before their jlig- rnata are vifible.
€£ Quarto tempus. Primum hie atten-
*£ dendum venit quod flam in a et piftilla una
sc proveniant,
(e) Phil, Bet. p. 91 . if) See No 10. fupra.
( g) Differt, p . 9 1 .
PHYSICAL and LITERARY. 243
/
<c proveniant, exceptis tantum paucifiimis. c£ Alterum, quod ubicunque flores mafculi cc diftin£tis a foemininis gaudent thalamis, aut cc in eadem aut diverfa planta, et ubi mafculi cc flores nec perpendiculariter fupra foemineos cc erecii funt ; ibi, florefcentia ante foliorum “ exortum peragatur, neceffe eft 3 ne, foliis cc intervenientibus, inhibeatur foecundaiio : cc ex.gr. in moro,vifco, mercurial! per entity &c.5S Wablbom (h). How juftly thefe three are in- ftanced, any body may judge. But finee he admits of exceptions, as to the firft notandum 3 and many other plants emit the flowers be¬ fore the leaves 3 this argument proves no¬ thing.
£C Tempos. In declinis flores ante germi- £C nationem foliorum plerumque prodeunt, ne cc folia tegant piftilla 3 falix , populus , cory- £C las, &c.” Linnaeus (/). Here, as com¬ monly, we find plerumque 3 and an imagina¬ ry reafon .
28. Argument 5th, viz. pluviae 3 “ Fit in- cc de ut, dum pluvia eluit pulverem ftaminum, ££ germina piftilli decidant, aut in frudlus ££ nafcantur abortivos, ut ftillant vites, perco-
££ quantur.
i 3
[h) Amaen. Acad. i. p. 92.
(j) Phil. Eot. p. 91.
2U ESSAYS and OBSERVATIONS
£C quantur, marafmo exarefcant, locum con- 4£ cedant infeftorum nidis et eorum evoluti- e£ oni, ut fruges uftiiagine pereant, et quae “ font alia vitia. Sedulo itaqueNatura ubique ££ fqlicita fuit, ut genitura illibata ad piftillum ££ perveniret/5 Gefnerus (/&). But how does it appear that fuch are the confequences, of the duft’s being wafhed away by rain ? Has too much moiflure no bad effedts, after the fiami-* na have ihed their dufts ? Does it not fre¬ quently rot the plants ? $cc.
S£ Qtiinto pluviae . In omnibus fere fieri- ££ bus confpicitur, quomodo, urente foie, fefe ^ expapdant, vefpertino vero tempore, et £C acre hum i do, flofculos complicent, ne £C aqua pollen antherarum attingat et coagu- fc let, quo fa&o, ad ftigmata efflari nequeat ^ 4£ at ftigmate, minim fane ! femel foecunda- i£ to, nec vefpere, nec pluyia ingruente,
fefe contrahant flores,,? Wahlhom (/). But our author knows, that many plants clofe their leaves in the night or in rain ; as the acaciae , mtmcfae , &c. that many open iheir flowers in the night, and fhut them
when
[k) DilTert. p.
{/) Amaen Acad', i. p. 93,
9
PHYSICAL AND LITERARY. 245
•when the fun is hot ; as fome cerei, ketmiae, xyla, lychnis nocli flora, mirabilis peruvial ra, &c. fli) Does not the paflion-flower keep open in the night as well as day, until it Ihut up roi good and all, and that whither it be fun-fhine or rain ? He adds, “ Secale florens “ antheras filamentis infidentes exferit, quo “ tempore, fi pluvia cadit, pollen congloba- tur, hincque annonam difficiletn auguratur agiicola, nec immerito ; grana enim im- minuuntur exinae, quod plenque flofculi " abortum paffi fint.” That fecale, triticum , many gramma , plant agines , pimpinellae, &c. thruft out the apices on pretty long Jiamina , when in flower, I deny not ; but that rain at tticit tiinc caufes icarcity ot any of them, I never obferved; and aitho it were granted, that tins commonly happens, How does it appear that rain caufes the flofculi to abort, or this abortion caufes fcarcity of fecale ? fmce, at the fame time, the other plants are fufliciently fertile, yea the manner of flower¬ ing in iome of thefe plants, feems to afford an argument, not contemptible, again fi the fex-
ual
' ^ C< M’.rat)5jls eft planta quae tam fpeciofos fl ores nodi
" atrae objicit, et fereno diei fubtrahit.” Lin. H. Cliff;
?• 54* • '
{ - 1
246 ESSAYS AND OBSERVATIONS
ual fcheme. For in fecale and triticum too* there are three jlamina for one germen , both included within, and well covered by the fame hulks (be they a corolla or calyx , or both, no matter here) before the flowering time. Now if the dull be neceflary to the impreg¬ nation of the feed, and, in order to this, it mu ft fall on the jligma ; Why is not this accomplilhed, before the covers open ? Why are the jlamina fo long ? Why do they thruft out the apices fo far from their ftigmata , and throw out, if not all, at leaft the great- eft part of their dull, in the common air ? Does not all this look as if this duft, was not deflgned by Nature for the impregnation of the feed ? as is often noticed.
sc Pluviae (fays Linnaeus') hi) combibunt *c pollen, ut in ftigmata cadere nequeat ; *c hortulanis notiflimum in drupiferis, (fo C€ he calls the amygdalus , perjica , prunus , cc armeniaca^ cerafus , laurocerafus , &c.) et
cc pomiferis. Agricolis deteftabilis in agris 4C fecalinis, (why not alfo triticeis i ) Fu - <c mus idem etiam facit, abforbendo humi- “ dum ftigmatis.” So the Jligma muft nei¬ ther be wetted nor dried. But this is fully
anfwered
(») Phil. Bot. p. 91.
PHYSIC AL and LITERARY. 247
anfwered above. Non caufa pro caufa is here very frequent.
29. 1 he fxth argument, which the Sexuahfts triumph in, as a demonftration of tae<r c!oitrine, is taken from the culture of the palm-tree. “ Inftar omnium argumento- rum efle poieit (lays j. Gefnerus) (0) mo- “ dus 9U0 foecundatio palmae dadvliferae “ ad °^inendos dadylorum frudus matures,’ “ aPud perfas snftituitur, a cl. Kaempfero,
“ lnhls !ocis* annotates.” It would be too long t° tranlcribe all that modern authors have faid concerning this tree. The reader may, if he pleafes, confult John Leo (p), Proffer Alpinus (q), Hadgi Mujlapha A?a (r), Emel- bertus Kaempfer (,), Pere Labat Cbrift. Got. Ludwig. ( u ), &c.
30. These authors are agreed only in this, that tne date-bearing palm-tree has no flowers: and unlefs the flowering or male palm-tree be fufficiently near, or the dull of its apices be , , n._ feme
(°) Diflert. p. 85.
{p) Harris collect, vol. i. p. 347.
(9) -^e pl* Aeg. p. 24.
(r) T. Juft. p. 69.
M Amen. exot. p. 706.
(9 Voyage aux lflos de L’Amerique, Hague edit. vol. 1, part 2. p. 209.
(«) In J. Gefner. diftV p. 86.
t4^ ESSAYS and OBSERVATIONS
feme how conveyed into the Jpatha of the female; its date ftones will not grow. I fhall pafs the very wide differences among them, as to the manner of conveying it ; and only obferve, that without the influence of the male, the female will either be barren, or caft her unripe fruit, according to the anti- ents, and Alpinus ; that the dates will want ftones, be harfh, and not eatable, except by camels and cattle, Hadgi. C( Omnia fua fru- cc ftuum rudimenta, indeclinabili abortu di- tr mittunt, Kaempfer . cc In fructu pulpae loJ cc co adeft cortex durior, ficcus, adftringens, 4£ ofliculum vel nullum vel tenue,” Ludwig . which are all contradicted by Lab at.
31. c * It is pretended, fays that reverend father, that the date-tree is male and female; that the male bears bloffoms, but no fruit, that being left to the care of the female but that fhe would carry none, if fhe had not the male by her, or at leaft within fight of her.” lam lorry that Icannot fubferibe to this opi- mon of the naturalifts, but it is a mod certain experiment, diredly oppofite to their fenti- ments, that hinders me ; for we have a date- tree faefide our monaftery in Martinico , which carries fruit, tho’ fingle : whether it is male
PHYSICAL and LITERARY, 249
or female, I know not 3 but this I know for certain, that there was not another of the kind within two leagues of it. Whence we may conclude, that the prefence of the male is not neceffary to render this tree fruitful, as naturalifts pretend A Fie fays indeed al¬ io, that the fiones of the dates of the iflands will not grow ; fo that thofe who would raife palm-trees , are obliged to plant the Barbary dates; and that dates do not ripen fo perfect¬ ly in Martinico and Guadaloupe , as they do in Africa , in Afa, or even in St. Domingo A For altho' our dates, fays he, become foft, yellow, and as it were lufcious, and in a word, appear perfectly ripe ; yet they Rill retain a certain fharpnefs, which fhews they want at leaft fame degree of maturity A
Thus Pere Lab at. 1. c.
♦
fo. Banhinus («) relates, that he faw only one date-bearing palm-tree at Montpelier < Centeiimum annum fu per are creditor, (fays <c he) et vulgo ibi perfuafum, ante grandem aetatem fru&um non proferre, et vix ante “ quin qu age iimum annum, ut quidam per- sc hibebantA Hence Pont anus s fiftion is ea- fily accounted for, if there be any truth in it $
I i and
(«) Hi.lt* s p. 360..
250 ESSAYS AND OBSERVATIONS
and perhaps fome others, particularly con-* cernirig the amours of thefe trees ; for which fee Pliny (x), and Caffianus Bajjus (y).
39. But I cannot omit the opinion of He¬ rodotus , the mod: ancient author, who has left any thing concerning the ufefulnefs of the male, to the female palm-tree*, “ In Baby - lonis agris, fays he, palmae magna ex parte cc frudtiferae proveniunt; ex quibus non folum ce cibum, vinum, et mel conficiunt, fed eti— €C am eodem modo quo ficus curantur. Pal -
cc marum enim, quas Graeci mafculas vocant, cc fruftus palmis glandiferis alligant, ut earum €C frudtum maturet culex fubiens, ne ex ar- bore is defluat. Ferunt enim palmarum ma- res (z) culices in frudtu, quemadmodum C£ caprificiA Thus Herodot , as rendered by Bed. a Stapel{a ). Whoelfewhere {b) quotes a famous traveller for fuch a culture of this
tree, as confirms Herodofs opinion (c).
Again
(x) L. 1 3. c. 4.
(j) In Theoph. p. 103,
(z) ^riva.
(a) In Theoph. p. 115.
(b) P. 103.
( c ) “ Agricolae etiamnum, ut refert dodtiffimus Guil- land, in Arabia, JEgypto,Mefopotamia, Iudaea , Phoenicia , et tota Syria, volentes cavere ne foeminae, aut fterilitatis nox-
“ am
PHYSICAL and LITERARY. 251
Again Joan. Vejlingius , who was long in Egypt, differs not a little from Alpinus , as to the culture of palm-trees there : cc Caufa tarn foecundi proventus (fays he) in telluris ha- cc bitudinem referenda eft, arenofam fcilicet <c et falfam, plantae huic gratiffimam. Vidi <c his locis in palmarum veluti fylvis, terram “ copiofiffimi nitri calida nive late confper- cc fam, vel aquis Nili, vel rofcida nodium u humiditate fervidiore foie peruftis. Nec <c opus hie mar it all cinere palmae effoeminatae “ vigorem incitare. Flantibus enim ab au- cc ftro per ^Ethiopian!, et fteriles Arabiae de- cc fertae campos urentibus, ventis 3 ingens ni- cc trofi pulveris fublata vis, abunde cacumi-
na
e< am incurrant, aut fruOum, quem aliquando imaginations ££ libidinis, ut ita dicam, concipere folent, ante maturitatem ££ amittant, ita ordinant utriufque fexus palmas, ut mares eo ££ faltem intervallo a foeminis diftent, quo pulvis, ventorum “ flatibus a foliis mafcularum fublatus, in foeminarum folia “ incidat ; idque fatis ad foecunditatem, et fruftus matura- <£ tionem facere compertum ed. Sed mirum diclu ! quod fi ££ qua procul a mare abditerit, ut neque pulvis, neque aura, ££ pdorve ejus, ad earn permeare poflit, excogitaverunt colo- “ ni funem a tnare religatam ad foeminam ufque pro due ere ; at-* “ que ita quad maritali vinculo copulatam, mafeuii virtute <c clanculum per funem irrepente, foecundam fieri, quae prius “ in ea fterilefeebat folitudine.” It is eafy to conceive how infedls may creep along a rope, but not how a powder or dud can be thus conveyed from one tree to another.
252 ESSAYS AND OBSERVATIONS
cc na palmarum vegetat.— Meminique fic o° cc nuftum fuifle dadylis fuis unicum race- cc mum3 ut eum attollere a terra prae pondere £< vix fuflinerern (</).” And Alpinus himfelf is obliged to own, that the fruitfulnefs of the palm-trees in the deferts of Arabia , is not ow¬ ing to any artificial culture, but to the winds carrying the duft and flowers of the male to the female (e). Is it probable, that nature has left the fertiliiing of fo ufeful a tree, to the uncertain motions of the air ?
Besides, that great and curious botanift ! Tour report , after mentioning the opinion of 5 Theophrajlus , Alpinus , and others, concerning the male palm-trees , adds, £C Cum in Hifpania £C Baetica, palmarum feraci, a prudentioribus viris de hac re fcifcitarer, certum nihil ac- cc cipere potui. De lupulo certius loquor. In cc Horto Regio Parifienfi, luxuriat frudibus v quotannis onuftus. Qui vero floribus gau- C£ det, non occurrit nifi in infulis Sequanae et 5C Matronae, longe diftantibus : in Horto Re- £C gio tamen femina profert ” ( / ).
This
(d) Veiling in Alpin. c. 7. p. 1 1.
(e) Y. Alpin. de plant. Mg. p. 25 =
If) JnfL p. 69.
9
PHYSICAL and LITERARY. 253
This objeaion againft the fexes of plants drawn from the lupulus , appears to be ftrengthened by the anfwer made to it ; which is this, ££ Humulus duplex omnino eft $ “ unus floribus fuperbit ftaminiferis, alter pif- €£ tilliferis 5 idque quod fniBum vulgo vocant, “ eft calyx tantum explicatus et elongatus : <c hinc humulus , quamvis foemina, nec foe- C£ cundata, conos tamen proferre valet. Hoc cc Tournefortium decepit, nefexum plantarum <c agnofceret, quum lupulus (foemina) in hor- “ to Parifienfi luxuriabat, frudtibus quotannis “ onuftus ; qui vero floribus gaudebat (mas) cc non occurrebat nifi in infulis Matronae et €C Sequanae multum diftantibus (g). Idem Cf fit in moro et blito, cujus baccae calyces funt cc fucculenti 3 minime pericarpia, feu ova- £C ria ”(h).
34. For I am at a lofs to find wherein Tournefort was deceived. He gives an accu¬ rate defcription, as well as elegant figures, of the parts of the flower and fruit, as ftanding on different plants (/), without which the charafter of the humulus , in Linnaei Genera
plantarum
(, g ) Tournefort, Hag. p. 69.
(b) Amaen. acad. 1. p. 99.
U) Vid. T. p. 535. t. 309.
$54 ESSAYS and OBSERVATIONS
plantarum (k) is not very intelligible to a be¬ ginner. But he calls the enlarged calyx, Jru - Bum : the cones he calls fruBus ; and fo they are, in the moft proper fenfe of the word. T Annaeus himielf, in his p undame j it a
hot . teaches, that “ effentia frudus in femine « confiftit”(/ ) > an d, in his Philofophia Bota - nica (m)y ££ frudus ex femine five pericarpio, « five non tedum fit, dignojfciturV No matter therefore, whether ye call thefe cones calyces elongates , or fruBus , if they contain feeds : and Tour ne fort expreflly adds, €£ In « horto regio femen profert which Mr; Wahlbom is pleafed to omit, for what reafon I fhall not fay. As for the morus and blitum , I fee not why their baccae fucculentae may not be called fruBus alfo s efpecially fince Lin¬ naeus {n) gives blitum a pericarpium 3 and de¬ fer ibes a pericarpium to be <c vifeus gravidum C£ feminibus, quae matura dimittit ”(0) : and confequently Wahlbom and he don’t well a- gree. But, to return to the palm-tree ,
35. 'Sexto*
(*) p- 477- [l) § 88.
{m) P. 56.
§
(») Gen. pi. p. 5,
(0) Phil. Bot» p. 53.
PHYSICAL and LITERARY. 255
35. cc Sexto, Palmicolas palmarum fpadi- • tfc ces mafculos divellere, eofdemque fupra
foeminas collocare, memoriae mandarunt* cc Theophrafusi P limits, Alpinus , Tournefor - <c tins , Kaempferus , alii : quo neglefto da- £c dtyli acerbi, et nucibus deftitutae, hunt,” Waklbom ( p ). This is anfwered above (N° 3 1 ) : then the author gives a long paragraph out of Kaempfer (y) ; as does Gefnerus (V), from the fame page ; yet they differ widely, I have not at prefent Kaempfer by me ; but may be allowed to notice one thing, not very credi¬ ble in each, according to their principles, viz.
Nemus foecundari univerfum poteft ab una
phoenice florida,” Gejher. cc Singulare quod €C fpadices exficcati ad thalamos apti funt, et C£ in annum pofterum, falva virtute, affervari €C poffunt,” Wahlbom.
36. “ PALMicoLiE : notiffima Theophrafo, €C Phmo , Kaempfer o, aliifque. Pifaciae cultu- cc ra in Archipelago : Pourne fortius. Caprifi~ sc catio veterum, et adhuc in Archipelago^ £C per infedla.” Vid. differt. noftr. de ficu,
Linnaeus
iP) Amaen, Acad. i. p. 94,
(q) Amaen. p. 706,
(r) Differt. p. 85.
25o ESSAYS AND OBSERVATIONS
Linnaeus (t). Neither Theophraffus , Pliny, nor ILaempjer, relate the culture of palm-trees, as from their proper knowledge ; and are contradicted by an eye witnefs, Fere Lab at.
As for the culture of pijlacia in the ArchL pelago, for which Lournefort is alledged, I cannot find any fuch thing in his works. Such a culture, indeed, is mentioned by the editor of M. Geoff? of s Materia Me die a [u], as praCtifed in Sicily : but he neither fays he was in that ifland himfelf, nor tells us who informed him. However, if fuch is the cul¬ ture of the pijlacia , either in Sicily or the Archipelago , it feems to be very modern, and founded on the imaginary impregnating vir¬ tue of the duft of the apices 5 and, no doubt, the terebinthus will foon be treated the fame way, it can do no harm ; tho’ it is not very probable, that deficiente tali impreg¬ nation e frublus abortiant in this tree, more than in the palm-tree .
3 7* Concerning caprification, if you con- fult Lheophrajlus (x), Pliny (y), and Tourne -
fort
(t) Phil. bot. p. gz.
(u) T om. 2. p, 417.
(*) Be caul', pi. 1. 2, c. 12.
{y) 1. 15. c. iq.
PHYSICAL and LITERARY. 257
fort ( )., or Pontedera (a) only, who quotes all the three, together with the learned DiC- fertation our author refers to, which I take to be Cornelii Hegardt Hijioria naturalis et medica ficus fi) ; it will be eafy to judge, whe¬ ther it is at all probable, that the fig infetls carry the duft of the caprificus to the unripe figs, and thus impregnate the feeds (c).
K k 38, If
(z) Voy. let. 8.
{a) Anthol. 1. 2. c. 33, 34, 35.
[b[ In C. Linnaei, Amaen. Acad. vol. i. p. 213. 243.
(c) “ Cnpido ficus nobis dicitur, quem antiqui pfenem feu te infeftum vocarunt jicarium , et Pontedera, Anthol, 172,
<c defcripfic, eftque fpecies ichneumonis. Hifce ichneumo-
nibus jam mutatis, alifque inftrudtis, tempus adeft, quo “ caprificus, feu ficus mas, florefcit, h. e. farinam edit anthe- “ rarum ; tunc ichneumones e caprifici cavitatibus, farina,
“ tnolitoris inftar e mola fua prodeuntis, obdudi evolant, et “ conjugibus acquifitis de ovis pariendis foliciti funt : hinc “ ad fingulos grofibs tranfvolantes, cavitates ficus foeminae,
“ dolii infiar, clavis ferreis vel fpiculis feu piftillis ab omnibus <c lateribus intus completas, intrando, non poifunt non fan- «* nam illam, qua contedi funt, excutere. Patet igitur hoc “ modo, Jicum hanc foeminam facillime irn pregnant’ Thus Mr. Hegardt, Amaen. Acad. 1 p. 231. A fine appen¬ dix for Pont anus’s poem ! But,
According to Pontedera, “ Ficarii culices, forma i( ad vefpas, nafcendi autem modo ad mufcas, accedere mihi 6i videntur. Ut primum groffi grandiufculi fadi apertum fun- *‘-dum oftendunt, ingrediuntur foemellae, et ex infimo ven”
4‘ tre produda tuba, foeturae in frumentis nidum excavant, et
ovula
258 ESSAYS AND OBSERVATIONS
38. If it be ftill alledged, that the infoe- eundity of the date ftones of Martinico de- monftrates the foecundating virtue of the male duft ; I anfwer, by no means : for Pere La-
bat
At ovula deponunt. Nafcuntur in his vermiculi, qui deinde 44 nymphaeevadunt immobiles, durae, corpore oblongo, ca- 44 pite cum dorfo luteolo, caetera primum albae mox nigrae. 44 Perforato deinde nido, exit animalculum, plerumque non- 64 dum pinnis explicatis. Egreffum ftatim fenedtam deponit “a capite incipiens. Tuncflavum cernitur, quod tamen 54 mox exficcatum nigrum evadit. Dum vero involucris 44 fpoliatur, hue et illuc revolvitur ; et propterea apicum 44 pulvifculo, quo tota pomorum cavitas repleta eft, infarci- 44 tur, quippe molliulculum. Quare e grolfis egreffum, et 64 foie exficcatum, pulverem difeutit ad hunc modum; 44 ftatis quatuor anterioribus pedibus innititur, et duobus po- 44 ftremis abdomen, lumbos, pinnas pulvere mundat, iterum 44 atque iterum cruribus detergens ; deinde quatuor pofteri- 44 oribus fefe librans, duobus anterioribus caput, dorfum et 44 cornua purgat. Quemadmodum feles et alia elegantiora 44animalia folent. Tunc, depofito onere, evolat.” An- thol. p. 174. And p. 175, he adds, 44 Hujufmodi animalcu- 44 iis tota groftbrum caro et frumenta corrumpuntur. In fativae 44 vero ficus pomis, haec animalcula nunquam inveni: num 44 vero ad haec volent ignoro ; fedulo hoc mihi inquirenti, 44 nullum fane in fativis ficubus apparuit. Neque enim Ita- 44 lia caprificationis indiget, fed fine groffis fativae ficus fua 44 coquunt poma. In Graecia hoc culturae opus perpetuum 44 non eft, ferotina poma non caprificantur; neque praeco- 44 ciorum in macro folo, et in aquilonio, in ipfa Graecia ei ulla-fit caprificatio. Pomum caprificatum bonitate inferius 44 eft non capriftcato et infuavius, Hinc illi qui in Graecia
44 ficus
PHYSICAL and LITERARY. 259
bat does not fay that he tried them ; but in general, that the date ftones of the French iflands would not grow; and, it can fcarce be fuppofed there were no males among all their palm-trees . Befides many things con¬ cerning palm-trees , which appeared to be as well attefted, are found to be vulgar errors. But, granting that they really are barren ; this may be owing to the climate, to the foil, to bad culture, or to the want of Pontederd s culices , rather than of the male duft, for any thing yet appears.
39. Argu-
44 ficus venundabant, quo facilius emptores allicerent, «- 64 isplvccrcc iterum atque iterum clamitare folebant.” And? after explaining the ufe of caprihcation, he adds, 44 Quare 44 concludendum, caprificationem in Graecia ob externas 44 C2ufas effe neceffariam, nequaquam ob ficus naturam, cum 44 alibi poma coquant non caprificata. Eadem etiam de 44 caufa palmas in quibufdam regionibus effe caprihcandas, 44 in aliis minime ; id autem per culices fieri, non vero per 44 affedionem, quam apices embryonibus communicent, fatis “ demonhratum eh.” See Anthol. 1. 2. c. 34, and 35. p. 172, &c. Now fince M. Hegardt’s Cupid , or Miller does not goe abroad, till well brufhed, and freed of the dull; fince there is no caprification in Italy ; and fince, this notwithftanding, he, and Linnaeus alfo affirm, 44 Ficus 44 in Hollandia quotannis prolici e feminibus, vel frijdu 44 lacerato terrae commendato, frudu tamen illo ex Italia al- 44 lato.” Amaen. Acad. 1. p. 233. Exam. Epicris. p. 16. Sec ; I leave it to the reader to determine, whether caprifica¬ tion affords an argument for, or againft the fexes of plants.
s6o ESSAYS and OBSERVATIONS
39. Argument 7. Septimo jlores nu- u tantes . Cum pollen mafculus, plerumque cc acre fpecifice gravior, difficile furfum ten- 5C deret^ apud plerafque plantas, piftillum lon- gius gerentes, florem nutantem fecit Crea¬ tor, ut ftigma eo melius attingat pulvis : tc e. gr. in galantho, leucoio , cyclamine , narcif- sc fo, fritillaria , campanula, erythronio , &c.” Wahlborn (e), u Flores nut antes gaudent cc piftillo, ftaminibus longiore, ut cadat pol- u len in ftigma : campanula , leucoium , galan - thus, fritillaria ft Linnaeus (f).
I readily grant, that the pollen mafculum, or pulvis api cum, is heavier than air, it being often heavier than water 5 and alfo, that fome pores nutantes have the piftillum longer than the Jlamina ; but cannot allow the reafon to be gc ut cadat pollen in ftigma for thus it mull fall on the back of the ftigma, when the ft plus, is there thickeft 5 or fall by it quite, when there flendereft and, in neither cafe, can thus have ready accefs to the feed. Again, in many genera of plants, not only in different fpecies , but even on the fame ftem, fome flowers hang down, others ftand eredt, o-
thers
{e) Amaen. aead. i. p. g^,
(/) Phil. Bot, p. 9 z.
PHYSICAL and LITERARY. 261
thers horizontal, while the piftillum and \ ft ami- na bear the fame proportion to one another : ?.g. fome fpecies of the narciftus , campanulajili- um, &c. And altho’ every ftos nutans had the//-. ftillum longer than the ftamina , yet it could not thence be inferred with any probability, that the defign of the great Creator, in thus form¬ ing them, was what our authors allege, un- lefs every eredt flower had its piftillum fhorter than the ftamina, which is far from being fabl, as is proven above (g). °
40. Argument 8. “ Videte et admire-
mini folertiam, quam Natura adhibet in plantarum aquaticarum, quae farinam foe- “ cundantem habent, floribus. Tempore “ Aorefcentiae, flores fpecifice leviores reddin', “ ultra acluae fuperficiem attolluntur, ut in “ aifre foecundatio fiat, nec humiditate dilua- tur gemtura . dum vero fub aqua flores ad- huc reconduntur fuomerxi, fblicite per pe- “ talorum commiffuras clauduntur, apicibus !>! verfus ftigma inclinatis, et verfus interio- t[ ra tantum farinaceis, exteriori fuperficie membranacea et lata j ut in nymphea et affinibus apparet, Gcjnerus (* h ) .
Octavo
{£) Vid. No 25.
(£) Differt. p. 9^
262 ESSAYS and OBSERVATIONS
<c Octavo fubmerji . Plantae haud paucae « caule fub aqua latent ; inftante vero floref- « centia, enatant flores, ut nympbaea , &c.
Aliae vero fub aqua omnibus fuis partibus cc occultantur 5 ut myriophyllum , ftratiotes, po - fiC tamogetones plerique, qui o tunes, fub fioref- sc centia, fpicam floris fupra aquas exferunt, « delude iter um ? perada florefcentia, de- €C mergitur fpicaf Wahlbom (/).
« F/cm fubmerji adfcendunt fub florefcen¬ tia : nympbaea, fratiotes, myriophyllum, poiamo- <c geton, hydrocharis, valifneriaf Linnaeus [k).
Although fome aquatic plants blow on¬ ly above the water, it cannot be proven that all do fo : yea it is certain, that many fubma- rine ones frudify under water. But, grant¬ ing all the alledged fads, it by no means fol¬ lows, that the defign of Nature is, to procure the better accefs of the duft to the jligma ; but rather that it may be difperfed in the air. For fmce, under water, the flowers C€ folicite per <c petalorum commifiuras clauduntur, apici- cc bus verfus ftigma inclinatis, et verfus interim cc ora tantum farinaceis f the duft, or its aura feminalis , muft there have much eafier accefs
to
(?) Amaeri. acad. i. p. 96.
[k) PhiL Bot. p. 92.
PHYSICAL and LITERARY. 263
to the Jligma, than it can have, when the Jla- mina are feparated, and expofed to the winds ; efpecially, if it be true, as Mr. V aillant has it, that, in hermaphrodite flowers, and fuch, ac¬ cording to the Sexualifts, is the nymphaea , and fome other aquatics, the duft is not thrown out at once with fuch violence, as it is where the fexes are feparated, <c fed adlum generations (adds Mr .Gefner) floribus clau- cc As exercent, dum ftigma ad hue intra me- “ dias antheras eontinetur.” (/)
41. I mention thefe two learned authors,
t
tho’ I have the misfortune to differ from them, not only becaufe they are commended by Linnaeus , efpecially V aillant^ of whom he fays, *c primus clare fexum expofuit (m), ” but alfo that I may help them to a better in fiance, than th eparietaria, of the fudden exploflon of the dufl: of the apices in barren flowers : it is the common flowering nettle , or urtica urens maxima , B, p. 232. (n); for one cannot
obferve
(/) Vid. n. 2i. fupra.
(m) Bib. bot. p. 173.
(#) That is for a fpecimen of botanical fuperfluity ; urtica foliis cordatis amends, cylindraceis, fexu diftin&is, mas , FI. lap. p, 299 ; urtica foliis oblongo-cordatis, dioica, H. Cliff, p. 440 ; urtica dioica foliis oblongo-cordatis, FI. fuec. p. 282 $ urtica maicula, Syft, Nat. 1335 urtica perennis, Amaen. Acad. 2. 25. 99.
264 ESSAYS and OBSERVATIONS
obferve this flinging nettle for a few mi¬ nutes, in almoft any of the fummer months, if the fun (hines, efpecially before noon, but he muft fee many little clouds of duft, thrown with a fort of explofion out of the burfting apices , which foon difperfe and fail down. This, however, being a iingle inftance, and by me not obferved in fpinacia, mer amahs, cannabis , or any fuch barren plant ; no ge¬ neral conclufion can be drawn from it.
42. Arg. 9. cc Nono, Syngenefia fruftranea. c£ Flores compoftti variis modis fabricati funt. « _ Polygamia fruftranea foeminis exfultat “ maritatis, totum difeum occupantibus 5 flof- « culi vero foeminei radium conflituentes, ob « defedum fligmatis, abundante licet difei «c pulvere, familiam propagare nequeunt,” Wahlbom (0). I omit the reft, ftnee Livnczus ( ft) fays only, cc fyngenefta fruftranea: ubi “ ftigma deeft, ibi nulla foecundatio : in ra~ dio centaureae , helianthi , rudbeckiae , corcc- ££ pftdisP But, in the radius or corona of all thefe flowers, the flylus is alfo wanting, as well as the ftigma, which may be many
ways
d
(0) Amaen. Acad. i. p, 96. ip) Phil. Bot. p. 92.
