bptad Fae ene ie . % ha rte ary Eo BS ERV'ATIONS, PHYSICAL AND LITERARY. | hie i Binder ea Oo Na Bete 7 Me Reon take a a greene As Read before the/Philofophical $ © SOCIETY in if vale : es r fc and publithed by them. ; (ie cat sf ty Se oF VOLUME L SECOND EDITION, 1 £D RB UR C He ‘Printed for JOHN BALFOUR. M, DCC, LXXI. a ie | i A hae MMR aio. eer a lings 7 Frer the medical fociety of Edinburgh had publifhed 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 carry their difquifitions into other parts of nature, be- fides fuch as more immediately relate to the branches of medicine. All the {ciences are remarked to have.a clofe connexion together; but none more than thofe of me- dicine and natural philofophy: And the fociety foon obferved, that, fhould it turn its inquiries into more ge- neral knowledge, it could reap the advantage of prefer- _ ving all its old members, and needed but open its door to gentlemen of other profeilions, who might entich it with their obfervations and difcoveries. Soon after the fociety had received a new form, feveral misfortunes happened, which retarded its progrefs, and have hitherto prevented it from communicating any thing to the public. The rebellion broke out in this country 5 and both fcattered the members for fome time, and en- _ gaged their attention to fubjetts lefs agreeable, and more interefting, than general difquifitions into nature. No fooner were public affairs compofed, than we met with jan iv PR E F A C'E. an irreparable lofs in the. death of Mr Mactaurin, one of our fecretaries. ‘The great talents of that Gen- tleman are generally known and highly efteemed in the literary world ; but the fociety have, alfo, particular rea- fon to regrete in him the lofs of thofe qualities which form an excellent academician. Indefatigable himfelf, 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 difcoveries, fufficient to have formed a vo- lume, had been communicated to him; but, being mingled with his other papers, have been diffipated by various accidents 3 and the fociety could recover but few ‘of them. Tue object 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 phi- lofophy, and of literature, by communicating to the pu- blic fuch differtations as fhall be tranfmitted to them, either by their own members or by others. Tis allow- ed, that thefe two branches of learning, efpectally the former, are more promoted by the obfervation of faéts than by the moft ingenious reafonings and difputations. - To a diligent, and even fometimes to a carelefs inqui- rer, many valuable experiments, no doubt, occur; and thefe would enrich our collections, though, without this method of conveyance, they would be intirely loft to Seale Base lial PREF A C:E. Vv the public. The united judgments too of men correc& and confirm each other by communication, their fre» -quent intercourfe excites emulation, and frorn the com: -parifon of different phenomena, remarkéd , by different perfons, there often refult general truths, of which, from one of thefe phenomena, no man of the greateftfagacity could entertain any fufpicion. ‘Though the colleCtion of experiments feems continually, by means of the learn- ed focieties, and the labours of individuals, to, be’ aug- menting, 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, through every age. ‘There arife, from time to time, bold and happy geniufes, who introduce method and fim- plicity into particular branches of feience ; and, reducing the {cattered experiments to more general theorems, a- bridge the fcience of ‘nature. Hints of this kind, we hope; may be able to'pafs through our hands; and, at worft, our collections ‘will be a fpecies of magazine, in . which faéts and obfervations, the fole means of true induction,, will be depohi ited for the purpofes of philo- fophy. Tue fciences of theology, morals, and politics, the fociety are refolved intirely to exclude from their plan. However difficult the inferences in thefe fciences, the faéts on which they are founded are extremely obvious; and vi PREFACE. and we could not hope, by our colle€tions, to be, ih this refpect, of any fervice to the public. The great de- licacy of the fubje&, the imperfeCtions of human un- derftanding, the various attachments and inclinations of mankind, will for ever propagate difputes with regatd to thefe parts of erudition. And it is the peculiar happi- nefs of geometry and phyfics, that, as they intereft lefs the paflions of men, they admit of more calm difquifition and inquiry. Ir is not that the fociety expeé&t ot propofe, that what they communicate will be intirely above doubt or difpu- tation. The papers, indeed, which they print, were all read before them ; and they gave their confent to the in- ferting them in their colle€tions: But they pretend not to warrant the juftnefs of every teafoning, nor the ac- _ curacy of every obfervation. The author alone of each paper is anfwerable for the contents of it: And the fo- ciety are as willing to infert what may be communicated in oppofition to the fentiments of any of its members, as in confirmation of them. Tue fociety are fenfible that it belongs alone to the public to decide concerning the value of any invention ; and all the merit to which they pretend, is- that of ex- citing the induftry ofthe learned, and of conveying their productions to the notice of the world. They affume not fuch authority as to ftamp their approbation on any performanee, even thofe which they communicates, much lefs : PUR EeF ACE, vii lefs thofe which have barely been read before them. If ever their teftmony has been cited by any author in fa- your of his books, reafonings, or machines, they hereby declare, that this liberty has been ufed entirely without their confent or knowledge, and proceeded alone from the _ fond opinion which the writer had entertained of his own performance. Wuoever will favour the fociety my any difcourfe which it comprehends in its plan, may fend their pa» _ pers to their fecretary Dr ALExanpER Monro Pros feflor of Phyfic and of Anatomy at Edinburgh, Edinburgh, 1 773 oe » il tbc i — ty i= ee. MISES task Fe } na An rw Re his : ee SIA Ra a9 diy) the eens ben seul elaine pe shia oot LontounseE aml youth? works ior oth Souidoeni 0, agriaens ednel. tho AOV sheaf ytivints 2 ce el rpvadil, sil, sic “Sut mneit 4cobs bohsaqrp linn rybolworbin: ‘ad ia distros bth air ora Moddiun & ree oe : ae “ghusadib yite slsiae Yisioc* ths wordt Hine "aie “He tiods bast yeu etait; evi ebasdaqinay Pe Astdve. = ae otnoM azatax safe 1 yietviot Tedd ot eitg bi “a ged 1 x ri stidl, do. bns oft “i Ye rh ¢ by, 5 de aut sorter ter nlc cate os 203 VI. Obfervations on Thunidér and BleEeicity, by EBENEZER M‘Farr, M.D. > 20g VII. Some Phenomeni obfervable in fozgy weather; by the fam,, - - 219 Vou. J, _b : vill, ay x CONTENT SS ART. Pag. VIII. Of the Meafures of Scotland, compared with thofe of England, by James Gray. - 223 IX. A Differtation on the Sexes of plants; by Curves Atstron, M. D. King’s Botanift in Scotland, Fellow of the Royal College of . Phyficians, and Profeffor of Medicine and Bo- tany in the univerfity of Edinburgh. (228 X. Remarks on Chemical Solutions and prepara- tions, by ANDKEW Prummer, M. D. Fel- low of the Royal College of Phyficians, and Profeffor of Medicine and Chemiftry in the Univerfity of Edinburgh. - ° - 319 XI. Experiments on neutral Salts, compounded of different acid Liquors, and alcaline Salts, fix- ed and volatile ; by the fame. mo cm XII. Experiments and Obfervations upon the Hart- fell Spaw, made at Moffat 1750; and an ac- count of its Medicinal Virtues, fo far as they have hitherto been difcovered from experi- ence ; by W1LL14M HorseBuURGH,M.D. 384 XII. Of the various ftrength of different lime-wa-, ters, by RopERT WuytT,M. D. F. R.S, Fellow of the Royal College of Phyficians, and Profeffor of Medicine in the Univerfity of E- dinburgh. ° - - 420 XIV. Of the anthelmintic virtues of the root of the Indian Pink, being part of a Letter from Dr Joun a CONTENTS. xi - ART. Pag. Joun Lininc, Phyfician at Charleftown in South Carolina, to Dk Roper T WurYTT; Pro- feffor of Medicine in the Univerfity of Edin- burgh. - - 436 er XV. The hiftory of a cure performed by large dofes of an alterative mercurial Medicine, com- municated to Dk PLUMMER 3 by Mr GEoRGE DENNISTOUN, Surgeon in Falkirk. - 440 IT Re XVI. A defcription of the feminal veffels, by ALEX- ANDER Monro, Student of Medicine in the Univerfity of Edinburgh. - 447 XVII. The diffe&tion of a Woman with child, and remarks on gravid uteri; by Dr DonaLp Monro, Phyfician at London, » 455 XVIII. Additional obfervations on gravid uteri, by ALEXANDER Monro, Student of Medi- cine in the Univerfity ofEdinburgh. - 481 XIX. Of the difference between ‘Refpiration and ‘| the motion of the Heart, in fleeping and wa- _~—-——si«&ing perfons; by Ropert WuyttT, M. D. . &e - . 492 XX. Remarks on the Intercoftal Mufcles ; by A- LEXANDER Monro, F. R. S. Profefflor of A- __ natomy.in the Univerfity of Edinburgh. - go4 XX. si CONTENTS. A RT. 2 Pag. XXI. THe cure of a fra€ured Tendo ‘Achillis 5, by the fame. *’ me Py “Eze JXxI. we Seeount ‘of. the difeate called Mill reek by the miners at Leadhills, in a Letter from Mr‘ faa iris Witsdn, Surgeon at Durrifdeery ‘to Abexaxpen Mono, P.' Ae a 517 a0 14 y ape c wt LaA yd eelviiow [avin od: io BiG SoA LIZ E S 5 AnrY-S A N*D ae sF Nan 4 OBSERVATIONS . PHYSIGAL ano LITERARY. SES Sena . a ARTICLE La of the Laws of Motion ; by the Fini ee Henry Home, E/quire, one of the Sena- tors of the College of Jupice, | Oruinc has retarded tHe? rials of philofophy morethan an unlucky yi “propenfity that makes us grafp at __ principles without due regard to fats and experiments. Tho’ fond of knowledge, we are willing to purchafeit at the eafieft rate ; _ and general principles delight us, becaufe é. _ they fhorten the road to knowledge. This bent of the mind is. productive: of mani- folderrors. Prepoffefled once by a fayou-- rite principle, we areno longer open to.con- © viction. Every phaenomenon mutt be ac- ~ commodated to that. principle, and. ‘eve- Bae VOL, . Te. A ry _ * 2 ESSAYS anp OBSERVATIONS ry oppofite fact, however obftinate, goes for nothing. And thus we endeavour to mould nature to our with, inftead of defiring to know nature in her genuine | appearance, We fee, then, that in fcience, not lefs than in action, appetite and inclination prevail. Even in natural philofophy, theory was introduced before experi- ment, and every philofopher urged his wn notions, without regard to truth or reality. This produced a mafs of undi- gefted and contradictory theory; having no foundation but fancy and chimera. After fo much wandering, philofophers became more cautious ; they began with . doubting of every thing, and then with fearching after truth in the more pain- ful road of induction. By this means, a greater number of important truths have been brought to light within acentury or two, than before that time from the be- ginning of the world. BuT,tho’ our only fure guides to truth are facts and experiments, it is however expedient § PHYSICAL anp LITERARY. 