PHYSICAL and LITERARY. 265
ways neceffary to the ripening the feed. It does not therefore appear, that this proves or confirms the foecundating virtue of the dufh
43. Argument 10. is a very extenflve one. £t Ita fete in plantis habere didlitat de~ tc cimo omnium fiorum genuina conji deratio, u Brevitatis caufa nonnullos tantum hie exa- cc minare lubet,” Wablbom ( z ). And, for brevity’s fake aifo, I fhall here pafs them all > fome of them having been noticed already, as others will be below ; with this obvious note, that fuch a general pofition can be pro¬ ven only by an as general induction 3 which is altogether impradicable.
44. But fince Malpighius , whom I reckon one of the mod genuine contemplators of flowers, obferves (a), that, cc Turgentibus <c orbicularibus corporibus quibus ftaminum {c capitula replentur, exjiccataque continent e “ capfula , foras prodeunt globuli minimi et “ difperguntur 5” and that this exficcation does not, cannot well happen, before, by opening of their covers, the Jlamina be ex- pofed to the free air 3 and fince in fa the
L 1 apices
(2) Amaen, Acad. i. p. 97, {a) P, 63. edit, in 4to,
266 ESSAYS and OBSERVATIONS
apices do not fplit, at leaft generally fpeak- ing, fo far as I have obferved, until their co¬ vers open ; it appears to be a more natural Inference, that this duft is not defigned to fall on the Jligma , or to impregnate the feed {&). And, confequently, that £C Omnium florum ££ genuina confideratio, nec diftitat, nec con- ££ firmat, generationem vegetabilium fieri1 J in the manner the Sexualifis pretend.
45. Althg’ 1 have already, perhaps, been too tedious, and faid enough to overturn the modern do&rine of the fexes of plants 4 yet there ftil-1 remain fome arguments for it, which I cannot pafs. For Linnaeus fays, ££ An- ££ fheras effe plantarum genitalia mafculina , et S£ earum pollen veram genituram , docet exTen- *£ tia, praecedentia, fitus, tempus, locu- C£ lamenta, caftratio, pollinis ftrudura : jii- €£ gmata, germini uhique adnexa, zffzgeneta- ?£ lia foemimna, probat efifentia, praecedentia, £C fitus, tempus, cafus, abfciffio (c)” Which in Phil. Bot. (</), and Sponf. PI. (^), are ex¬ plained : but confirmed only, either by mis¬ takes, or by falfe conferences. Thus,
C£ Situs:
(b) Vid. No 40. fupra.
(c) Lin. Fund. Bot. § 143. 144,
(d) P. 90.
PHYSICAL and LITERARY. 267
<£ Situs : Didynamiftis ftamina adfcendunt <£ fab corollae labrum fuperius, quo et fe pi- <c ftillum fledtit.” Rut in the defcription of his clafs 1 4. or didynamia , cc Antherae fob ££ labio fuperiore faepius reconditae” (/). And, concerning the fitus, he adds, <£ Monaeciae <c pleraeque flores ftamineos fupra piftilliferos “ gerunt : zea, ricinusd But the flores fla~ minei are below the piflilliferi in ricinus . What he fays of tempus , is anfwered above $ of caflratio , below : and what he obferves of the loculamenta anther arum , and pollmis JlruBura , teach nothing, but the author's conjectures.
46. But, whether thefe arguments be concluhve or not, caflratio florum molt cer¬ tainly demonftrates the ufe of the farina foe - cundans , and confequently the fexes of plants ? cc Veritatem hanc probat cajiratio. Si an the- ££ ras alicuhis plantae uniflorae auferamus, et, €£ ne aliqua alia ejufdem fpeciei adfit, cure- t£ mus j abortit frudtus, vel faltem ova profert ££ fubventanea 5 quod adeo certum, ut quif- “ que nullo non fucceffu id expend queat,5> Wahlbom(g ). l£ Caflratio : Melonis flores fta-
<c mineos
(/) Vid. Lin. Gen. pi. p. 261.
[g) Amaen. Acad. 1. p. 86.
?68 ESSAYS and OBSERVATIONS
<£ mineos qui diligenter auferunt, fruSus non obtinent. Tulipae folitariae fi aurerantur «e antherae ante cafum pollinis, flerilis eva- tc det,” Linnaeus (b).
So the winds feem here to forget their du¬ ty. But, granting all here aliedged, it proves nothing. For plucking off the petala may have the fame effedl ; “ Saepius avullis flo- ris foliis, antequam hiarent, in tulipa prae- ^ cipue, expedtavi an ftylus incrementa ca- cc peret ; et interdum ejufdem incrementum remorari obfervavi, quandoque quaedam femina, abfque noxa, debitam fortita funt magnitudinem,” Malpighius (i). Wounds alfo in otherways neceffary parts, may be the caufe of fuch barrennefs, by depriving the feeds of their proper juices, &c. Never- thelefs there is reafon to deny the fadt : for furely M. Wahlbom did not make the experi¬ ment in every fpecies of flower's : M. Geof¬ freys mays ripened fome feeds, tho’ caftrated (k) : and I made the trial in tulips, nulk cum fuccejfu . Thus.,
(b) Phil. Eot. p. 90. and 92, f/) Oper. p„ 70.
[h) Vid. Mem. Acad. 1 711.
47, One
PHYSICAL and LITERARY. 269
47. One year, obferving two ftrong tu¬ lips growing together, in an inclofure fur- rounded with a tall and thick quickfet haw-* thorn-hedge 3 I cut down two or three more tulips y which Rood at fome diftance from them, fo as to leave none within that inclo¬ fure, fave the two I mentioned : out of thefe, gently opening the pet ala , I plucked all the Jlamina with their apices ftili intire. The confequences of this too rude caflration^ was a conliderable extravafation of the juices, in the bottom of the flower, and a fudden decay of the ovarium or fruit, which never increafed, but turned yellow, fhrunk, and withered. In order to difcover whether this abortion was owing to the wounds, or to the want of the dufl: of the apices 3 I fullered thefe two tulips to remain in the place where they were : and next Seafon, with the fame precaution that no other tulips fhould flower within the inclofure, I opened the pet a la , and took out carefully, not the jlamina , but only all the apices 3 which prevented any fen^ Able bleeding of the parts. This more gen¬ tle caftration, they bore perfectly well 3 the ovarium buffered nothin e. in either of them,
but
ESSAYS and OBSERVATIONS
but increased, and came to maturity, quite full of feeds. See alfo Gardeners dictionary, ar¬ ticle generation , near the end.
48. Thus I think I have fufficiently an- fwered all the arguments for the fexes of plants, taken either from the ftrufture of flowers, or experiments of any confequence that I could meet wi ll. But fince no (mail ftrefs feems ftill to be laid on the analogy be¬ tween plants and animals, as much favouring this doctrine; I muft beg leave, a little to con- lider it alfo, altho’ it is certainly true, to ufe Mr. Needhams words ( /), that the method of reafoning by analogy, is but too apt to lead us into mi flakes ; and therefore we ought to be very diffident of confequences deduced this way : for mere analogy, founded on fadls, and extended by conjecture, however plan- lible, can, at moft, but furnifli motives for a reafonable doubt, and further inquiry.
49. €£ Omne vivum ex ovo ; per confe- • c quens etiam vegetabilia : ovum, non foe-
cundatum germinare, negat omnis experi- cc entia; adeoque et ova vegetabilium,” Lin¬ naeus ( m ). I fhall not here enquire, whether ei¬ ther of thefe propofitions are certainly true ;
but
(/) Phil. Tranf. No 490.
(ffl) Fund. bot. § 132— 1 <roa
PHYSICAL and LITERARY. 271
but only notice, that they neither prove nor explain any thing : for if omne vivum include vegetables as well as animals, as certainly, according to our author it does ; then he might as well have faid, Omnia animalia et *vegetabilia ex ovis , et per confequens etiam ve- getabilia : if vivum do not include vegetables, the confequence does not follow. The fame holds in the fecond, and feveral others of his aphorifms.
50. In how many things foever plants and animals may agree, certainly they do not a- gree in every thing. “ Ad fummum, (fays “ cTheophraJlus') [n) non omnia fimiliter atque “ in animalibus accipi debent : nam (in plan- £C tarum genere) vis undique germinandi ha- £C betur ; q.uoniam et undique animatum eft.’* And Malpighius (0), C£ In vegetantibus, ubl <c non eft tantus organorum apparatus, et <c cuilibet fenfibili particulae, omnia infunt <c quae in toto deprehenduntur : nulla inter ce - denie generatione , abfciffi quicunque rami <c frequenter in novam fobolem excrefcunt; cc vel naturae minifterio, deciduae minimae “ et compendiariae plantulae, a tenellis fur-
culis
( n ) Da hift. pl.l. i. c. i*
(0} Anat. pi. p. 76,
ESSAYS and OBSERVATIONS
272
cc culis fub feminum fpecie, propagationem ouocimque anno perpetuant.” Hence ma¬ ny plants are much better and eafier propa¬ gated by cuttings, layers, offsets, gems or buds, than by feeds : hence garlicks , onions , leeks , &c. carry gems frequently, on the top of the ftalk, among, or in place of the feeds, as well as at their roots under ground. What are bulbuous roots but gems ? and fuch Caefal- pinus obferved on the leaves of the moly ; as they are frequently feen on the ftalks of tu¬ lips y lilies : and it is to buds that the increafe of many trees is owing.
51. Now, what is a bud? how does it differ from a feed ? “ Biffert foboles a femi- 4C ne, ut foetus vivens ab ovo ; femen enim u tanquam ovum eft, in quo eft. principium 4 c vitale, at vita nequaquam; foboles autem “ vivit, primo quidem juxta parentem, ut “ ejus germen, poftea vero per feipfum, pro- “ priis radicibus ex, terra humorem trahens,” Caefalp . de plantis (p) : and Malpighius , (q) 44 Gemmae funt velut infans, feu foetus ita cc cuftoditus, ut fuo tempore auftus, in fur- culum exciefcens, tandem ova promat.
ec Erit
(p) Lib. 1. c. 5.
(?) Anat. Plant, p. 39. 77,
PHYSICAL and LITERARY. 273
£C Erit igitur probability* femen quafi gemma ££ pendula et decidua, alieno gerrninatura tc foloA And although the learned Petrus Lofling , in his treatife called Gemmae Arbo - rum (r), or rather the publisher himfeif, is pleafed to fay, ££ qui gemmam fibi reprefen- ££ tant ut alterum femen, fallunt et fallun- £C tur” ( / ) ; yet his defcription of a gemma feems not altogether to agree with this not an- dum : for (/) he fays, ££ gemma eft pars plan- ££ tae radici iniidens, quae occultat fquamis, 56 foliorum rudimentis, embryonem futurae £C herbae And below (u)i he explains what he means by radix thus, “ Hae gemmae infi- £C dent, vel radici fub terra reconditae, vel ra- £C did fupra ter ram in truncum ramofum aJjur - £C genti \ iliac, ubi carnofae fuerint atque mag- ££ nae, bulbi nomine veniunt, &c.” And elfe- where (#), ££ Gemmam proinde concipio in- £C ftar herbae in compendium redadlae, tedlae £C et contra&ae fua inter extrema folia, ut ab ££ aeris injuria confervetur ; cui herbae nihil
Mm <£ amplius
(r) Amaen. Acad. 2. p. 182 224. (/) P. 1 85. note k.
(/) P. 185.
( u ) P. 186.
(*) P. 192,
ESSAYS and OBSERVATIONS
27 4
“ amplius deeft, quam vis fe extendendi ; e- fiC am autem calor demum excitatT Is not this as applicable to feeds, as to gems ? tc Se¬ men, (fays Linnaeus ) (y) proprie, novum ve- £C getabilis rudimentum, humore rigatum, <c vefica tunicatum.” And is not a gemma the fame ? or a more perfect feed ? however, call it embryon , compendium, primordium plantae* or what you pleafe, with its covers : lince Linnaeus owns, <c Generationes plantarum ex fe mine et gemma efie coevas (z) ; and “ gem- mas , proinde ac femina , in fe continere pri- cc mordium. plantae [a) f it comes to the fame thing for our purpofe. For,
52, If gems contain the primordi a plantarum, they contain the moft effential part of feeds becaufe the feminis ejjentia conjiftit in corculo (b) ; and the corculum is nothing but the novae plantae primordium (c). Now fince buds or gems are copioufly produced by numberlefs plants, and often break out of the fmootheft part of the bark, efpecially of pruned trees 5 and, fince the fmalleft
part
(y) Lin. Phil. hot. p. 54,
(x) Phil. bot. p. 88.
(а) Gem. arb. Amaen acad. 2. p. iS^.
(б) Phil. bot. p. 56.
(c) Ib.p. 54.
PHYSICAL and LITERARY. 275
part of a plant may be made to grow and emit gems, whether it be naturally fertile or barren, male> female , or hermaphrodite : does it not clearly follow, that neither dif¬ ference of fex, nor illapfus pollinis anthe - rarum fupra figmata nuda , are neceflary to the production of the primordia plant arum, the efience of feeds, as well as of gems; and that no imagined analogy between plants and animals, can warrant or excufe the fulfom and obfcene names, impofed by the Sexualifs on the different parts of the fructification of vegetables ( d ) ?
53. Not a few other arguments againft the modern doCtrine of the fexes of plants, might be brought from the ftruCture of ma¬ ny compleat flowers, as well as from the nu¬ merous tribes of fuch as are called lefs per¬ fect 5 fome of which produce feed, but want flowers; others have neither flowers nor feed. For it requires more than an ipfe dixit to prove, that £C omnis fpecies vegetabilium flo- “ re et fruCtu inftruitur, etiam ubi vifus eaf-
<c dem
[d) Vid Cl. Linnaei fundamenta botanica, § 140, 143, 144, et 146, and the learned commentaries on thefe, in the Sponfalia pi ant arum, and Pbilofophia botanica ,
276 ESSAYS AND OBSERVATIONS
£C dem non affequitur/7 as Linnaeus afferts (^). I know he attempts to prove it thus(/), cc Muf- cc corum femina A7w ; lemnae flores delineati €C a Vallifnerio-, fucorum flores obfervavit Reau- iC mur ; pilulariae flores invefligavit B.JuJjiae- cc us*, fungorum ftamina defcripfit Michelius ” And this is all, and affords but a lame proof, and mofliy conjedurah
Thus, although Dillenius (g), in the end of a particular defcription of the felago foliis et facie abieiis, R. fyn. p. 106. or upright Jirr-mofs , fays, £< plura non obfervavi, nec femina in his vel calycibus, vel foliis bra- ■ c deatis invenire potui:” yet becaufe he adds, *£ Sufpicor autem bradeas illas folia femina- <c ha effe, et novarum plantarum produdioni cc infervire J the learned author of the Je¬ mma mufcorum (h), pofitively concludes, Haec foliola, tempore autumnali matura de- S£ cidunt a calyce perfiftente, et novam plan- “ tarn propagant, radiculas e bafi exferentia” Eut, fince below (/) he owns, that “ Semi- €C na mufcorum tanquam nuda corcula, fine
£C cotyledonibus3
(e) Fund. bot. § 1 39.
(/) Phil, bot. p. 89. '
ig) Hid. Mufc. p. 437,
[b) Amaen. acad. p. 2. 295,
(d 299,
PHYSICAL and LITERARY.
2 77
cc cotyledonibus, fine tunicis animo concipi- u enda funt. — Flos autem obfcure nobis per- cc cipitur, cum nullum Jlylum , nullumque ftig - cc ma habeat if, what he calls a feed, real¬ ly takes root and grows (for I find not that either he or Dillenius made the experiment) j it has a better claim to the character of a gem, than of a feed. And, whether or not, it is evident that the €C generatio mufcorum <c minime fit, mediante pollinis antherarum "c illapfu fupra ftigmata nuda.”
54. The fame learned author (k) afferts, u Quod pulvis in capitulis mufcorum fit pol- cc len mafculum:” that the “ femina lycopodii “ officinarum, funtpurum putum pollen {/);” tho? others think them all rather feeds. But, whether they are either, I fhall not, can¬ not determine : only they feem to refemble more the feed of the lingua cervina ; which has been found fertile (m), without the foe¬ cundating influence of any antherae yet difco- vered, that I know of. But, granting the above cited aphorifm to be true in its largefi extent, it can never prove the alledged ufe of
. the
(£) p. 300.
(/) p. 293.
(w) Vid. It. ox, 3. p. 555,
» 1 . ‘ 1 *
278 ESSAYS AND OBSERVATIONS
the duft of the apices in imperfedt plants, where it does not appear 5 fince the contrary is demonftrated in the moft perfedt of the vegetable kingdom.
55. I noticed above, that feveral argu¬ ments might be taken from the fructification of fome of the moft compleat plants : and the author of the femina mufcorum ( n ) gives fome inftances, and anfwers them ; how fa- tisfyingly, I leave the reader to examine. On¬ ly, fince there are there three fpecies of the viola, I fhall add a fourth, viz. viola martia purpurea Jlore Jimpli ci odoroy B. p. 199. or com¬ mon March violet . This plant puts out its flowers with the J lamina in March , on long foot-ftalks; no fruit fucceeds them, nor ap¬ pears for fome weeks, yea months after, when clofe on the root, and well covered with the leaves, the fruit is formed, foon ripens, and contains plenty of feeds; tho’ all the flowers were plucked in March. Does either tempus or proportion here confirm the fexual fcheme ?
56. Fo conclude ; Had the modern do¬ ctrine of the generation of plants, continued only to influence the learned more accurately
£0
(«) P. 1 86, &c.
PHYSICAL and LITERARY. 279
to inquire into the ftrufture of vegetables, I would never been at fo much pains to confute it : but, fince it has given occalion to an in¬ tire deformation of botany, and to the in¬ troduction of an infinite number of new names, and perplexing, tho’ childifh terms, whereby this moll ufeful fcience, is like to be¬ come not only vaftly more difficult, but even ridiculous; I thought it high time to publilh fuch arguments as to me appeared fufficient, by Tapping the foundation, to overturn this hideous fuperilrudlure. For furely no me¬ thod at all, is much better, than fuch an one, whofe nomenclature is more difficultly acqui¬ red, than the knowledge of the plants them- felves, which alone is true botany. But of tnis more elfewhere (c). It remains only that we inquire a little into the real ufe of the dull of the apices.
SECT. IV.
56. Authors are fo much divided in opi¬ nion, as to the primary ufe of this dull, that it may be doubted whether it be of any to the plant wffiich produces it. And, fince ve¬ getables ferve only, or at leaft chiefly, for the
ufe
M Tyrocin. Bot. I. p. 40. 50,
2> So ESSAYS an to OBSERVATIONS
nle of animals 3 what the great Mr. Boyle fays of the one, may well be applied to the o- ther (/>). And fince we fee bees frequent¬ ly come out of flowers loaded with their duft, and apparently carrying it to their hives 3 it is not improbable that they feed on it. For, if Mr. Geoffrey s experiments can be depended on (y), it cannot be the materia of wax, with¬ out being digefted and prepared in the in- fed 5 and, how many other infedts may live on it, I cannot telh
57. But*
{/>) “ The whole animal is but a part of that greater body 6t the univerfe ; and therefore cannot eafily be fuppofed to e* have been framed and furnifhed with the parts it confifls of, intirely for its own fake. And, when we fay, that all “ its parts are contrived for the bed advantage for the animal, “ I conceive it to be underdood in this limited fenfe, that * the parts are excellently framed for the welfare of the ani- mal, as far furtb as that welfare, is confident with the ge- 6i neral ends of the Author of nature, in the conftitution <£ and government of the univerfe. All which ends it is not ic an eafy talk to difeover, tho1 fome of them may be inve- “ ftigable by us. And, it feems prefumption to fuppofe, il that the welfare of particular animals, is any further de- ({ figned and provided for, than will confift with the cofrni- “ cal ends of the univerfe, and the courfe of God’s general providence, to which his fpecial or particular providence, “ about this or that mere animal, ought, in reafon, to be 64 fubordinated.” Vid. Boyle’s Works, vol. 4. p. 548.
(?) Vid. Mem. acad. k. 1711.
PHYSICAL and LITERARY. 281
57. But, if it be infifted on, that its primary ufe muft refpeft the plant itfelf : perhaps Caefalpinus may be in the right, with relation to the plants, whereof fome, in the fame fpecies, carry /lamina , and others the feed (r) : and Malpighius (/), and Tourne - fort, with relation to fuch as bear both on the fame individual plant : viz. that it carries off what is excrementitious, and unfit for nou- rifliing the feed ( t ). I own, indeed, that this opinion does not well agree with that of Caefalpinus, ; it being more than probable* that the dull: of the apices , in barren as well as fertile flowers, is of the fame nature, and defigned for the fame ufe.
$8. And, from what has been obferved of the parietaria , ficus^ viola , &c. yea and from the general ftrudture of fertile, as well as bar¬ ren flowers ; it is adfo more than probable, that this duft is rather excrementitious and
N n noxious
(r) Vid. fupra. N0 6,
( /) Vid. p. 70.
(/) “ Petala, '(fays Tournefort) alimentum a pediculo a c- “ ceptum vifceris inftar, perficiunt, et fru&ui nafcenti fuppe- “ ditant ; ineptis humoris partibus per ftamina, feu vafa ex- “ cretoria, abeuntibus in apices feu receptacula Diximus “jam apices, quicquid minus apti continet alimentum, in fe “ recipere, rerumque valvas a congeitis excr emends deduci.” Inft. p. 69 and 70,
2$2 ESSAYS AND OBSERVATIONS
noxious, than ufeful to the nourifhment, or foecundity of the feed. Nor is this inconfi- ftent with its influence, on the production of the numberlefs varieties of new flowers^ which yearly adorn the gardens of the curi¬ ous : if the opinion, which has for fome time prevailed, be well founded ; to wit, that it is the beft way to obtain new varieties of fine flowers, to plant near together fome of the beft kinds of the fame fpecies, differently va¬ riegated, and fave their feeds : reckoning that the dufts of thefe flowers have fuch influence on one another, that their feed will produce finer varieties, than the feed of the beft of them would do, if it ftood alone, however o- therwife managed. And on the fame foun¬ dation it is, that M. Du Hamel's fcheme, for producing new varieties of fruits, is built («)„ I fay, allowing all this to be fac ft, which I cannot confirm 5 it feems rather to eftablifh, than to be an objection againft Mr. Tourne - fort's opinion.
59. F or, lince all double flowers are mon- fters, “ Luxuriantes fibres (fays Linnaeus) “ nulli naturales, fed omnes monftra funt ; 5< pleni eunuchi evaferunt, proliferi monftro-
<c forum
{?/) Vid. Mem. acad. an. 1728.
PHYSICAL and LITERARY. 283
cc forum augent deformationem (a:)” j fince the fined varieties of flowers are the mod tender ; fince variegation of flowers, as well as of leaves, is preternatural ; and fince even the improvements of plants, or fruits by cul¬ ture, with relation to their ufefuinefs to us, are but difeafes in the plants, confidered in their natural date : may it not be properly in¬ ferred, that, whatever influence the dud of the apices has in producing thefe, it mud be owing to its noxious, not foecundating va¬ pours ?
60. And, to conclude, although it fhould be granted that we have not fuflicient data, to enable us to determine pofitively of what real ufe this dud is to the plant : yet, fince it has appeared, to a demondration, certain, that fertile feeds may be produced without it ; our ignorance herein, can never be an argument of any confequence, for the modem fexual fcheme, or dodrine of the fexes of vegeta¬ bles, againd which I have been arguing ;
with what fuccefs, I fubmit to the learned to * *
determine.
(*) Fund. Bot. §150.
Art.
284 ESSAYS and OBSERVATIONS
Art. X.
'Remarks on chemical Solutions and Precipitated ons , by Andrew Plummer, M. D . ; Fellow of the Royal College oj Phyficians , and Profeffor of Medicine and Chemiftry in the Univerfity of Edinburgh. *
THAT I may not give the firft in fiance of breaking in upon the order and rules eftablifhed in this fociety, I fhall lay be¬ fore you, at this time, fome mifcellaneous obfervations, on the folutions and precipitati¬ ons which frequently occur in the profecuti- pn of chemical enquiries.
I fhall lay down thefe remarks by way of propofitions, and, after each, fhall mention the fads or experiments which gave occafion to the remark, or which confirm and illu- Jlrate the propofition.
Although many of the in fiances which I am to adduce, are common, and well
known to every one verfant in chemical ex¬ periments: yet, as the hiftory of chemical
folutions
V • . ‘ ‘-■ft V
f January 17 38,
PHYSICAL and LITERARY. 285
folutions is very extenflve, and as many An¬ gular conditions and appearances, are to be obferved in the actions of various folvents, upon the bodies which they diflfolve; it may poffibly be of fome advantage, to any one who (hall afterwards undertake to give a ra¬ tional and fatisfadtory account of the caufes which produce fuch effedts, and of the laws by which thefe caufes adt in particular cir- cumftances, to have in his view a great ma¬ ny inferior axioms or canons, comprehend¬ ing as many particular inflances as poffible $ becaufe thefe may enable him to afcend to more general canons; and at length to the ultimate phyflcal caufe ; and again, from, thence to explain the phcenomena> in particular inflances.
By Jolution , is here meant, the feparation and diviAon of a folid body, or of a thick and confident mafs, by means of a fenfible fluid, into parts fo fmall, as to difappear and be equally difperfed through the fluid.
That liquor which makes the feparation of parts, I call the fohent ; or, in the Rile of the Chemifts, the menjlruum .
I muft take the liberty, to make one preli¬ minary remark, before I delcend to particur
Jars |
286 ESSAYS and OBSERVATIONS
lars : for, if the affertion of certain Chemifts was well founded, it would, in a great mea- fure, fuperfede any further enquiries.
I. The notion of an univerfal menflruum> capable to diffolve equally every body to which it is applied, appears repugnant to the nature of things, and to thefe limited powers which we difeover in all known bodies.
I (hall not undertake, in this place to ad¬ duce and examine the bold afiertions and high pretenfions of fome Chemifts to the difeovery of an univerfal folvent ; becaufe it would exceed the limits which I propofe to myfelf, and perhaps afford little entertain¬ ment or inftruftion. But I rnuft be allowed to doubt of the pofiibility of an univerfal iol- vent, until more certain evidences are produ¬ ced than what have hitherto appeared. For, as there is a vaft variety of bodies which dif¬ fer much from one another in denfity, foli- dity and texture, in the bulk, (hape and com- pofttion of the conftituent particles, in the degree of force with which thefe cohere a- mong themfelves, and in the number, ftze, and figure of the pores or interftices be¬ twixt the folid parts ; it is fcarce conceivable,
that
PHYSICAL and LITERARY. 287
■ that any one liquor can be endued with powers correfponding to all the various cir- cumftances of fiich a variety of bodies, fo as indifcriminately to diffolve all : it is therefore much more agreeable to the nature of things, that there fhould be a variety of liquors en¬ dued with different qualities, in different de¬ grees, to feparate the particles of fo many different folid bodies ; and daily experience fufficiently confirms the truth of this conclu- fion. There is perhaps no body, natural or artificial, but there may be found a menjlruum proper to diffolve it : and, tho’ fome liquors are known to diffolve feveral bodies which differ in many refpe&s ; yet even thefe fol- vents, which are allowed to be mod: exten- five, are found incapable of diffolving a great many other bodies.
II. The denfity, folidity, hardnefs, fix- ednefs and other manifeft qualities of bodies, can afford us no certain mark or indication of the qualities of the liquors, requifite to dif¬ folve them, if experience is wanting. Nei¬ ther can we conclude, from the (Length, fharpnefs or corrofiver.efs of liquors, difco- vered by their effeds on the human body,
the
288 ESSAYS and OBSERVATIONS
the fitnefs of fuch liquors to diffolve different fub fiances.
Iron and copper, the hardeft of the metals, which require the greateft force to extend them, and the ftrongeft fire to bring them to fufion, will be corroded and diflblved by li¬ quors moft harmlefs to the human body ; as vinegar, juice of lemons, a folution of tar¬ tar, rhenifh wine, nay moift air : whereas quick-filver, whofe particles are fo mobile, eafily feparable and diffipated by a moderate heat, and tin, which is very foft and eafily melted, require more corrofive menftrua. Coral, and fome of the hardeft gems, will be better diffolved in a weak vegetable acid, than in a much ftronger one of the mineral kind* Oleum vitriolic fpiritus nitric or aqua fortis , the moft ponderous and corrofive of the a- cid liquors, cannot diffolve bees- wax or crude fulphur, which will readily relent in the mild and foft oil of olives ; fal tartari , or 0- kum tartari , p. d. is almoft equally corrofive, with regard to the human body, as aquafortis : yet the folvent powers of thefe liquors, with refpedt to other fubftances, are moft oppo- fite.
III. The
physical and Literary. 289
III. T he fitnefs of a liquor to diffolve a certain body, cannot be certainly learned from the agreement of that body in feverai pro¬ perties with another, which we know can be diffolved in that liquor. Neither can we fafely conclude, that two liquors, which nearly referable one another, will mutually diffolve all the fame bodies.
W e meet with abundance, of inftances, in chemiflry, to make us cautious in drawing fuch conclufions. Well redified fpirit of wine, makes a very compleat folution of colophony or any of the common rofins ; but there are feverai fubftances which have a great affinity to rod ns, as lacca, copal y amber , fulphur , which being digefted with highly redified fpirit of wine, will fcarce give a tindure to the fpirit ; that is, thefe bodies remain either altogether, or, for the far greater part, indiffo- iuble in that liquor, unlefs they are previouff ly prepared and difpofed to a folution, by the interpofition of another body, as a fixt alca- line fait, &c. Deftilled vinegar will readily diffolve -copper, lead, iron; but, it would be rafh to conclude, that the fame liquor will alfo diffolve gold, filver, antimony, what¬ ever agreement we find between thefe bodies
O Q afld
290 ESSAYS and OBSERVATIONS-
and the former. On the other hand, aqua fortis and aqua regia appear to be much of the fame nature ; and the former, by a very fmall change, may be converted into the latter j yea, further, they diffolve equally feveral bodies, as copper, iron, fpelter, tinglafs : yet, it would be erroneous to conclude, that, whatfoever body one of thefe liquors dif- folves, the other would diffolve the fame ; for aqua fortis diffolves filver and not gold, and, vice vcrfa , aqua regia diffolves gold and not filver.
IV. The foivent power of fome liquors, with refpedt to certain bodies, may be in- creafed, diminifhed or deftroyed, by a very fmall and almoft imperceptible change of the liquors.
I put two grains of gold into a drachm of fpiritus falis marini , and fet the glafs on warm fand ; after fome hours, I could obferve no fen fib! e change of the bits of gold, in colour or bulk, nor of the liquor : then I put into the glafs, as cautioufly as I could, one drop of fpiritus nitric after fome time, I found the liquor had affumed a bright yellow, or goiden colour, and the gold quite difiblved ; ioi there remained only a few white particles
PHYSICAL and LITERARY, 291
at the bottom, which were probably filver. Thus the very fmall addition of fpiritus nitri very much increafed the folvent power of the fpiritus falls mar ini. It is known, that ole¬ um vitrioli poured on quick-ill ver, and kept in the common air, or in a very gentle heat, does not corrode or diffolve it ; but, if they are brought to a heat exceeding that of boil¬ ing water, then the folution takes place. Mr. Boyle teflifies, that, by his care to rectify or dephlegmate aqua forth very much, he ren¬ dered it unfit to dififolve filver. While aqua forth is diflfolving copper with a brifk motion, if a little alcohol is poured in, the folution will be ftopt.
V. Some bodies which we know can be eafily diflolved in certain liquors, may be fo changed by the fire, or otherways, that the fame liquors will not afterwards diffolve them. On the other hand, the fire renders fome bodies fit to be difiolved in certain li¬ quors which could not be diflolved in them before.
The oil of vitriol, as I faid before, alii fl¬ ed by a proper degree of heat, readily e- nough difiolves quick-filver : but when quick- fiiver is, by long digeftion in a moderate heat,
deprived
^92 ESSAYS and OBSERVATIONS
deprived of its fluidity, and turned into a red calx , or has been firft diffolved in aqua forth ? and afterwards, by evaporation and calcinati¬ on, freed from the acid, and reduced to a red powder ; if either of thefe red powders, I fay, is digefted with oil of vitriol, and made to boil, this liquor will not now diflolve the mercury, or fo much as change its colour. On the other hand, tho y fpir.fal. mar . is not efteemed a proper menjlruum of quick-filver in the immerfive way, but when applied to it in form of vapour in fublimation ; yet if this fpirit is poured upon the red precipitate mer¬ cury, it prefently changes its colour to white, and quickly diffolves it. Again, fpir* jal. mar . readily diffolves clean and frefh fiie- ings of iron : yet if thefe are frequently moifl> ened with water, and by trituration and cal¬ cination turned to a crocus y fp. fal . mar . poured upon this, raifes an effervefcence indeed, but does not feem to make a folution; for the iron lies at the bottom not fenfibly diminifhed and the colour of the liquor is not changed. Some ores, as they are taken from the mine, tho’ they appear pretty rich and clean, yet will pot readily diflolve in the fame menftrua , which are fit to diflolve the pure metals, un¬ til
PHYSICAL and LITERARY. 293
• til the ores are roafted, wafted and fmelted? The calces of lead and tin will more eafily diffolve in fpirit of vinegar, than the thin plates or (havings of the fame metals.
VI. Some liquors which diffolve feveral different bodies, while they perform the fo~ lutions, feem to adt in a different manner up¬ on each body, require different helps, and diffolve different quantities of each.
This is very remarkable in the adtion of oil of vitriol upon iron and quick- filver : to make oil of vitriol diffolve iron fuccefsfully, it muff be diluted with a quadruple quantity of water; when the clean fiieings are put in¬ to this liquor by degrees, there arifes a ftrong ebullition and effervefcence, with a confider- able heat and thick (teams of a penetrating ful- phurous fmell, which are apt to kindle and make a fulminating noife upon the approach of the flame of a candle ; and, laftly, one ounce of oil of vitriol thus diluted will diffolve an equal weight of pure fiieings of Reel : but, when oil of vitriol is employed to diffolve quick-filver0 it muff be ftrong and well de¬ phlegm ate d ; when it is poured upon the quick-filver, it raifes no inteftine motion or heat ; it does not begin to corrode or diffolve
the
294 ESSAYS and OBSERVATIONS
the quick-filver, till there is fuch a heat ap¬ plied, as will almoft bring the liquor to boil, and even then the folution goes on flowly and quietly : iaftly, to diffolve one ounce of quick-filver, it requires, at lead, three ounces of oil of vitriol ; and yet the quick-filver will not he entirely fufpended in this ponderous liquor.
Even water, tho* it diffolves all kinds of falls, yet it does not adt upon all of them with the fame eafe ; that is, the fame quan¬ tity of water cannot diffolve an equal quanti¬ ty of each fait, in the fame time, or with the fame degree of heat 5 for an ounce of cold water will foon diffolve half an ounce of fait of tartar ; but half an ounce of crude tartar cannot be diffolved in lefs than ten ounces of water ; and that quantity of cold water will make no folution until it is brought to boil, and continues to boil for fome time, new water being added to fupply the wafte. Even that compound fait, made of the fixt fait and chryftals of tartar, which, from its fo- lubilify, with refpedt to common tartar, gets the name of tartarus felubilis , requires little lets than ten times its weight of warm wa¬ ter to diffolve it fully.
VII. Some
PHYSICAL and LITERARY. 29-5
. VII. Some bodies can be diffolved in li¬ quors of very different qualities, but in differ¬ ent proportions, with different helps, appear- ances and effefts.
Common iulphur or its flowers diffolve in any oil, but more eafily, and in greater quantity, in a thick, mild, expreft oil, than in a thin, hot, aromatic, diftilled oil. When flowers ot fulphur are digested with oil of olives, or lint-feed, it becomes a thick bal- fam ; three ounces of oil will diffolve one ounce of fulphur ; and any fmall part of ful¬ phur which remains, has the appearance of melted fulphur. But when the flowers are digefted with ethereal oil of turpentine, fix ounces of oil will fcarce diffolve one of ful- piiur, and what remains is not like the ful¬ phur in the former cafe 5 for, if the veffel is cooicd gradually before the baliam is pour¬ ed off, the fulphur appears almoft like nitre when it chryfiauizes, or a vegetating fait branched out into long {lender ftalks. Sul- phiu likeways diliolves in fpirit of hartfhorn, but ftill in leis quantity, and with a fmaller degree of neat. And it is to be obferved, that the unrectified or oily fpirit will dif¬ folve more fulphur than the clear and pure
% /» * •
ipmt.
2 96 ESSAYS A^D OBSERVATIONS
fpirit. To make fulphor foluble in water or fpirit of wine, it mu ft be melted, then mix¬ ed and incorporated with a fixed alcaline fait, by which means it will moftly diffolve in warm water, and give a deep and ftrong tin dture to fpirit of wine.
The calx of lead, litharge or minium , dif¬ folve in diftilled vinegar ; but more fully and quickly in aqua jortis diluted with fix times its weight of water. The folution of lead in fpirit of vinegar, being evaporated ftowiy, to a due confidence, and then remo¬ ved to a cool place, never (hoots into fair di- ftindt chryftals ; but thickens, as it Were, into a faline niafs, like coarfe fugar, fome- what moift ; and, with difficulty, can be
brought to a tolerable whitenefs : but the fo¬ ci
lution in diluted aquafortis , treated in the fame manner, gives large, folid, finning white chryftals, regularly lhaped. The calx of lead or minium will like wife diffolve by digefting or boiling in oil of olives or lint- feed; but as it diftblves, it thickens into the eonfiftence of an unguent or plaifter.
Good aquafortis or fpirit us nitri will dif¬ folve about an equal weight of quick- diver, and the folution is performed with a great
commotion
PHYSICAL and LITERARY. 297
.commotion, heat, and thick red fmoke : ftrong oil of vitriol diffolves fcarce a third part of its weight of quick-filver, and the foliation is made in a flow and imperceptible manner, and requires the affiflance of a great exter- nal heat.
The manner in which the acid of fea fait is applied to quick-filver, in order to diffolve and be united to it, is dill more extraordi¬ nary : there are two methods pradtifed, but both depend on the fame principle, and pro¬ duce the fame effedt. For either the quick- filver is rubbed in a marble mortar with green vitriol calcined to whitenefs, decrepitate fea fait, and a fmall proportion of dry falt-petre^ till the quick-filver is extinguifhed and dis¬ appears, this mafsisput into a fubliming glafs, a gentle heat is made at firft, and gradually increafed ; in the beginning strife white fleams* if thefe are collected, they condenfe into a li¬ quor, which proves a weak aqua regia 5 then there will fublime a white fhining ehryftal- line body, which is a vitriol of quick-filver* and goes under the name of mercurius f ublima - tin corrojivus : that the quick-filver is here diffolved by, and united to the acid of fea fait, with a fmall quantity of the nitrous a-
P p £idb
2$S ESSAYS and OBSERVATIONS
cid, is evident, becaufe the fame materials* without the addition of quick-filver, proper¬ ly treated, yield a good aqua regia which dif- folves gold. Or quick-filver is firft diffolved in aqua fortis , the folution is evaporated till there remains a white, dry, vitriolic body* which is to be mixed and rubbed with an equal weight of decrepitate fea fait, and fu- blimed as before : here like wife the acid of fea fait, with a portion of the nitrous, is join¬ ed to the mercury \ for one way of prepa¬ ring an aqua regia , is by pouring aquafortis upon decrepitate fea fait, and drawing off a liquor by diflillation, which is in effedt done in this cafe, only the acid incorporates with the quick-filver into a vitriolic form.
VIII. The folvent powers of certai nmenfrua are not deftroyed in the adt of folution, but can be exerted on other bodies ; and the men - ftrua feparated from the diffolved bodies, may retain or recover all their former qualities.
This property of feverai folvents, will be found to obtain* in many more inftances. than is commonly imagined. Many folvents, when they are adtually diifolving bodies, excite a ifrong and remarkable effervefcence, with a great expan fion, biffing, bubling, heat and
fmoke
PHYSICAL and LITERARY. 299
* fmoke ; and, after the folution, the liquors frequently acquire new qualities which were not confpicuous before, either in the folvents or in the bodies diffolved : whence it is ge~ nerally imagined, that, from this ftruggle or adfion and reaction betwixt the bo¬ dies, the particles of the menjiruum are broken, their points blunted, and their fi¬ gures changed, by penetrating into the pores of the folid body, by disjoining and dividing the parts very minutely. But, I fliall en¬ deavour to make it appear, from experi¬ ments, that the adtive particles of mod: li¬ quors, employed as folvents, are extremely tenacious of their figure, bulk and denfity, at leaft of the powers and properties which depend on thefe, and conftitute the particular marks and characters of thefe liquors : that, tho’ they have diffolved feveral different bo¬ dies, have entered into many competitions, and have paft thro’ a great variety of forms ; yet, after all, molt of them can be brought back to their primitive ftate, and made to exert the fame powers which they did at firft, and again run thro’ all the fucceffive changes;
o o y
fo that it may be doubtful whether art can
intirely
*
JOO ESSAYS AND OBSERVATIONS
intirely change the nature of fome of thefe folvent liquors.
To begin with fome familiar inftances to confirm our remark. Water can diffolve a certain quantity of any fait ; yet, when it is fully impregnated with one fait, it will hill diffolve a portion of another fait, tho’ not fo much as the fame quantity of pure water would do. From fea water, by evaporation and <rfiryft alligation, are procured three diftindt falts, befides other fubftances, as the ingeni¬ ous Mr. Brown has obferved, viz. the muria¬ tic, or fait for common ufe, the bitter pur¬ ging fait, and a fiery calcarious fait, different from the other two ; yet fea water will diffolve, at the fame time, a pretty confider- able quantity of feveral other falts, as fugar, fait ammoniac, fait petre and fait of tartar ; and, after it has diffolved fufficiently of two or more of thefe falts, it will, even then, diffolve fome more fea fait, and ft ill more of the epfom or Glauber s fait. Hence, by the way, we find fuch a variety of mineral or medicinal waters, impregnated in various proportions, with' different falts, vitriols, me¬ tals, earths, &c. The acid of fea fait, which has diffolved quick-filver, and chryftallized
with
PHYSICAL and LITERARY. 3oi
with it in the fublimation of corrofive mercu¬ ry, will diffolve the metallic or reguline part of antimony into a liquor, called butyrum an - timonii ; and this will afterwards diffolve gold. Diffolve filver in aqua fortis> when the folution is finifhed, add to it fome crude fait ammoniac, in powder, and fet the vef- fel in hot fand ; the filver will all fall to the bottom : then pour the clear liquor into an¬ other glafs ; this will be found a good aqua regia fit to diffolve gold, regulus antimonii , &c. There is another noted experiment which evidently illuftrates and confirms the remark. If fine copelled filver is diffolved in proof aqua Jortis , and the folution is di¬ luted with an equal quantity of diftilled wa¬ ter ; it will continue clear and limpid, with¬ out any precipitation : if then a piece of po- lifhed copper is put into the folution, the filver falls gradually down, and the copper is diffolved, as appears by the green colour which the liquor acquires in a little time. When the filver is all feparated, take out the remaining copper, and put in a piece of clean iron ; the green colour goes gradually off*, by the copper falling down, and the i- ron is diffolved in its place : after allowing a
fufficient
302 ESSAYS and OBSERVATIONS
fufficient time for the folution of the iron, and precipitation of the copper, put into the folution a piece of iime-ftone 3 the aqua forth immediately works upon it with frefli vigour : laftly, add fome fait of tartar, or oleum tartari , p. d 3 this precipitates the Ro¬ ney matter, and renews the effervefcence. This feems to finifh the work, and quite to abforb the acid, and deftrov all its folvent powers : yet even here the acid only lurks and conceals itfelf by its ftridt union with an oppofite fait. But art can again produce it to view, and refiore all its former powers. If in this procefs, live or fix ounces of fpir . ni¬ tric or aqua forth , were employed in the be¬ ginning, and, after the laft ftep, the liquor is diluted with fome more water, ftrained thro' brown paper, fully fatiated with the alcaline liquor or fait, and then flowly eva¬ porated and chryftallized 3 there will be pro¬ cured a fait perfectly refembling common falt-petre, in the fhape of the chryftals, ex- plofive quality, and other marks. This, fa¬ ctitious falt-petre, then may be employed in place of the common 3 and I diftilled fome ounces of a fait, made much in the fame way (for I imagine the intermediate fteps
will
PHYSICAL and LITERARY. 305
will make no alteration) with oil of vitriol, in Glaubers manner, and obtained a ftrong fmoking fpirit, which anfwers all the cha¬ racters of Glaubers fpirit of nitre, and diL folves the fame bodies ; and therefore may run thro’ the fame courfe, over and over, without any change, unlefs that it may be gradually wafted, lome part of it being dif- iipated in every operation.
I found the fame thing hold in other acid liquors, as fpirit of fea fait, fpirit of vinegar, the acid of tartar, &c. which I joined to al- caline falts, and recovered the acid by diftil- lation. Thefe and fome other experiments of the like nature, which I have not yet had leifure to confider in their full extent, I fhall take another opportunity to lay before the fo~ ciety. In the mean time I fhall proceed to make fome
Remarks on Precipitation .
By precipitation is meant the parting or feparating the fmall particles of a diffolved body from the folvent liquor by means of a third body folid or fluid, which is therefore called the precipitant.
There
So4 ESSAYS and OBSERVATIONS
There is indeed another manner of part¬ ing the diffolved body from the folvent, which is fometimes, tho’ lefs properly, called pre¬ cipitation 3 when, by drawing off part of the folvent liquor by evaporation or diftilla- tion, the diffolved body falls down gradual¬ ly in proportion to the quantity of the liquor wafted,
I fhall chiefly confider the firft or more proper precipitation, in which there is both greater variety, and more difficulty to account for the change.
Remark I. All precipitations do not hap¬ pen from the oppofition of an alcali to an acid 3 but there are different means of precipitating different folutions.
It is certain, from experience, that what^ ever bodies are capable of being diftblved in a- ny acid liquor, may be precipitated from it by an alcaline fait or liquor. On the other hand* any body that is diffolved in an alcaline li¬ quor may be parted from it by the addition of an acid. This then is a pretty general' method of precipitating : however this op- pofition of acid and alcali is not the foie caufe of precipitation 3 for many metals and
metallic
PHYSICAL and LITERARY. 305
I
metallic fubftances diflfolved in their proper acid menflrua , may be precipitated by other bodies that are not alcaline, fome by plain water, fome by neutral falts, natural or arti¬ ficial 5 fome by another metal, fome by an¬ other acid liquor ; and, laftly, fome of thefe folutions may be precipitated in two or three different ways ; of all which I fhall give inftances afterwards. But further, acid and alcaline liquors are not the only folvents 5 for water, ardent fpirits, oils, and feveral com¬ pound liquors, neither acid nor alcaline, dif- folve a great many different bodies, which likeways may be feparated from them by pre~ cipitants of diff erent qualities. Therefore an acid and alcali do not always concur to make a precipitation.
II. The weakening or diluting foliations, by a liquor fpecifically lighter than the foh vent, is not the foie caufe of precipitation.
Some who would account for precipitati¬ ons upon mechanical principles, contend that diminifhing the fpecific gravity of the folvent liquors is the caufe of all precipita¬ tions : but this, altho’ it obtains in fome in¬ ftances , yet, in many more, it will be found contrary to experience. If" any fait is diffol-
3o6 ESSAYS and OBSERVATIONS
ved in water, and if fpirit of wine, a liquor fpecifically lighter than water, is added to the folution ; no precipitation will enfue.
When filver is diffolved in good aqua jortis , the folution may be diluted with fair water to any degree you pleafe ; yet the par¬ ticles of filver continue fufpended in the li¬ quor, tho? rendered fpecifically lighter : whereas, when the thineft and lighted: parts of the folvent are carried off by evaporation, the filver falls down. In the fame manner, a folution of quick-filver in aqua forth y a fo¬ lution of gold in aqua regia , of lead in fpirit of vinegar, and fome other folutions of me¬ tallic fubftances, may be diluted with Ample water without precipitation. Further, fome- times a liquor fpecifically heavier than the folvent is added to the folution, whereby the fpecific gravity of the compound liquor is increafed; yet the particles of the diffolved bo¬ dy are no longer fufpended in it, but fall to the bottom, quite contrary to this hypothe¬ cs. Vv ben rofin of jalap is diffolved in high¬ ly rec lined fpirit of wine or alcohol , if water, which is fpecifically heavier than the fpirit, is poured in, the refinous particles can no longer be lufiained. ihe fubiimate corrofive
mercury
O’
PHYSICAL and LITERARY. 307
* mercury can be diffolved in lime-water or common water : upon pouring in oil of vitri¬ ol, a very ponderous acid liquor ; the mercu¬ ry lubfides. Coral diffolved in fpirit of vine¬ gar, will be thrown down by the fame oil of vitriol. Thefe inftances naturally lead us to another remark.
III. Some bodies diffolved in one acid li¬ quor may be precipitated by another acid.
To the two former examples of this man¬ ner of precipitation, I fhall add fome others. Silver, diffolved in aqua forth , will be thrown down, if fpir.fal. marini is put into the fo- lution : on the other hand, a folution of gold in aqua regia , fuffers a precipitation by the affufion of fpir. nitri . That corrofive acid liquor, called butyrum antimonii , is known to be a folution of the metallic part of anti¬ mony in aqua regia : if we pour into it fpir. nitric after a pretty flrong effervefcence, we fhall find a metallic powder at the bottom.
IV. Some metals diffolved in an aad li¬ quor, may be precipitated thence by ano¬ ther metal or metallic, ftony or calcarious fubftance, capable of being diflblved in the fame menflruum .
Under
3o8 ESSAYS and OBSERVATIONS
i
Under the head of folution, I had occa- fion to adduce a well known inftance, to fbow that a menjlruum having diffolved one body, will fucceffively diffolve feveral others in a certain order. I am obliged to mention the fame again, as a confirmation of the pre- fent remark. If pure filver is diffolved in proof aqua forth , and the folution diluted with fair water; the filver will be precipitated by copper, the diffolved copper by iron, and that by lime-ftone. This however is not the foie inftance of this way of precipitation : o- thers may be found. The fublimate corro- five mercury may be juftly looked upon as a folution of quick-filver in the acid of fea fait, or aqua regia, brought into a chryftalline or vitriolic form by fublimation : when this corrofive mercury is mixed with an equal weight of common antimony, and thefe rubbed together, left to moifien in the air, and then diftiiled ; there happen fuch changes to this mixture, as evidently fhow a real pre¬ cipitation of the quick-filver by the reguline part of the antimony ; for the acid forfakes the quick-filver, and diffolves the regains,
which makes the bitty rum antimonii : and the
•/ ’
gmck-filver freed from the acid, is by the fire
incorporated
PHYSICAL and LITERARY. 309
incorporated with the fulphur of antimony into a black powder like /Ethiops miner alls, which may be fublimed into the cinnabar is antimonii . Quick-filver diffolved in aqua for - tis, may likeways be precipitated by another metallic body, as zink or bifmuth.
V. Some bodies diffolved in their proper menjlrua , may be precipitated thence, by fe- veral bodies of different qualities.
W e meet with a great many inffances in chemiftry to confirm this remark. I (hall mention a few examples, in which the great- eft variety obtains. Pure filver being diffol¬ ved in good aqua forth , and the folution di- ftributed into fix or eight glaffes, we may make as many precipitations by different pre- cipitants ; for folutions of fea fait and crude fait ammoniac, fpirits of fea fait, vitriol and fait ammoniac, a fixt alcaline fait, or its lee, and a piece of copper, will, each of them feparately, make a precipitation of the fil¬ ver.
Quick-silver diffolved in aqua fortis , may be precipitated by a folution of fea fait, by a folution of crude fait ammoniac, by frefh urine, by fpirit of fait ammoniac, by oL tart » p. d. and by zink.
P^EGULUS
po ESSAYS AND OBSERVATIONS
Regulus of antimony diffolved in aqua re - gia, will be precipitated by plain water, by a folution of falt-petre, by fpirit of nitre, and, by the alcaline liquors, fixt and vola¬ tile.
VI. The matters precipitated from the fame folution, by different precipitants, dif¬ fer from one another in feveral remarkable qualities.
When either a muria of fea fait, a foluti¬ on of fait ammoniac, or fpirit of fea fait (for thefe three have nearly the fame effedts) is put into a folution of filver ; it becomes milky, and, as it were, cruddled, and, at length, a white powder fubfides to the bottom : this powder being wafhed with warm water and dried, is foft and impalpable 5 its weight ex¬ ceeds that of the filver diflolved, by more than one fixth part. This powder comes much fooner to fufion than filver, but does not recover the appearance or properties of that metal ; for it looks like a piece of yel- lowifh glafs, fe mi-opaque and brittle, yet bending or yielding a little, whence it gets the name of luna cornea , or horny filver ; and it is with great difficulty that it can be reduced to true malleable and dudtile filver.
When
\
PHYSICAL and LITERARY. 311
When a plate of copper is put into a folu-* lion of Elver diluted, the furface of the cop¬ per is immediately covered, as it were, with a coat of Elver ; this becomes gradually thicker, and appears tufted, fpungy and loofe : upon fhaking the plate, large pieces of this cruft falls off, which either rife to the top, or fwim about in the liquor for a while, till difcharging many bubbles of air, they grow heavier, and fall down in form of a white powder ; the Elver being in this manner fe- parated from the liquor, then walked and dried, is nearly of the fame weight with the Elver diffolved ; and, when melted, runs into a lump of pure malleable Elver, without any confiderable lofs.
If an alcaline liquor, as fpir . fal. ammoni - &ci , or cl. tartari p. d. is dropt into a folution of Elver, it excites a ffrong effervefcence, which will be renewed when more of the al- caline liquor is dropt in at intervals, until the acid is fatiated ; and there appears a white, bulky and frothy matter, which gradually fubfides : all being thrown into a cap of brown paper, fitted to a funnel, and warm water poured in, the frothy matter diminifhes confiderably in bulk 3 and there is left a
gi2 ESSAYS AND OBSERVATIONS
powder of an aih colour, which being dried, a little exceeds the weight of the Elver dif- folved.
The precipitations of mercury (hew ftiil a greater variety, at lead, as to their effects, being ufed as medicines. If fea fait, diffol- ved in a good quantity of water, is put into a folution of quick- filver in aqua forth > it turns the clear and limpid folution turbid, opaque and milky ; at length the white mat- ter fubfides, which being feparated from the fluid, waflied and dried, remains a very white powder, and a little exceeds the weight of the quick-fliver diffoived : but it is to be ob« ferved, that the muria does not precipitate all the mercury ; for the liquor, thus feparated from the white powder, is known to have the effedts of a cofmetic or deterflve mercurial water 5 befides if oL tart . p. d. is dropt into this liquor, a fmall quantity of a brown mercurial powder will be precipitated. Phyficians know that this white precipitate is a pretty adtive and brilk medicine, and produces greater ef- fedls, even in a fmaller dofe, than calomel , but is more mild and tradrable than the mere 4 fuhlim . corrojhus ; for, when this laft is fome^ what tempered by fpir . faL ammoru it be¬ comes1
PHYSICAL and LITERARY. 313
comes a medicine much of the fame nature with the preceeding white precipitate. A fo¬ liation of crude fait ammoniac, and fpir. JaL mar. have the fame effefts on the foliition of quick- (liver, as the muria has*
If a little frefh urine is put into a folution of quick-filver in aqua portis , there will like- wife happen a precipitation 3 but the powder is not white, but of a pink or fiefhy colour, it appears pretty bulky, and has acquired a little additional weight. This precipitate is not ufually prefcribed by phyficians 5 but M. Lemery pretends that it is milder than the: white, and only operates by (tool.
It would appear then, that, in many in-^ * fiances of precipitation, the particles of the diffolved body are increafed in denfity and fpecific gravity 3 by reafon that feme parts ei¬ ther of the precipitating matter only, or of the compound, made up of the fclvent and precipitant, are very firmly united to them, fe that they cannot longer be fuftained in the liquor. But, in other cafes, where the matter precipitated has acquired no addition of weight, no new or remarkable properties* and is eafily reducible to the native form of the body diffolved 3 there muff be feme o-
R r
3i4 ESSAYS and OBSERVATIONS
ther caffe of precipitation, which may pro¬ bably be, that there is a greater affinity betwixt the precipitating body and the folvent, than betwixt this and the body diffolved ; whence, from the difpofition of thefe bodies to unite, they fhake off, or drive away from them, the particles already joined to the folvent.
Art.
PHYSICAL and LITERARY. 315
Art. XL
Experiments on Neutral Salts , compounded of dif¬ ferent acid Liquors , and alcaline Salts, fixt and volatile ; by the fame.
T a former meeting of the fociety
A ( January 1738) I read fome re¬ marks on chemical folutions; the laid of which gave me occafion to mention fome ex¬ periments, in which I was then employed, but had not finifhed : and therefore, at that time, I could not confider them in their full extent, or have a juft view of all the confe- quences that might be drawn from them.
I now proceed to relate the experiments, and to obferve how far they may be uieful to extend our knowledge.
I prepared a parcel of fa&itious, or (as the Chemifts are pleafed to call it) regenera¬ ted nitre, in this manner 5 I took two ounces of an extemporaneous fixed alcaline fait, made of equal parts of nitre and tartar ; I
diffolved
* June 7. 1739.
&
JI 6 ESSAYS AND OBSERVATIONS
diflolved this fait in warm water, filtred th folution, and poured into it ftrong fpirit of nitre, a little at a time, until the alcaline li¬ quor was perfectly fatiated with the acid, which required one ounce and a half of the fpirit of nitre. From this faline liquor, by evaporation and chryftallization, I procured two ounces and a half of fait, when it was all colleded and well dried. The chryftals were long, flender and prifmatical ; the fait had a pretty mild and cooling tafte ; and bits of it put upon a burning coal, made it fpar- kle and give a bright flame.
We may obferve by the way, that the compound fait exceeded the weight of the fixed fait by half an ounce or 240 grains ; this additional weight it procured from the fpirit of nitre : therefore one ounce and a half, or 720 grains of the fpirit of nitre which I ufed, contain 240 grains of true a- cid, which is capable to fatiate four times its weight of alcaline fixt fait.
I put two ounces and a half of this facti¬ tious nitre into a fmall glafs retort, and pour- pd upon it one ounce of oil of vitriol, which immediately begun to raife an ebullition with peat and red fumes ; a receiver was inftantlv
joined
PHYSICAL and LITERARY. 317
joined to the retort with pafte 5 the glafs fet in a fand furnace, and the fire increafed gradually. After the operation, there was found in the receiver, a fmoaking acid liquor, of an orange colour, which weighed one ounce, two drams, three grains : there re¬ mained at the bottom of the retort, a cake of white folid fait ; which being diffoived in warm water, the folution filtered, and part of the water again exhaled, fhot into chry- ftals ; and thefe being all carefully collected, weighed two ounces, twenty two grains.
The fpirit obtained in this manner was fiery, aftive, and conflantly emitting red fumes ; it diffoived filver, kindled with oil of cloves, and agreed in all other char afters with ftrong fpirit of nitre. The fait which remained in the retort when purified and chryftallized, no way refembled falt-petre, or the fait employed in this operation, in the fhape of the chryfials, tafte, or other pro¬ perties ; for thefe chryfials were polyhedras, having feveral triangular faces and folid angles ; their tafte is rough, bitter, and fomewhat aftringent ; they do not readily melt or fparkle in the fire, as common or faftitious nitre does.
3i$ ESSAYS AND OBSERVATIONS
I made another factitious fait, by impreg¬ nating a folution of the fame alcaline fixt fait with fpirit of fea fait, pouring it in by degrees, till there appeared no effervefcence3 and the liquor tafced briny. Four ounces and a half of this fpirit were employed to fatiate two ounces of the fixt fait : when the two faline liquors were duly proportioned, there appeared, before evaporation, a great many fmall grains of white fait at the bottom, which, as well as the liquor furrounding them, had the true muriatic tafte.
The fait obtained out of this liquor, had the genuine figure of the common fea fait ; but the chryftals were fmaller, more hard, white and opaque : the fait is not altogether fo pungent as what we commonly ufe ; but more agreeable and cooling, yet without any acidity. This fait, while moift, weighed two ounces, fix drams and a half $ but, when well dried, and flightly decrepitate, the weight was reduced to two ounces and two drams. I put this quantity of powdered fait into a fmall glafs retort, and poured upon it two ounces of ftrong fpirit of nitre, which
occafioned an ebullition with heat and finoke.
«
I proceeded to the diftillation, with a fire gra-
PHYSICAL and LITERARY. 319
dually increafed ; when the veffels were cool¬ ed, I found in the receiver, two ounces four drams and a half, of an acid liquor, of a faint greenifh colour, which fmoked much when the veffels were firft disjoined ; but the fumes were paler and whiter than thofe of fpirit of nitre, and fooner ceafed, I put a few drops of this liquor into a folution of fil- ver in aqua fortts\ it made it white and crud- dled, and at length a white powder fell down. I poured a fmall quantity of it upon a few grains of filings of gold; with the affiftance of a little heat, the fpirit pretty quickly dif- folved it, leaving only a few particles at the bottom. From thefe characters I think we may conclude, that the acid liquor, produ¬ ced in this operation, is a true aqua regia : I chufe rather to call it fo, than fpirit of fea fait ; becaufe I found it had a greater and quicker effeCt in diffolving gold than the plain fpirit of fait had, therefore it is probable, that a fmall quantity of the nitrous acid had accompanied the acid of fea fait.
The ke remained in the retort, a cake of fo¬ lk! white fait, like melted nitre, or fal prunel- iae : after it had been diffolved in warm water, the folution filtered and evaporated j
there
426 ESSAYS ANO OBSERVATIONS
there appeared many regularly fhaped chry¬ ftals, long, Header, and prifmatical, of the nitrous kind 5 which being removed, and more of the moifture exhaled, the chry ftals which formed were not fo large nor fo regu¬ larly fhaped as the preceeding, but the whole appeared like a mafs of white fait coarfely powdered : however I could difcover, among thefe chryftals, fome that had a quadrangu¬ lar bafe, but long fides, like two cubes joined^ others varioufly compounded or broken : e- ven this part of the fait had the cooling nitrous tafte ; and, part of it put upon a. live-coal, fparkled and excited a bright flame like falt-petre.
Again, I took two ounces of that neutral fait, called tartarus folubilis , the preparation of which is very well known ; in this com- pofition, the native acid of white tartar, or the chryftals of tartar, is impregnated with an alcaline ley, or oh tart.p . d . from the union of thefe in due proportion, arifes a mild neutral fait, which diffolves more eafily in water, than tartar or its chryftals ; whence it hath the epithet of foluble. I put two ounces of this preparation into a fro all glafs retort, and poured upon it one ounce of oil of
PHYSICAL and LITERARY. 321
vitriol, which raifed a babbling and efferves¬ cence. In diftillation there came over fix drachms of liquor, of a brownifh colour, with a little oilinefs upon it : its tafie was fowre, but difagreeable and empyreumatic ; it had an un- pleafant fmeil, but not very ftrong or pun- gen t ; it effervefced with alcaline falts fixt or volatile : in all which properties it agrees with the acid liquor drawn by diftillation from crude tartar, which is commonly called its jplrit . I obferved, in diftilling this mixture, that there came up fome volatile fait, but in very fmall quantity, which fpread itfelf upon the neck of the retort, in very fine and fub- tile ramifications : the upper part of the bo¬ dy of the retort was fullied with fome thick black oil ; and the faline matter at the bottom was of a dirty afh colour, like tartar half-burnt. I poured warm water into the retort, and left it on hot fand, to diffolve the fait ; I found it neceffarv to pafs this folution through a filter, and there remained in the paper a good deal of black earthy matter. The liquor was very acid, and had a vitriolic roughnefs, becaufe more oil of vitriol had been poured upon the tartarus folubilis than was fufficient : to overcome the acidity, I dropt into the li-
S s quor
322 ESSAYS AND OBSERVATIONS
quor fome oL tart . p . d. till the effervefcence ceafed ; and then, by evaporation and chry- ftallization, I procured a fait, in every refped:3 like the tart arm vitriolatus , as ufually pre-
Upon two ounces of the fame tart.folubih I poured one ounce of fpirit of fea fait, made after Glaubers manner ; by diftillation there was produced a liquor of the fame kind, with that of the preceeding experiment. The re¬ maining fait indeed was not diffolved nor chryftallized ; but from its tafle, and by its precipitating a folution of fiiver in aq. fort . it appeared to be of the muriatic kind.