3 expedient to keep the end in view. Facts and experiments are ufelefs lumber, if we are not to reafon about them, nor draw any confequences from them. In all our operations, we may have an eye to theory: Nay we mutt have it; for fuch is the con- - ftitution of our mind. Theory becomes only a fource oferror, when we indulge in it too much, or attach ourfelves to it be- yond what facts and experiments can ju- ftify. In fhort, theory is vain without ex- periments, and experiments are beft un- derftood by applying them to theory. _Naturatv philofophy, it muft be ac- knowledged, is far from being ripe for firm and lafting theory. But we have facts and _ experiments in great abundance, to bea _ foundation for theoretical fketches ; which may be fafely indulged, provided they be done in fo flight a manner, as to leave the mind free from any wrong bias. Tho’ we have not materials for a regular build- ing, there is nothing to hinder us to ven- ture upon a model. AumosT every author who treats of the laws of motion, has thought it incumbent upon 4 ESSAYS ann OBSERVATIONS. upon him to fet out with a definition of motion. And, in a thing {o fimple, it may appear ftrange to find fuch a variety of definitions: Whence one thing may be ga- thered, that none of thofe definitions have been approved of by fucceeding authors. Epicurus defines motion to be “ a paflage- from one place to another:” And he might as well have defined it to be motion from one place to another; becaufe paflage : in this fentence means nothing different from motion. Sturmeus defines motion to be “/uccefiva rer motae in diverfis locis «6 exifientia;” which is juftly blamed by Leibnitz as defcribing the effect of motion, rather than the formal nature of it. And “ motus eft “ continua loci mutatio,’ is not more fatis- factory. But, of all the definitions that ever were attempted, Ariftotle’s definition of motion is the moft unintelligible, “ Ac- “© tus entis in potentia quatenus in potentia ;” which Locke condemns as abfolute jargon; and which, he fays, would puzzle any ra- tional man, to whom it was not already known siecle its famous sc to guefs what yet Leibnitz’s own definition, ee PHYSICAL ann LITERARY. ¢ ewhat word it could ever be fuppofed to be the explication of *, | BuT it’isno wonder thefe authors have . not given {atisfaétion to each other, nor to their readers, upon this fubject; for they - have attempted what is utterly impoflible, 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 o= ther fimple feeling. It is to be regreted, that natural philofophers and mathemati- cians are not always well fkilled in logics, and of this truth we fhall have but too often occafion to give inftances, * SCARCE any author that I know has thought of giving a definition of reft; yet it is not a more fimple object than motion. I can guefs at the reafon, that reft is the more familiar object ; a greater number of things appearing to be in a quiefcent 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 - * Locke concerning edwoan Lica it ta B. 3. ch. 4, o§8. 6 ESSAYS anp OBSERVATIONS _ thing to others: But both are equally inca- pable of a definition. They are fimple ob- jects of fight, and perhaps of touch. De- prive us of thefe two fenfes, and we could never have the leaft notion either of refl or motion. WHEN a being moves itfelf or moves, we conceive the being as acting; and, in this view, motion is a fpecies of action. Burt, when a body is moved by being acted up- on, we conceive the motion of the body as an effeét produced by a proper caufe. In this cafe the body does not act, but is aéted upon. This, though an evident di- ftinGtion, does not exclude felf-motion from being alfo confidered as an effect in a certain light, viz. an effet produced by a being upon itfelf, Every thing which moves, and is not barely moved or acted upon, muft be en- dued with a power of motion. For this power is involved in the very conception of felf-motion. And the term power is. equally applicable to animate and inani- mate beings, fuppofing them to be equally felf-movers. WHETHER ~ PHYSICAL anp LITERARY. 7 WHETHER matter in any cafe be cadul ed with a power of motion, is a celebrated queftion, which is generally refolved in the negative: And, as this queftion cannot be overlooked in the prefent fpeculation, I fhal]l endeavour to examine it with all the accuracy podflible. MATTER is generally reprefented as ale together unactive and inert; and indeed, in a fuperficial view, the fact 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 acted upon 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 voluntary motion; and yet, that it is endued with a power of motion in certain circumftances, appears to me an extreme clear point. Dropping a ftone from a high tower, it falls. to the ground without any external impuife. Here is 8 ESSAYS anbd OBSERVATIONS is. an effect which every one, who has not ftudied philofophy, will attribute tora pow- er in the ftone itfelf One would not hefi- ’ tate to draw this. conclufion, fhould the {tone move upwards}; and yet, fetting a- fide habit and cuftom, it muft be evident, that a ftone can as little move downwards as upwards without a wis 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 effect produced to a power which he pof- feffes to move his limbs. Why then do ‘philofophers deny to the ftone, in the act of falling, the power of beginning motion, a power which they fo readily afcribe to the man? If ic be objected, that man is a being endued with a power of moving himfelf and of moving other things, the plain anfwer is, that we are indebted for the knowledge of thefe facts to experience; and we have the fame experience for a voucher, that a ftone fet free in the air will move itfelf. And if it be farther urged, that man is a thinking being, the anfwer will readily occur, that a power of be- ginning PHYSICALanp LITERARY. 9 ginning vifible motion is no more con- nected with a power of thinking, than it is with any other property of matter or fpirit. Nay, Mr Locke holds, that mat- ter may be endued with a power of think- ing; and, fuppofing this power fuperad- ded to the other properties of matter, it cannot be maintained, that matter would be rendered thereby more or lefs capa ble of beginning or continuing vifible motion, rah Bor this is iiot the only inftance in which we difcover an agency or active power in matter. A billiard ball driven againft an obftacle, rebounds with 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-be- twixt the oppofite directions of the mo- tion. The ball rebounds, and the bow __ teftores itfelf to its former fhape, with- out any external force, by an inherent power which is known ‘by the name of 2 , élafticity. But we need not dwell upon padre inftances. Chemiftry difco- ‘vers in matter various powers of the moft Vou. I, . B active Jo = ESSAYS any OBSERVATIONS active kind ; and every man who is con< verfant with the operations of chemiftry, muft have a {trong impreffion that mat- ter is extremely active, For the fake of illuftration, let us fup- pofe a fubftance or thing having the fol. lowing properties, that it makes no re- fiftance to bodies impinging upon it; that, when carried along in a man’s hand, even with the moft violent motion, it does not increafe the momentum of the hand, and that it ftops fhort the inftant the hand ceafes to move. This would cer- tainly be the moft inert of all conceivable things. And if fo, matter cannot be abfolutely inert or paffive, when. its pro- perties differ fo widely from thefe deferi- bed. In many circumftances matter bes gins motion, and acts often with great violence. It has a conftant endeavour, when once fet in motion, to preferve it- felf in the fame degree of motion, and, when at reft, is not put in motion with- out refiftance, Bur it is maintained by the bulk of our philofophers, that matter is altoge- ther PHYSICAL ano LITERARY, 11 _ ther incapable of active powers ; that activity is confined to immaterial fub- ftances, and that inertnefs is implied in the very conception of matter. This makes them afcribe to fome invifible a- gency, all that activity which we difcover in matter. In every one of the above in- ftances, matter, they fay, does not act, but is acted upon by the Deity, who in- terpofes by general laws to preferve the uniformity of nature. Thus, when a ftone falls, it is not the ftone which a@s, but the Deity. It is the continual action of ‘the Deity which keeps the planets in elliptical orbits: And; when a plague in- fefts the world, it is the Deity who {preads the infection, and directs inert matter to ravage and deftroy.. Arfenic is not of itfelf a poifon; it is the imme- diate finger of God which makes it fo, WITH regard to this whimfical doc- _ trine, which declares war againtt our fen- fes, it may be obferved, that natural phi- lofopy is not much affected by it, of _ whatever errors it may be produétive in the more abftraét f{ciences. For it is ad- mitted, 12 ESSAYS anp OBSERVATIONS mitted, that the Deity, in ating upon matter, fubjects himfelf to the fame ftrict and invariable laws which govern mat- ter, fuppofing it to have a power of mo- tion. Therefore, the hiftory of nature will be the fame, upon either fuppofition. At the fame time, as this hypothefis not only contradicts common fenfe, but, in place of a beautiful chain of caufes and effects, difcoverable in the operations of matter, prefents a deformed and crude fcene, which detracts from the wifdom of the Deity ; I think it of confequence to ; beftow fome thoughts upon it: And is am hopeful to make it evident, that this hypothefis has no fupport from reefon more than from experience. 5 a - To put anend to a good deal of loofe reafoning upon this fubject, it will be ne- cellary to afcertain the meaning of the terms material and immaterial ; which are ufed by writers without any accurate meaning. All beings and exiftences muft be either material or immaterial; or, in other words, muft be matter or not mat- ter: Therefore, if we know what is mat- | nee ee PHYSICAL ann LITERARY. 13 ter, we cannot be at a lofs about what is mot matter. I take it for granted, that we have no conception of matter but as fubftance or body, endued with colour, figure, extenfign, impenetrability, or o- ther properties of fuch a nature as to be objects of our external fenfes. The di- rect oppofite muft of courfe be an accu rate defcription of an immaterial fub- ftance, 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. Thus it comes out, that immateriality is merely a negative term, comprehending every thing that is not matter. And it is of confequence to be obferved, that the di- ftinGion betwixt material and immateri- al, not being founded on the nature of the things which are fo diftinguifhed, but on the limited nature of our external fenfes, has not the leaft tendency to ex- plain the nature or properties of immate- rial fubftances, further than barely, that the properties of fuch fubftances are not objects of any external fenfe, ; - FRoM 14 ESSAYS anp OBSERVATIONS 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 per- ceived by our external fenfes : But there is none fo foolifh to maintain, that matter can have no qualities but what are objects of an external fenfe. It would be the fame as to deny the exiftence of immate- rial fubftances, becaufe thefe do not exhi- bit themfelves to our fenfes. Power isa property or quality, of which none of our external fenfes afford us the perception ; and therefore our want of perception of power, does not more conclude a negation of power to matter, than to fpirit. In ge- neral, we have no means to come at the knowledge of a cau/é, but by the ef pro- duced. We cannot, 4 priori, conclude, that animate beings are endued with any fort of powers, more than inanimate, Ex- perience is here our only guide. We find | by experience man to be a reafoning be- ing, endued with many powers and facul- ties: And, by the fame experience, we find PHYSICAL ann LITERARY. 5 find matter to be endued with certain powers and faculties: Both are dif- covered by the effects produced; and we have no other means to make a dif covery. We fee a ftone fall without a- ny externalimpulfe. From that effeét we have a juft foundation to conclude, that y J ‘. i the ftone has a power of moving itfelf, And, if we have not a juft foundation to make this conclufion, we have not a jut foundation to make this other conclufion, that aman has a_ power of felf-motion when we fee him walking. And after all, it muft appear extremely whimfical to de- ny to matter a power of motion, merely becaufe matter difcovers itfelf to our ex- ternal 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, either in whole or in a. Oo endue Ir is fuggefted above, that matter with a power of acting according _ to general and invariable laws, exhibits a more beautiful and compleat fyftem, than tS 16 ESSAYS anv OBSERVATIONS to leave it abfolutely inert, to require a continued interpofition of the deity, To illuftrate this point, I chufe to borrow the honourable Mr Boyle’s fentiment, whofe piety was not inferior to his knowledge. Tt feems manifeft enough, that whatfo- “ ever is done in the world, at leaft where “ the rational foul intervenes not, is really ‘* effected by corporeal caufes and agents, iy according to the laws fettled by the om- “ nifcient author of things.” * And he obferves, “ That as it more recommends “ the {kill of an engineer to contrive an “ elaborate engine, fo as that there need “ nothing to reach his ends in it, but the “ contrivance of parts void of underftand- - *« ing; than if it were neceflary that, ever . “and anon, a difcreet fervant fhould be ‘ employed to concur notably to the ope-~ «¢ rations of this or that part, or to hinder the engine from being out of order: So, ‘sit more fets off the wifdom of God, in «¢ the fabric of the univerfe, that he can ‘© make fo vaft a machine perform all ** thofe Inquiry into the vulgar notion of nature, p. 60% PHYSICAL ann LITERARY. 