After this, I made an experiment on an¬ other neutral fait in which the acid of vine¬ gar is united to the alcaline fait of tartar, which is commonly known by the name of tartarus regeneratus. I took one ounce and an half of fait of tartar, and poured diflil- led vinegar upon the dry fait at feveral times, fhaking the glafs frequently, till fifteen oun¬ ces of the acid were employed : the veffei was then let on a fand- bath, and the liquor gradually infpitTated till there rema’ned four ounces 27 grains of a moift, greafy, fa line fuoftance, of a brownifh colour, like coarie ‘ fugar.
PHYSIC AL and LITERARY.
323
fugar. I did not think it for my prefent purpofe to bellow more time and pains to bring this fait to a greater degree of white- nefs and drynefs ; but l put it into a retort* and poured upon it one ounce and an half of oil of vitriol, diluted with three ounces of water : in diflillation there came over near feven ounces of a thin limpid acid liquor, which, in talle, refembled diftilied vinegar, but was more ftrong. The faline mafs left in the retort being diffolved in warm water, the folution filtred and evaporated, the chry- ilals could not be diflinguilhed from the or¬ dinary tartarus vitriolatus in fhape, colour, or talle.
To fatisfy myfelf, that a volatile aicaline fait or fpirit may like wife be difengaged from an acid to which it has been united, and re- ftored to its former llrength & qualities, 1 made the following experiment. I took eight ounces of that compound faline liquor, which is defcribed in our College* difpenfatory un¬ der the title of Spiritus Mindereri ; it is made by pouring diftilied vinegar upon volatile fal-ammoniac, until the fait is diffolved and fatiated by the acid. This neutral faline li¬ quor, however, will not chryftallize or co¬ ale fee
324 ESSAYS and OBSERVATIONS
alefce into a dry folid fait, nor will the vo¬ latile alcali feparate from the acid, by a Am¬ ple diftillation, but they rife together. I put eight ounces of this fpirit into a bolt-head ; and, adding half an ounce of dry fait of tartar, I prefently fitted a capitel and recei¬ ver to the body, luted the joinings, and fet the veffels in a fand heat ; in a little time a white volatile fait fublimed into the capitel, which was foon wafhcd down by a watery vapour into the receiver. This liquor being tried, was found equally ftrong, pungent, clear and volatile, as the heft fpirit of fal- ammoniac : the faline matter left in the bo¬ dy was of a greyifh colour, foft and greafy to the touch, and would hardly dry or chry- ftalhze, refembling tartarus regeneratus .
I need not confirm this by any further ex¬ periment, becaufe it is known to every body, that the volatile fait and fpirit of fal-ammo- niac are procured by adding a fixt alcaline fait to the crude fal -ammoniac : now, as we can prepare an extemporaneous or artificial fait, by impregnating the volatile fait or fpi¬ rit of fal-ammoniac with the fpirit of fea. fait ; j/V P ftav e no reafon to doubt, but, by means
of
PHYSICAL and LITERARY. 325
of a fixt alcaline fait, we may again difen- gage the volatile fait or fpirit from the acid.
But it may be of more importance to dis¬ cover what kind of acid is oined to the vola-
j
tile alcali in the common or crude fal-ammo- niac: for this purpofe I made the following experiment. When all the volatile fait and fpirit are drawn off* from crude fal-ammoniac by the addition of a fixt alcaline fait and wa¬ ter, there remains a faline mafs ; which, when diflfolved in warm water, the folution ftrained and evaporated, the chryftals very much refemble thofe of fea fait, in Ihape, tafte, and other diftinguifhing characters of that fait, efpecially when it is well depurated and carefully chryflallized. This fait, how¬ ever, has been dignified with the title of fal jebrifugum Sylvii . I put three ounces of it into a retort, and poured in one ounce of oil of vitriol, and as much water. In the aiftillation, the receiver was filled with white fumes, which condenfed into a liquor of a pale colour, fomewhat turbid at firft, of which I had near three ounces. The liquor had all the appearances of the fpirit diftilled in Glauber s manner, from common fea fait ; and when fome of it was dropt into the folu-
tions
22 6 ESSAYS AND OBSERVATIONS
tions both of filver and quick-ftiver, it turned them both milky, and made a white precipitation. From all which I have no dif¬ ficulty to conclude, that the acid contained in crude fal-ammoniac is of the muriatic kind, or the fame which is produced from fea fait. But, whence this acid fhould proceed, is a matter of greater intricacy ; fince we are af- fured that no fea fait is neceflary to, nor em¬ ployed in, the preparation of that fal-ammo¬ niac which is brought to us from Egypt .
This queftion 1 fhall not undertake to dif- cufs, as being foreign to my prefent purpofe $ but fhall fubjoin fome remarks on the experi¬ ments above related, or deduce fome corol¬ laries which feem naturally to arife from them.
I. The acid fpirits, as thofe of vitriol, ni¬ tre, fea fait, vinegar, &c. are faline liquors, or fluid falts, made up of the very minute particles of an acid fait, and a certain pro¬ portion ol phlegm or water.
II. The particles of thefe acid falts cannot be brought to unite, among themfelves, by chryftallization or fublimation, fo as to ap¬ pear in the form of a folid or dry fait : but
they
I
PHYSICAL and LITERARY. 327
they readily lay hold on the particles of cer¬ tain metals or femi- metals, calcarious or ab- forbent earths, or oppofite falts, fixt or vo¬ latile, which ferve them as a bafis ; and* joined to thefe, they aflame a chryftalline form.
III. When any of the acid liquors are joined, in due proportion, to any alcaline fait, whether fixt or volatile ; the particular acrimony and pungency of both, as to our fenfes, and their power of diflolving certain bodies, in a feparate ftate, are quite deftroy- ed, at leaft, overcome and fufpended, by their union.
IV. When an acid liquor has difiblved a metallic body, and is united to it 5 the folution and the vitriol made of it, are frequently more acrid and corrofive, with refpeft to the human body, than the acid by itfelf. I do not affirm this univerfally: but we have in~ ftances of it in the folutions and vitriols of filver, quick-filver, copper, antimony.
V. When the fpirits of nitre or fea fait are joined to fait of tartar, or pot-a(h, and chryftallized ; the chryftals aflame the pecu¬ liar fhape, and mo ft remarkable properties cl the natural ialt, from which the acid fpi-
rit
]
*
328 ESSAYS and OBSERVATIONS
rit was originally produced. Confequently - there appears to be fome affinity betwixt the native fixt bafes of thefe falts, and the fixt falts of plants.
VI. The artificial vitriols compounded of the fame acid fpirits and metallic particles, do not referable the original falts ; but the vitriols of different metals, or metallic bo¬ dies, have different fhapes, tho’ they are join¬ ed to the fame acid falts.
VII. The acid falls, tho’ combined with the alcaline, into mild neutral falts, yet are not fo changed by this union but, when they are again artfully disjoined, they may exert the fame powers and produce the fame ef- fedts as before their union : therefore we may conclude, that the figure, bulk, and denfity of the acid particles are not changed tho*
the liquors may differ fomewhat in ftrength
*
from the greater or fmaller proportion of phlegm, or water accompanying the real a- cid.
VIII. One acid which has been united to an alcaline fait may be fet at liberty, or ex¬ pelled from its cohefion with the alcaline Talt, by another acid of a different origin. But this does not happen indifcriminately ;
for
PHYSICAL and LITERARY, 329
for the oil of vitriol expels any other acid, but cannot be diflodged by any of the reft,, A volatile alcaline fait is expelled from its union with an acid, by a fixt alcaline, but not contrary ways.'
General Scholium .
We can have no other idea of a folid or confident body in general, as diftinguifhed from a fluid, than that the parts of a folid cohere together by fome power, which re¬ tains the particles in their fituations, with re- fpedt to one another, and makes them to relift their feparation or divifion, till that power is overcome by a fuperior force.
When we obferve that a certain fluid, as water, poured upon a hard folid body, as a lump of falt-petre, in fome hours, makes fuch a change upon the lump, that it whol¬ ly difappears, if the glafs is fliaken a little, that is, the fait is divided into particles, fo imall, that they efcape our fight, and are equally diftributed through the liquor, and fufpended in it 5 when we obferve this, I fay* we cannot but conclude, that the particles of
T t Water
ESSAYS and OBSERVATIONS
33°
water are endued with a power capable to o- vercome the force by which the particles of falt-petre cohered with one another.
If a known quantity of cold water has diffolved as much falt-petre as it is capable to hold, in this folution the water is to the fait as O to i ; (in Raiding water the pro¬ portion is as 4 to i ). If then f of the wa¬ ter is wailed by evaporation, many of the frnali particles of nitre being brought into contact, join together, and form chryftals in fhape and other properties refembling the nitre which was diffolved in the water. It follows, therefore, that the particles of nitre mutually attract one another, when the inter- pofing matter is removed, the diftance betwixt them very much dim in iff ed, and no fuperior power acting upon them 5 and, when in contact, they cohere with a certain degree of force. Again, it appears, that the par¬ ticles of water do attract the particles of nitre more ftrongly than thefe laft attract one ano¬ ther ; and, confequently, overcome their coheiion, and fufpend their mutual attraction. Laftly, it is evident, from the above appear¬ ances, that tho’ the parts of nitre which fwim in the water are fo fmall, that they
are
PHYSICAL and LITERARY. 331
are not perceptible fingly, even when viewed thro’ a pretty good lens ; yet they mu ft be fimilar to one another, and retain the proper¬ ties of real nitre.
Let us next confider the effects of an¬ other liquor, upon the fame falt-petre.
If oil of vitriol is poured upon a parcel of nitre, there happens like wife a folution, but with appearances different from thofe in the former 5 for this is accompanied with a confiderable inteftine motion and expansion, fmoak and heat, and produces a much great¬ er change on the nitre *: for, by the help of external heat and ciofe veffels, there rife from the mixture copious red fleams, which are condenfed into a corrofive acid liquor, ve¬ ry active and volatile, and there is left a white faline mafs, no way refembling nitre.
From what has been faid formerly of this experiment, it appears that the oil of vitriol makes a more minute and fubtile di- vifion of nitre than what fimple water can do ; that the fluid acid fait of the oil of vi¬ triol attracts one part of each real particle of nitre, viz. the fixt and alcaline bails, while this fame vitriolic acid feems to repell another part of nitre, that is the acid and volatile
part.
332' ESSAYS AND OBSERVATIONS
part, which attrads, or is attraded by the phlegm or watry part of the mixture, is ea¬ sily raifed up in vapour by heat, and turned into a faline acid liquor.
It may be juftly queftioned, whether this is an ultimate divifion of nitre, or a reparation of it into its moft Ample principles or firft e- lements. It is very hard to find an experi¬ ment that can give full fatisfadion in this point $ for there are certain bounds fet to art, as to the divifion of bodies : but if that part of nitre, which unites with the acid of vitriol into a neutral fait, is the fame with nitre fixt by deflagrating with char-coal ; or if it is no other than that fait which can be extraded from the remains of the diftillation of nitre with bole ; then we have fome rea- fon to conclude, that this part of nitre is not a Ample elementary matter : lince fixt nitre 1 can, by frequent folutions and fufions, be fo changed, that little of it will remain, but a mere earth.
Many of the folutions which happen in chemiftry, are of the firft kind, that is, the fol vents ad no otherways upon their proper pbjeds than water does upon nitre or any o- ther fait, by diflbiving the cohefion of the
larger
PHYSICAL and LITERARY.
333
-larger particles which compofe the body, without reiolving the particles into their pri¬ mary elements.
When fpirit of nitre or aqua forth is poured upon pieces of filver, the appearances plainly point out that there is an attraction betwixt the particles of the folvent and the filver, and that there is likewife a repulfion of the particles already diffolved from the filver, to make way for the application of new particles of the folvent to other parts of the filver 5 for there is a remarkable motion and agitation in the liquor, the furface of the fil¬ ver foon becomes rough and difcoloured, air bubbles are formed upon it, which foon fly off, and a conftant fucceffion of thefe arife, break and diffufe themfelves : if a little of this liquor is carefully taken off from the top, even before half the filver is diffolved, and dropt into a muria of fea fait ; it will give evident marks that it contains a portion of filver. When all the metal is diffolved, the folution becomes clear and limpid, and ail is at reft. Thefe things evidently fhew, that fuch metallic particles as are freed from their cohefion by the faline parts of the iren~
jiruum , recede with them from the filver,
^nc?
334 ESSAYS and OBSERVATIONS
and are fucceeded by other acid particles to perform their part of the operation, until all the parts of the folvent are equally char¬ ged with particles of filver.
The attractive force betweetf the faline particles of the fpirit of nitre and the filver, mu ft be fuperior to the power by which the particles of filver attracft one another 3 for it diffoives their cohefion, feparates them, and keeps them fufpended in a fluid which has only about one tenth part of the fpecific gra¬ vity of filver: yet thefe particles, thus fufpend¬ ed, differ in nothing, when freed from the acid, but bulk from granulated filver or the bits rubbed off plate by a fine file. That this power of attraction between the particles of fpirit of nitre and thofe of filver muft be very great, will appear, if we confider, ftrft, that it requires a very great heat to melt filver ; but this melting is nothing elfe, than, by the force of fire, to overcome the cohefi¬ on among the particles of filver, and bring the mafs to a ftate of fluidity, fo that the par¬ ticles may eafily move and Aide one upon an¬ other while that degree of heat laftsj but fpirit or nitre produces the fame or rather a greater effeCt. In the next place, tho’ fpi-
PHYSICAL and LITERARY. 335
rit of nitre is of itfelf pretty volatile, yet, when it has diffolved filver, the faline parts adhere fo firmly to the metallic, that a very ftrong degree of heat is required to feparate them ; for, if a folution of filver is fet in a heat that would make water boil, the light and watry parts indeed fly off, but afterwards the evaporation goes on {lowly, unlefs the fire is confiderably increafed ; and, after fe- veral hours, the matter has ftill the appear- ance of a very moift fait, which is very cor- rofive, and, in bulk and weight, greatly ex¬ ceeds the filver that was diffolved. When the fand-heat can make no further change on
o
the mafs, put it into a crucible, and fet it in a pretty brifk and clear fire: this expells the re¬ maining moift ure and fuperfluous acid 5 after this the matter melts like wax, and, when cold, is turned to a hard fubftance ; the cauftic quality of which, the increafe of weight above that of the filver, and its apt- nefs to moiften, fhew, that, after all the heat which the mafs has fuftained, there is ftill a good quantity of the faline part of the fpirit of nitre intimately incorporated with the fil¬ ver. Now, when a piece of this hard ftony fubftance is put upon a piece of well kindled
char-coal.
336 ESSAYS and OBSERVATIONS
char-coal, and blown a little, it makes an ex- plofion with a fparkling and flame, like a piece of common falt-petre ; the faline mat¬ ter is confirmed or turned into flame or fmoke, and the pure fllver is left on the coal. By the way, this may be fome fort of proof, that the volatile acid part of nitre is not more a Ample elementary matter than is the fixt part.
Notwithstanding what has been fhewn, concerning the ftrong attraction be¬ tween the particles of fpirit of nitre and thofe of fllver, and the difficulty of feparating them by the force of fire ; yet, if a piece of clean copper is put into a folution of fllver in fpirit of nitre, the faline particles moflt readily (hake off the fllver, and diffolve the copper : which fhews that the particles of copper have a ftronger attractive power, with refpeCt to the fpirit of nitre, than the parti¬ cles of fllver have- ; which difference of at-, traCtion will probably arife from the different hulk, figure or denfity of the particles of the two metals, the acid being the fame. The fame thing may be faid of iron, zinc, chalk, volatile alcaline fait and fixt fait, each of which attraCl fpirit of nitre more ftrongly
PHYSICAL and LITERARY. 337
than filver does, and the laft more than the' preceeding.
Here then we have a feries of bodies from (ilver to fait of tartar, whole attractive powers, with refpeCt to the fame faline li¬ quor, are continually increasing; but, whe¬ ther uniformly or in any certain proportion, is not eafy to determine : there may be found a body which attracts the acid of nitre more than the firft, and Jefs than the fecond, and fo thro’ other degrees ; which can only be afcertained by a great variety of trials.
As the fait of tartar, or any ftrong fixt alcaline fait, is the ftrongeft attraCter of the nitrous acid, and throws down or Sepa¬ rates any other body that has been diffolved in it ; fo it likeways attracts every other acid, and disjoins it from whatever it has diffolved : therefore we may confider that fait as a Stand- dard whereby to compare the feveral attractive powers of the different acid liquors. But it is certain, from the experiments that have been related, that, if three parcels of the fame fixt alcaline fait, are joined to the three dif¬ ferent acids of nitre, fea fait, and vinegar, and if oil of vitriol is poured upon each of thefe faline mixtures or compound falts ; the vitrL
U u olio
33S ESSAYSand OBSERVATIONS
olic acid will attract, or be attracted more ftrongly by, the alcaline fait than the other acids, which will be driven from their places ; and the acid of vitriol will be fo firmly united to the fixt fait, that no other acid or known body is capable to feparate them.
Again, If fpirit of nitre is poured upon a compound faline liquor, or fait made of fpi¬ rit of fea-falt and fait of tartar, and upon an¬ other made of fpirit of vinegar and the fame fait of tartar ; the fpirit of nitre, by its fuperi- or attractive power, will join itielf to the al¬ caline fait, and drive away the other acids 5 hut is not able to refill the Hill greater force of the vitriolic acid.
Lastly, If fpirit of fea-falt is poured up¬ on a compound of fpirit of vinegar, or any other vegetable acid and a fixt alcaline fait -y this will be more ftrongly attradted by the acid of fea-falt, than by the vegetable acid which will be expelled : but the fpirit of fea- falt may likewife be diflodged by the acids of vitriol or nitre.
In molt folutions, precipitations, and other operations by which the texture of bodies are much changed, there are fome appearances, fuch as an expanfion and bubbling, the pro¬ duction
PHYSICAL and LITERARY. 339
duCtion of an elafiic fluid like air, and a com¬ motion fo great, as to produce fome remarkable degree of heat, and in fome cafes fmoak and flame : which appearances, I fay, plainly dis¬ cover, that the Small particles of bodies are endowed with fome very aCtive powers, ca¬ pable to introduce certain motions tending to union or disjunction, attraction or repulfion.
That many parts of matter are endowed with an attractive power tending to union and cohefion, may be deduced from the in¬ stances already mentioned : and many more might be brought from occurrences in che¬ mistry to confirm the fame. That other parts of matter are endowed with an elaftic or repelling force, may be concluded from the properties of air and light, demonstrated by the greateft philofophers of the laSt and prefent age. The curious experiments of the ingenious Dr. Hales , in his Analyjis oj the air , and the furprifing experiments on electricity now fo much in vogue, may Satisfy us, that particles of the fame nature and qualities with thofe of air and light, may be joined to particles of a grofler nature and attractive quality, in various maSTes of matter, to fome adhering more loofely, to o-
thers
1 4o ESSAYS and- OBSERVATIONS
thers more firmly connected. For fome time they may lie concealed without mani- nifeft motion or addon ; their repelling or elaftic power being overcome or balanced by the attractive force of the furrounding cor- pufcles, till by certain concurring circum- ftances, as external motion, heat, moiflure, the addition of other matter, &c. the attra¬ ctive force is diminifhed, or the repelling in- creafed : then they are roufed, as it were? into adion, and difcover themfelves by great and remarkable effeds, in changing the tex¬ ture of the maffes to which they were united. Such changes we daily fee happen in fermen¬ tations, putrefactions, effervefcences, foluti- ons, acceniions, explofions, &c.
Thefe principles of motion in matter, are not the vain fictions of men merely fpecula- tive in philofophy, but evidently deduced from obfervations and experiments on a great variety of bodies in, many different circum- fcances ; and every one who reflects upon the moil ordinary occurrences in the works of nature and art, will be convinced of the exhlence of fuch caufes, and find that they gre io univerfal and unalterable, that they can poly be referred to the firft caufe, that is, to fhe will of the Supreme Being.
A R T.
PHYSICAL and LITERARY. 341
Art. XII.
Experiments and Objervations upon the Hartfell Spaw, made at Moffat 1750 ; and an Ac¬ count of its Medicinal Virtues, fo far as they have hitherto been dfcovered prom experience ; by William Horserurgh, M. D .
^TT^HIS Spaw fprings from the Hartfell JL mountain, about three miles north of Moffat ; and is commonly called Willi amfon s water , from Mr. John Willi amfon , who dis¬ covered it in 1748, and who has been at a good deal of pains, and fome expence, to make it acceffible, by mending the road, clearing away the dirt about the fpring, and fitting it with a fpout, that it may be more conveniently taken up.
The water on which I made the following experiments, had been taken up three or four days from the fpring, and was contained in bottles well corked and waxed ; it was ta¬ ken up on the 26th of Augufl , after a very rainy feafon.
1. It was quite clear and pellucid.
2o It
342 ESSAYS and OBSERVATIONS
2. It had a fharp, aluminous, ftrong cha¬ lybeate, and ftyptic tafte.
3. It curdles with foap.
4. Its fpecific gravity to that of Annan ri- ver water (which is efteemed the beft water they have hereabout) is, as four ounces five grains, to four ounces eleven grains.
5. By fhaking it in a vial, or mixing it with tartifh wine and fugar, it gives no figns of its containing a fpirit more than river- water.
6. When boiled with an equal quantity of new or fweet milk, it does not curdle the milk.
7. With fyrup of violets, it gives a faint green.
8. With powder of galls, it prefently be¬ came blue 5 and turned gradually darker, till it became of a deep purple, and then of an ink-colour : it does the like with an in- fufion of tea, tho’ not in the fame degree as with the galls.
9. When oleum vitriolic or fpiritus vitriolic is dropt into it, no effervefcence, or change of colour, is produced.
10. With oleum tart art per deliquium , it made no effervefcence 5 but light green clouds
gathered^
PHYSICAL AND LITERARY. 343
•gathered, and were fufpended, in the mid¬ dle of the water 3 and a great number of fmall air-bubbles, like particles of quick-fil- ver, appeared adhering to the bottom of the glafs, to its fides, and upon the furface of the water 3 multitudes of the like air-bubbles were intermixed with the green clouds : after Handing about an hour, a great many of the air-bubbles difappeared, and the clouds in the middle of the water grew thicker, and of a darker green, and afterwards precipitated.
1 1 . An aqueous folution of faccharum Ba¬ tumi ^ turned it a little whitiih, but not fa much as it did the river- water 3 and much lefs than it did the river-water, when there was a very little fea fait diflfolved in it 3 in all thefe three trials, a white powder precipita¬ ted*
12. On September iH, I poured a chopin or Englijh quart of this water into a clean, white, Hone-bowl 3 and covered it with a piece of paper, to keep out the duH.
On the ad, there was precipitated a brown powder, like brick-duH 3 and, on the furfacc of the water, there were many finning fpangles of a copper-like colour.
On
344 ESSAYS and OBSERVATIONS
On the 3d, there was more of the brown- Eh powder at the bottom 3 all the parts of the bow!, which were covered with the water, were tinged yellowifh 3 a pellicle covered the furface of the water, and all the fpangles were gone.
On the 6th, the {harp aluminous tafte was pretty ftrong, but the chalybeate tafte much weaker 3 there feemed to be no more of the brownifti powder at the bottom than there was on the 3d 3 the yellow fubftance that adhered to the bowl Was alfo thicker, and had a fmooth oily look 3 the pellicle on the top had now acquired the thicknefs of writing paper 3 it was eafiiy taken up, as it adhered to any thing put into it, and was of a golden colour : I took up as much of the water as filled a wine glafs 3 and, with pow¬ der of galls, it immediately ftruck a blue.
On the 13th, the fharp aluminous tafte ftiil remained ftrong, but the chalybeate was icarce to be diftinguiftied 3 the quantity of the precipitate, and the pellicle on the top, were much the fame 3 but the yellow fubftance, adhering to the bowl, was rather more : into a glafs of this water, I dropt fyrup of violets 3 it turned of a faint green : to another glafs
PHYSICAL and LITERARY. 345
of the fame, I put powder of galls ; it im¬ mediately (truck a blue tindlure, but not fo deep as on the 6th.
On October 9th, it had a more aluminous tafte, than the frefh Spaw water ; the chaly¬ beate tafte was fcarce to be diftinguifhed j the precipitate, yellow fubftance adhering to ' the bowl, and the pellicle on the furface, much the fame as on the 13th ult. 5 the wa¬ ter was as limpid as on the firft day} fyrup of violets changed its colour to a deeper green than before, and, with powder of galls, it immediately gave a blue tincture.
13. I boiled a chopin of this Spaw water, in a clean tin pan, till there remained of it only one fourth part ; it turned of a yellow- ifh colour and was muddy : when this was cold, and the okry flakes precipitated, it had a harfher and more aluminous tafte than the frefti Spaw water, or than that which had been fo long expofed to the air (12.). To a glafs of this I put powder of galls ; it changed very flowly, and, after it had flood about eighteen hours, it exhibited a faint blue.
14. In a clean tin-pan, over the fire, I e- vaporated a chopin of the fame Spaw water, till there remained only about one ounce and
X x 2.
346 ESSAYS and OBSERVATIONS
a half; this I immediately poured into a China tea-cup, and, when cold, filtrated it : the fil¬ trated liquor was clear and limpid, and had a ftrong chalybeate tafte ; this was evaporated by a fand-heat, in a wide- mouthed glafs ; there was left a fait of a whitifh-brown colour, which had an aluminous, and ftrong chaly- be ate rough tafte. The whitifh-brown co¬ lour of the fait was owing, I believe, to its having been a little fcorched at the bottom of the glafs ; for, when I afterwards gently exhaled the water before the fire, the fait was of a pure white.
15. A little of this fait put into a glafs of water, made the water of a yellowifh co¬ lour ; and, in a little time, it began to fepa- rate into fmallyellowifh coloured flakes, which growing gradually larger, and thicker, pre¬ cipitated ; after handing a night, the water was quite clear, with a few detached, fmall flakes, floating clofe to the Tides of the glafs ; the water had the original tafte of the Spaw , but rather ft r on ger.
I poured off the clear water, half into one glafs, and half into another : into the firft poured off, which was the cleared, I dropt fyrup of violets ; after handing a little,
it
PHYSICAL and LITERARY. 347
it gave a faint green tindure : to the other half, I added powder of galls ; it flowly changed to a violet colour, then to a purple, and, after {landing all night, it was of a ve¬ ry dark blue, inclining to black : into the re¬ maining water, with the fediment, I dropt fyrup of violets, and ftirred all about ; it caufed a tindure of a deeper green than the clear water : all thefe three mixtures, which did not exceed an ounce and a half, I pour¬ ed into a chopin of common water ; and the whole became of a deep violet colour.
16. This fait, after ol. tartari p. d. has been dropt upon it, and then diffolved in a little water, yields a deep green.
17. The fait of this Spaw , after it is burnt on a hot iron, exhibites the like phe¬ nomena (15), and always lofes its aluminous tafte.
18. This fait turned moift and bubbled on a hot iron ; and, when calcined in a crucible, it became of a purple colour, exadly like that of the vitrioli Marti s calx rubra ; and there was a manifeft attradion of feveral of jts particles by the magnet.
19. Neither the fait nor earth of this SpaWy make any effervefcence with fpiritus
vitrioli s
34s ESSAYS AND OBSERVATIONS
vitriolic oleum vitricli, or oleum tartaric p. d> when by themfelves, or when diluted with water ; nor does the fait emit any fumes with
oL vitrioli :
20. A glafs of this water, into which ten gutts of oL tart, p . d . were dropt, and another glafs of the fame water, turned, with powder of galls, to a faint violet colour ; be¬ ing mixed together, produced exactly the co¬ lour of old red port- wine.
Experiments made on the fame Spaw Water , taken up Odober 12. 1750, after five or fix Weeks of dry Weather .
21. The fharp aluminous tafte was much weaker, and the chalybeate ftiptic tafte fcarce to be diftinguifhed.
22. With fyrup of violets, even after (landing all night, there was a little, and but very little, tendency to green.
23. With oL vitriolic no effervefcence, or change of colour.
24. W ith gL tart.p . d. no effervefcence 1 but the like clouds appeared as (10), tho5 in imaller quantity, and of a yellow colour. With fcarce any green.
25. With
PHYSICAL and LITERARY. 349
• 25. With the Eolation of faccharum Ba¬ tumi, it gave a little milkinefs, but fcarce to be diflinguifhed.
26. With powder of galls, it changed very flowly 3 and, after Handing a night, it exhibited but a faint violet colour, fomething inclining to purple.
2 7. A chopin of it, evaporated in a clean tin-pan, yielded a very white faline fubffance, of a (harp, aluminous, chalybeate and Hip- tic tafle.
28. A chopin of this Spaw water, taken up from the fpring, after a long rainy feafon, yielded of fait, nine grains 5 and of earth, fomething more than one grain : the like quantity taken up after three weeks of dry weather, gave of fait, but feven grains 3 and of earth, about half a grain : the like quantity taken up, after between five and fix weeks of dry weather, afforded of fait, on¬ ly five grains and a half 3 and of earth, a- bout a quarter of a grain.
29. 1 here is another fpring, about forty foot Irom this, which feems to be of the fame kind 5 for it has the like tafie 3 and, with fyrup of violets, powder of galls, oh vitriolic oh tartan , p. d. and the folution
of
35o ESSAYS and OBSERVATIONS
Jaccharum Saturni, it exhibit es the like phe¬ nomena.
From the preceeding Experiments we may oh~
ferve ,
l That this Spaw contains a principle of iron, which is volatile ; for its chalybeate quality is much weakened by boiling (13), or even by being expofed for fome time to the air (12).
2. It contains an iron-principle, which is fixed 5 for its chalybeate quality is not in- tirely deflroyed, by being expofed to the air (12), nor by boiling (13)3 nor by evapora¬ tion to a drynefs (14, 15), nor by burning the refiduum (17) ; and, when its fait is cal¬ cined a fufficient time, it is attracted by the magnet (18).
3. It fecms, by turning green with fyrup of violets, to contain an alcaline principle, which is likeways fixed ; for neither by be¬ ing expofed to the air, nor by evaporation to a drynefs, nor by burning the rejiduum , does it lofe this quality.
As neither the water nor its fait or earth, make the leaft vifible effervefcence with fpi- ritus, or oh vitrioliy either bv the mfelves, or
when
PHYSICAL and LITERARY. 351
When they are diluted with water ; fo, it may be faid, that it contains no alcali, and that its turning green with fyrup of violets, is of itfelf no proof; becaufe common water does, with fyrup of violets, change to a faint green colour, after it has flood fometime: but this I imagine rather to be a proof, that there is in common water an alcaline princi¬ ple, viz. abforbent earth ; for rain-water, or fnow-water, have not the leaf! tendency to green, with the faid fyrup.
4. It feems to contain a very little fea fait (lefs than common water) by its precipitating the folution of faccharum Saturni (11).
5. It feems to contain lbme portion of il¬ ium.
<*. From the tafle of the Spaw water, as it comes from the fpring, which is remarkably aluminous.
£. From its tafle becoming more alumi¬ nous, when part of the water is exhaled, by being expofed to the air, for between five and fix weeks (12).
y. From its tafle after three fourths of the water was evaporated, which was more harfh and aluminous, than that of the frefh Spaw,
or
352 ESSAYS AND OBSERVATIONS
or than that which had been fo long expofed to the air (13).
From the aluminous tafte of the fait (14, 27).
£. From its fait fwelling and riling into a blifter on the hot iron (18).
£. From this fait lofing its aluminous tafte when calcined a fufficient time ( 17), which alfo happens to alum, when treated in a like manner.
The nitrum murale, it is true, alfo fwells and rifes in blifters on the hot iron 5 like ways borax, and the purging fait of Scarborough- water : but the nitrum murale differs from this fait in tafte, and, when calcined, falls down into a loofe powder, like lime ; which this fait did not do, tho’ calcined for a confi- derable time, in a ftrong fire.
Borax likeways differs in tafte from this fait, and vitrifies in a moderate heat, in a few mi¬ nutes • which this fait did not, after being calcined in a ftrong heat for a confiderable time. T his fait has not the bitter penetra¬ ting tafte of the purging Scarborough- fal t, neither its purging quality.
I don’t however pretend that all thofe marks amount to a demonftrative proof that
there
PHYSICAL and LITERARY. 353
there is alum in this water, but only to a great probability : for, to be fure of it, we muft fee the alum chryitallifed, which is not eafily done * ; and requires, for that procefs, a greater quantity of fait than I had.
It may be objected, that, when equal quantities of this water and new milk were boiled together, the milk did not curdle(6.) ; therefore there can be no alum in it. This objection is fpecious ; its validity, however, like that of many other things which have ve¬ ry plauhble appearances, can only be determi¬ ned from experiment : wherefore I diifolved in water a greater proportion of alum> than there is, or feems to be, in this Spaw ; and, when equal quantities of this folution, and frefh milk, were boiled together, the milk did not curdle.
6. This water contains very little earth, it gives not the lead: fign of it, when cL tart . p . d. is dropt into it; but the little it contains, feems to be of the white calcarious kind : and tho’ okry-earth is commonly allowed to be a confiituent principle in chalybeate wa-
Y y ters,
* Vid. Shaw’s Inquiry into Scarborough* water, part i. § 4- art. 43.
354 ESSAYS and OBSERVATIONS
ters, yet I am of opinion, that no fuch thing exifts in them in a found, natural ftate ; and that it is never to be found, till the acid, or whatever it is, that diffolves the iron- principle, leaves the water, or, at leaft, its u- nion with the iron-principle, then it ap- pears in the form of an okry fubftance ; but, while the diffolvent of the chalybeate princi¬ ple remains united to it, that is, as long as the water continues in a found ftate, okry-earth is never to be found in it. The earth, there-^ fore, of this kind, which is left in the filter after evaporation and filtration, is owing to its diffolvent principle being loft in that pro- cefs. And I have reafon to believe, from ex¬ periments which I have made, that, by re¬ peated folutions, evaporations, and fiitrations, the pureft and mod genuine cryftals of vi~ triolum Martis may be all reduced to an okry, or bolar earth ; efpecially if the folutions be made in common water.
7< The quantity of mineral principles in this water varies ; and is lefs after a dry fea- fon, than a wet one (28); an unufual circum- fiance, which probably proceeds from this caufe, that the water in a wet feafon, rifes higher in the veins, which contain the mine¬ ral
PHYSICAL and LITERARY, 355
ral principles, and confequently diffolves and carries a greater quantity of thefe principles along with it. Whence it is likewife evi¬ dent, that experiments made on this water at different times, will not always exactly cor- refpond, but will vary more or lefs, in pro¬ portion to the mineral contents of the water.
8. The tenth experiment feems to be an indication, that this water contains a vitriolum Martis nativum ; no other mineral water, that I know of, turns green, with oL tart, p. d. : but, when this oil is dropt into a folution of vitriolum Martis , it becomes green. And tho’ there is no vihble effervefcence in this experiment (To,), yet the many air-bubbles generated feems to be the effedt of the alka¬ li’s uniting itfelf to the acid, which kept the chalybeate principle diffolved, and which chalybeate principle, being now by the oLtart , difengaged from its diffolvent, appears in the form of green or yellow clouds 5 and at kift is found, at the bottom of the glafs, under the form of a fubtile okry, or bolar earth.
It may perhaps be faid, that iince there is probably alum in this water, the air-bubbles are generated by the alkali’s uniting itfelf to the acid of the alum. To deftroy this lup-
pofition2
356 ESSAYS and OBSERVATIONS
pofition, I diffolved alum in water, and that in a greater proportion, than it can be in this Spaw , and then dropt into it ol. tart.p. d. ; there enfued no effervefcence, or fenfible change upon the water ; but a few air-bubbles ga¬ thered at the bottom of the glafs ; nothing, however, in comparifon of what appeared when the ol. tartar . p . d . was dropt into the Spaw ; and no more than what formed upon dropping oL tart, p. d. into a giafs of pure river-water.
9. As chalybeate waters, in feveral parti¬ culars, refemble a folution of vitriolum Martis in water, hence many have been induced to think, that thofe waters contained a vitriolum Martis fuch as is prepared by art : but fome of the late ft, and moil learned authors, as Hoffman , Boerhaave , &c. are of a contrary o- pinion, and for a very good reafon, becaufe no vitriolum Martis could ever be found, upon evaporation of chalybeate waters : the expe¬ riments however made on this Spaw, feem to prove that it contains a fixed vitriol of iron ; tor it not only turns green, upon the addition qi ol. tart. ( 10.) , but like ways, upon eva¬ poration, there is a fait left, which has all the properties of vitriolum Martis .
I
PHYSICAL and LITERARY.
357
■ I diffolved, in a chopin of fountain water, vitriol. Mart . gr. xv. and in every refpedt treated it as I had done the Hartfell Spaw- water, viz . it was evaporated over the fire, till there remained about two ounces ; this was filtrated, and exhaled, in a wide glafs, before the fire : there was left in the glafs gr. xi fs of a light-yellowifh coloured fait, and in the filter a dark-brown earth. With this fait, I repeated all the experiments I had made with the fait of th t Hartfell Spaw $ and I had the pleafure to fee, that they corre- fponded in every thing, without any material difference ; only the fait left upon evaporation of vitnolum Martis , did not rife in a blifter on the hot iron, and, when diffolved in water, gave, with powder of galls, a redifh tindture inclining to purple : whereas the fait of the Hartfell Spaw , being diffolved in water, with galls, flruck a blue. The reafon of which I take to be, that there is a greater propor¬ tion of acid, in the compofition of the fait of the Hartfell Spaw , than there is in the vitrio - him Martis 5 for, if you add an alkali, as oh tartaric to the blue tindfure, produced by the fait of Hartfell Spaw , it changes to a red¬ ifh 5 and if an acid, as oLvittioli , is added
to
S58 ESSAYS and OBSERVATIONS
to the vitriolum Mart is y (e.g. if to a folution of two, three, or four grains of vitriolum Mar- tisy in eight ounces of water, be dropt one gutt. of ol. vitrioli) this, with powder of galls* tho* indeed it changes but flowly, will give a blue, not a redifh tinfture y and again, if the acid is weakened, by dropping into this blue tindlure ol. tartaric the blue will change to a redifh* And this conjecture feems to be confirmed by the following experiment, viz. if vitriol. Mart . be burnt on a hot iron, till it becomes quite dry, and of a yellowifh brown, and diffolved in water, it gives much the fame redifh purple with galls, as before it was burnt ; if this burnt fal Martis be pow¬ dered, and the dry powder wrapt up in a An¬ gle paper, and left in a room without a fire for three or four weeks, it will become moift, and, when diiTolved in water, ftrikes with galls no more the former colour, but a blue $ which, I prefume, is owing to the act dam va- gum which it has imbibed.
Seeing therefore the fait of Hartfell Spaw has all the properties of vitriolum MartiSy I cannot fee, why it may not be allowed, that this Spaw contains a native, fixed vitriol of i- ron ; and it is the only water (I know of)
which
PHYSICAL and LITERARY. 359
which has been difcovered to contain fuch a fait.
In the PhilofophicalTranfadtions, N° 245. mention is made of two mineral waters* which yielded a real, fixed vitriol of iron, one near Eglingham in Northumberland , the other near Haigh in Lancafhire ; but thefe waters were found by Dr. Cay, who made particu¬ lar inquiry into the matter, not to be mine¬ ral fprings, but drifts made for the draining of coal-pits 5 and that the vitriol found in thefe waters, was owing to their running o- ver marcafite beds which had been expofed for fome time to the air. I was fufpicious that fomething of this kind had communica¬ ted the vitriol to the Hartfell Spaw 5 but Mr, Willi amfon , who difcovered the fpring, allured me, that the water, on which I made the pre¬ ceding experiments, had run over nothing at all, after its exit from the fpring, but was ta¬ ken up by himfelf immediately, as it ilfued out of the rock. Dr. James Hunter, Phy- fician in Moffat , afterwards fent me fome of the fame water, which he received into bottles, by applying their mouth to the ori¬ fice of the vein, in the rock from which it if- fued 5 and from it I obtained cryftals of vitri-
olum
I
360 ESSAYS and OBSERVATIONS
olum Marti s, which were of a paler green than the artificial.
In Auguji 1752, this Spaw , with fyrup of violets, ftruck no green tindure.
With oL tart. p. d. it immediately turned green, and clouds of a deeper green and more in quantity than in Auguji 1750, were form¬ ed, and that much fooner than in the prece¬ ding experiments.
With powder of galls it fcarce changed its colour ; and, even after ftanding fome time, it exhibited but a faint blue. I was at a lofs for the reafon of its giving fo faint a blue with galls 5 when, at the fame time, I knew, by its immediately turning green with the oL tart., together with the quantity of the clouds that prefently formed, and the deepnefs of their green, that it was very ftrong of the chalybeate principle : I there¬ fore fet the mixture before the fire, to fee what change a little heat would produce; and, when I obferved that a fmall heat had no elTed, I gradually increafed the heat, till bubbles appeared on the furface of the water ; but this occafioned no change on the colour of the water, the faint blue remaining much the fame. I then conjedured, from the wa¬ ter
PHYSICAL and LITERARY. 36i
ter not turning green with fyrup of violets, as in the former experiments, that there was a greater quantity of acid than ufual united to the chalybeate principle : and, to difcover whether my fufpicion was right, I dropt into the fame glafs, containing the water and pow¬ der of galls, one or two gutts ( I don’t re¬ member which) of ol. tart . ; and, having mixed it by ftirring, it immediately produced very deep blue.
From this experiment, I think it appears, that a water may be very (Long of the cha¬ lybeate principle, and yet difcover very little of it by the common experiment with galls \ fo that it may be proper always to try it with the ol . tart, alfo : for the (Length of the iron- principle is, as the colour and quantity of the clouds formed by this oil ; that is, if the clouds are of a light yellowilh colour and fmall in quantity, the chalybeate principle is weaker ; if they are of dark brown and more in quantity, it is (Longer ; if they are of a green colour, the deeper the green and more in quantity, the (Longer is the chalybeate principle $ which I have found to correfpond with truth, by repeated experiments, not on¬ ly on this Spaw, but on folutions of vitriohim
Z 3 Marfa
n6 2 ESSAYS and OBSERVATIONS
Mart is of different ftrengths, in common wa¬ ter : but, how far this will hold in chaly¬ beate waters that are volatile, I have had no opportunity to try.
I took a chopin bottle of this water, three months after , it had been carried fifty fix miles, and poured one half of it into another clean chopin bottle, and then corked them both very tight j the one bottle I fhook frequent¬ ly and ftrongly for two days ; the third day, I tried both, with powder of galls and ol. tart . j p.d. ; with the galls, both gave a very deep blue ; but the water which had been fhaken, with the ol. tart . rather yielded a fainter green, than that which had not: I let both bottles Rand corked up as before for ten or twelve days longer, without fhaking \ then tried them again with the galls and ol. tart. ; they both ftruck much the fame deep blue, tho’ not fo deep as at firft ; and, with ol. tart . the water which had not been ihaken, gave a green, tho5 fainter than at fir ft 3 the other icarce offered any green ; the clouds formed in it were fewer, and of a lighter yellow, than thole of the other. From which it feems, that fhaking fomewhat weakens the
chalybeate
PHYSICAL and LITERARY. 363
chalybeate principle of this water, tho’ not much nor fuddenly.
This water feems to belong to the clafs of the aqua Marti at a ; for it efferve'ces not with acids, like the acidula and thenna ; nei¬ ther is its volatile iron-principle fo volatile as theirs : hence in general, it may be faid to be aperient and (Lengthening, both when ufed internally and externally : whence it muft be of ufe in difeafes where the folids are relaxed and the blood too watery and weak. But, altho’, when the principles of a mineral wa¬ ter are known, we may, from analogy, de¬ duce its virtues in particular difeafes ; yet, as this method is not fo certain, no reafoning being equal to experience, I (hall confine my- felf to the laft alone ; tho* it is to be pre¬ fumed, that there have not been yet fuffici- ent opportunities of difcovering all the vir¬ tues of a water fo lately found out. Howe¬ ver, it has been obferved to be of great ufe in curing itchy, hot, tettarous eruptions, old obflinate ulcers and fores, internally ufed, and externally applied : it has likeways been of great fervice in diforders of the flomach and bowels ; in the bloody flux ; bloody u- rine 5 (pitting of blood; immoderate flux
of
364 ESSAYS and OBSERVATIONS
of the menfes j obEruaion of the menfes$ the floor albus ; gleet; rheumatic pains; in the firftftageof confumptions, and even when they have been further advanced ; in preventing mifcarriages 3 and in reftoring health, when the conflitution has been im¬ paired by long illnefs : all which will ap¬ pear from the following hiflories, moft of which were wrote down from the patients Own mouths, and attefted by the phyfician or furgeon who attended them*.
Before
* There were given in to the Society, with this paper, twen¬ ty two well attefted hiftories of patients cured of the above mentioned difeafes, by meano of the Hartfell Spanv \ which it was thought proper to omit, fince they would have (welled this article to a bulk too great for a work of this kind. But as the good effects of this water in confumptions of the lungs are fomewhat extraordinary, and may, perhaps, be doubted of by thofe, who have imbibed early prejudices againft all chalybeates and aftringents, in fuch cafes; it may not be amifs to give a place, here, to the two following hiftories.
1 . Mrs Gkndinning, wife to. Mr. Robert Glendinning , fchool- mafter in Moffat, aged 51, was, on the 20th of December 5750, attacked with pains in her right fide ; a conftant (harp pricking pain under the middle of the breaft-bone ; a hard, tickling, dry cough ; third:, difficulty of breathing, and frequent gripes in her guts : all which fymptoms increafed, fill the fifft of January 1 75 1, when {he began to fpit, with difficulty, a little thick grofs matter. In the beginning of ftbruar y, the fpittingwas fp extremely foetid and ill-tailed.
PHYSICAL and LITERARY. 365
Before one enters upon a courfe of the water, it will be proper to cleanfe the prime e vice, by an emetic and a gentle- purge or two ; unlefs forbid by fome particular circumftances
of
that it made her often vomit : fhe frequently wafhed her mouth with fait and water ; but thill felt a tafte and fmell which the thought refembled that of ftinking flefh : the now became very weak and emaciated ; had he£tic fits and night- fweats : which fymptoms continued increafing till the mid¬ dle of April ; about which time (having tried no medicines before) fhe began to drink the Hartfell Spa w, to the quantity of half an Englijh pint every morning. She had fcarcely ufed it a week, when her breathing became much eafier : after a fortnight, the fpitting loft the foetid fmell and ill- tafte ; and, in three weeks, fhe was perfectly free of the pain of her breaft, cough, fpitting, difficulty of breathing, he&ic fits and morning-fweats : and has continued ever fmee in good health.
2. Mrs. Haiti day in Barntyvipan , aged 28, of a plethoric habit, complained, in the beginning of September 1750, of a pain under the upper part of her breaft-bone, which fre¬ quently darted to the point of her right fhoulder ; a pain in her head and neck ; her breathing was not quite free, and fhe could not lie upon her right-fide. About the middle of October , fhe began to fpit florid blood, which continued three wreeks, at the rate of a fpoon-ful every day ; then flopped a week, and returned again. In this manner it went on about four months : after which, beginning to fear the confequence might be fatal, as many of her neareft re¬ lations had been carried off by confumptions of the lungs $ fhe applied to Mr. Johnflon furgeon- apothecary in Moffat? >vho, finding the fpitting of blood increafing, and her pulfe
pretty
366 ESSAYS and OBSERVATIONS
of the patient : or, if the patient’s body has been long codive, and the excrements harden¬ ed^ emollient glyfters may be ufecL Such
as
pretty full and frequent, ordered her to be blooded, to take the decodlum tamarindorum of the Edinburgh Difpenfa- tory, and to fwallow four of the following pills thrice a-day. R Extraft. cort . Peruvian, drach . ii. balfam. Peruvian. Jcrup. h pulv. cort. Peruvian, q. f. ut f. mafia, ex cnjus fingul. drachm . for merit ur pil. xii. The blooding and decoCtion were repeat” edas often as they feemed neceffary; and the pills were con¬ tinued ten weeks without fuccefs: for foon, after fhe left off ufing them, fhe began to cough up purulent matter with blood. Whenever the fpitting dimimfhed, her breathing be¬ came very difficult ; and the pain of her breaft increafed, with a particular forenefs ail along the breaft-bone when fhe coughed.
She drank goat’s and ewe’s whey, from the beginning of June , to the end of Auguft , without any fenfibie benefit ; for fhe continued ftill to fpit blood and matter : foon after this, fhe was attacked with fudden flufhes of heat and morn¬ ing fweats, which increafed till the middle of January 1752, when fhe was become feebler, much emaciated, and often faintifn. At this time, fhe was advifed to drink the Hartfell Spavo in fmall quantity ; but, finding it fit eafy on her (to¬ rn ach, fhe drunk an Englifi pint of it daily. During the firft week after drinking the water, (he expectorated dark, blueifh, putrid fluff, without blood ; and found her breaft much eafier than it had been any time from the beginning of her iljnefs. Soon after, lhe began to breathe freely ; and, after having drank the water fix weeks, was perfectly recovered : fince which time, fhe walked, or rather run, three Scotch miles in an hour, without being either hurt, or much fatiguecf by it.
PHYSICAL and LITERARY. 367
as are plethoric, or have their veffeis full, fliould let a little blood.
This water may be drunk at all times of the year : tho’ I prefer the fummer or warm months ; becaufe perfpiration is then freeft, and the operation of the water, as an alte¬ rative, is aftifted by the warmth of the wea¬ ther : befides, this feafon is more convenient for the ufe of exercife, and the patients are lefs apt to catch cold. The propereft time of the day for drinking it, is, when the ftomach is mo ft empty, as in the morning, fallings before dinner, and fometimes in the evening. Some patients have a cuftom of drinking it with their victuals : but I don't approve of this 3 as it may retard, or, in fome meafure3 hurt digeftion.
The quantity to be drunk is to be deter¬ mined by the age, ftrength, and other dr- cumftances of the patient: they ought to begin with a fmall dofe at firft, and increafe it gradually: fuch as are very weak and much extenuated, fhould begin with a gill or lefs ; this quantity they may take twice a-day ; and, by degrees, increafe it, in proportion as they recover their ftrength, till they come to arink an Englijh pint a-day, a pint and an
half.
568 ESSAYS and OBSERVATIONS
>
half, or two pints, which is about a Scotch cho- pin, and is the larged quantity ufually drunk of this water in twenty four hours, If the wa¬ ter fhould be uneafy on the domach, the pa¬ tient may mix with it an equal quantity, or lefs, of new milk, or fuch a proportion of it as may be found moft convenient: it may alfo be proper to warm the water.
As few of the patients, whofe cafes I have collected, obferved any rule in their diet or exercife, and neverthelefs met with a cure this (hows that there is no great dridtnefs re¬ quired in thefe matters : and, indeed, fuch as have any tolerable degree of health and ftrength, need not much recede from their or¬ dinary way of living; tho5 temperance in eat¬ ing, a moderate ufe of wine, and gentle exer¬ cife, is what all infirm people fhould conform themfelves to : but, fuch as are very weak, and much emaciated, or that labour under dangerous difeafes of the lungs, or abdomi¬ nal vifcera , muft obferve a very dried regi¬ men; their diet fhould confift of what is lighted and eafied of digedion, fuch as n ew milk, broths, panadoes, thin jellies, frefh eggs, chicken, veal, fowls, &c. ; and a little wine may be allowed, when not prohi¬ bited
Irf O-
PHYSICAL and LITERARY. 369
bited by the circumftances of the patient ; moderate exercife may be proper for feme, and reft for others; they mu ft avoid the night air, fitting on the grafs, and every thing that difcompofes the mind.
Upon the firft ufe of this water, feme complain that it makes them lick, others that it makes their head giddy ; but thefe inconveniences almoft always proceed from their having taken too large a quantity : the dofe is therefore to be diminifhed; and if, in a fmaller quantity, it fliould be uneafy on the ftomach, chewing cinnamon, or cara¬ way feeds, or comfits made of them, are frequently ufeful; or any other aromatic, moft agreeable to the patient. It fometimes occa- fions gripes, when the inteftines are weak, on account of its coldnefs ; it ought therefore to be warmed ; the beft way of doing it, is, to put as much as the patient intends to drink at one time, into a vial ; cork the vial, and fet it before the fire, or put it into warm wa¬ ter, till it acquires a fufficient degree of heat. On its firft ufe, it fometimes purges fuch as are troubled with a diarrhoea ; but that is to be reftrained by a gentle emetic, or by giving fame gutts of the tinSi. cpii in every
A a a dofe
37o ESSAYS an£> OBSERVATIONS
dofe of the water, or rather fome little time before it; or three or four grains of the piL Matthcei may be given at bed time, and as much, if requifite, in the morning: it will be convenient likeways to warm the water,, But it oftener occafions ceftivenefs; for which it will be proper, now and then, to give a little fal. Glaub . polychr . manna , or cream of tartar ; or, which perhaps is preferable to a- ny of them, the purging fait of Scarborough - water. If, upon catching cold, any fe¬ ver i ill fits fhould arife, the ufe of the water muft be fufpended till thefe fymptoms are gone. When the water does not pafs eafily, it will be proper to loofen the belly, or give diuretics ; and fuch whofe ftrength will per¬ mit, and whofe veffels are full of blood and juices, fhould let blood.
There is no determining precifely how long it fhould be drunk ; the advantage the patient reaps from it muft decide that : fome have uied it only twelve days, others three weeks, others four, others fix, fome two months, and others many months ; and yet they have all been fo happy as to meet with a cure : fo that, in general, as long as there is any profpedt of its working a cure,
its
PHYSICAL and LITERARY. 37E
• its ufe fhould be perfxfted in ; and, tho' the patient may think himfelf well, I am of o- pinion he (hould not immediately difcontinue its ufe, but gradually diminifh the quantity., and leave off by degrees. Some recommend purging, and other medicines, after the courfe is finifhed ; but, if the patient has been cured, all medicines are ufelefs, and rather hurtful ; if the cure has been impeded, then fuch helps may be called in as the cafe requires.
As to the external ufe of this water : the pradice has been, to waih with it, when warmed, itchy, hot, tettarous eruptions, and old obftinate ulcers, two or three times a-day, and, in fome cafes, during the wdiole day ; to keep linnen cloaths wetted in the fame water, applied to the parts affeded; which method has been very fuccefsful? but, it muff be remarked, that the water was always ufed internally alfo, in the fame cafes.
It feems proper to obferve, that, as this wa¬ ter, put in bottles, well corked and waxed, may be carried to any diflance, and will keep good a long time; longer than either the Pyr- mont water or Liege Spaw : people living in any part or Great Britain , or even beyond leas, may reap almofl: the fame benefit from it, as thofe who r elide in its neighbourhood.
A r Tf
372 ESSAYS and OBSERVATIONS
Art. XIII.
Of the various Strength of different Lime- waters , by Robert Whytt, M, D, F. R. Sa Fellow cf the Royal College of Phy - fcians , Profeffor. of Medicine in the U-
niverfty of Edinburgh.
THE Reverend and ingenious Dr. Ste¬ phen Hales , having informed me, in a letter dated May 1751, that he had found the ftrength of lime-water much increafed, by pouring it a fecond time on quick-lime, frefh from the fire ; I thought it might be worth while to make a few experiments, in order to determine, with fome degree of certainty, the different ftrength of different lime-waters : from thefe experiments it ap¬ peared, that lime-water acquired a confider- able addition of ftrength by being poured on quick-lime newly taken from the fire ; and that the firft water got off quick-lime, was fenfibly ftronger than the fourth and fuc- ceeding ones *a
On
* EBay qn the virtues of lime-water, Sx . p. 38 39,
PHYSICAL and LITERARY. 373
. On the other hand, my worthy friend and Collegue Dr. Alflon, having obferved, feveral years fince, that quick-lime continued to communicate its virtues to water much longer, than any one, before, had imagined 3 tells us, that he found afterwards, by expe¬ riments, that half a dram of ftone quick¬ lime yielded forty ounces of lime-water 3 and that, after a pound of the fame quick-lime had afforded five hundred pounds of lime- water, the water procured from it was as ftrong of the lime as ever *. Hence he i- * magines, that as water can only be impreg¬ nated, to a certain degree, by quick-lime, fo this will happen equally, whether the quick¬ lime be frefh from the fire, or has had five hundred times its weight of water poured on it before 3 provided the water be allowed time enough to extradl the virtues of the lime *j~. And further affirms, that the ftrength of lime- water cannot be increafed by flaking new- made lime in it, becaufe the water can take up no more of the lime than it had before j.
As
* Philofoph. Tranfaft. vol. 47. p. 266, and D:fTertation on quick-lime, &c. p. 4, 5, & 6. where the fame thing is affirmed of oifterihell-lime.
■\ Diiiert. on quick-lime, p. 11. & 53.
x Id. p. IJ,
374
ESSAYS and OBSERVATIONS
As thefe experiments and conclufions ap¬ peared inconfiftent with what I had advan¬ ced, the DoBor has endeavoured further to weaken the credit of my experiments, by fome arguments drawn, chiefly, from the imperfe¬ ction of the hydroflatical balance, and from the nature of quick-lime and its water. In order therefore to know whether I might not have been miftaken in what I had faid, con¬ cerning the ftrength of different lime-waters, I thought it neceffary to make fome new ex¬ periments ; an account of which I beg leave to lay before the fociety.
I. ( a ) Having got from my ingenious friend Mr. James Cray , a cylindrical copper- veffei ending in a narrow neck, which con¬ tained exadly ioo cubical inches; I filled it with the fountain water of this city, and, by means or a very nice balance, found it weighed 25320 Troy grains # befides the weight or tne veflel itielf, which amounted to *3°55 grains; (£) I
According to Mr. Grays experiments, the water which this veffei contains, qnly weighs 25318 grains, two grains lefs than we have made it. See above, p. 20 1. This difference may have arifen from our having pur* few pore drops of water into the veffei than Mr. Gray did. But
al|hQ*
PHYSICAL and LITERARY. 37$
• (b) I poured upon 90 grains of calcined oi- fterfhells, newly taken from the fire, and re¬ duced to a powder, 96 ounces, or five hun¬ dred and twelve times their weight of boil¬ ing water. After 92 hours, during which time the infufion was frequently ftirred and fhaked, I decanted off the clear water, and filtered it thro' a piece of very thick iinnen- cloth doubled 5 by which means it was ren¬ dered free of any crufts, and equally pellu¬ cid with fountain water. With this lime- water I filled the above vejfel , and found its weight to be 25356 grains*.
(c) Monday, at feven in the evening, I poured upon a pound of calcined oifterfhells, frefh from the fire, ten times their weight of water ; next morning at ten, I decanted off the clear lime-water; and having filtered
it
altho, in weighing fluids with this veflel, one might err fix times more than this, yet it would not affeft the point we have in view, which is not to determine with the greatefl accuracy the different fpecific gravities of different lime- waters, but only to fnew that they are different.
* The oiflerfhells made ufe of in this, and the following experiments, were got from among the rubbifh on the fouth fide of the Caftle of Edinburgh, and were quite free of any fea fait.
376 ESSAYS and OBSERVATIONS .
it as above, filled the vejjel with it 5 it weigh¬ ed 25297 grains.
(d) Tuesday at mid-day, I poured feven pounds of the fingle lime-water, ( c ) upon one pound of calcined oifterfnells, newly ta¬ ken from the fire, ftirring them well for fome time after $ at three quarters paft fix in the evening, I decanted off, and filtered as above, the clear lime water ; and, having filled the roeJJel with it, found its weight to be 25457 grains.
HENce it appears, that 100 cubical inches of the lime-water (b) exceeds, in weight, that quantity of fountain water by 36 grains :
( c ) exceeds it by 77 grains, and ( d ) by 137 grains.
The fpecific gravity therefore of the weak lime-water ( b ) is to that of fountain-water nearly, as 704 to 703. The fpecific gravity of the fingle lime-water ( c ) is to that of com¬ mon water, nearly as 329 to 3285 and the double lime-water ( d ) is in fpecific gravity to water nearly, as 186 to 185.
It is obfervable that the fpecific gravities of the fingle and double lime-waters (c) and
(d) y are confiderably lefs than the fpecific gra¬ vities of the tingle and double lime-waters ( a )
and
PHYSICAL and LITERARY. 377
A. and B. mentioned p> 39. and 40. of my Effay on the virtues of lime-water, &c. But, if it be coniidered, that, in making the latter, a much lefs proportion of water was added to the quick-lime, than in making the former % it will appear that this difference of their fpe- cific gravities, does not infer any thing againfi the accuracy of the hydroftatic balance ; but clearly fhews, that the ftrength of lime- water varies according to the quantity of wa*9 ter poured on the quick-lime.
It may be worth while to obferve, that the fpecific gravities of the lime-waters, [b\ (c) and [d] did not differ more than their taftes* The firft was weakeff and leaft difagreeable 3 the fecond was flronger ; and the third {fill ftronger and fomewhat pungent. Further, while the double lime-water [d) gave, in a few minutes, a copper-colour to {liver; the weak lime-water (b) produced no fenfible change upon it.
II. Having, formerly, found that lime- water and claret wine, mixed together, in a certain proportion, acquired a colour like that of gun-powder^: I thought, that, by mixing claret with different lime-waters, one
B b b might
* EiTay cn the virtues of lime-water, p. 47*
37S ESSAYS AND OBSERVATIONS
might judge whether they were all equally ftrong of the lime or not. The refult of the experiments was, that one tea-fpoonful of claret required four tea-fpoonfuls of the lime- water (b) ; two and about one third of (c) y and one and a half of (*/), to give it the full gun-powder colour. Thefe experiments, tho? not fo accurate as thofe made with the balance, yet clearly demonftrate a remark¬ able difference of ftrength betwixt the above lime-waters.
III. Twenty grains of fait of tartar be¬ ing mixed with eight ounces and two drams of the weak lime-water (b), after it had flood five days on the lime, the mixture became immediately white and turbid, and foon pre¬ cipitated a white powder ; which, being fepa- rated from the water, by filtration, and dried, weighed 2y gr.
The fame quantity of fait of tartar, mix¬ ed with eight ounces and two drams of double lime-water, that had Rood eight days on the lime, became confiderably thicker and whi¬ ter than the former; and afforded rather more than 7 grains of white powder.
The fame quantity of fait of tartar being mixed with eight ounces and two drams of
the
PHYSICAL and LITERARY. 379
the double lime-water (d), which had flood 24 hours on the lime, gave eight grains of a white powder.
It was obfervable, that thefe three lime- waters retained the tafte of the lime, after being mixed with the fait of tartar, and this equally after precipitation, as before it.
Since the earthy powder precipitated by thefe different lime-waters, proceeds wholly 9 or altnoft wholly, from the waters, and not from the fixed alcaline fait ; * thefe experi¬ ments (hew, beyond doubt, that double lime- water may contain thrice as much lime, as lime-water made by pouring, on quick-lime, 512 times its weight of water.