17 *¢ thofe many things which he defignied it i fhould, by the mere contrivance of fe “brutermatter, managed by certain laws ‘* of motion, and upheld by his ordinary és and general concourfe ; than if he em- : ployed, from time to time, an intelli- ** sent overfeer to regulate and controul 9? “the motion of the parts *.” What may be the opinion of others, I cannor fay; but, to me, this argument is’ perfectly conclufive. Confidering this univerfe as ‘A great machine, the workmanship of/an intelligent caufe, I cannot avoid thinking it is the more compleat, the lefs mending or interpofition it requires,’ The perfec- tion of every piece of workmanthip, hu- man and divine, “confifts in its\ anfwering the defigned purpofe, without beftowing further labour upon it.’ And therefore, upon the whole, as we have no founda- tion, either in reafon. or;experience, to de- ny activity to matter; I: conclude, that . the doérine» of the abfolute inertnefs of _ Matter, is not only repugnant to truth, Vou.b- C ee bur * Inquiry into the vulgar notion of nature, p. 7- 18 ESSAYS anp OBSERVATIONS but tends, in an indire&t manner, to ar- raign the Deity of want of power, or of wifdom, or of both. Of the VIS INSITA or VIS INERTIA. H”™ Nc thus brought our fabjec within bounds, by evincing that we have no occafion to fearch for any o- ther immediate caufe of natural appearan- ces than the activity of matter itfelf; I fhall proceed to examine fome of the powers of matter, fuch of them as are pro- ductive of the moft remarkable effects: And thall begia with the vis zjfita, or vis mertie, that fignal property of matter, whereby, as philofophers teach, “‘ A body “‘ always perfeveres in its ftate of reft, or “of uniform motion, in a right line, till, “by fome external influence, it be made “to change its ftate.” This property is handled: by writers without any degree of accuracy. The bulk of them refolve it in- te. PHYSICAL ann LITERARY. ‘19 to the inertnefs and paflive nature of mat - ter, andconfider the prefent ftate of a piece of matter, whether of motion or of reft, to be an effect, which, once produced, mut continue to exiftas itis, tillit be changed or deftroyed by the operation of a new caufe. But, as this conception of the matter is liable to ftrong objections, which fhall by and by be mentioned, the moft rational . writers admit of a power in matter to preferve itfelf in its prefent ftate; but then, confidering the perfeverence in reft and in motion to be effects of the fame kind, they, without making any diftinction, attribute both to the fame power or caufe, I cannot fubfcribe to either of thefe no- tions. It is obvious to me, that the mere negation of a caufe, though it may account for the continuance of a body at reft, as it may account for its preferving the fame figure or colour; yet can never account for the refiftance made in the change from reft to motion, or from mo- tion to reft. And it is equally obvious, that a ftate of motion is very different from a ftate of reft; and that the prefer- ving 20 ESSAYS anp OBSERVATIONS. ving a body in motion, muft be an ope- . ration of a different kind, from that of preferving it at reft. In order to handle this fubject with fome degree of accuracy, I fhall endea- vour to make out the three following propofitions : - Firf, That motion is a continued action, which mutt infer fome power continually acting. Secondly, That as matter refifts a change from reft to motion, as well as from motion to reft; this refiftance i is not to be accounted for by the mere negation of a caute, but is a pofitive effect to require a caufe as much as motion does. And, /a/ily, after ex- plaining the caufe of the continuance of motion, I fhall endeavour to fhow, that it is an effet of a different kind from the refiftance which matter exerts againft any impulfe which puts it in motion. WiTH regard to the frit propofition, motion evidently differs from the other properties of matter. It is not like ex- tenfion, figure, and fuch like qualities effential to matter. Every body mutt be. of a certain fize and figure ; but it is ea- fy ————- en. PHYSICAL anp LITERARY. 21 fy to feparate motion from body, by fup- pofing i itto be at-reft. But what we haye principally to confider in the prefent ara, gument is, that the moulding of a body into a certain figure, or the giving it a certain colour, are not imperfect, but com- pleated effects ; ; which, once produced, mutt continue invariably the fame, esi fome power be exerted to make an altera; tion. This is involved in the very, con- ception. of colour and figure, and.is fo fimple and clear a propofition, as to be in- - capable of any illuftration. The bare ne- gation of a new caufe, is fufficient to ac- count for the continuance of fuch effects. Reft is of the fame kind, It requires no action nor operation to preferve a body at reft, more than to preferve its colour or figure. But motion, being the direct oppotite of reft, cannot be one of thofe compleat effects, 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 a@tion; and, as ac= tion implies power, there muft be a Nsticine aa power 22 ESSAYS anp OBSERVATIONS power continually exerted to preferve a body in motion. Again, if motion be con- fidered as an effect, it canonly be compa- red to figure or colour, with regard to that part of it which is paft: What part re- mains to be performed, is fo far from a compleated effect, that it is not fo much as commenced; and therefore muft ne- ceffarily be conceived as a different effect, to the production of which there muft be a new exertion of power. Motion then is a continued effect, or rather a feries of different effects, to require a caufe in continued a@tion. Accordingly, when we attend to our own perceptions, we do not inquire for a caufe, when a body cea- fes to move, If the caufe of the motion ceafe, we feek no other reafon for the ceafing of the motion. If a thing fo evi- dent can admit of illuftration, let us fi- gure an anima! in motion. It never came into the mind of any perfon, that a man is paflive in the action of walking orrunning. In this cafe we reafon juft- ly, that walking or running requires a continued exertion of power. It requires no PHYSICAL ann LITERARY. 23 no exertion of power to put an end to thefe motions. The man has but to for- bear to exert his power, and reft enfues. In this matter there is no difference be- twixt animate and inanimate beings; not even though it fhould be fuppofed, that. matter is altogether paflive. _ For, if mat- ter itfelf has not a power of motion, the fpirit which a@tuates matter cannot o- therways preferve it in. motion, but by a ¢ontinued exertion of power. THe fecond propofition i is almoft felf= evident. To account for continuance at reft, nothing is required except barely the negation of acaufe, But matter at reft not only continues in that ftate, but plainly refifts. every force which tends ta change its ftate trom re{t to motion. 5 Matter makes no refiftance to any caufe which produces an alteration in its fi- gure or colour. Refiftance is a pofitive ‘effet which requires a politive caufe. And this property of refiftance, which all ‘matter is endued with, is a principle di- _ reétly oppofite ‘to inertne{S or pafleity, if ~Imay ufethatterm. Refiftance is plain- Ss ly 54 ESSAYS AXp OBSERVATIONS ly action, which every man may readily perceive in himfelf, when an impulfe is made upon him: And, were matter ab- folutely paffive and‘inert, it would make no refiftance, but be carried on by every impulfe, without diminifhing the Aust _ Of the impelling body. WITH regard to the third red we cannot be at any lofs to affign a caufe for the continuance of that quantity of motion which is once given to a body. If the intervention of fpirit be rejected, as above, there is but another hypothefis to recur to, which is, That inanimate mat- ter.is endued with a power to preferve it- felf in motion, as well as animated mat- ter is, without any other difference, but that the former, having no will or feeling, acts blindly and invariably by an efta- blifhed law. It has no fpontaneous mo- tion, becaufe it has no will. Neither has it in every circumftance a power of begin- ning motion ; but, when once fet in mo- tion, it has a power given it by the Au- thor of nature to continue itfelf in motion. And this is a law which regards all mat= ter without exception. . ANB ae a. PHYSICAL ano LITERARY. 25 _ Anp this power being once eftablithed, it remains only to be made out, that it is of a different kind from that which re- fits 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 effects, the caufe cannot be the fame of two effects diametrically oppofite, vz. preferving a body in motion, and oppofing motion. It may ferveto clear this matter, if we at- tend tothe diftin@ion betwixt impuléfe and refiftance. They are fimple ideas, and therefore incapable-of a definition; but their difference will be obvious, by confidering aman in the a& of puthing againft an obftacle, and barely refifiing force applied againft him, without puth- ing again, or counteracting. The man, no doubt, is active in refifting, as well as in pufhing; but the ations are very dif ferent in their nature, and carefully. to be diftinguithed ‘in accurate reafoning. In a word, the tendency of impulfe is, to produce motion; the tendency of reliftance is, to prevent it. Thefe powers, therefore, WoL. 1,” ) {9 26 ESSAYS 4np OBSERVATIONS. fo oppofite to each other, fhall hereafter be diftinguifhed by different names. The vis infita {hall be appropriated to that power which ts favourable to motion; Jeaving the other power which refifts mo- tion to be denominated by the vis iner- tie, or rather vrs refi/tentic. THOUGH this wis. znertiae be a power, as obferved, inherent in all matter, there are certain experiments which may appear to. clafh with it, and which, upon that ac- count, merit attention. Hf a round ball be-laid upon a horizontal table: im vacua, in which fituation there will be no coun~ teraction of gravity, it is certain, that the fmoother the ball and table are, the re= fiftance will be the lefs: And they may — be made fmoother and f{moother, til! the refiftance be quite infenfible. If the re= fiftance do. not vanifh altogether, it may be owing to our want of art to: make any furface abfolutely fmooth. ‘There is ne reafon, it may be thought, to- afcribe the fall remaining refiftance to a fuppofed vis inertiae, when it can be accounted for by other caufes; and that it is unphilofo- phicat PHYSICAL ann LITERARY, 27 phical to fuppofe the exiftence of a caufe, when we cannot point out a fingle effeat that refults from it, and from no other caufe, | | Bur there is another experiment of the very eafieft operation, and which is liable to no ambiguity. Let a body of any de- termined weight be fufpended by a thread or rope fix’d to a hook in the ceiling: The leaft conceivable force will put this body in motien. If any refiftance at all be felt, it ought to be attributed to the denfity of the air, not to the body. And indeed thefe experiments infer, no more than what is admitted by every philofopher, that the fmalleft force is fufficient to move the greateft body. It is acknowledged, that, were the globe of the earth fufpend- ed by a chain, there is no force fo {mall which it would not yield to. Thefe, and fuch like experiments, look as if matter had no attachment to reft, no vis refiffen- tiae, but that it readily yielded to motion. That a body is put in motion by the ve- __ ty fmalleft force, and yet that it refilts a _ change from reft to motion, are propofi- tions 28 ESSAYS anp OBSERVATIONS. tions which may appear not to be very confiftent: Yet both are true in fact. And the difficulty will vanifh, by attend- ing to the vis inértiae or refifientiae, that it is not meafured merely by the fize or bulk of the body in which it is inherent, but has a relation to the momentum of the impinging body. The leaft force will put the greateft body in motion: But from this it does not follow, that matter does: not refift a change from reft to motion. It only follows, that this refiftance is al=- ways lefs than the vis motrix. .'Fo calcu= late the proportion betwixt the vis motrix and the refiftance of a body at reft, fhall be the fubject of the next chapter. | i ' ( z PHYSICAL AND LITERARY, 29 Or THE PME PENI -oF MOTION, HE communication of motion. from one body to another, has been ex- tremely puzzling to metaphyficians ; ; tho’ ~ mot to practical, philofophers, who make no difficulty to fuppofe, that motion ac- tually paffes out. of one piece of matter into another. Let us figure one billiard ball at reft, and another directed: upon it with a certain velocity. It is underftood that part of the motion of the impin- ging ball paffes into that which is at reft, after which it proceeds ta move with that degree of velocity which is communicated to it. ‘This account of the matter ap- -- pears to me altogether abfurd. Motion cannot fubfift. by itfelf, to be transferred from place to place, or from bady to bo- dy. Itis one of the qualities or proper- | ties zo ESSAYS anp OBSERVATIONS — ties df matter; and itis no lefs repugnant to the very conception of the thing, that the motion of one body can pafs from it to another, than that the figure of one bo- dy can pafs from it to another. In gene- ral, qualities, properties, and affections, are infeparable from the particular bodies to which they belong. They have no fe- parate exiftence; and therefore cannot be conveyed, even in imagination, from one body to another.. The green colour of this field, cannot be taken from it, and beftowed upon another: All that can be done, is to give the other a fimilar colour. My ideas or feelings cannot be conveyed from me to any. other perfon, though fi- milar feelings or ideas may be produced in that other perfon. This is not a play about words; it leads to the explanation of a: phenomenon which natural philofo- phers have not been able to explain with any fatisfaction. When motion is pro- duced in one body by the impulfe of ano- ther, there is no neceflity to embrace fo abfurd a dodtrine, as that motion pafles from the one to the other. The motion produced PHYSICAL anv LITERARY. 3 produced is eafily deducible from the inciples above laid down. The vis infita and the vis refifientiae are fufficient _ to’account for all the effects that proceed from the collifio ion of hard ‘bodies which fave no elafticity. If the refiftance of a ai be always Tefs ges oe imprefled is oiadeind: “halt neceflarily be carried ene with the body that impinges upon ~ And, being once put im motion, its opel infita preferves it in the fame de- gree of motion. I here put the fimpleft cafe, that of a ‘body i in motion, ~impin= ging upon one at reft; and, for the eafe of the itmagination, I fhall fuppofe thefe two _ Bodies equal. “With refpe ‘to 'this cafe it ‘is‘afcertained by experiments, that the | ‘two bodies in contaé go- on with half the eelerity which the impinging body had before the collifion. For it ‘is a general rule in the percuffion of hard bodies, that _ the momentum or force, direéted to the fame _ point, continues the fame after contact as ee before. ‘There is no difficulty here: For “after half of the force of the impinging body 32 ESSAYS anp OBSERVATIONS body is deftroyed by the refiftance of the body at reft, the other half remains, with which the impinging body moves, and carries 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 imprefled force without any further oppofition; and, by its impenetrability mutt be carried along with the other. BuT, in order to form.an accurate no- tion of percuffion, two preliminary points | mutt be fettled. The firft is, to fettle the precife nature of the action exerted 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 react, or does it barely re- fift? That it refifts only, and does not re- aét, will be evident from a fingle confide- ration, which is, that motion is effential to impulfe, not at all to refiftance. .Now, if the body at reft reacts, by returning | ftroke for ftroke; it. muft, rufh upon the | impinging body, and carry it backwards | at leaft for fome fmall fpace; which can- | not be; becaufe, once admitting a retro= grade | : PHYSICAL anv LITERARY. 33 grade motion, the vires infite of the two bodies muft carry them on in the fame direGtion, which is contrary to faa. It — _ is obvious, then, that there can be no re- e- percuffion or rea¢tion of the body at reft. ; All the obftruAiion it gives to the ation : of the impinging body, muft be merely by refiftance. The other point to be fet- tled is, whether the operation be inftanta- neous, or whether it be performed in time? That it is inftantaneous, will thus appear. A gradual change of motion - fuppofes, that the foremoft body patffes through every degree of velocity from reft till ic acquires its greateft velocity; and that the motion of the impinging body is gradually retarded in proportion. But 5 ‘this fuppofition is inconfiftent with a a known fact, that the bodies continue con- ba joined after contact ; whence it is evident, that both muft move with the fame velo- ¢ity from the inftant of contact. THESE preliminary points being fet- | tled, the operation may be eafily analy- fed. Tho’ the whole is performed in an ‘inftant, it may, however, be diftinguifh- You. I. E ed 34 ESSAYS any OBSERVATIONS: ed into different fteps. The firft is, that, by a certain degree of refiftance, a pro- portion of the momentum or force of the impinging body is deftroyed, and con- _fequently 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 refifls no long- er, whereby it begins to move with the remaining velocity of the impinging bo- dy. And the laft ftep is, that it is carried on with the fame aa of velocity by its own vis infita, From what is faid, it will be eafy to adjuft the proportion betwixt the vs mo-— _ trix, and the refiftance of a body at reft. For tho’ refiftance and impetus are fo ef- fentially different, as not to admit of a comparifon betwixt themfelves; yet, the effeis produced by them are capable of a comparifon. Now, the force loft by the impinging body is a juft meafure of the refifance of the body at reft; and if the momentum, before and after impulfe, continue the fame; it mutt follow, that the © . + “ PHYSICAL ann LITERARY. 35 the momentum of the body which is put in motion, is equal to the momentum Toft by the impinging body. Therefore the momentum of the impinging body is to the refiftance of the body at reft, as the quantity of matter of both bodies is tothe quantity of matter in the latter. Tuas power of refiftance in matter, which is never exerted but when an im- pulfe is made upon it, is of fo fingular a nature, as to lead us to expect fome wife contrivance. Writers have given very little attention to the laws of motion, con- fidered. in the light of final caufes, tho’ a waoft beautiful fpeculation. It would carry me too far from my prefent pur- pofe, to enter directly upon it: I take liberty only to make a fingle obfervation with refpect to the property of refiftance. Gravity, an univerfal law of matter, ferves the nobleft purpofes. In conjunction with the vis infita, it preferves the folar fyftem inorder. The vis infita is ufeful in ano- ther refpe&t; becaufe by its means, we can apply force greatly fuperior to our own. 36 ESSAYS anp OBSERVATIONS own, The refiftance of bodies again is of admirable ufe to keep force within proper bounds. If the fnalleft body, impinging upon the greateft, had theef- fect of communicating its own velocity, which it would do, were there no refittance, the {malleft force: would be fufficient to give a new violent motion to the earth, and to put the lives of all mankind i in the power of CUEEY individual. o8 a S CS oe eC 1 PHYSICAL anp LITERARY. 37 laeepe Or ACTION anp REACTION. T is laid down as an ery law of matter, “ that reaction is always con- * trary 2 and equal to action.” Or, “that * the mutual actions of two bodies upon each other, are hits equal, and with * oppofite dire@tions.” And Sir Laac Neieon, in illuftrating this law, gives particular inftances of its taking place im all the different actions of matter ; to wit, in impulfe, in preflure, and in refiftance. For my part, Lhave always been puzzled about this law, and/am uncertain, after all, whether Ihave a juft conception of it Are we to underftand it to bea pro- perty of matter in general, that when act- ed upon, it exerts an equal and contrary. action? Or only, that in thefe particular cafes where matter reacts, the reaction is always equal and contrary to the action? The 7 38 ESSAYS anv OBSERVATIONS - The former is Sir Ifaac’s fenfe of this law; which is evident, from his placing it a- mong the laws that govern all matter in general; as well as from his various in- ftances, 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 feem to make a figure. The firft is, that, ac- cording to this law, there cannot be in matter fuch a thing as refiftancé without reaction; a bold -affertion, that contra- dicts what in common apprehenfion ap- pears to be the fact; and therefore ought not to have been taken for granted with- out offering any evidence. But, not.to reft upon the negative, it appears clear, that, in the collifion of hard bodies, there. is refiftance without reaction; and I flat- ter myfelf with having made. out above, that, were there reaction in this cafe, the effects of collifion would be very. dif- ferent from what they are in fact. And. this leads to another difficulty, that. af reaction were, in every cafe, equal to action in hard bodies, for example, as well! RES Sere PHYSICAL Anp LITERARY. 