IV. 1. Monday 24th December , at eight in the evening, I poured upon a dram of frefh calcined oifter-fhells, reduced to a powder, 520 drams of boiling water.
2. At
* What proves this, is, that the calcarious matter preci¬ pitated by mixing fait of tartar with lime-water, is greater or lefs, in proportion to the ftrength and quantity of the lime-water ; but not in proportion to the quantity of the fait. Thus 12 grains of fait of tartar, mixed with four ounces of ftrong lime-water, yielded as much of this matter, as the fame quantity of this lime-water, mixed with s8 grains of the fait.
380 ESSAYS and OBSERVATIONS
2, At the fame time, I poured upon a pound of the fame calcined (hells, 8 pounds of boiling water,
3. Tuesday, at eleven before noon, I poured fifty ounces of the lime-water N° 2, on nine ounces frefh calcined oifterfhells 5 and, at eight in the evening, I filtered, through brown paper, thefe three waters, and put fixteen ounces of each of them in¬ to a bafon by itfelf 5 and, having placed the bafons in a clofet, where they might be pretty free from duft, I let them .ftand 19 days. After this, I filtered the feveral waters through brown paper, and having collected the earthy crufts, and dried them well ; I found, that N° 1. afforded very near four grains, N° 2, near 12 grains, and N° 3, rather more than 3 3 grains,
Althg3 thefe three lime-waters had, at the time they were filtrated, quite loft their tafte; yet, obferving that N° 2. and 3. be¬ came turbid when mixed with fait of tartar, I added eight grains of this fait to twelve ounces of thefe two waters ; and the white powder which was precipitated, when dried, weighed juft one grain and a half*
Having
y f \ - v * : - - *
PHYSICAL and LITERARY. 38*
Having filtered the lime-waters of N° 2, and 3 . into the fame bottle, before I fufpected that any thing of die lime remained in them* it became impoffible to know, which of them afforded moft of the calcarious powder preci¬ pitated by the alcaline felt, or whether it did not proceed wholly from N° 3.; in which cafe, fixteen ounces of it m u ft have contain¬ ed 17 gr. of the earthy part of the lime, and and N° 2. only 12 gr.
Since N° 2. and 3. were not quite free of the lime, altho’ they had flood expofed £9 the open air 1 9 days, and had loft above |r by evaporation 3 it follows, that the fureft way of knowing the quantity of calcarious earth, contained in lime-water, is to evapo¬ rate it, as Dr. Langrijh did * : and, if it be objected to this, that all water affords fome earth, when evaporated 3 the quantity of this may be determined by experiment : tho’, in many waters, it may well be negledted, on account of its fmalnefs,
j
It has been argued that quick-lime muft5 after many repeated affunons of water, yield as ftrong lime-water as at firft 3 becaufe, as long as there remains any virtue in the lime,
the
•• v t e
f Pbyfical experiments pn brutes, p. 3 u
382 ESSAYS and OBSERVATIONS
the water will extrad it, and continue to do fo, till it has taken up as much of the lime as it can bear. But to this we cannot a- gree : for, the’ there is undoubtedly a cer¬ tain degree of ftrength which lime-water can never exceed ; yet, in order to communicate to water, this degree of ftrength, flaked lime may not only be infufficient, but repeat¬ ed additions of quick-lime may be neceffary; unlefs perhaps a very fmall proportion of wa¬ ter is poured upon it. Quick-lime, frefh from the fire, yields its virtues more eafily, than when weakened by long expofition to the air, or by many affufions of water : the water mull extrad the virtues of the latter, while the former, by a fort of explofive force of its own, quickly impregnates the water. Nor is it to be wondered at, that quick-lime, frefh from the fire, fhould, at firft, impregnate water more ftrongly with its virtues, than it does afterwards. This Is as eafily conceived, as that boiling water fhould extrad more of the virtues of tea or coffee, than cold water. 1 he only difference is, that the menjlruum in the latter cafe acts more powerfully, while In the former the fpbftance to be extracted
affords
PHYSICAL and LITERARY. 383
affords its finer parts more readily, and in greater abundance.
Upon comparing the experiments N° L
with thofe of N° III. and IV. it appears, that the difference between the fpecific gravities of
different lime-waters and common water, is much more than the weight of the calcari- ous matter contained in thefe lime-waters : there muff, therefore, be fomething elfe be- Tides this earthy matter, which quick-lime communicates to water, by which its weight is increafed*. Perhaps quick-lime may alfo, in fome other way unknown to us, alter the
* As lime-water, after its earthy part has been precipi¬ tated by an alcaline fait, continues to tafte ftrongly of the lime ; it follows, that, befides this earth, it contains fome more a&ive and fubtile part, to which its take and virtues are chiefly owing : for we know that the calcarious matter of lime-water, is perfectly infipid and void of any other vir¬ tue, than what all abforbent earths poffefs. This aftive and more fubtile part of lime- water, feems to be feparated from its earth by the alcaline fait, which ftrongly attracts and em¬ braces it. And hence lime-water mixed with fait of tartar, does not lofe its tafte of the lime by being expofed to the open air. Does not a folution of a fixed alcaline fait in wa¬ ter, poured on quick-lime, feparate this fubtile aftive matter of quick-lime from its earthy part, by ftrongly attra£ling it ? And qo not foap-leys confift of water and a fixed alcaline fait united with this aftive part of quick lime, without any, or almofi any, of its earthy part ?
334 ESSAYS and OBSERVATIONS
fpecific gravity of water. But, whatever may be in this, it is evidently unreafonable to deny that lime-water is as much fpecifically heavier than common water, as the hydrofta- tic balance, or other accurate experiments fhew 3 becaufe we cannot account for this excefs of gravity from any thing we know of the contents of lime-water. This is no lefs imphilofophical, than if, one was to doubt of univerfal gravity, becaufe philofophers have hitherto attempted, in vain, to account for it. If we miftake not the matter much, the contrary has always been the opinion of man- kind, viz. that every well attefted fa£t is to be believed, altho" we are ignorant of its caufe, or cannot fhew the particular way in which it happens.
Enough, it may, perhaps, be thought more than enough, has been faid, to fhew that the ftrength of lime-water is very diffe¬ rent, according to the different quantities of water poured on quick-lime. However, I mu ft be allowed to fay, that this point, which has been difputed by my good friend, is of that confequence, as to deferve to be fully cleared up ; fince, to fuch as drink lime-water, with a view to the cure of the
ft one.
PHYSICAL and LITERARY. 385
ftone, it is of no fmall importance to know, how it may be prepared, fo as to have the fureft and fpeedieft effects. And, as lime- water, injefted into the bladder, will un¬ doubtedly diflblve a ftone lodged there 5 it is evident, that, after the bladder has been accuftomed to the weaker lime-wa¬ ters, or to thefe even foftened with a little fweet milk, the dilTolution of the ftone may be much haftened, by injecting fuch as are more ftrongly impregnated with the virtues of the lime.
With regard to the lithontnptie powers of oifter-fhell and ftone-lime water, I (hall only fay, that, as in a variety of experiments made during the courfe of ten years, I had always obferved the fuperior efficacy of the oifter-lime-water I thought it to no purpofe to make a new trial : any one, who doubts on which fide the truth is, may eafily fatisfy himfelf. But, in making the experiment, the calculi fhould either be immerfed in a large quantity of lime-water, or elfe it fhould be renewed upon them every three or four days.
C C G
A P Tz
386 ESSAYS and OBSERVATIONS
Art. XIV.
Of the anthelmintic Virtues oj the Root of the Indian Pink, being Fart of a Letter from Dr. John Lining Phyfcian at Charles¬ town in South Carolina, to Dr. Robert W hytt, Profejjor of Medicine in the U~ niverfty oj Edinburgh.
THERE is a plant, commonly called, by the Carolinians , Indian Pink , which grows in this province, the root or which is ufed as an anthelmintic, and was firft communicated to the Englijh by the In¬ dians.
The root is either given in powder, or an infuiion is made of it in boiling water : but the powder is moft effectual. When I give the powder, I add fome rhubarb (a fufficient quantity to keep the belly open) and a little of fome of the effential oils, as the ol. rut . fabm . or abfinth. To a child of three years of age, 12 grains of the root in fubftance is a moderate dofe : and I repeat it morning and evening for fome days; ordering, at the fame
time.
PHYSICAL and LITERARY. 387
•time, a proper regimen. When the root is given in infufion, 20 grains of it make a fuf- ficient dole for a child of the fame age.
It has an advantage above all other anthel¬ mintics that I am acquainted with, as it is lefs naufeous, and may fafely be given in fevers without heating too much : likeways children, when they awake in the morning, may be deceived with it, by giving the infu¬ fion with a little milk, and a fufficient quan¬ tity of fugar, in place of tea. Tho’ it does not always fucceed in expelling worms ; yet I have obferved, that children's complaints were remarkably relieved after having taken it for fome days.
I fnall only trouble you with one fhort hi- ftory, where I gave it the other day with fuc- cefs. I was fent for to a Negro-child, about four years of age, on the feventh day of a continual fever : and, as I fufpefted that the fever was kept up by the irritation of worms, I ordered the following, that morning ; R. aq. theriac. drach. ii. aq. font. line. Wfs. pufo. rad . anthelmicz (for fo I called the Indian pink) tart, regenerat . ana ferup . i. pulv. croci anglic. gr. v. facch . q.f. M. fumat coch . unum fecunda quaqne bora , Next morning, I ordered
388 ESSAYS and OBSERVATIONS
a repetition of the fame ; and, in the after¬ noon, when the child had a ftooi, 30 large worms, the teretes , were at once voided ; and that afternoon, the fever went intirely off, and did not leturn. Next morning I repeat¬ ed the fame mixture j and, that day, the child voided 9 more of the fame kind of worms.
When too great a dofe of the powder or infuiion is given, it has fome ftrange effedts, which appear very foon after the dofe is ta¬ ken. Children become vertiginous, com¬ plain of a pain in and over their eyes, and the mufculi adduffiores and abdudlores oculorum , feem to be greatly affedted, from their irre¬ gular adtions ; while the other mufcles of the eye, fo far as I have had an opportunity of pbferving, remain unaffedted. Thefe fym- ptoms, however, foon go off ; and their re¬ moval may be haftened by giving fome weak fpirituous liquor, to which volatiles or faffron, or any of the warm effential oils, are added. But, to prevent any of thefe bad effedts of this medicine, fome gutts of the oils before mentioned are added.
I
PHYSICAL and LITERARY. 389
• I have been the more particular in my ac¬ count of this medicine, as I imagine it may, when properly introduced into pra&ice, be of great ufe in faving the lives of many. It has been, for many years, ufed in this part of the world, not only by all the practiti¬ oners, but likeways univerfally by the plant¬ ers.
\
A R T.
S9o ESSAYS AND OBSERVATIONS
A R T. XV.
The Jiifiory of a Cure performed by large Dofes of an alterative mercurial Medicine , com¬ municated to Dr, Plummer , by Mr . George Dennistoun Surgeon in Fal¬ kirk.
A BOUT the month of December 1737* ±\_ a gentleman applied to me for cure : he complained, that, for fome time pad, he had felt pricking pains in feveral parts of his body, efpecially about his fhoulders and fhin- bones, which were now become intolerable. Pie had dry fcurfy fcabs over the whole in- fide of the thighs, the glands of both groins were a little tumified ; and hard crufty fcabs were here and there fcattered upon the fcro- tum^ hips, and about the podex. From the fe, and other circumftances, I had no reafon to doubt that my patient's difcemper was the venereal lues • upon which, I raifed a faiiva- tion with mere. dulc. in the courfe whereof, all the fymptoms gradually difappeared. I then put him upon a courfe of the pil. JEihiopic.
and
PHYSICAL and LITERARY. 39s
and decodion of the woods; by which means* he feeming to be very well, I flattered my- felf that the difeafe was intirely eradicated. He had no complaints for above twelve months 3 but then he began to feel the old pricking pains, efpecially in his legs 3 and, in a fhort time, he difcovered a fweliing on the mod prominent part of his fhin~hone, about the bignefs of a walnut, the’ flat 3 with fuch fcabs, &c. as were formerly mention¬ ed : and all this (as he told me) without rea- fon to fufped a new infedion.
In fhort, he applied to me a fecond time, and, having advifed with a phyfieian, very eminent in his profeffion, he defired me to put him upon a new courfe of mere. dulc. but to give fuch fmall dofes, at fuch intermediate diftances, as to raife the falivation very flow- ly 3 and, when once railed to the quantity of lib. iii. or lib. iv. in a day, to keep it up at that rate, by now and then dropping in a bolus, for two months at leaf!: ; and, at the fame time, to annoint the node on his fhin- bone with ung. mercurial. &c, I followed his directions punctually; and, indeed, all the fymptoms went gradually off, except the forementioned node, which was little or no¬ thing
392 ESSAYS and OBSERVATIONS
thing altered, only he felt no pain in it : 1 was then ordered to give him the piL JEthi- epic , and decoB . lignor . after the ufe of which, for above a month, he began to feel fome flinging pains in the node, and even through the whole leg, which daily increafed. I had read the hiftory of your alterative pills, fome time before : and, judging they might be more forcible than the pil. Mthiopic . in re¬ moving thefe fymptoms, and the remains of the di he m per I hinted the fame to the Do¬ ctor, and he chearfully agreed to ufe the one in place of the other. I fhall here obferve that the firfl fai Nation was railed with ferup . iv. of mere . dulc. and that he only fwaliowed jerup . viih through the courfe of the other ; by which it would appear that that medicine, had by no means become familiar to him. I prepared your pills precifely as directed in Medical Effays vol. i. art. vi.; only inhead of calomel , I took the fame quantity of mere . dadc . and indeed of the fame kind with which I had raifed the laft falivation : and, having divided the maf$3 as is there alfo di- refted j I ordered him to take three pills morn¬ ing and evening with a draught decoB < lignor „ after each dofe, and to drink plentifully of
th©‘
PHYSICAL and LITERARY. 393
the fame thro’ the day. This cotfrfe, with a due regimen* he obferved regularly for a month : but as he was quite wearied with the tedious courfe he had formerly under* gone; and, as he afterwards told me, was refolved his difeafe fhould terminate foon, either in death or recovery 5 he frequently begged I would increafe the dofe of pills : upon which I allowed him to take four, morning and evening, but told him I durlt venture no further ; and withal what quantity of mercury they contained : he at the fame time afked me, what would be the effedt of over-doling them? I told him, I believed they would either caufe him vomit, or raife a fali- vation : this he pocketed up, as being figns fufficient to know when to flop 3 in Abort, as he had accefs to get the pills renewed at my (hop when he pleafed, without my know¬ ing any thing of the matter ; he had taken 24 pills each day for the continued fpace of fix weeks, without being attended with the fmalleft inconvenience : and in that time the erratic pains and node had intirely vanished : but he afterwards made ufe of the pills, thoJ in fmaller dofes. Having thus conquered his difeafe by his ralhnefs * he triumphed as ha*
Ddd ving
394 ESSAYS and OBSERVATIONS
]
ving alfo conquered the too timorous caution of his phyficians. Upon a calculation, I find he had taken unc . xiv. of the alterative pills, which may contain about unc . iii. of fweet mercury, from the firft day of December 1739, to the firft of May immediately there- after 3 but that he had taken unc . ix. (confe- quently above ferup xv. of fweet mercury) within the fpace of fix weeks without inter- million. And ever fince he has enjoyed per- fedt health. From this accidental experi¬ ment, I conceived fuch a good opinion of thofe pills, that I have frequently ufed them fince, in many different cafes ; and with much fuccefs : I have found moft cutaneous difeafes yield very foon to this remedy ; a- mongft others, what is vulgarly called Sib- bens , which rages in the moorlands near this place : whether this diftemper is really a pox, I fhall not pretend to fay ; only it is at¬ tended with the fame fymptoms : and I now begin to think, that, if thefe pills are given in fuch large dofes as before mentioned, in which, I accidentally found there was no danger 5 I don’t doubt, but moft of the di¬ feafes which ufually yield to mercury, may be fubdued by this medicine. I fhall only
add
PHYSICAL and LITERARY. 393
add that I now omit the refna guajac. and increafe the quantity of the gum ; and I boil the lign . guajac . much longer than is di¬ rected in the Edinburgh Difpenfatory, which, I am fenfible, makes the decoCtion much ftronger.
Art,
S96 ESSAYS and OBSERVATIONS
Art. XVI.
4
A Defcription of the feminal Vejfels , by Ale¬ xander Monro, Student of Medicine in the Univerfty oj Edinburgh.
%
THO’ all anatomifts agree, that the feed feparated in the tefticle, paffes thro1 the epidydimis to rife in the vas defe¬ rens ; yet few have a right notion of even the proffer tubes in which it is conveyed. I have
o ' ' J
luckily made quickfilver pafs farther in thefe feminal veffels, and thereby brought more of them into view, than I iee defcribed in any anatomical book; as you may judge by the preparations and pictures which I now fend you, at my father’s defire.
De Graaf had formerly endeavoured, by diffedtion, to unravel the epidydimis ; and paints it as riling from the tefticle in fix or feven branches, which join at its caput or fir ft remarkable turn into one pipe, the nu¬ merous contortions of which form the body
£ t l v / f ; : •-1 ■ t ' * ■ i j t ' ; ; • • v J
f Df Fir, Organ, 7 ah. I. Fig. p ei Tab. 4. Fig. p
PHYSICAL and LITERARY. 397
•of the epidydimis , terminating at its other end in the vas deferens .
This feems to have been overlooked, or not well underftood, by mod: of the modem anatom ills, who have differed widely, or talked with uncertainty, about thefe pipes; till of late, that the ingenious Dr. Haller , by inje&ing quicklilver from the vas deferens , in the manner propofed by my father in the Medical EJJays and caufing it to pafs as far as the teflicle, has been able to explain to us, with greater accuracy, the ftrudure of this intricate organ •f'* He agrees with DeGraaf that the epidydimis , from the vas deferens to its head, feems to be compofed of a fmgle pipe, which he thinks might poffibly be un- loofened, as De Graaf has reprefented ; but does not affirm his having executed it. At its head indeed, he could divide it into ten or more vafcular cones, from which veffels go out, that, after forming a network with com¬ munications, give off (freight pipes which ieera to plunge into the body of the teflicle, —His injeHion here generally failed, tho’ he fometimes obferved, that it entered a few con-r
v olu ted
* Vol. v. Art. xx. § 29. f Phil. Tranf, 494. § xi}8
ESSAYS and OBSERVATIONS
voluted tubes.— He mentions his having thrice feen a veffel going off from about the middle of the epidydimis towards the fpermatic cord* which he imagines is a lymphatic .
That this accurate anatomifFs improve¬ ments, and the additions I am to make to
them, may be better underftood; I have firft
«
copied his elegant figure, and then fubjoined
fome others I caufed to be drawn of thofe parts.
Tab. 3. fig . 1. from Dr. Haller .
A. The vas deferens .
B* The end or laft turn of the epidydimis .
C. Its body, as it appears when the exter¬ nal membrane is diffeded off,
D. Its head unloofened*
see. &c. The vafcular cones into which if divides.
ffi The vafa efferentia, as he calls them. gg. The network with communications. hh. The ftreight veffels which feem to plunge into the tefticle. fig* 2a The tunica vaginalis of the te- fticle is cut off, and the tefticle, injeded e- pidydimis and fpermatic cord, are reprefent- €d covered with their membranes#
A,
PHYSICAL and LITERARY. m
A. The ferpentine beginning of the vas
deferens .
B. The globus minors or laft turn of the epidydimis , from which the fmall convo¬ luted veffel, C) which Dr. Haller fup-
pofes to be a lymphatic, rifes.- - If it
is fo, it has not the valvular ftrudture common to thofe veffels; for I can caufe the quick- filver to flow either way in it.
D. The corpus py rami dale.
E. The body of the epidydimis, where the convolutions feen thro’ the membranes, are larger than they appear in fig, i.
F. The head, globus major , or fir ft remark¬ able turn of the epidydimis „
G. Its rife from the tefticle.
In fig . 3. and 4. ' The tunica albuginea is taken off from the ftdes of the tefticle, and turned over upon the epidydimis .
A. The tunica albuginea .
B. The tefticle.
hh . Dr. Hallers ftreight pipes from which
ccc. The fmall convoluted tubes upon the fides of the tefticle are continued.
dd. In fig . 4. Reprefents a number of them upon the convex part of the tefticle, at the greateft diftance from the epidydimis ,
Fig.
4oo ESSAYS
and OBSERVATIONS
Fig. 5. Reprefents the tefiicle drawn afun- der in its middle from its convex furface to¬ wards the epidydimis .
Fig. 6. A fmall piece is in the fame man¬ ner feparated from the fide of it.
In both we obferve Dr. Haller s ftreight veffels entering at hh ; and then dividing into ecc inumerable convoluted pipes, which com¬ pote almoft the whole fubftance of the tefti- cle.
dd. A number of them where the injecti¬ on has gone very far.
N. These preparations had been kept fe- veral months in fpirits, and fo often handled before the drawings were made, that many of the injeded vefiels are defiroyed, and the painter could not diftinguifh the membranous partitions of the tefticle.
As many of the moil accurate anatomiftsy and even Winflow *, have imagined, that the body of the epidydimis is compofed of a num¬ ber of pipes. — — As Dr. Haller does not po¬ sitively affirm Siis having unloofened it. -
As the vas deferens is much larger than any
P*Pg
Exp. anat. traite de bas ventre. § 4,33.
I
TAB. in.
PHYSICAL and LITERARY. 401
•pipe in the epidydimis , and as it feems diffi¬ cult to conceive how the feed can be propel- ed thro’ a tube fo finally fo much convoluted, and of fuch a length as the (ingle one, which* according to De Graaf , forms the epidydimis : on thefe accounts, I think, there is reafon to doubt this drudiure which he afferts, till we have more fatisfying proof of it than has hi¬ therto been adduced.' — —Such the following appears to be. If, in attempting to make preparations like to thofe above defcribed, an extravafation happens in any part of the epi- dydimis , or if any of its convolutions are tied, not a drop of the injection can be pdfhed farther towards the tedicle than this extrava- fation or ligature : and, if the epidydimis is cut acrofs, while quickfilver is poured into the tube fixed in the vas deferens , it fquirts out only at one orifice in this cut part * which is the plained and mod convincing demon- ft ration of the body of the epidydimis , being entirely compofed of a fingle tube convoluted in a mod wonderful manner.
Tho’ my injection penetrated far into the feminal pipes • yet dill we are unacquainted with their origin. De Graaf * attempted in
Eee vain
* De vir, orgc p. 4 1,
402 ESSAYS AMD OBSERVATIONS
vain to difcover this by maceration in water * nor have anatomifls fince his time been more fuccefsful.
I have endeavoured feveral times to force quick- fiiver from the fpermatic arteries into the feminal veffels ; but, tho’ I made it re¬ turn by the 1 Dermatic veins, I could never caufe it to pafs into thefe convoluted tubes.
This I attempted the oftener, becaufe of the feeming probability of our being able to determine, better in this than in other glands* whether fecretion is performed in continued cylindrical canals, according to Ruyfch , or* by the intervention of follicles, with Mal¬ pighi us y fince we can feparate the parts of the tefticle, without cutting, and even al~ mod without laceration.
Art,
PHYSICAL and LITERARY. 403
Art. XVII.
The Dijfedlion of a Woman with child ; and Remarks on gravid uteri, by Dodlor Donald Monro Phyjician at London.
Gentlemen,
THE few hifiories of difledions and fi¬ gures there are of gravid uteri , make me imagine, that an account of what I ob- ferved in one that fell under my examination, illuftrated with a few figures which I took from the fubjed itfelf, would not be unac¬ ceptable to you.
While I was at Edinburgh laft year, the body of a woman, faid to be fix months gone with child, was brought to the anato¬ mical theatre ; which my father defired me to examine accurately, and particularly to en¬ deavour what I could to (hew the anadomofis
between the vefiels of the womb and thofe
% /
of the fecundines, if there were any Inch,
as Nortwyk * affirms there are, and Haller ,
in his Primee Linece 4*, feems to all edge ;
tho’*
* Hift. uteri human, p. i . § 7. and p. 2. § 83. t § 830.
4G4 ESSAYS and OBSERVATIONS
tho’ in private converfation with this laft named gentleman, when I was his fcholar at Gottingen , he told me, that, what he had wrote concerning that fubjedt, was upon the authority of others, and not from his own obfervation \ for that he had had three wo¬ men with child for fubieds, whofe bodies he had injedted and diffedted ; but had found nothing like an anajlomofis between the uterine and fecundary veffels in any of them : fo that he now believed there was no fuch anaftomofis as was alledged.
I opened the body of this woman ; and, at firft, imagined we had been miftaken a- bout her being with child $ for the inteftines came as low down as the ojfa pubis , and co¬ vered intirely the uterus : but, in turning tip the inteftines, we were foon undeceived, and faw the diftended womb. — - — -I then laid bare the defeending aorta \ and, having fix¬ ed a large pipe of a fyringe into it, and warmed the uterus well, by pouring warm water upon it, and by keeping afterwards applied to it fpunges filled with the fame 3 I injected hot oil of turpentine, coloured with very fine powder of vermiilion, into the f, ffltg 1 and, pfter that, a coarfer injedtion
PHYSICAL and LITERARY. 40$
of melted tallow, dilated and coloured with
part of the former injedting materials.- -
My father then demonftrated to his pupils the parts in their natural fituation ; and I made the fketch of the uterus , as reprefent- ed in tab . iv. where the containing parts AAAAA, being laid afide, you fee the womb BBBB, with its fundus , raifed higher in the right fide than in the left CCC, the larger branches of the arteries on the forefide of the womb of a very ferpentine form, and ana- ftomofing with each other 5— — -DD, the round ligaments ; EE, the Fallopian tubes fixed to the uterus , a good way below the fundus , infiead of being fixed to its angles, as they are in an unimpregnated womb ;• — F, the urinary bladder, which, in this fub- jedt, rofe a good way above the pubes> turn¬ ed down over it with a piece of the integu¬ ments ; — G, the left ovarium.
Next day, the fubftance of the womb was cut thro’ cautiouflv, a little farther fore- wards than the round ligaments ; and, when the incifion had penetrated into the uterus , a fubftance appeared which feparated quite eafily from the more external parts, by being gently prefled with the finger 5 and, by pufh-
ipp?
40 6 ESSAYS AND OBSERVATIONS
ing the finger alternately upwards and down¬ wards, fo much of this fubflance was fepa- rated from the womb, as to allow a probe- pointed pair of fciffars to be introduced for enlarging the incifion, parallel with the fide of the uterus , I then faw that this fubflance was a villous membrane, which feparated al- moft of itfelf from the cut fides of the womb, when we attempted to raife them. In doing of this we could not obferve any tearing of veffels or fibres, except in fome places where fmall convoluted arteries were broke off* from the forepart of the uterus to adhere to this villous membrane. In this manner, this outer lamella of the chorion was every where feparated from the forepart of the uterus , which was cut thro* with a pair of fciffars all around its fundus and edges, as low down as the ojfa pubis , and was turned down over thefe bones.
The uterus was, as near as I could judge, about the thicknefs of an unimpregnated one: fome of the gentlemen who were prefent at the diffedion, thought it was thicker, and o- thers, that it was thinner.
The fubflance of the v/omb was compo- fed of its firm flrong outer membrane which
is
PHYSICAL'and LITERARY. 407
is a continuation of the peritoneum : this ad¬ hered by a cellular membrane, thro’ which a number of arteries ran, to a red colour¬ ed fubftance, which was about one half the thicknefs of the womb, and had a mu- fcular appearance ; but I could not obferve in it any real mufcular fibres, laid in regular fir at a — Within this there was a whiter co¬ loured fubftance, which, on ftretching, ap¬ peared plainly to be a cellular membrane, with its infide fmooth and polifhed; but with a cellular appearance whenever it was ft retch¬ ed, by endeavouring to raife it from the fub¬ ftance of the uterus. : for the internal very- thin membrane, which covers the infide of the womb, and is continued from the exter¬ nal cuticida , is fo fine, that it is fcarce to be diftinguifhed. Numerous veflels, both arte¬ ries and veins, ran every where thro’ this cel¬ lular fubftance.
In the middle of the cut fides of the ute- rus , the empty veins were of a great fize, in companion to what the arteries, diftended with inje&ion, were.
On the internal furface of the part of the womb which was turned down over the pubes , convoluted arteries were feen j and fome ori¬ fices
4o8 ESSAYS and OBSERVATIONS
fices of veins appeared. The outer lamina of the chorion , was fcabrous, fucculent, fomewhat villous, of a pale flefhy colour, and not at all tranfparent. The convoluted arteries which I formerly faid had adhered to it, when the womb was feparated from it, were taken off with a pair of differing for¬ ceps, without any difcernable tearing of fi¬ bres. Crofs incifions were then made into this cuter covering of the ovum , and it was laid to a fide, when we faw the fecond lamel¬ la or clear tranfparent proper morion , which feparated almoft of itfelf, from the outer membrane ; they being only connected toge¬ ther by a very fine and tender cellular fub- ftance. This internal lamella or proper cho¬ rion being cut thro’, the fine amnios appeared, thro’ which was feen the foetus fwimming in its waters.
In Tab. vi* fig. i. are reprefented AAA, the edges of the cut uterus , with large ob¬ long orifices of the cut empty collapfed veins, and of the irnaller round injected arteries;— B, the forepart of the uterus turned down be¬ tween the thighs;— CC, part of the outer la¬ mina of the chorion-,— DD, part of the inner lamina of the chorion ; ™E, the amnios un*-
opened.
PHYSICAL and LITERARY. 409
opened, thro" which is feen the foetus in its waters.
The membranes being all cut thro7, and the waters let out, we more plainly obferved, as in Tab. v. fig. 1. the foetus A, with its head downwards ; B, the navel-llring twill¬ ed round its neck;— the placenta CC adhering to the back part of the womb, with the mem¬ branes DDE), lying folded upon its edges; and the cut Tides of the uterus EEE, where
the orifices of the veins and arteries appear,
> *. t
as in the figure formerly referred to;— F, the vena cava G, aorta defcendens H, the inferior mefenteric artery, to fhew how high the fundus of the womb was railed.
That a comparifon of the fituation of
#
this foetus , with others, might be made ; I fketched in miniature the outlines of Bldlod s, and Albums s figures. Fig. 2. of Tab. vi. is Bidlocs , where the foetus lies in a bended pollute, with its head uppermofl, and its placenta adhering to the forepart of the womb. And, fig . 3. of the lame table, is copied from Albinus , where the foetus is with its head more perpendicularly downwards than in my fubjedt ; and no more, than the edges
Fff o*
4io ESSAYS and OBSERVATIONS
of the placenta adhering to the back part of the uterus , can be feen.
W e fought diligently for an allantois ; but could fee nothing that bore any refemblance to it.
The following day, tallow diluted with oil of turpentine, was thrown into the umbili¬ cal arteries towards the placenta ; and fome of the fame materials, coloured with rad. anchufce , was injected into the umbilical vein.
Tallow, diluted with oil of turpentine* and coloured with verdigreafe, was likeways thrown into the uterine veins, after its cut edges were all tyed.
The foetus being taken out, we fa w how far down the placenta adhered to the womb* as in Tab. v. Jig. 2. where A A, is the low¬ ed: part of the placenta , with fome of the membranes turned upon it ; — BB, a duller of finufes, which appeared where thefe mem¬ branes had been taken from $— C, the entry to the cervix uteri D, a fhare of the forepart of the uterus turned down.
Upon taking the uterus out of the body, and opening the back part of the vagina , there was, as in Tab. iv. jig. 3. A, a confi- derable part of the cervix uteri very little
diflended 5
PHYSICAL and LITERARY. 411
diftended ; and the os tine re B, appeared like a' (mall rima, befet all around with a glandular ring, which was filled with a thick mucus.
After this, the upper half of the pla- cent a was feparated from the womb, to which it adhered, by a cellular membrane of a ftronger appearance than what connected the womb to any other part of the ovum .