939 well asiin aliftics the effects of collifion ‘mutt be the fame in both. Two elaftic balls; meeting in oppofite dire¢tions, re- bound; becaufe, after their force is {pent by collifion, the fame force is reftored’ to each, by their mutual reaction ; and the - fame mutt happen to hard bodies, if they have the fame power of reaction, In a word, I cannot diftinguifh elafticity from a power of reaction; and a hard body - differs from an elaftic only in this, that _ the former has no power of reaction, but only of refiftance. A third difficulty is, - that, in the bulk of the inftances common- ly given to illuftrate this law, I cannot difcover an equality of a@tion and reac- tion. And, laftly, what appears the moft _ unfurmountable difficulty is, that, except- ing the cafe of elafticity now mentioned, and that of fluidity to be mentioned af- terwards, I have not found a fingle in- {tance of an effect produced by the action _ of one body upon another, but what may be fairly explained by acknowledged prin- ciples, laying. afide altogether this fup- pofed equality of a@ion and rea@ion. And 40 ESSAYS anp OBSERVATIONS | And if no fa&t can be condefcended on; to prove the point with regard to hard bodies, why fhould we adapt this as an univerfal law of motion or of matter? For furely it is irrational to admit of any law or principle without evidence, Tuese difficulties will be beft illuftra- ted by entering upon particulars. And with regard to Sir Ifaac’s firft inftance, of a man’s prefling a ftone with his hand ; we mutt diftinguifh betwixt 2 moveable and immoveable obftacle. If aman prefs an immoveable obftacle with his hand, I cannot here difcover any thing but mere refiftance, which is not to be overcome by the force of the hand. This is an effect which muft follow from the impenetra- bility of matter, without neceflity of ta- king under confideration any other of its properties. I difcover here no reaction. There is no counter-action or impulfe int the {tone, to correfpond to thé a@ion or impulfe of the hand. There is nothing but refiftance, which is indeed an action, but an action which is not exerted upon the hand: The aétion is exerted within the _ PHYSICAL anv LITERARY, 41 the refifting body irfelé,. to preferve it from motion, And, if this refiftance fthall be conceived as a counter-action; ‘which it may bein a loofe way of think: ing ; I cannot however conceive any e+ _ Quality betwixt the preffure of my hand i and this fuppofed countér-action of the fore. At this rate, the counter-action of the ftone is equal to’ every degree of imprefled force, provided thé imprefied co “3 not =i who ab to" Seite the time to a thoufand different dewteae of forcé. ‘To talk of the equality of aétion and’ réaction in fach a cafe, means really. nothing more than that the hand ‘has not? _ force enough to move the ftone. Acatn, if the obftacle be moveable, it coincides with another inftance given, _ thatof percuffion, or the collifion of hard: bodies; Heré indeed itis true, that there is as much force loft by the one body, as° _ is genérated in the othér, But then this P is plainly the efea of the wis refi ifentia, as explained above; and therefore it is un philofophical to introduce any other prin- = Vot. I, F ciple 4z ESSAYS anv OBSERVATIONS » ciple by which to account for this phe- nomenon. At the fame time, I cannot difcover any equality of action and re- action in this cafe; on the contrary, it is eftablithed by infallible experiments, that the impreffed force or action is always greater in a determined proportion, than the refiftance or reaCtion. And it is this very proportion which produces the effect of an equality of motion before and af- ter impulfe ; or, in other words, the ac- quifition of as much force by the one, as is loft by the other. ANOTHER inftance is of a horfe draw= ing a {tone by a rope; and it is faid,that . the ftone draws the horfe, as much as the horfe the ftone. Were this fo, there could be no motion. All I can difcover here, is mere refiftance in the ftone, occafioned: partly by its wis refijientie, and partly by friction. And after this refiftance is over- come, which fpends or exhaufts fo much of the horfe's ftrength, the {tone is drawn along with the horfe’s remaining ftrength, without any further refiftance: | WITH PHYSICAL ann LITERARY. 43 WiTdu regard to gravitation, which is given as another inftance of ‘the equality of action and reaction ; it is very true, ‘that there is an equal tendency in every _ particle of matter to every particle; but ") : am at a lofs what further can be made of this, than that fuch is the law of gra- vitation. Why then fhould we endea- - your to account for this effe& by any fe- parate law? Imight add, that this at bet. is a doubtful inftance of the mutual ac- tions of bodies upon each other. It will perhaps, upon examination, be found’the ‘more fafe opinion, that bodies a@ not upon each other by the power of gravity. . But of this afterwards. _ KEILt, in explaining this law of na- ture, feems to confine it to the percuflion of bodies; and refts it wholly upon this faa, that equal changes of motion are : ) produced upon collifion ;: which is, in o- _ ther words, that, whatever. force is loft by the one body, an equal force is gene- ‘fated in the other, And indeed it appears : robable, that the law has been invented. chiefly 44 ESSAYS anp OBSERVATIONS | chiefly to account for this effect: If fo, it is extremely rafh in philofophers to ap-. ply it, as they do, in every cafe where there is the leaft appearance-of action and reaction, as if it were an univerfal law of nature that mutt obtain in every cafe whatever. It was not difcovered, it weuld teem, that the equality of motion before — and after percuffion, is the genuine effe& of the vis refifientia. Therefore, to ac= count for this phenomenon, a new law muft be invented ; which, to difguife the’ matter, mutt be confidered as a general law: For, had it been plainly {poke out, what in effect is faid by Dr Keill, that this law is only applicable to the percuffion of bodies ; ; every perfon would be fenfible, that accounting for the law of percuffion in this manner, was doing no more than repeating the fact itfelf in different words. For, to fay that the actions of two bodies in percuffion are equal and in oppofite di- rections, is, in an obfcure and indiftinét manner, really faying no more, than that a force is generated in the one body, equal to that which is loft in the other. In . PHYSICAL anv. LITERARY. 45 In accounting for the preffure of fluids yindeguaque, Mufchenbroeck reafons. thus ; _ he fuppofes the water in a veflel to be compofed of. perpendicular,.columns:. of {pherical particles, one refting upon another from the furface downwards, and all refting upon the bottom of the, veflel. .Thus the bottom of the veflel is preffed downwards with the weight of a column: And, becaufe action and reaction muit be equal, there- fore, {ays our author, the bottom of the weflel muft prefs upwards with the fame force, 7.¢. with a force equal to the weight of ‘the. column ; whence, fays he, the whole preffure upwards muft necef- farily be equal to the whole meee downwards. | So.far our author’s argument appears. conclufive, that, admitting the law of ac- tion and reaction, a preflure undequagque muft be the confequence: And as the law is not confined to fluids, but is fuppofed to be an univerfal law of matter ; a pref- ff dure sa i a mutt not only be the con- ee 46 ESSAYS anp OBSERVATIONS. fequence in fluids, but in folids equally. Here then is a fair dilemma. We mutt either acknowledge a preffure undequaque in fand, powder, and indeed in all loofe bodies, as well as in fluids; or confine this law of the equality of action and re~ aétion to fluids) Can we remain a moment in doubt betwixt thefe op- pofites? We are certain that a preffure undequaque is not a property of folids. The equality of ation and reaction is but an affertion without evidence. What re- mains then, but that we adhere to the former, and reject the latter, except as to fluids. And thus our author luckily, though without intention, has furnifhed a very convincing argument againft the univerfality of this fuppofed law of ac- tion and reaction. If an undequaque preflure is an effect of this law, it follows clearly, that this law takes not place in folids, at leaft not univerfally, as in fluids, : OF ‘PHYSICAL anv LITERARY. 47 ° w+ 4. Or GRAVITY, : RAVITY is one of the moft re- markable properties that belong to matter. By this property, which is uni- verfal, every particle of matter tends to every other particle; whereby, if not ob~ ftructed, all matter would be gathered in- to one mafs. As every particle of matter has this tendency, the tendencies of any two bodies to a mutual union, muft be in proportion to their quantities of mat- ter. And it is obferved that the force, which, at different diftances, is exerted by two bodies i m order to be conjoined, is im the reciprocal proportion of the fquares of thefe diftances. It is by this property that the heavenly bodies move round the. fun, and arekept trom flying off in a tan= 4 oa And it is by the fame property that . bodies 48 ESSAYS’ anp OBSERVATIONS bodies left free at any height, fall to the earth with an accelerated motion. When applied to the latter, itis commonly called gravity; when to the former, attradtion. Sir Ifaac Newton, to whom the great dif= covery was referved, that the defcent-of heavy bodies, and the curvilinear motion of the planets, are effects of the fame caufe, chufes to talk of this property of matter with great circumfpection and re- ferve. He pretends only, in his Principia, to have afcertained the facts, without ven- turing to point out the caufe. In the ge- neral /cholium, which concludes that ela~ borate work, he fatisfies himfelf with ha ving explained “ the motion of the cele- * ftial bodies, and of the fea, by the foree ** of gravity, without afiigning the caufe “ of gravity.” He only obferves, “ That “ gravity muft bethe effect of fomecaufe, ** which penetrates into the very center of ** the fun and planets, and which acts not * in proportion to the furfaces, but the “ folid quantity of matter ; its action on=- “ fy decreafing in a duplicate ratio of the ** diftances. SS ee een o PHYSICAL AnD LITERARY. 49 diftances.” And adds, “ That he has not’ been able to find out from phzno- mena, the reafon of thefe properties of _ “sravity, and that he does not chufe to *¢ deal in hypothefes.” It need not be fur- prifing, that this great philofopher fhould be referved upon the caufe of 2 . theory fo extenfive and fo wonderful, when it was his own child. New difcoveries are always received with fome degree of hefitation: Becaufe it is the effect of no- _yelty to produce doubts as well as fur~ _ prize. Butnow, that this theory is ful- ly eftablifhed by habit, as well as by 'rea- foning, and has got a firm hold of the ‘mind; it is not obvious, why later philo- fophers fhould affect the fame referve. For my part, I cannot fee any difficulty of explaining the caufe of attraction or gra- vity, more than of explaining the caufe of a body’s continuing in the fame degree of motion with which it begins to move. And this I fhall now attempt. Ir is above eftablifhed, that the conti- i a nuation of motion in bodies muft bean effe& of a power inherent in all matter, bee: EVion. I. : G of 50 ESSAYS anp OBSERVATIONS. of preferving that degree of celerity which is once beftowed upon it. ‘The body, by this power, is directed tomove in a ftreight line. But we perceive nothing in the na- ture of this power to confine its operation to a ftreight line, more than a curve. And we may fuppofe the power {till fur= ~ ther varied, to make the body, inftead of moving in a ftreight line, or in a curve, to direct its equable motion towards any other given body, within a certain di- 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 dif= covered by the fame means. We have no fuch conception of any power as to regu- late its operations by one law more than by another. And this leads to the caufe of gravity or attraction. We eafily con- ceive the vis infita, or a power in matter to continue its motion in a ftreight line: It is equally eafy to conceive a power in matter by which every particle has a ten- dency to be united with every other par= ticle. Vary the vis infil ta in the two fol- lowing. ; 2 wards other bodies, the difficulty vanithes) ~ PHYSICAL AN» LITERARY. 51 lowing particulars, and we fhall have an exact defcription of gravity: Firft, That it have the effect of beginning motion, as well as of continuing it; and; next, That it direct its body not in a ftreight line, but towards every body greatand finall with- in its {phere of activity. THE grand difficulty that puzzles fos reign philofophers is, to admit of a power ina body to draw otlhier bodies to it ; for this is their conception of attraction, fug- gefted by che terri itfelf. They obferve} that fuch a power is inconfiftent with a general maxim, that no being can act where it is rot 3 whence they juftly con- élude, that one body cannot act upon an- other at adiftance. It muft be confefled, that attraction is an unlucky term, fince it has led philofophers into the above mif- take; tho’ Sir Ifaac Newton cannot be juftly blamed, who made ufe of a term invented to his hand, ‘By varying the concéption of attra@ion, and by confider- ing it as a power in matter not ‘to draw other bodies to it, but to move itfelf to- lr x2 ESSAYS anv OBSERVATIONS Ix bodies aét upon each other by thé force of gravity, it is eafy to conceive that the exertion of gravity fhould be fainter and fainter in proportion to the diftance; but it is not fo eafily conceived that di- {tance fhould have any influence, if the gravity of each body be exerted within itfelf, and not upon another body ata diftance. This has the appearance of a difficulty, and no more but the appear- ance. If matter has a power toact in any one cafe, its actions may be varied by any affgnable law: And, in. particular, to imagine a power in a body impelling it towards a body at hand, with a greater force than towards. one at a diftance, is, in reality, not more difficult, than to i- magine it exerting always the fame force, without regard to diftance. _ If is not improbable, that the above mentioned objection of a body’s acting where it is not, has led Leibnitz and other foreign philofophers to adopt the vorti- ces_of Des Cartes, rather than Sir Ifaac Newton’s theory... Yet. there cannot be sarin! a more whimfical hypothefis, . than lala Bi a PHYSICAL avn LITERARY, §3 than that of a fluid circulating about the fun, in which thé planets are involved and carried along, like a fhip ima torrent, _ The ingenious Mapertuis, in his eflay up- on attraction, moves feveral objections to it, even as new moulded by later writers. He‘objcéts, in the firil place, that the pla- nets do not move in a circle, but in an ellipfe : In. the next place, that they do not move with celerities proportionable to their-diftances from the fun ; which they behoved to do, if carried along in a vors _ tex moving, hke a wheel, equably round the fun, Thefe objections are well found- ed; but, in my apprehenfion, he has o- verlooked the moit folid and’ weighty ob- jection. Whatever caufe can be afligned for the motion of this fluid round the ’ fan, will equally account for the motion of the planets, without necefflity: of in- troducing a new fund of* matter, of the exiftence of which we have no evidence. More particularly, motion “is obvioutly an effet which muft have fome caufe. This caufe muff either be a continued in- terpofition ofa voluntary agent, or a pow- er #4 ESSAYS anp OBSERVATIONS er given to matter to continue itfelf itt 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 ; and one or other of thefe caufes is fufficient to ac- count for the motion of the planets, with- out neceflity of inventing a fluid to pro= duce the effect. Des Cartes, therefore; and his followers are guilty of the famé fort of abfurd reafoning, for which we juftly laugh 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 the fame inconfiftency of a body acting where it is not, has moved our Britifh philofopher to invent an zthe- rial medium much rarer than air, as the caufe of gravitation, I cannot fay. Inthe twenty-firft query, at the end of his Optics, he obferves, ‘‘ that this medium is much “‘ rarer within the denfe bodies of thé * fun, flars, planets, and comets, than ini “ the PHYSICAL aNDLITERARY. 55 f the empty celeftial fpaces between them. “ And, in pafling from them to great di- is ftances, that it grows denfer and den- : “fer perpetually; and thereby caufes the gravity of thofe great bodies towards © one another, and of their parts towards ® the bodies; every body endeavguring fF to go from the denfer part of the me: dium towards the rarer.” I am not better fatisfied with this hypothefis than that of Des Cartes. For, without loofing time upon a minute inquiry into the ve- ry peculiar properties with which this ' fappofed aether muft be endued, in or- der to produce the effects affigned it; the fame objection lies againft it, that is a- bove urged againft the vortices of Des Cartes, that it is a new fpecies of mat- ter invented without evidence, and indeed without neceffity : For it is as eafly to en- due the planets with a power which im- pells them towards the fun, as to endue this fuppofed aether with a power which ° : repel! s it from the fun, Therefore the argument which is juftly urged by this |" author himfelf againtt a plenum in the | Be. 28tle 56 ESSAYS anp OBSERVATIONS: - 2°th query, at the end of his optics, may be urged with equal fuccefs againft this fuppofed aether, “It is of no ufe; *6 and, as there is no evidence for ‘its ex= * iftence, it ought to be rejected.” I muft own, at the fame time, great re- ‘Ju@ance to a doctrine which overturns, or feems to overturn, the moft beautiful part of Sir Ifaac’s own theory, and that which affords the ftronge{t conviction of its truth, viz.-the connedétion, by a com- mon caufe, betwixt the curvilinear motion of the planets, and the defcent of bodies towards the center of this earth. Sup- pofing an aetherial medium to be 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, mutt be, quam proxime, nothing: And the confequence is, that the bit of matter ins volved in a medium which preffes equal- ly undequaque or quam proxime, will either remain at reft, or move with a very flow pace, But this is contrary to fa@; for the PHYSICAL ayy LITERARY. & "the acceleration of falling bodies, withiri the leaft perceivable diftance, is percei- _wable. _. THE powér of gravity has a fingular "property not commonly attended to, that _ its force is not {pent by being exerted up- _ on any fingle body: . Its whole force is _ exerted upon a multitude of bodies, all at the fame time. Thus the earth tends at _ once both te the fun-and moon; and the _ whole force of its tendency is directed to each juft as much as if the other were anni- hilated.. Thus the fan is impelled towards the whole fyftem of planets and comets ; and its total impulfe is directed ‘upon e- very one of them at the fame inftant, dt cannot fail to appear fingular and fur- _ prifing, to find a force exerted in fo many different and even oppofite directions at ‘one tiinie, without being diminifhied by _ -divifion. Yet all this proceeds from one ‘fingle property, that every particle of mat- ‘ter tends to every other particle, and confé- ' quently by increafing the quantity of mat- “ter indefinitely, the fum of the tendencies of any one particle of matter may be reater than any afignable quantity. Bit Vor, 15 ros nature 58 ESSAYS anv OBSERVATIONS nature is wonderful, as well as various, in her operations ; and we ought to fub- due our incredulity, when, upon fearch- ing into her works, we find fo many ap- pearances differentfrom what we are ac- cuftomed to in common life. Havine thus eftablifhed, that there is a power inherent in matter, by which every particle tends to be united to every other particle, and which power is in con- tinual action withaut ever being fufpend- ed even for a moment; the curvilinear motion of the heavenly bodies, as well as the defcent of bodies towards the centre of the earth, are obvioufly the effects of that power. With regard to any particu- lar planet, the earth for example, we have no more to fuppofe, but that it is fet. in motion by the hand of the Almigh- ty: It will endeavour to preferve itfelf in the fame degree of motion by the wes m/i- ta. Having likewife a tendency to the fun, thefe two powers conflantly acting in different direCtions, carry it round the fun. At the fame time, the propor- | tion of thefe two forces is fo adjufted, that the earth, as well as all the other planets, def{cribes PHYSICAL ann LITERARY. 59 deferibes an elipfis, in ‘one of the foci of r which the fun is placed. Tw the defcent of heavy bodies towards the centre of the earth, the force of gra- vity is fuppofed to be invariable. For, _ though this force leflens by diftance, yet the diftance of any two points, from which we have accefs to drop a body, is fo inconfiderable in refpect of the diftance of either from the centre, that it is left out in all calculations as imperceptible, ‘Hence, the following queftion is readily faggefted: How comes it, that the pow- er of gravity, which in this cafe 1s fup- pofed invariable, has the effect of accele- rating the motion ofa falling body? It fhould be thought, that the power of gra* vity, fuppofing it invariable, muft pro- ~ duce an equablemotion downwards, with- out acceleration; juft as the ws injita does, laying afide gravity, in whatever | direGton the body is thrown, For, in ge- neral, as effeéts muft always correfpond with their caufes, every force which is uniformly exerted without diminution or augmentation, muft produce an equable motion, 60 ESSAYS anp OBSERVATIONS © ~ motion, without acceleration or retarda=. tion: And, on the other fidg, every vaz. ried effet which is gradually diminifhed or augmenied, muft proceed from a va-= ried caufe. THis difficulty is endeavoured to be. explained in the following manner: Gra- ‘ yity, it is faid, has a remarkable proper- ty, © That it acts with the fame force “‘ upon a body that is already in motion, “as upon a body that is at reft, fo as to “ produce equal accelerations in falling * bodies in equal times *.” But. this manner of conceiving the effe@ of gravi- ty, 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 effects pro- duced by it; which holds in_ general, whether the power be internal or external, From the uniformity of the ‘effects, we conclude the ws infita'to be an uniform power; and we have the fame founda» tion, ¥ M‘Lanrin’s account of Newton’s philofophy, p. 248. PHYSICAL ann LITERARY. 6 tion, from its varying effects, to: conclude _ gravity to be a varying power. In fhort, # when acceleration is produced by an ex-, ! ; ternal caufe, it will be evident to every. 4 one, that the force of the impulfive caufe _ muft be continually increafing, to pro- i duce fuch an effect ; and it will be a hard tafk to affign any juft foundation for a difference in this particular, betwixt ex: _ ternal and internal force, WE muft therefore yield to the difficnl- ty, becaufe it is unfurmountable. It is wery 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 force of gravity is, quam proxime, the fame _ when a body is dropt fromthe hand at thefe different diftances. . But then, tho’ gravity is. fuppofed invariable, where the difference of the diftances is fo {mall ; _ yet. this only holds where other circum- ftances are the fame: That i is, where the i) body i is either at ref{t, or moves with the fame celerity. For it is extremely clear, | that, in the perpendicylar defcent of a ', i body, 62 ESSAYS anp'OBSERVATIONS body, the force of gravity varies every inftant, and increafes in its progrefs downwards. And indeed gravity can- not otherways produce acceleration, more than the vis fita does. Nor is there a ny thing fingular in this property of gra- vity. The vis infita has a property fome- what fimilar: For, though it continues invariable after the body is fet in motion, yet. it is not always the fame. It keeps pace with the imprefled force ; and is ve- ty different, according to the different — forces with which bodies are put in mo+ tion. In a word, fince effects muft al- ways corre{pond 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. Of rather, confidering the matter in a different light, perhaps more accurately, the tendency or ni/us of a bo- dy towards the center of the earth, which is greater in motion than at reft, and which gradually increafes with the velo- city of the motion, being nothing elfe but the exertion of its power of gravity, makes ea. PHYSICAL aypLITERARY. 