Extravasated injection of all the four different kinds, was found between the pla¬ centa and uterus , the greateft part of it, however, was of the vermilion injection, that had been thrown into the defcending aorta . Tho* the extravafated injedtion had made its way into the cellular fubftance both of the uterus and placenta ; yet not one fingle velfel of the placenta was filled with any of the injedtion that came from the uterus > nor was a veffel of the womb filled with that which came from the fecundtnes,— In fome places where there was none of the extrava¬ fated injedtion adhering to the placenta \ I obferved that it was covered with the outer chorion ; and fome arteries broke off from the womb, adhered to it, but were taken a- way without laceration.
Most
4.12 ESSAYS AND OBSERVATIONS
Most of the apertures commonly called Jinujes , were full of the green injection; and fome few of them had a very little of the vermilion in them. The internal membrane of the uterus was extended over part of each of their orifices5 and there formed a fort of valve.— Some of thefe orifices were fo large, as to have allowed one's little finger to have been put into them ; while others were fo final!, as fcarce to admit the point of a probe : and there were of all the different fizes be¬ tween thefe.— The veins continued from them were of a confiderable diameter ; but
• V.. J
not fo large as the Jinufes themfelves.
The extravafation having made the conti¬ guous furfaces of the placenta and womb of my fubjed lefs diflind than I could have wiflied ; I drew fmall figures of thefe parts, from Albinus s elegant large original ones. Fig. 4» of Tab. vi. is the placenta, exhibited with its furiace contiguous to the uterus ip. view; where the engraver has not done ja¬ il ice, in reprefenting the monticuli and Juki of the placenta .
Fig. 5. is better copied, where the oviform figure of the uterus of his fubjed, ftrikes the eye* with the orifices of the cut veffeis in its
fpbftance.
PHYSICAL and LITERARY. 413
fubftance; and the infertion of the round li¬ p-aments are feen, at AA. The numerous Jinujes fufficiently (hew where the placenta ad¬ here to it. To fome few of the valvular membranes of thofe Jinujes , I have put a\ and b is placed near to what reprefents their orifices cc, point fome of the ferpentine fmall arteries ; — -D, the valvular protuberance at the back part of the cervix uteri 5 —e, the gs tincae with part of the vagina opened.
Tab. vii. jig. 1. Is the appearance which a part of the uterus of my fubjedt had, where the fjiufes were not diftended ; and fome of the ferpentine uterine arteries were diftin&ly feen.
Fig. 2. A Jinus A, with its valvular mem¬ brane cut away, when the orifices of three veins B are feen.
Fig. 3. The three veins flit open, till where they meet in one trunk.
Fig. 14. Is a copy of a little piece of Al¬ bums $ figure, where the finufes and ferpen¬ tine arteries are reprefented of the natural fize.
The fpermatic vein appeared of fuch a monftrous fize, and fo much larger than the fpermatic artery, that I differed and made a
draught
ESSAYS and OBSERVATIONS
draught of them, as reprefented in fig. $e where the vein AA, '.and the artery BB, ap¬ pear twifted frequently round each other; and fometimes as if the artery entered into the vein;— C, the fimbriae of the tuba Fallopi - ana-, — D, the ovarium,— E, part of the liga - mentum latum .
That others may judge how long my fob- jedt had been with child, 1 have added the outlines of the foetus of the natural dimen- lions, in fig. 6 .
Thus, Gentlemen, I have fairly related all that I obferved in the dififedtion of this pre¬ gnant uterus ; and beg leave to be allowed to add fome few remarks upon the whole.
From the figure of the womb I difTedted, compared with thofe of Cowper , Nortwyk , Albums, Hunter and others, it appears, that the fundus of the impregnated womb, is al¬ ways greatly extended upwards, in the time of gravidation, by which the round liga¬ ments and Fallopian tubes, which are inferted into the angles of the unimpregnated womb, are then much lower than the fundus : for, in my figure, thefe ligaments and tubes, are almoft one third of the length of the womb
lower
TAB
4.
+
»■
4
X
4
-l
T AB . AT.
L
rP A ~n> TTT
*
PHYSICAL and LITERARY. 415
lower than its top: and Ve [alius Nortwyk *j* and others, have obferved, that the further advanced the woman is in her pregnancy, the lower they defcend.
The uterus, by impregnation, maybe for¬ ced into different fhapes. My figure and that of Bidloo , which refemble each other greatly, fhew, that one fide of the womb may be raifed much higher than the other. Vater and Albinus , have painted the uterus as oval ; and Nortwyk has reprefented it flat at top : but, as all thefe three Gentlemen’s figures were done from wombs which were previous¬ ly taken out of the body, we can form no judgment of the fliape of the womb from their draughts ; becaufe when the uterus is taken out of the body, it aflumes a different ihape, according to the manner in which it is laid down. In Mr. Hunter s elegant figure, which was taken from the uterus in Jitu, the womb is more oblong than in mine. And in two other pregnant women I faw differed, the one feven, and the other four months gone with child ^ the uterus was in both more
globular
* lib. 5. cap. 17.
f Hilt. Uteri, pars 2. § 77. p. 70.
4i 6 ESSAYS and OBSERVATIONS
globular than in the prefent fubjedt. Pofii- bly the figure of the womb may gradually become more oval, as the woman approaches to her time. The part likewife to which the placenta adheres, or the different fituation of the child, may caufe great Variety here.
The ftrong outer membrane and cellular one immediately within it, did not feern in
any of the pregnant uteri I faw diffedted,
*
or by the accounts of any authors, to have been much altered by the great diftenfion they underwent.
Heifter % Nortwyk T, and Mr. Hunter, obferved the fame mufcular appearance un¬ der this outer cellular membrane, as I did
a
without any regular layer of fibres ; as Ruyfch has defcribed and painted nor could I obferve any fuch regular fibres in a woman who died a few hours after child birth, whofe body I difledled while I was in Mr. LeCaf s houfe at Rouen , tho’ Nortwyk || feems to think, that if they are to be feen in any ute¬ rus j
* Anat. Compend. Tom. 2. p. 80. f Hi ft. Uteri pars 2. § 87. p. 106. t Advers. Dec. sii. Tab. 3. FW. i.
} Hill. Uteri pars 2. § 87. p. 107*
PHYSICAL and LITERARY. 417
fus> it mufl be in fach a one. Some few fi¬ bres there were, that went in an irregular, tho’ fomething circular manner; which, with the help of my differing knife, I could have carved into a very pretty mufcle* Authors have differed much about this mufcle 3 fame affirming that they have feen it, while others have denied that any fuch thing ever exifted. Thefe different opinions are all taken notice of, and quoted, in Boerhaave s PraeleH . pu¬ blished by Haller 3 Vol. v. § 664* to which book I (hall refer you.
I have already mentioned, the womb’s be-* ing much about the thicknefs of an unim¬ pregnated one : this however is not always the cafe 3 and authors have differed vaftly in their opinions in this point : fome alledging, that the uterus is always thicker 3 others that it turns thinner 3 while others have affirmed, that it does not alter in its thicknefs by im¬ pregnation. This great difference of opini¬ ons, muff have been owing to the different uteri which have been examined. As Dr. Nortwyk has quoted the paffages of different obfervators concerning this difpute 3 I Shall refer you to his Hytoria Uteri % for their fen-*
G g g timents
* Pars 1, $ 5>o,
4i8 ESSAYS and OBSERVATIONS
I
timents about this matter ; and only obferve, that Dr. Smellie , Mr. Hunter , Mr. McKenzie and others, who pra&ife midwifery here, and have had occafion to fee a good number of impregnated wombs, are of opinion, that in. genera!, the uterus does not alter much in its thicknefs by being diflended; tho’ fome- times it is found thicker, and fometimes thin¬ ner, than ordinary : and in a collection of u- teri in Dr. Smellie ’s poffeffion, there are wombs which feem to favour all the three dif¬ ferent opinions. One of the wombs in this collection, is remarkably thin, not being a- bovethe third part fo thick as an unimpregna¬ ted uterus generally is. If I was to form a judgment, from the few gravid uteri I have feen, I would be inclined to think, that if the womb alters in its thicknefs at all, it rather turns thinner \ but the difference is fo fmail, for the moft part, that it is difficult to form a judgment about the matter. I ought howe¬ ver to obferve, that the gravid uteri will be considerably thicker during life, when they are full of blood, than thev are in dead ho- dies, where the veffels are all collapfed. The difference was confiderable, in the bulk and thicknefs of the womb, before we injected
the
PHYSICAL and LITERARY. 4x9
the veins, from what they were, after we had filled them with tallow.
By fome few of the finufes having a little of the red injedtion in them, it may be con- jedtured, that fome of the final! branches of the uterine arteries opened into them : but I could not obferve their orifices ; and they themfelves were fo fmall, that I only faw one or two fmall twigs running along the mem¬ brane, that lined fome of the finujes .
Since, neither in this fubjedt, the leaf!: drop of either the injedtion that was thrown into the arteries or veins of the mother; nor in another woman, who died when four months gone with child, whole uterine ar¬ teries I injedted with coloured tallow; any of the injedtions were found in the fecundary vefiels, tho’ a great deal of injedtion, in both fubjedts, was found extravafated between the placenta and uterus ; I muft be of opinion, that there is no anaftomojis between the uterine and fecundary vefiels ; and I could eafily fee, how the extravafated tallow, injedted with force, could make its way into the cellular fubftance both of the placenta and womb.
Such ferpentine convoluted very fmall ar¬ teries, which Dr, Albinus has taken notice of,
and
420 ESSAYS AND OBSERVATIONS
and which I faw likewife, in this fubjed, on the inner fur face of the womb, are not to be obferved in any other organ of the body, fo far as I remember.
Nothing remarkable was obferved in the membranes of the ovum, more than what is mentioned by the accurate anatomifts Albirus and Haller : but Mr. Hunter obferved a num¬ ber of veins going from the uterus in conti¬ nued trunks, into the fubftance of the outer lamella of the chorion , in a pregnant woman he drfiedted, and whofe veins he had previ- oufly injected with yeliow wax ; thefe he has delineated in one of his figures, which will foon be published. We could obferve none of them in our fubieCt , but then, all the forepart of the uterus was feparated from the outer lamella of the chorion , before the veins were injeded. Tho’ Mr. Hunter obferved veins, he could not fee one artery, continued from the womb to the chorion ; and the arte¬ ries of his uterus had been filled with injecti¬ on, as well as the veins.
In five of the fubjeds mentioned by my father, in Medical EJJays two of which I fyw, the placenta adhered to the forepart of
the
( , • ». ,
fV oh 2. Art. q.
PHYSICAL and LITERARY. 421
the womb ; while in our prefent fubjedf, and thofe of Vater and Albums, the placenta was fixed to the back part of it, and Dr. S nielli e allures me, he has found it attached to the os uteri . I think therefore it is plain, that there is no particular part to which we can fay the placenta is always fixed : from which it may be juftly concluded, that the chorion is not all equally capable of being placenta ; and that the placenta does not owe its exiftence to the energy of any particular fpot of the womb 5 but that it is an original part which adheres to whatever place, not only of the womb, but of the Fallopian tubes * or abdo¬ men, -f* it happens to be contiguous to $ where it caufes a confiderable flow of liquors, by the abforbing powers of its veffels ; in the fame way as the fucking of the nipple is the mod effectual way of caufing a flow of milk to the breafts. Thus the part of the human womb where the placenta is applied, has its extreme veins enlarged into Jinufes : and the fmooth furface of the womb and its cornua
t
in cows, is raifed into glandular-like bodies where each placenta is placed. Tuo*
* See two examples of this in De Graaf de mulieT. orga- nis, cap. xiv. quoted from Riolan.
•J- An example of this, in Hip. de VAcad. des Sciences 171.6,
422 ESSAYS AND OBSERVATIONS
Tho* the contrivance of the blood re¬ turning from the foetus being poured into Jimifes , is a very good precaution againft hae- morrhagies ; yet the veins of the womb that communicate with thofe Jtnufes , being fo large as they are, one would think, that more frequent haemorrhagies might happen at delivery, was it not for the oblique man¬ ner in which the moft internal coats of the womb are placed by way of valves over the orifices of thefe Jinufes 3 fo that whenever the womb collapfes or contrafts, thefe orifices are aim oft inti rely covered by thefe mem¬ branes.
The oblique fituation of the foetus , the erect, or what is generally called the natural one, in the two I faw formerly, the tranf- verfe one of Nortwyk and Cowper , perfuade me, there is no determined fituation for a foetus , as is commonly thought 3 but that it may change places in its flirtings* as women generally feel.
It has long been the received opinion, that foetufes are moftly placed in the womb, in what is called the eredl or natural fituation 3 that is, with the child’s forepart towards the mothers belly 3 its head uppermoft, and re¬ clined
PHYSICAL and LITERARY. 423
dined forwards and downwards, and that in the laft months of pregnancy, or immedi¬ ately before birth, the head, by its weight, falls down towards the os uteri , fo that the face of the child is turned towards the os fa- crum of the mother, and in this manner is de¬ livered. All this account, both of the child's pofition, and falling down of the head, I mufc doubt of ; for, when I attended courfes of midwifery I examined a great number of women, in all the different times of pregnan¬ cy, from fix to nine months gone with child, and in the greater number of them I felt the head down ; and Dr. Smellie and Mr. Hunter affure me, they have generally obferved the fame thing : fo that this feems to be rather what ought to be called the natural fituation. If the child be fometimes in the erect lit na¬ tion, and its head falls down, I cannot think that this change of pofture is owing to its greater weight at this, more than at any other time ; for, the head of a foetus is proportionally larger and heavier, the younger it is: but to the child, thro' a natural inftindt, endeavouring to avoid the preffure which its head would futter by the contraction of the bottom of the womb, and the detrufion
of
424 ESSAYS and OBSERVATIONS
of the diaphragm during labour- pains, and that, by being turned, its feet may act with advantage, by pufhing againft the fundus li¬ ter i, to afiift the delivery.
The enlargement of the veins of the womb during pregnancy, is really furprifing, as may be judged by obferving their tranfverfe fedtions in their collapfed date, as reprefent- ed in the cut edges of the womb 5 fee Tab. iv. and v. and by the fize of the fpermatic Veins, in Tab. vii. fig . 5. I ought however to obferve, that the trunk of the vein is here represented lefs than it fhould have been 5 for when the womb was cut out of the body, fome of the injection was, by accident, pufh- ed out of the veins, before the figure was made. The fituation of this vein and artery, may let us fee, how eafily Arantius ^ and o- ther anatomifts, before the injedting art was found out, might imagine the artery entered into the vein ; that the arterious and venous blood might be blended together before they reached the womb. Injediions plainly fhew, there is no fuch uncommon anafiotnofis be¬ tween the vein and artery.
* Arantius de foetu, eap, iii. p, jr.
PHYSICAL and LITERARY. 425
. The womb, by being diftended, preffes on the iliac veins, and makes a difficulty to the blood returning from the lower extremi¬ ties, and even to the blood returning by the branches of the iliac, from the womb itfelf, long before the uterus has rofe fo high as to prels upon the fpermatic vein : is not then this difficulty of the blood’s returning by the iliacs, the caufe of the vaft difteniion of the fpermatic veins during gravidation, as well as it is often the caufe of the oedernatous legs3 and i welled labia pudendorum> at that time?
H h h
A R Ta
4,
©
426 ESSAYS and OBSERVATIONS
Art. XVIII.
Additional Obfervations on Gravid Uteri, by Alexander Monro, Student of Medicine in the Univerjity of Edinburgh.
Gentlemen,
HAV I N G wrote to my brother a few obfervations which I had made in exa*- mining a gravid uterus ; he defires me to add fuch of them, as I thought might be a pro¬ per fupplement to the paper which he fent you lately on this fubjedt.
The woman I diffedted was about forty years of age, had born four children, and was faid to be five months gone with child * her uterus being almoft as large as in my bro¬ ther’s fubjedt, tho’ more of an oval fhape, with the forepart of it contiguous to the peri¬ toneum.
Having obferved fo far haftily, I was o- bliged to remove it from the body.
The os tincae , then feen from the vagina , was confiderably larger, and the cervix uteri
was
©
PHYSICAL and LITERARY. 427
was diftended lower down than is reprefented in your Tab. v. jig. 3. which poffibly might be owing to this woman's weaknefs, and to the number of children which fhe had born, A liquor, of a thicker confidence than the oil of turpentine and Vermillion which my brother made ufe of, being injected into the hypogaftric arteries, filled the fpermatics, and a confiderable artery in the round ligament. The joining of the trunks of the two former upon the fides of the uterus was fo large, that it was impofiible to fay, from which of them the branches diftributed to its fubftance were . derived. The right fpermatic was fmall, but the left was as large as a goofe quill ; the hypogaftrics being of a middle fize betwixt the two.— By blowing air into any of the veins, we had fufficient proof of their mon- ftrous fize, and of their numerous and very large communications; the whole uterus be¬ ing at once inflated. — Correfponding to the artery before mentioned in the round liga¬ ment. , I obferved a large vein in it, which pro¬ bably difcharged itfelf into the external iliac.
When the uterus was cut open upon its fore part, near three fourths of its thicknefs had plainly the appearance of a mufcle; the
fibres
428 ESSAYS and OBSERVATIONS
fibres being of a pale red or flefh-colour : and when part of it was boiled in water, we could not have diftinguilhed it fprn any other piece of boiled flefh ; moil of its fibres then feeming to run obliquely from the cervix to- wards the fundus ; others appearing tranfverfe. To which if we add the known fenfibility of the womb, and its ftrong and hidden con¬ traction at birth, we have enumerated all the effentiais required in the constitution of a mufcle.
? *• ♦
As the internal cellular, or rather hi ecu-
lent fungous membrane of the womb, efpe- daily where the placenta is fixed, is of a con- liderable thicknefs; I cannot conceive, how any thing like to an orbicular or radiated mu- fcle could ever be aliedged to be feen upon its inner fide, .without diflfeCtion.
The placenta and f etus were fituated near¬ ly in the fame manner, as is reprefented by Bidloo ; a fmall Sketch of whofe figure is in your 'Tab. vh jig . 2.: the/ poffibly the fitua- tion of the foetus might have been altered, by our having carried the uterus above half a mile before we examined it.
The liquor amnii was of a clear brown co¬ lour s upon adding oil of vitriol , or oL tart .
p, d*
PHYSICAL and LITERARY. 429
p. d . to it, no remarkable change could be ob- ferved : which proves that it contains little ferous or urii us ; for the oil oj vitriol would have coagulated the former, and the latter would have betrayed itlelf upon the addition of the fixed alcali.— — When it was brought
o
to a boiling heat, it threw up a thin whitiih fcum ; and an ounce of it boiled dry, left a - bout a fcruple of what appeared to be a fe¬ rous coagulum .
We could not obferve any thing like an allantois : and, when the urachus was after¬ wards examined, it neither allowed air, wa¬ ter, or quick- filver, to enter it from the blad¬ der ; tho’ I have feen it pervious for an inch or more in children, born at the full time.
The cervix uteri being now cut open ; the whole inner fide of it was covered over, efpe- cially near to the os tinea, with clufters of veficles, fome of which were of a confide- rable fize, filled with a dark brown-coloured mucus ; and fmall orifices, containing the fame kind of liquor, appeared in their in- terftices.
When the placenta was taken off, the in¬ jection, which had been thrown into the hy- pogafcric arteries, was found extravafated be¬ twixt
430 ESSAYS and OBSERVATIONS
twixt it and the uterus $ many lumps of the wax being, as it were, wedged into the hab¬ it an cc of th t placenta, without having enter¬ ed any of its veffels, — -We then faw many final! ferpentine arteries with their orifices o- pening upon the internal membrane of the uterus 5 and other, generally larger* convo¬ luted arteries, whofe extremities we could not as yet obferve, appearing prominent in the interfaces of cavities filled with the wax 5 and which, in the foregoing paper, are men¬ tioned under the name of finufes : the real ilruclure and Situation of which, being little underftood, tho’ often talked of, I finall re¬ late all that I obferved in this fubjedf ; and then, by comparing it with the common de~ fcription, we may better underftand what has milled mod anatomifls.
The finufes are feen without any previous diffedion upon the inner fide of the uterus , chiefly where the placenta has been fixed $ for there are but few of them, and thefe ve¬ ry fmall, in any other part of it.—Their fides are membranous, that, next to the cavity of the womb, being in each very thin, with a large orifice in it.— They can be readily dif- tended, by blowing air, or injecting a li¬ quor
PHYSICAL and LITERARY. 43*
.quor into the veins 3 or they may be filled from the arteries, tho’ with much greater difficulty, as happened in our injection: when ftretched, they appear of a fpheroidal ffiape ; and, the diameter of their orifices being lefs than that of their cavities, we may give them the name of Jinufes.— Upon diffedli- on, we obferve arteries opening, at leaf!: into fome of them, as I fhali afterwards prove, and confiderable veins are continued from all of them 3 the veins and Jinafes ha¬ ving all large communications with each o- ther 3 and, tho’ fome of the finufes may have only two or three fmall veins opening into them, yet, in general, the diameter of the veins continued from them, is not greatly in¬ ferior to that of the fin us .
Since, from this defcription, it appears, that thefe cavities are only the fomewhat di¬ lated extremities of the branches of the veins 3 we may account for their formation, from the more than ordinary difficulty there is in the return of the blood from the gravid ute¬ rus 3 which being therefore accumulated, mu ft ftretch all the veins greatly, but fuch parts of them moft as refill: the leaft : confe- quently their extremities which are only co¬ vered
432 ESSAYS and OBSERVATIONS
vered by the lax internal cellular membrane of the womb, will be moft dilated, or put on the appearance of finufes ; and this effedb will be moft confpicuous where the greateft flow of liquors is, that is, at the place where the placenta is attached to the womb; as my brother has juftly remarked.
If we compare the above defcription with the common notion of a Gnus, we (hall find they differ widely.*— They are generally de¬ fined to be large cavities in the middle of the fubftance or fie (by part of the womb, that have fmall branches of arteries and veins o- pening into them, with canals, whofe dia¬ meter is confiderably lefs than that of the Gnus, running obliquely thro' the fubftance of the womb to open upon its inner fide.-— But fince, after a diligent fearch, no finufes
S.
of this form could be feen in this fubjedt ; as neither my brother nor the accurate Albi- nus paint or defcribe any fuch ; and, as the ingenious and diligent Dr. Haller pofitively affirms, in one of his lateft works that af¬ ter repeated experiments, he could not oh- ferve them ; it feems probable, that the trunks of the veins have been miftaken for finufes; and their branches; for canals opening
into
* Prim. Lin. phyf. § 804,
PHYSICAL and LITERARY. 433
into the cavity of the womb ; nay, a late learned author applies thefe names of finufes and canals, to the trunks and branches of the veins painted in Albums § 7th table of the gravid uterus .
The exiftence of finufes and canals be‘ng then imaginary, and the cavities which we have defcribed under the name of finufes being in- tirely the creatures of impregnation, and not to be found in the uterus virgincus ; or being at any rate, from the fize of their orifices, un¬ fit receptacles of the blood ; we cannot furely account for the menftrual flux or any other phenomenon from fuch a ftruCture.
As the finufes were filled by our coarfe in¬ jection, thrown into the arteries, I imagined, that, by a careful difleCtion, the openings of the arteries into them might pofiibly be ob- ferved ; but, I found more difficulty than I expedted, from the fize and very large com¬ munications of moft of the finufes and veins. Near to the edges of the placenta , where they were not fo frequent, I was lucky e- nough to difcover, with certainty, feveral ori¬ fices of arteries, fome of which were of a confiderable diameter, opening direCtly into the finufes : and fince none of the anatomifls
I i i have
434 ESSAYS and OBSERVATIONS
have painted or defer ibed thefe openings, tho*s in the imaginary ftru&ure of the Jinufes , they are fuppofed \ 1 have caufed a few of the mod diftind to be reprefented in Tab. 7. jig. 7. where A reprefents the inner furface of the womb, to which the edge of the placenta had been fixed ^ — ib, two fmall arte¬ ries appearing after having pierced the muf- cular fubftance ; — ccd , their ferpentine and fpiral turns their openings into the f mu - j'es 5 which were plain beyond difpute, when the wax was taken out of the Jims , and the artery gently preffed, the jams being again in part filled from it, as is reprefented at f. w. Nay, it is evident, that the arteries had communications with the : Jinufes alfo in my bro¬ ther's fubjed ; fince the placenta was covered over with the extravafated oil of turpentine and vermilion, which wras injpded into the aorta defeendens ; and which therefore feems to have filled the Jinufes , but to have been thruft out of them by the coarfe green injecti¬ on afterwards thrown into the veins.— fmaii arteries which were obferved every where opening upon the internal membrane of the womb \—ff, others which feem to have been torn in feparating the placenta .—
, And
PHYSICAL and LITERARY, 435
And, in all that part of the womb to which the placenta had been fixed, when the cellu¬ lar membranes and extremities of the veins were differed off ; innumerable arteries, of all fizes, from that of a crow-quill down¬ wards, convoluted in a moft furprifing man¬ ner, were obferved; which were nothing fo confpicuous in any other part of the womb, treated in the fame manner.
Art,
43 6 ESSAYS and OBSERVATION^
A R T. XIX,
Of the Difference between Refpiration and the Motion of the Heart., in fleeping and wa - king Perjons, by Robert Whytt, M. IX &c.
I /
OF all the parts of the human body, there is none whofe ftrudture is more fub- tile, and whofe feveral functions and ufes are lefs known, than thofe of the brain . It is little to be wondered at, therefore, if au¬ thors have failed of giving a fatisfa&ory ac¬ count of Jleep , which is one particular date of this unknown organ,— We have elfe where offered our conjectures concerning the reafon why the vital motions continue in time of Deep ; when the organs of fenfe become lefs . fit to receive the impreffions of external ob¬ jects ; and when the mufcles of voluntary motion are more relaxed and remain at reft 'h But, as refpiration and the motion of the
hearty
* EfFay on the Vital and other Involuntary motions of a* nimals, fedt. xii.
PHYSICAL and LITERARY.
437
heart, fuffer fome change in time of deep, /. e. become then flower, fuller and more e- quable, than when we are awake it may be worth while to enquire a little into the reafon of this phaenomenon .
It has been fhewn, that as the dilatation of the ventricles of the heart, is owing to the force of the refluent venous blood > fo their contradtion is produced, by the fame blood adting upon them as a Jlimulus and that the heart can only be affedted by Jlimuli , in fo far as it is a fentient organ, i. e . en¬ dued with feeling J. Whence it muft follow, that the flownefs of the pulfe in fleep, and indeed in every other cafe, can only arife from one or more of the following general caufes. viz. i. A diminution of the ftimu- lating quality of the blood. 2. Its flower re¬ turn to the heart; or, 3. A lefs degree of fenflbility or aptitude for motion in the heart itfelfo
* Boerhaave Inftitut. Med. § 599.
•f Vid. Effay on Vital and other Involuntary motions of animals, left. iii. and iv.
J Ibid, fe&. x. p. 271. &e.
43S ESSAYS and OBSERVATIONS
»
L When one has eat or drunk a great deal before deep, his pulfe will be, not flow, but quick and fulls becaufe the ftimulating power of the blood is increafed, by a large quantity of chyle received into it. Much the fame thing may happen from fleeping in too hot an air, or under too great a weight of cloaths: for we know, that heat quickens the circu¬ lation of the fluids in all animals. On the other hand, when one has failed long before fleep, and lies very cool, his pulfe will, in time of it, be unufually flow.
But when the blood is neither loaded with new chyle, nor altogether deftitute of it ; neither too much heated by cloaths or the external air, nor too cool, thro' want of proper covering s its ftimulating quality will neither be augmented nor diminifhed by fleep ; but will continue the fame as in a per- fon who is awake in the fame circumftances* It remains therefore, that the flownefs of the heart’s motion in time of fleep, be owing, either to the flower return of the venous blood to it, or to fome diminution of its fen- Ability.
II. Every one knows, that the affections of the mind difturb the motion of the hearty
that
PHYSICAL and LITERARY.
that the pulfe is quicker when we fit or ftand than when we lye ; and that the a&ion of the mufcles of voluntary motion, not only promotes the return of the blood to the heart, but determines it thither, with much greater force than ufual. In fleep therefore, where the horizontal pofture of the body, the quiefcence of the voluntary mufcles, and compofure of the mind, all concur to render the return of the venous blood to the heart, more equable and flow, the contraction of this mufcle muft be renewed at greater inter¬ vals, and with more regularity, than when we are awake, and the circulation is quicken¬ ed or difturbed by fome, or all, of the above- mentioned caufes. But, if no farther cir- cumflance, tending to retard the heart’s mo¬ tion, were found in deep, the pulfe flhould be equally flow and full in a waking perfon lying at red in a horizontal pofture, and whofe mind is compofed, as in the fame per¬ fon in time of fleep ; which, however, does not feem to be entirely the cafe : for tho’ the difference may be fmall, and there may be many caufes which may render it difficult, by obfervation, to determine that difference with any degree of certainty ; yet the remarkable
flowncfs
440 ESSAYS and OBSERVATIONS
fiownefs and fulnefs of the pulfe in the deep fleep, accompanying an apoplexy or occafioned by opium , makes it highly probable, that even in the much gentler fleep of perfons in health, the pulfe is fomewhat flower and fuller, than it would be, merely from the compofure of mind, horizontal pofition of the body, and quiefcence of the mufcles of voluntary motion. Let us therefore fee, whe¬ ther the flown efs and fulnefs of the heart’s motion in time of fleep, may not be in part owing, to fome diminution of the fenfibility of this organ.
3. In time of fleep, as the exercife of the feveral fenfes, is either fufpended or much impaired 1 fo the fenfibility or feeling, with which the organs of the body are more or 3efs endued, feems to be rendered lefs acute. Thus we feel ourfelves affeded with a kind of Jiupor , when we are juft falling afleep, and are then infenfible of lefler Jiimuli . The thin rheum, which, by irritating the wind¬ pipe, keeps us almoft perpetually coughing when awake, gives us little or no difturbance m fleep : any extraordinary Jlimulus in the guts is alfo lefs perceived then ; and hence it is, that 4 dofe of any purgative taken at night, is
piuch
PHYSICAL and LITERARY. 441
. much longer before it operates, than when it is fwallowed in the morning. If the heart therefore, like the other organs of the body, becomes lefs fenfible or irritable in time of fleep, it will not be fo quickly excited into contraction as ufual,by the venous blood rufh- ing into its cavities ; and hence its contracti¬ ons will not only be more flowly repeated, but the pulfe will be full, becaufe the ventri¬ cles do not contradt, till they are much dis¬ tended with blood. This will thill further appear, if wre confider how remarkably flow and full the pulle is, in an apoplexy, where the fenlibility of all the parts and their apti¬ tude for motion, are much more impaired than in common fleep: and how opium , which occafions fleep, and leflens the fenfe of feel¬ ing every where thro’ the body, when given in a large dofe, renders the pulfe uncom¬ monly flow and full. Thus the heart of a frog, into whofe ftomach and guts I had, an hour before, injeCted a folution of opium , was obferved to beat near four times flower than ufual ; and the auricle and great veins leading to the heart, were remarkably dif- tended with blood, as was alfo the ventricle of the heart before every contraction. At
K k k the
ESSAYS and OBSERVATIONS
44^
the fame time the other mufcles of this ani¬ mal were fo intirely deprived of feeling as not to be, in any degree, affeded by prick¬ ing or tearing their fibres 'h
Does not the flower digeftion of the ali¬ ment in time of fleep, proceed, partly, from the periftakic motion of the ftomach and guts being then repeated after longer intervals? In dogs who have got a large dofe of opium , this motion is very much !effenedor totally fufpend- ed, the food laft received into the ftomach re¬ mains there indigefted, the guts are more than ufualy empty, and the ladeal veffels in- vifible*f\ In fieep, therefore, not only the heart but the ftomach and guts alfo, become lefts fenfible of the Jlimuhs ufually affeding them, and confequently repeat their contra- dions more flowly.