63 makes it evident that the power of gra- _¥ity is continually increafing from the _ beginning to the end of the motion, _.. IN accounting for this phenomenon, I have neglected the vis infita, though. it may probably act in conjunction with gravity in the defcent of bodies towards the centre of the earth, as well as in the curvilinear motion of the planets. For, if the force of gravity be fuppofed inva- riable, the addition of the vis ifita, which is alfo an invariable force, will only bring out a greater invariable force, which can never produce an acceleration of motion. The acceleration therefore muft be attri- buted to gravity alone, the force of which, in the beginning of the motion, is fup- -pofed to be Jefs than any affignable quane. tity, whereby a body, fet in motion by the force of gravity, paffes through every degree of velocity, from reft till it acquires - that velocity which it has when it touches _ the ground. Thave dwelt the longer upon this pro- perty of gravity, becaufe there is connec- _ ted with it another property ; which is, that 64 ESSAYS AnD OBSERVATIONS that in motion, the action of gravity is not to be confidered as one action exerted through a length of time, but as a num+ ber of different actions exerted inceffant- ‘ly. For, if the gravity of a body in mo- tion continues not the fame any two fuc- ceflive moments, but is continually vary- ing, the action muft vary with the pow- er; and confequently is not one, buta number of different actions. Gravity in a body at reft, is, like the vis infita, one invaried power, which produces one in- varied action exerted through a length of time. But, when once the body is put in motion, we. muft neceffarily admit, firft, that gravity is exerted by repeated impulfes; and next, that thefe impulfes, continually turning ftronger, form an in- creafing feries, holding an exact propor- tion with the growing velocity, 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 ftone, in its perpen=— dicular motion, is carried upwards by its wis infita cownter-acted by gravity: In its return, PHYSICAL Ann LITERARY. 65 return, it is carried down by gravity without any counter-action. At firft _ view, the afcent will be confidered as the operation of two powers acting in oppo- | fite directions ; the effe& of which com- at monly is, to produce an equable motion ; with the difference of the forces. And, _ were the action of gravity one uniform action, like that of the vis infita, fuch would truly be the effect : But, as gravity is exerted by repeated impulfes, a diffe- rent effect muft follow, ‘The very firft impulfe of gravity takes off from the force of the vis infita; what remains is leffen- ed by the fecond impulfe ; and fo on, till the vis infita, gradually decreafing by the repeated counter-actions of gravity, be annihilated altogether. In the return _ dowawards, gravity being exerted with- out an antagonift, every new impulfe pro- duces an acceleration of motion; and, _ thefe impulfes being repeated inceffantly, the acceleration goes on, till the ftone ; touch the proud. _ It remains only to be obferved, that, as the force of gravity is accurately pro- | (Ge I - portioned 66 ESSAYS anp OBSERVATIONS portioned to the velocity, gravity muft produce the fame effect, whether its force be exerted in the direction of the motion, or coutrary 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 e- qual to the gradual acceleration of down- ward motion. ‘The fame feries of num- bers reprefents both ; a progrefs from the fmalleft to the greateft number being fi- milar to acceleration ; the contrary pro= grefs, to retardation, And hence it is that thefe two contrary motions are perform- ed precifely in the fame time. - Ir is now eafy to account for the dif- ferent velocities of a planet in the diffe- rent points of its orbit. The motion of a planet may be juflly reprefented by per- pendicular afcent and defcent. A planet moving from the fun, refembles a flone moving from the earth upwards ; and, in its return towards the fun, refembles the fame ftone returning to the earth, after its ee 8 P HYSIGAL ann LETERARY. 67 its upward motion is fpent. And, indeed, by prolonging the greater axis indefinite- ly; an ellipfe coincides at» laft with a ftreight line; and the motion in the for- mer coincides with the motion in the latter. mies aa then that gravity and the vis in/ita are the two powers ‘which govern motion in the curve as wall as in the ftreight line, it muft follow, that the law of motion is the fame in both. _ 68° ESSAYS anp OBSERVATIONS Or tHe FORCE or BODIES INn MOTION. BN explaining the firft law of motion, viz, 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 en- dued with, of moving on with its origi- nal velocity; and to which power I have chofen to confine the term wis infita. I now proceed to unfold fome further pro- perties of that power. It appears clear, that the vs infita might have been fo or- dered, 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 fmalleft oppofing force, which is the cafe of the vie refiffentie when the . body is at reft. There is no difficulty to conceive a body endued with fuch a pro- perty, PHYSICAL ann LITERARY. 69 perty, as to preferve itfelf in its original _ degree of motion where there is no ob= “ftru@tion, and yet to yield to the fmalleft __refiftance or oppofing force.. But the vis q wnfita is plainly not of thatnature. The body not only preferves itfelf in motion ‘where there is no refiftance, but exerts a ‘certain force againit every thing that re- filts its progrefS. And itis with a view ‘to this force exerted in motion, as well »as with a view to the refiftance exerted at “eft, that Sir Iaac Newton, in his third definition, defcribes the vis. infita to be “that power in matter, by which every “body, as much as in it lies, perfeveres ‘in its prefent ftate of reft or motion.” -The force, however, exerted in. motion, vis effentially different from that exerted 9. reft.. The latter is mere refiftance ; the former is.an impulfive force, by which ‘the body endeavours, guantum in fe eft, to overcome every obftruction to its motion, t The force of refiitance is above afcertain- ‘ ed, and a rule laid down for eftimating it, about which all philofephers are'a | persed. They differ widely about the im- . pulfive 7 ESSAYS AND OBSERVATIONS : pulfive force of the vis infita: The Ger- mans holding it to be as the fquares of the velocities; the Englifh and French holding it to be fimplty as the velocities. The difpute is fpun out toa great length: The parties, as is ufual, being more foli- citous to enforce their own arguments, than to give fair play to thofe advanced by their antagonifts. And, by profu- fion of writing, the point is rendered fo ‘perplexed and intricate, that there ap- pears not a better way to come at the truth, than, neglecting the arguments on both fides, to apply direAlly to fats for a folution, as one would do upon a point newly ftarted. . ConsIpERING the matter abftradly, I cannot find that there is any inconfift- ency in the German hypothefis.. As we may conceive the vis ixfita to be exerted according to any affignable law, fo we may conceive it to be exerted in any af- fignable degree. When we confider the vis infita as employed in preferving the fame degree of velocity, it follows necef- farily, that its force, which is the caufe, mutt j PHYSICAL anp LITERARY. 71 muft be meafured by the ‘velocity, which is the effect. But, when we confider an- other branch of its operations, viz. its m7 Jus to overcome every obftruction to the’ equable motion, we have no other means i. to eftimate this mi/uzs, but its effects ; for, however probable it may be, it does not neceflarily follow, that this mi/us mulft al- fo be meafured by the velocity. Facts and experiments, then, are the only ; means _ by which we can determine this contro- » _ verfy ; and, when we look about for facts and experiments, there can be none lefs _ Tiable to exception than thofe, where the Re wis infita of one body is oppofed to the wis infita of another, by collifion and per- | cuffion. If a pendulum of one pound weight be let down from fuch a height, as to acquire at the loweft point the velo- city of 10, it will exa@ly balance a pen- dulum 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 remain- ing at reft upon conta@t, is compleat evi- dence, that the forces of the two bodies are 7z ESSAYS anp OBSERVATIONS are equal; confequently that their forces are as their quantities of matter multipli- ed upon their velocities; and therefore that the force of the fame body is always as its velocity. A thoufand different ex- periments of the fame kind, make it evit dent, that the force of every moving bo- dy is in the precife ratio of its velocity. And thofe experiments muft be abfolute- ly unexceptionable, in which we compare the force of one body with the force of an- other equal body moving with a different velocity; for this is in effect comparing the different forces of the fame body mo- ying with different velocities. | Ir being thus afcertained, that the force of a body moving by the wis infita is always in proportion to its velocity, we have reafon to conclude, from, analo- gy, that the fame rule holds where bo- dies move by the force of gravity. And accordingly this is alfo made evident from a courfe of unexceptionable experi- ments. | THE PHYSICAL ano LITERARY. 73 THE German philofophers, in their ex- periments, have been mifled, by a{cribing, tothe force of the moving body, effects which obvioufly refult from other caufes. Not to lengthen out this paper too much, I fhall fatisfy myfelf with giving an in- ftance or two. Itis a fact agreed upon, that a pendulum, fwung upwards with a double velocity, will reach a quadruple ; height. Hence it is inferred by Leibnitz, and his followers, that the forces muft be as the fquares of the velocities; feeing the effects produced by the different for- ces, viz. the fpaces gone through, are as the fquares of the velocities. And, could it be juftly maintained that the {pace run through is purely the effect of the momentum or force. with which the body is thrown upwards, the argument would beconclufive, But itis not fo. Laying afide gravity, and the refiftance of the air, a body thrown upwards, with the fmall- eft force, will move on im infinitum. Itis by the operation of gravity, and the re- fiftance of the air, that motion ceafes, when the body arrives to a certain Vou. I, K height. v4 ESSAYS anp OBSERVATIONS © height. The retardation, therefore, of motion, in bodies thrown up with diffe- rent velocities, laying afide the refiftance of the air, may be a meafure of the force of gravity, of which it is the effect; but can never be a meafure of the force with which the body is thrown up, of which it is not the effect. And, from the fact of a body’s arriving at four times the height with doubie the velocity, 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 ac- quire four times the force of the other bo- dy, though it acquire but double its velo- city; which does not afford the fhadow of an argument. When a body is thrown up with a double velocity, and’ confe- quently with a double force, the reafon why it afcends four times its. former height is plainly this, that the’ counter- a&ion of gravity, while it has a double force'to ftruggle with, has but half the time in any given {pace to produce its ef- fect ; | 4 PHYSICAL anp LITERARY. 75 fect; and therefore this body, before its motion be totally fubdued, muft afcend four times the height that it afcends when thrown upwards with the fingle ve- locity and fingle force. | But the argument, which the Leibnit- fians truft moft to, is founded upon ex+ | periments of the falling of balls upon clay, or other foft body ; where it is efta= blifhed, that the impreflions made, are in proportion to the heights from whence the balls are let fall, and confequently to the fquares of the velocities. From thefe ex- periments it is inferred, that the forces mutt alfo be as the fquares of the veloci- ties ; 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 faid to be the immediate . and direct effects. The error of this rea- foning is of the fame kind with the for- mer. The retardation of the motion of a body falling through a refifting medium is not the effect of gravity, and therefore _ cannot be the meafure of its force. It is " the meafure of the refiftance of the me- dium, 76 ESSAYS anp OBSERVATIONS dium, becaufe it is the effet of that re- fiftance. All the world knows, that, when bodies move through a fluid, or any foft matter, a double force produces a qua- druple effeét ; which may be accounted for in the fame manner with the retarda- tion 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 counteraGion of gravity. And it is equally reafonable to fuppofe, that, when bodies fall into refitting medi- ums, a double force will carry the body a quadruple fpace downwards before the motion be quite ftopt by the refiftance of the medium. I fhall conclude this effay with the fol- lowing obfervation, that the feveral pow- ers I have afcribed to matter are in no- thing fimilar to occult qualities. ‘The er- ror of thofe who dealt in the doGrine of occult qualities was, in attributing every different effect to fome quality or caufe confined to that fingle effet; which was, in reality, faying no more, than, what all PHYSICAL ann LITERARY. 