De Gorier , differing from Boerhaave and o- ther authors, thinks, that the pulfe muft be, not fuller, but fofter in time of fleep, becaufe the circulation of the blood is allowed, then, to proceed more (lowly than when we are a-
wake.
* Eflay on the Vital and Involuntary motions, &c. p. 372*
4 Kauu iropet, faciens Hippocrat, di&um, No 434.
PHYSICAL and LITERARY. 443
wake-f'. But, from what has been Paid, it ap¬ pears, that thefulnefsof the pulfe in fleep, is not owing to the quicker circulation of the blood, but to a lefs degree of fenfibility in the heart, whereby its ventricles are not excited into contraction, till they have been more fully dilated, then ufual, by the returning blood. It is, however, to be obferved, that the fui- nefs of the pulfe in fleep, may be owing partly, to the fluids paffing, with greater diffi¬ culty, thro’ the very fmall lateral arteries, and the fecretory tubes of the glands^. For we know that the fulnefs or foftnefs of the pulfe does not depend, folely, upon the quantity of blood thrown out by the left ventricle of the heart, but alfo upon the more or lefs difficult paflfage of this fluid thro’ the extreme arteries ; fince, in proportion as thefe are obftruCled or open, a greater or lefs refiftance will be oppofed to the blood projected by the heart.
After what has been faid of the flownefs of the heart’s motion in fleep, it will be eafy to fhew why refpiration fhould be performed, then, at greater intervals.
* Boerhaave Inftitut. med. § 597.
$ Exercit. de fomno et vigilia, § xl.
The
444 ESSAYS and OBSERVATIONS
The caufe exciting the alternate contracti¬ on of the infpiratory mufcles, is an uneafy fenfation in the lungs, occafioned by the blood pudied into their veffels by the right ventricle of the heart If then lefs blood is fent, in a given time, into the lungs, in deep, than when we are awake 5 the neceffity of new fupplies of freih air will be leffened, and confequently infpiratron will be perform¬ ed at greater intervals.
Further, as in time of deep, the fenfi- bility of the lungs, like that of the heart and guts, mud be fomewhat impaired, re- fpiration mud alfo, on this account, be per¬ formed more dowly 3 for the infpiratory mufcles will not be excited into aCtion till a greater degree of irritation, than ufual, be occafioned by the blood accumulated in the pulmonary vellels. And, to this it is owing, that reipiration is not only dower but fome¬ what deeper in time of deep, than in a waking perfon at red in a horrizontal politico.
In ccmatous and apopledic cafes, where all the feelings of the body are much more impaired than in ordinary deep, refpiration is not only much dower and deeper than ufual,
but,
* EiTay on Vital and Involuntary motions,, &<p. p. 176. &:c*
PHYSICAL and LITERARY. 445
but, fometimes, after expiration is finished, a paufe of 15, 20, 30, or more feconds will intervene, before a new infpiration is begun. Much the fame thing happens to animals who have fwallowed too great a quantity of opium
Now, if it be reafonable to afcribe the flow, deep and interrupted breathing, in fuch cafes, to the infeniibility which attends thofe difeafes of the head ; and which opium never fails to produce, when taken too liberally ; are we not hence led to conclude, the lefs re¬ markable change of breathing which hap¬ pens in fleep, to be owing, partly, to the fenfe of feeling in the lungs, being then fomewhat diminilhed, tho’ in a much lefs degree than in thofe morbid cafes?
To conclude with fum ruing up what has been faid in a few words ; in ordinary fleep the fenfibility of the heart and lungs fuffer fo fmall a diminution, that their motions will be very little more affedted by it, than they would be from the horrizontal pofition and reft of the body, and compofure of mind attending it. In the deeper fleep, which fucceeds great fatigue, the motions of the
heart
f EiTa y on the Vital and Involuntary motions, &c, p. 194.
44 6 ESSAYS and OBSERVATIONS
heart and lungs will be more obfervably al¬ tered. And, in the moft profound fleep, oc¬ casioned by opium or a morbid Rate of the brain, where a general infenfibility reigns over the whole body 3 the pulfe will become much more remarkably flow and full, and refpiration flower and deeper.
Art,
j
PHYSICAL and LITERARY, 447
A R T, XX,
Remarks on the IntercoJIal Mufcles , by Alex- ander Monro, F. R. S. Profefor of Anatomy in the Univerfty of Edinburgh.
TAUVR T*, fhewed the mifapplication of ivlr. Bayle s propofed demon ftration of the adtion of the internal intercoftal muf¬ cles, from his inattention to the ribs not keeping in the fame parallelifm when they are raifed, as when they are depreffed, becaufe of the greater motion of the lower than of the higher ribs ; and he took notice of the fame demonitration, proving equally that tne anterior part or thefe internal intercoftals mint a 6t in inipiration, as Bayle would have their pofterior part to a dt in expiration : but neither he, nor any other writer of my ac¬ quaintance, has applied this demonftration of Bayle s, which, granting the parallelifm of the ribs to remain the fame, is a good one, to account for the defedt of the inter¬ nal
* AxaU raifonn, part, z, chap. 14,
448 ESSAYS and OBSERVATIONS
nal intercoftals between the fpine and the an¬ gle of the ribs, and for the deficiency of the external intercoftals from where the ribs be¬ gin to turn upwards to the Jlernum 5 a fadt which anatomifts are now all agreed in. The application of the demonftration to this purpofe, is the intention of this paper*
Let AB {Jig. 1. Tab. viib) be the fpine, CD the jlernum , EFGH, and IKLM two ribs ; then EK and GM are lines in the di~ redtion of the external intercoftal mufcles, and FI, and HL are in the direction of the internal intercoftals.— — Now, fays Bayle3 If both ribs rife, the angle FEI muft be in- larged, and its hypoteneufe FI, the fibres of the internal intercoftal, muft be longer: whereas mufcles generally are fhortened when they adh — Near to the fpine, where the ribs cannot be brought nearer at one time than another, this reafoning is juft 5 and there¬ fore the internal intercoftals are not placed nearer to the fpine than where the motion of the ribs is large enough to allow the lower rib to approach fo much to the one a- bove it as to do more than compenfate for the elongation of the hypoteneufe of the angle FEI, /. e . the internal intercoftal is only to be
found
PHYSICAL and LITERARY. 449
found farther foreward than the angles of the ribs.
Near to the Jlernum , the cartilages can¬ not be brought nearer ; and therefore, when they are raifed up, HL, the fibres of the internal intercoftal may be (hortened, becaufe the angle HML is made lefs : but, if there were fibres of the external intercoftal here, as GM, they would be made longer, becaufe the angle GHM is enlarged by railing the ribs ; and therefore no external intercoftal mufcles are placed at this forepart of the tho¬ rax .
L 1 1
A R T.
45°
ESSAYS and OBSERVATIONS
Art. XXL
The Cure of a fraSiured Tendo Achillis ; by the fame.
OU R predeceffors were either not fub- jed to the breaking or tearing the ten- do Achillis , or it was miftaken for a fprain, or fome fuch other difeafe by phyficians and fur- geons ; for it is rarely taken notice of in books ; and the oldeft and heft pradifers here aftiire me, they had not obferved it or heard of it, till between twenty and thirty years ago ; fince which this accident has happened to a confiderable number of peo¬ ple of this country, of whom I know fix- teen, and fever al of thofe have broke the tendons of both legs ; among the reft, I have been a fufferer this way; and, upon a compa¬ nion with my brethren in afflidion, my cure is the moft compleat of any I know ; there being neither pain,, ftiffnefs, weaknefs nor obfervable fhriveling in my left leg where the tendo Achillis was broken : whereas moft of the other gentlemen have fome of thofe un-
eafineffes.
PHYSICAL and LITERARY. 451
eafinefles, and feveral have all of them. On this account, I think it my duty, for the be¬ nefit of future patients, to make my method of management as public as I can ; which probably will be beft done, by communica¬ ting it to your fociety.
When my tendon was torn, it cracked as loud as if I had fuddenly broke a nut under my heel 5 which the company believed had happened : and I had fuch a feniation as made me imagine that the heel of my fhoe had ftruck a hole in the floor ; which is the feeling that feveral have had as well as I : while others complain as if they had recei¬ ved a fmart ftroke with a ftone or cane on the part. — I fufpe&ed immediately what the cafe was ; and therefore, after feeling where the hollow was, between the ends of the broken tendon, I took the left foot in my right hand, with which I extended the foot ftrongly ; and, as foon as I was put in a feat, preffed down the calf of my leg with my o- ther hand : in which poflure I kept them till Meff. John Douglas and James Rujjel fur- geons of this place came ; and, after being fatisfied of the rupture, by prefling their fingers into the hollow between the two ends
of
ESSAYS and OBSERVATIONS
452
the tendon, they applied compreffes, and a bended board on the upper part of my foot and fore part of my leg, which they kept, as near as they could, in a flraight line, by a tight bandage made with a long roller.— This dreffing became foon too uneafy for me to bear, and the board was liable to fhuffie whatever care was taken in the application of the bandage : therefore I changed it for the following compound one, confiding of two pieces. (See Tab. viii.)
Fig, 2. is a foot-fock or flipper A, of double quilted liking ; from the heel of which B, the quilted ftrap C, is of fuch a length as to come up above the calf.
Fig. 3. A ftrong quilted calf-piece L, with pye-holes MM on each fide, through which a lace, Jig. 4. is to be pafled 3 and, with a buckle N, fo placed on its back-part, that, when the lacing was on the outfide of the leg, the buckle was in the middle of the lower part. Two rows of pyehoies are here reprefen ted on one fide, either of which is to be ufed according; to the thicknefs of the
o .
w o
t *
Having
/
PHYSIC AL and LITERARY. 453
Having then wrapped foft flannel, fmoak- ed with the fumes of benzoin, round my foot and leg 5 I put on, as in fig. 5. the foot-fock A, and calf-piece L, and bringing the ftrap C, thro' the buckle N, I could by it extend the foot, and pull down the calf to what de¬ gree I thought fit, and there fecure it with the buckle.
This bandage anfwering my intention quite well, I wore it night and day, drawing the ftrap tighter when I inclined to deep, and re¬ laxing it when I was fully awake and on my guard ; at which time, likeways, I placed my foot on a ftool, in the pofture reprefent- ed at S, and frequently fhifted the calf-piece or made the lacing of it loofer, to prevent the dwelling of my foot, whichit was in dan¬ ger of occafioning, when it became too tight, by being drawn down by the ftrap.— After a day or two, I found my toes uneafy, from the foot-fock preftmg them ; and therefore I undid the fowing of it at the toes, from d \ tod-, and have caufed it always fince to be made open there, for others who ufed it.
During two weeks, I made no motion nor effort with my foot 3 but was carried on a chair, running on carters, from one part
of
454 ESSAYS and OBSERVATIONS
of my houfe to another. After this, I began to move the foot backwards and forewards fo gently as not to give pain, and gradually increafed thofe motions 3 but always flopped the flexion of the foot, or extenfion of the leg whenever 1 felt the lead: uneafinefs : fre¬ quently I continued thefe motions for half an hour together, with the difeafed limb 3 but kept the other as much at reft as I could.
When I began to walk, I always put the left leg fome way before the right, that the left foot might be well extended; making ufe of a cane in my right hand, to prevent any danger of falling.
The void between the two ends of the di¬ vided tendon, became infenfible in few days, except that a foftnefs was felt there, more than any where elfe ; but this part turned gradually thicker and harder, till a knot was formed in it, which one, in feeling thro’ the teguments, would have thought to be a piece of cartilage, as large as a middle fized plumb, which has greatly decreafed, and become Softer, for fome years pa ft 3 fo that, at pre¬ fect, it is much lefs perceptible than for¬ merly.
Some
PHYSICAL and LITERARY.
455
Some weeks after the accident, I began to pour cold water on my leg and foot, caufing them to be well rubbed immediately after ; but the water, inftead of flrengthening the member, as I expedted it would have done, made it cold and weak ; for which reafon I foon forebore the ufe of it, and caufed the leg to be rubbed twice a-day ftrongly, with unguent um altheae , or fome fuch greefy fluff, to protect the fkin from excoriation by the fridtion. This manoeuvre was continued till I began to employ the limb freely.
Being obliged to go abroad after fix weeks, I put on a pair of fhoes with heels about two inches high, and applied the machine, which I am juft now to defcribe, in the day time, inftead of the former bandage; which, how¬ ever, was always put on at night, for a month more.
The new machine, fig . 6. was a piece of fteel, the middle ftalk of which A, is nar¬ row but ftrong : the ends BB, are then broad and concave, adapted to the convexity of the foot and forepart of the leg. Three ftapples CCC, ftand up from the forepart of the fteel, one being in the middle of each of the broad ends, and the third in the middle of the
ftalk*
45 6 ESSAYS and OBSERVATIONS
ftalk. All the Reel except the ftapples was covered with chammoy leather, and the con¬ cavities of BB, wrere well buffed, as the foft- er rupture bands commonly are.
After 1 had put on my fhoes and {lock¬ ings, one end of this machine was put on the broad of my foot, nearer the toes than the buckle of the fhoe ; and the other end was placed on the fore part of the leg : then one ribband, or a thong of leather, fig . 7, 8, was put round the foot, and another round the leg, to pafs thro' the twTo ftapples near the ends of the machine, and there fecured with ftraps or buckles, but without being drawn tight,— A third ftrap or ribband, fig. 9. having its middle D, applied in the hollow of the foot, immediately before the heel had its ends pafied on each fide of the foot, thro5 a firms or noofe EE, of a fourth thong of leather F, that came round the quarter-heel of the fhoe, to be afterwards put thro’ the middle dapple \ where, after thefe ends GG were drawn as tight as was thought conveni¬ ent for extending the foot, they were fecured ’ with the buckle, or with knots. See the ap- . plication in fig . 10.— I wore this machine al¬ ways in the day time, for five months : tho*.
as
sBggBi -fl5fe> im^t IjjL: |
|
/
w
I
FHYSICAL and LITERARY. 457
as it is inconvenient, by fhuffiing out of its place fometimes ; I think a thong of leather fowed at one end to the upper middle part of the quarter-heel of the fhoe, and fattened at the other end to a garter, put above the calf of the leg, would ferve inftead of it
without inconvenience.' - - -All that time
I never walked the ftreets, but was carried in a chair.- — -In going down ftairs, I al¬ ways put the difeafed leg firft down at each ftep 5 and, in coming up, I put the found leg foremoft, by which I ffiunned the ftretch- ing and retearing of the new louldered Anew, which, I knew from what others had fuffered, might have made the cafe worfe than it was at firft. — The habit I had got of walking after this manner in ftairs, became fo much a fe- cond nature, that I had afterwards difficulty to learn to go up and down in the ordinary way, with the feet alternately.
I continued the high-heeled fhoes for two years, caufing my boots to be made after the fame fafhion, when I began to ride ; but have gradually fince retrenched their height, till now I wear them of the common make0
During all that time too, I mounted my horfe at the right fide inftead of the left one,
M m m th-M
458 ESSAYS and OBSERVATIONS
that I might fhun the rearing my whole weight, by the force of the weakened gaflro- cnemei mufcles ; and to prevent the accident of ftraining them, in cafe the horfe Rumbled, I kept the left foot deep in the ftirrup. In walking up hill, I put that foot a-crofs; and, in fhort, guarded againft every other ftretch- ing ftep or motion.
On comparing the lize of the calfs of the two legs at prefent, the left one is a little fmaller than the right one, efpecially in the morning ; but fo little, that it is fcarce per¬ ceptible : thro’ the day, the difference be¬ comes lefs. — -The tendo Achillis that was bro¬ ken, is, as mo ft other tendons cured after breaking, confiderably thicker and harder than the other ; but one muft be told it is fo7 before he can dilcover it by the eye.
A R To
PHYSICAL and LITERARY. 459
Art. XXIL
An Account of the Dijeafe called Mill-Reek by the Miners at Leadhills, in a Letter Jrom Mr. James Wilson, Surgeon ^Durrif- deer, to Alexander Monro, P. A.
IN obedience to your defire, I fend what I haveobferved concerning the difeafe, which the people at Leadhills call the mill-reek , and which all the inhabitants there are fubjedt to ; but it moftly feizes, and violently affedts the men whofe daily bufinefs it is to melt down the lead. The melting-houfes, where this is done, are called mills ; becaufe the bellows there are worked by water-mills.
In the {lighter fliage of this difeafe, an un- eafinefs and weight is found about the {lo¬ rn ach, efpecially near the cartilago enfij or mis ; and fometimes it appears like a colic in the inteftines. The fpittle of the fick is fweet, and fomething of a blueifh colour, refem- bling what one obferves when he chews lead, v— The pulfe is a little low; the {kin is all over
cold
460 ESSAYS and OBSERVATIONS
cold ; and a clammy fweat frequently breaks out, — The legs become feeble with a prick¬ ling numnefs ; and there is a debility and lazinefs in all the body.- — The appetite goes away, and they don’t digeffc what food they take,— Sometimes a diarrhea makes a cure ; but, if it continues too long, it is very hurt¬ ful, — -In this fiadium the fick are yet able to p* o about and to work.
o
Jbux, if thefe fymptoms continue long, and fpirituous liquors are drunk with an em¬ pty ftomach, or after working lead ; the di- feafe comes to its fecond ftage : in which, to the former complaints, are added a fixed pain in the ftomach and guts, efpeciaily in the lower part of the abdomen, extending itfelf from the one os ilium to the other.— The patients become very coftive, with the fenfe of fomewhat gnawing their inteftines ; and the pulfe turns quick with heat on the fkin.— Giddinefs, with vehement pain, feizes the head 5 which is fucceeded by an infenfi- bility and delirium , like madnefs of the worft kind 5 in fo much that they tear their own fiefh, and bite their hands $ the extremities tremble, and are CQnyulfed ; at laft they fall
low.
PHYSICAL and LITERARY. 461
low, the pulfe intermits at every 3d or 4th ftroak, and they die in a coma or apoplexy.
The reek or fmoak rifing from the melting lead, is believed to be the caufe of this di- feafe ; becaufe the melters, who are mod ex pc fed to the fmoak which comes out often full in their faces, are mod fubjedt to this difeafe, the mill-reek.— The people here fay they have feen birds, in a cairn moift day, attempting to fly thro' the fmoak of fuch a chimney, fall down dead.— Cattle, which pafture near to mills, are often killed $ and therefore fhepherds take great care to keep their fheep at a diftance ; which, if not by the fmoak, muft be hurt by the grafs, which J often fee made blue by the fmoak falling on it. And other animals differ from the water impregnated with the fumes, or with the lead wafhed in it.
The fymptoms in them are very like to what men differ. Dogs, in the laft ffage, lie either dull and ftupid, or bite and fnatch ate- very creature that comes near them ; nay, they will gnaw and tear up the ground on which they lie, after- they cannot raife thenifelves pn their lees,
Tm
46 2 ESSAYS AND OBSERVATIONS
The people at Leadhills are fo averfe to o- pening of dead bodies, that I could never prevail upon them to allow me to open any who died of this difeafe. But, in a dog who had it, I found jludge * lying on the in¬ ner coat of the ftomach and inteftines j and, in feveral parts, it was turned to a cruft.— The guts were much in flammed in fome places, and in others a mortification was begun with holes thro* them. —His faeces were very hard ; and, where they were of little quan¬ tity, the coats of the guts were thick, and the paffage thro* them lefs.
If proper medicines are given in the firft ftage of this difeafe, the patient generally recovers.— If it goes on till giddinefs begins, the fuccefs is doubtful ; and when the cure is delayed to be attempted a little longer, the difeafe almoft conftantiy proves mortal.
If the work-people at Leadhills would ufe the following precautions, they might fave themfeives from this difeafe, at lea ft would have it very mild.
I. No man ought to go to work falling ; and he ought to take oily or fat food : the Englijh
mill-
* The fine particles of lead which fubfide flowly in water* in which lead has been walhed.
PHYSICAL and LITERARY. 463
mill-men on this account hold much better out than our countrymen. A glafs of fweet oil pure, or mixed with a little aqua vitae ^ would be a good morning draught.
II. Physic fhould be taken Spring and Harveft, and whenever any effedts of the reek are felt.
III. Ardent fpirits ought to be drunk ve¬ ry fparingly ; and ought never to be taken in time of work at the mill, or immediately af¬ ter it. They increafe and fix the bad effects of the leady fmoak.
IV. No mill-man, when heated by work, ought to go into cold air ; but to put on his cloaths immediately, and return to his lod¬ ging, to change his working cloaths for o- thers, and cool gradually: by which he would prevent catching cold. In this article they are very carelefs.
V. Immediately after coming from work, the aliment fhould be moftly liquid^ as broths.
VI. Low and poor diet makes them more liable to be affected, and lefs able to under¬ go a cure : thefe workmen ought to feed on good meat.
VII,
464 ESSAYS and OBSERVATIONS
VIL When their bufinefs can allow, they fhouid go out of the reach of the reek, • to breathe an untainted air, and to take victuals free from lead. But I mu ft caution the la¬ bourers at Leadhills not to take long journeys : they are more hurt by travelling one day than by working two.
The cure of this difeafe depends principal¬ ly on cleaning the primce vice: and therefore, after blooding fuch patients, if they are ple¬ thoric, I give them a vomit of emetic wine or tartar 3 which muft be a dole double to what would vomit another perfon \ otherways it would have no effedt, efpecially when the difeafe is violent or has continued long. My father, who has had long practice with fuch patients under the mill-reek, has always fine¬ ly powdered vitrum antimonii ready > of which he gives half a drachm for a dore 5 and du¬ ring its operation, warm water is to be drunk plentifully. If the vomit operates well, and purges brifkly too, the patient is in a fair way of recovering ; which a fecond, but a milder dofe of ipecacuanna with feme tartar emetic mixed, often makes compleat: but, if the emetic neither vomits nor purges, the patient is generally Worfe for it> and a ftronger dofe
fli 0 uld
PHYSICAL and LITERARY. 4 65
fhould be given foon.— If it vomits but does not purge; a cathartic of the antimonial kind, or of jallap and mercury, in greater than or¬ dinary quantities, ought to be given : and during the time of purging by the emetic or4 cathartic medicine, the patient ought to drink Warm broth plentifully. —The vomits and purgatives ought to be repeated at proper in¬ tervals, till the uneahnefs in the domach and guts, from the difeafe, is gone.— If thefe me¬ dicines over-do, an opiate may be given at night ; but this is to be adminiftred fparing- ly, lead it bring or increafe codivenefs, which is the word thing can befal the patient. At the fame time, emollient, anodyne, and lax¬ ative clyflers, are frequently to be injected for emptying the guts, if the purgatives do not their duty.
When blood or matter are paffed with the faeces , the emetics and purgatives are to be abdained from, till, by healing, baifamic, but laxative clyfters, and mild food, this ap¬ pearance ceafes.
When the belly is much fwelled, emol¬ lient fomentations fhould be often applied to it 5 but, if the madnefs is begun, little elfe can be done, than to endeavour to keep the
N n n patent
466 ESSAYS and OBSERVATIONS
patient quiet during the little time he has to live.
Sometimes it happens, that, after the com¬ plaints of ftomach and guts are gone, a prick¬ ling pain and feeblenefs remain in the legs*, much like to a rheumatifm ; for which, fri¬ ction, with a coarfe cloath or flefh-brufh, is neceflary. If that fails, ung. nervinum with oh terebinth . mixed, is to be rubbed on every night, before the fires after which, the mem¬ ber is to be wrapped in flannel.— If thefe pains are violent, or the feeblenefs relembles palfy; bidders ought to be applied to the fkin under which the large nerves are fituated, and the medicines proper in a palfy are to be given.
Some are fo wafted before the cure is corn- pleated, that they remain afterwards emacia¬ ted, weak, and as if they were hedfic, with a giddinefs in their head : and fometimes they chat to no purpofe, or feem hypochondriac. In this condition, the patient fhould go to the country, to ride a-horfe-back fome miles every day ; and, at the fame time, fhould take bitters with bark and fteel. If the giddinefs continues, I have given with fuccefs, pilul. de myrrh . with a fmall proportion of camphor * 'End of the firji Volume »
INDEX.
A.
A&ion and re-a&ion in matter, pag. 33. and 134.
Adive being (what) 86.
Aether (Newtonian) not the caufe of gravity, 49.
Alutn, contained in the Hartfell $paw\ 351, and 357. &c.
Al st on (Dr. Charles) his differtation on the fexes of plants, 205.
Anajiomofis (none betwixt the uterine and fecundary veffels 419.
Attraction and repulfion, not owing to any aCtive power in, bodies, 1 2 1 .
Aurora Borealis , the matter of it, the fame with lightening and electricity, 195.
B.
Baxter (Mr.) an error of his, with regard to the Inertia of matter, n8.
Bodies, indifferent to reff or motion, 108.
C.
Caufes, the abfurdity of ah infinite feries of them, 130^
Circle, fome properties of it demonllrated, 147.
Conic fedions (fome properties of them) 1 70.
Confumption of the lungs cured by Hartfell Spaw9 364.
D.
Deity, his continued concurrence, no argument againll the perfection of the world, 133.
Penniston (Mr. George) his account of a cure perform¬ ed by an alterative mercurial medicine, 390.
E.
INDEX.
E.
Ecliptic, the caufe of the variation of its obliquity, 173, Fle&ricity, obfervations on it, 189,
Epidydimis , compofed of a fingle tube, 401.
F.
Farina of plants, conje&ures concerning its ufe, 279. Foetus, its fituation in the womb, 422.
Force of a body in motion, proportionable to its velocity, 64.
Forces of bodies in motion, 90. &c.
Fra&ure of the 'Tendo Acbillis , its cure, 450.
Gs
Gravity (of) 42.
. - a power inherent in matter, 52.
— - -the refemblance betwixt it and magnetifm, 11 1.
~ - —owing to the continued and regular operation of an
intelligent caufe upon matter, 1 15.
- .—/Theorems concerning the laws thereof towards Jufim
ter , 188.
Gray (James) of the meafures of Scotland, compared with
thofe of England, 20.0 .
Grew (Dr. Nehemiah) the fir# who taught that female plants were impregnated by the Jarina of the male, 213.
H.
Fd art fell Spanjj, Experiments and obfervations upon it, 341.
~ — - ftrongeft in a wet feafon, and weakeif in a
dry one, 354.
- - - — — - what difeafes cured by it, 363, and 364.
- Directions how to ufe it, 365.
Heart, its motion flower in fleep, and why, 437.
Home (the Honourable Henry) on the laws of motion, 1. Horseburgh (Dr. William) his experiments and obferva° dons on the Hcirtfell Spa<w, 341.
I
1 N D E
X
i.
Immateriality, the meaning of it, 124.
Impulfe ^an analyfis of it) 30.
Inertia of bodies, remarks on it, 30.
Inertia of a body at reft, 75. &c.
Inertia of a body in motion, 79. &c.
Jupiter, changes obferved on his furface, 1 84,
L.
Lead, a remarkable difeafe produced by it, 459,
Lime-water, of its various ftrength, 372.
Linnaeus (Carolus) his arguments in favour of the fexes of plants, 224. refuted, 232. &e.
Lining (Dr. John) on the anthelmintic virtues of the root of the Indian-Pink , 386.
M.
MacLaurin (Colin) on the variation of the obliquity of the ecliptic, 173.
— - - - ——on the fudden changes in the furface
of Jupiter , 184.
MacFait (Dr. EBENEZER)his obfervations on thunder anc| electricity, 189.
- - -his account of fome phenomena
in foggy weather, 197.
Magnetifm, owing probably to fome effluvia, 1 1 1.
Matter, whether endued with a power of motion, 6„
• - — incapable of thinking, 122.
Maupertuis, a notion of his refuted, 129.
Meafures of Scotland and England compared, 201.
Menjlruum , (an univerfal one) by no means probable, 286.
Mill-reek , a difeafe common among thole who work in lead- mines, its hiftory and cure, 459.
Monro (Alexander) his defcription of the feminal veftels, 396.
- - —his additional obfervations on gravid
Uteri , 426.
Monro
1
IN D E X.
Monro (Alexander, P. A.) his remarks on the intercofhl mufdes, 447.
- - - - — — - — —on the cure of a fradlured Tendo A-
chillis, 450.
Monro (Dr. Donald) his remarks on gravid uteri, 403. Morland (Samuel) his opinion concerning the impregna* tion of plants, 216.
Motion, the laws of it, 1.
- - -feveral definitions of it, 3, and 4.
- a continued adtion, 18.
• — - the continuation of it, owing to a power in matter,
22.
— — the communication of it, 26. the force of bodies in it, 61.
— remarks on the laws of it, 1 , and 70-
- - - not adtion, but the effedt of adtion, 85*
■ . the communication of it, 83, 88.
- - a body in it will continue fo for ever, 106*
"——of its continuation, 108.
— ■ — a power of beginning it, infers a power of thinking, 1 14.
Mufdes (intercoflals) remarks on them, 447.
N.
Newton (Sir Isaac) does not afcribe adtivity to matter* 13°,
P.
PajPpi (Alexandrini) fropofitio generation fatta, 141.
Pink ( Indian J its root a good remedy againfi: worms, 386. Plants, of their fexes, 205.
— — -conjedtures about the ufe of their jarina or dull, 279. Placenta , not always fixed to one particular part of the womb, 421*
Plummer (Dr Andrew) his remarks on chemical folutions, and precipitations, 284.
- - - experiments on neutral laics,
POLENJ,
I N D E X*
Poleni, his experiment of balls falling upon foftclay, 90. Polypus, the phenomena of it, confident with the indivift* bility and unity of a thinking fubflance, 125. Precipitations (chemical) remarks on them, 303.
Quick-fllver, injected into the epidydimis , 396.
R.
Rainbow, formed round one’s fhadow in the mill, 19$, Re-adion, equal to adion, 104.
Refinance in matter, the effed of an adive power, 21.
- of a fubflance perfectly inadive, 72.
Refpiration, flower in time of fleep, and why, 444.
S.
Salts (neutral) experiments on them, 313.
Sinufes of the womb, a defcription of them, 430.
Solutions (chemical) remarks on them, 2S4, and 329. Soap-leys, their component parts, 383.
Sleep, the difference it makes on refpiration and the motion of the heart, 436.
Streamers, of the fame materials with lightening, 193,, Stewart (Dr. John) his remarks on the laws of motion, 70 .
Stewart (Matthew) Pat pi Alexandria propojjtio genera- lior fadla, 1 4 1 .
Subfiances, material and immaterial, what, ua
T.
Thinking, has no relation to matter, 123.
Theophrastus, his account of the fexes of plants, 20$, tfc* Thunder, obfervations on it, 189.
U.
Uteri (gravid) remarks on them, 403, and 426,
Uterus , its figure when impregnated, 414,
Uteri (gravid) their thicknefs, 417.
V.
X.
I N D R
V.
Vis infita, or vis inertia, l6.
Vis infita and nris inertia or refijientia , different powers Ixi
matter, 23*
Vitriolum Mart is nativum, found in the Hartfell Spa<zv, 355. Venereal lues, cured by large dofes of an alterative mercu¬ rial medicine, 390.
, ’ ; f
V/
Whytt (Dr. Robert) on the various ftrength of different lime-waters, 372.
*= _ — — -his account of the difference between refpiration and
the motion of the heart, in deeping and waking perfons* 436.
Wti/SON (Mr. James) his account of the Mill-reek , 459.
ERRATA-
Page f 7 7. line 17. after thing , add that. p. 178. 1. 16. af. that add which, p. 184. 1. 4. for in read on. p. 311. 1. 8* for falls x.fall. p. 410. 1. ■penult, f. IF. r. V . p. 413. 1. 2 1. f. ‘14. r. 4. p. 424. 1. 10. f. IF. and F. r. F. and VI. p. 455. 1. 22. f. then r. thin .
To the BOOKBINDER.
*
Place Tab. I. fronting Pag. 172.
— - — — II. - — 184.
- - — —III. — — . 400.
- - -IV. V. VI. VII.—— 414.
•— - -VIII. - - 4$.
>