77 all the world knows, that every effe& muft have a caufe. This was mot advancing . fingle ftep in knowledge, but amufing one’s felf with words in place of things. The powers I have attributed to matter | refolve into general laws, each of them . productive of a thoufand different effects, And wehave no reafon to doubt that mere matter may be endued with various pow- ers, as well. as animals are. When we fay, that feeing, hearing, tafting, touch- ing, fmelling, proceed from fo many dif- _ ferent powers or fenfes, no perfon confi- ders this as afcribing effects to occult cau- fes. Have we not the fame reafon to con- clude, That there is a power in matter to continue itfelf in motion; another power, to refift a change from refit to motion; and a third power, to unite itfelf with every other piece of matter ; when we perceive effects which as direétly 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 that is the foundation | of all thefe powers, But ftill, it is gaining - ground 78 ESSAYS Anp OBSERVATIONS — ground and knowledge, to trace effects to their caufes, and to difcover that many different effets proceed from the fame caufe. To be diffatisfied with fuch difa coveries, merely becaufe of the poffibility of other caufes ftill more general, is in effect 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. ART. “PHYSICAL anv LITERARY. 79 2 ART. I. Some Remarks on the Laws of Motion, and the Inertia of Matter ; by JOHN STEW- art, M.D. Fellow of the Royal Col- | lege of Phyficians, and Profeffor of Natu- ral Philofophy in the Univerfity of Edin- burgh, | HE laws of motion, as delivered by ‘ Sir Ifaac Newton, are all founded on the fuppofition, that body of itfelf is abfolutely inactive. And inactivity is now commonly afcribed to matter as one. of its general proper. Body being de- - fined to be, whatever is extended, impene- trable, divifible, moveable, and inactive. _ At the fame time, every one knows, that ative powers are continually employed _ through all the parts of nature. The life ' and motion of animals, the produétion } and growth of vegetables, the attractions ta of gravitation and cohefion, with other i. inftances 80 ESSAYS anp OBSERVATIONS inftances of the fame kind, are always prefent to our view. | PHILOSOPHERS, who affert the inacti- vity of matter, ought therefore to he able to give fome good reafon, why they re- fufe to allow it the free pofleffion of fuch powers in its own right; and why it is only to be regarded as a paflive inftru- ment, under the direétion, and fubjeé to the dominion, of fome fuperior Being. But, in erder 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, repul- _fion, or any tendency to begin motion, till acted upon by fome foreign external caufe. And furely it would be fomewhat furprifing, if body, even in thefe circum- ftances, fhould be found to difcover any activity. Ir hath been imagined, however, by fome people, ‘* That, if body were utterly in- * active, the fmalleft force would be fufi- — * cient to move a great body and a little * body, with equal velocity: And that _ **'the 4 _ PHYSICAL snp LITERARY. 8 “ the fame power might communicate a “ oreat velocity or a finall velocity to any “body *.” Mr De Mairan, in Mem. de ? Acad. 1728, feems to ehtertain the fame opinion, when he afles, If the inertia of _ mftter (which he explains to be that re- | fiftance which body makes to its being drawn out of reft, and receiving a deter- mined motion, and which is more or lefS in proportion to its mafs) may not be the _ effect of fome motion; and if it ought not to be conceived as an actual force, ating & by fome fecret mechanifm? And the au-’ thor of an Effay on Spirit, lately publifhed; maintains, tn like manner, that there is an active refiftance to the beginning of mo- tion in every body ; tho’ indeed he attri- butes that activity t6 an immaterial canfe. And Meff. Buffon and Needham too, who have carried the activity of mattér to the Ingheft pitch, have drawn one argument in fapport of their fyftem from the refift! _ ahce of bedy to motion. Needham’s Ob- ' férvations, p. 435. myvOoL, tf. * ee lie 374 . Bs Effay L. p. 9. 21. 24. 82. ESSAYS anp OBSERVATIONS To give the queftion a fair examina- tion, we fhall, inftead of {peaking about matter or body, fuppofe for once, a fub- ftance before us quite inactive of itfelf, which is extended, impenetrable, finite, and confequently moveable. Let us try if any lefs refiftance to motion can be ex- pected here, than is actually to be met with from common matter. Place any. | mafs of fuch a fnbftance at reft. It can- not begin motion of itfelf by the fup- pofition. But an active animated being, as for example, a man, can move it. Some effort muft certainly be made, fome pow- er exerted, to produce this effe&. It will never be pretended, that.the fame effort can move the mafs either with a great ve- locity or a fmall velocity ;: that being as abfurd, as to fay that a great velocity and a fmall velocity, are one and the fame, thing. In like manner, it muft require one effort to move a {mall quantity of the fubftance with a certain velocity, and 2 different effort to move a great quantity with the fame velocity. The fame energy of the agent will never ferve to move a given j PHYSICAL anv LITERARY. 83 given quantity of this fubftance, or double the quantity of this fub{tance, with the. fame velocity ; no more than it will move the fame fubftance with different velocities. By this exertion of our own The animated being (or the mind) is differently affected by different objects, whether of the fenfes or underftanding. And why fhould it be affeéted in the fame way, when a great fubiftance and a | activity, we acquire the ideas of forces. little fubftance are moved by it, or __when a great velocity and a little velo- ; city are imparted to the fame fubftance? When we endeavour to communicate motion tofuch a fubftance, we muit be confcious of fome kind of feeling ; and thefe feelings mutt be different in different cafes. Thus the idea of refiftance, as it is called, to motion, in the moft inactive _ fabftance we can imagine, would be fug- gefted to us from thefe perceptions, and ) is precifely the fame with what we expe- % rience daily in haridling of matter. Nor is does it feem poffible to conceive an ex~ * tended, impenetrable fubftance, divefted of this kind of refiftance from inertia. ne 84 ESSAYS anp OBSERVATIONS The larger the fubftance is which we in- tend 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, THERF isa very extraordinary paflage in Mr M‘Laurin’s Account of Sir Ifaac Newton’s Philofophy; p. too, which, in re{pe of the high merit of the author, - deferves our attention. It is there faid, Dhat, for aught we know, matter may _ © be of kinds fo different from each other, “ that the folid elementary particles of “ the one may have a greater zuertia than » ‘equal folid elementary particles of the “ other kind.” This conjecture, if true, would effectually overturn what hath heen now advanced, But it appears to bee- qually inconfiftent with his own account of inertia, and occurs only in a pofthu- mous work. The zuertia of body is a negative quality, or a negation of all po- fitive power, and therefore can admit of no degrees of a greater or lefs than a gi- ven quantity of matter. Two bodies, or two elementary particles of equal quan- tities - PHYSICAL ann LITERARY. 85 tities of matter, if they are inert at all, mutt have equal znertiqg, or require equal forces to move them with equal velocities, And, in every cafe, the nertia is propor- tional to the quantity of matter. Ir a body left at reft does not begin motion of itfelf, it is determined to re- main in that ftate, not from any real re- pugnance to motion, which is as conform- able to its nature as a ftate of reft, but becaufe nothing is done without a caufe, and, when aéted upon by any external influence, it obeys without reluctance; the motion produced being in exaé pro- portion to the moving caufe. It has a conftant fufceptibility of motion, anda perfect facility in receiving it.” But we may as well afk, why an inactive fub- _ ftance does not begin fome degree of mo- tion of itfelf? as, why different powers are requifite to produce different moti- ons? When people talk of the refiflance of matter at reft, as of an adfive power, ftruggling againit any agent, and active- 4 ly oppofing it, they furely frame to them- q Relves fome notion of force antecedent to all 8§ ESSAYS anv OBSERVATIONS. all experience ;'and they would do well to inform the world, in what manner this idea was fuggefted to them, THE paffive nature of body is abun- dantly manifeft, from its yielding to the leait conceivable action. 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 finda horfe able to draw a loaded cart two miles in the hour, who cannot be prevailed up- on to draw it four miles in the fame | time. But are not fuch common phae- nomena as thefe more naturally account- ed for from the fluggifhnefs or inactivity of matter, than from its fuppofed adtivi- ty ? A great body fet in motion is one ef- fe&t : A little body moved with the fame velocity is another. A given body mo- ved with a great velocity, is one effect ; and when moved with a lefs velocity, it is a different effect. The o'd principle feems to apply well enough in this cafe, that efleéts are proportional to their caufes. Ir mutt be confeffed, that authors, in wreating of the inertia of matter, and of 1ts PHYSICAL anv LITERARY. 87 its refiftance.to motion, are very apt to exprefs themfelves in terms that import areal activity ; and which, if ftridly un~ derfiood, are. inconfiftent with inertia. _ Thus, when a perfon in a boat pulls. a. rope that is faftened to the fhore, itis. 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 exprefli- ons, will any one ferioufly maintain, that - the ground has an aétive power to pro- duce any fuch effect? It is evidently the _ force of the man extending himfelf, that draws the fhore with his hands one. way, and at the fame time pushes. the velfel with. equal force with his feet the oppofite way. In like manner, if a perfon ftanding in a | boat, puthes again{t the ground with a pole, it is not really the; reaction of the. ie ground that makes. the boat recede; it is _the force of the man that isthe only mo- ving power, ating equally upon both the boat and the ground. When a boat is rowed with oars, the oars are faid to 8 ESSAYS and OBSERVATIONS _ act upon the water in one direction, and the water to react upon the oars in the oppofite direction, and to produce the motion of the boat. Yet it is plain, that the motion is intirely produced by the rower, who, in fo far as he contributes to the motion of the boat, employs 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 pro- greflion of animals, whether it be of walk~ ing, flying, or fwimming, Borelli and alt other authors content themfelves with tel- ling us, That the animal aéts upon the ground, aif, or water, in one direction, and that the reaction of the miedium car~ ries the animal forwards in an oppofite direction. This is at beft but too con- cife, not to call it a falfe theory: Seeing: itmuft be manifeft that the medium, by any reaction which takes place here, cam only confame as much force as is imipref- fed upon it, and is utterly incapa- ble of producing any kind of motion. The PHYSICAL anp LITERARY. 89 - "The only immediate caufe of the motion, being the adtive force of the animal which - preffes the medium one way, and its own. body the other way, as might be parti- cularly fhown in every kind of progref- fion, if it were thought needful. Tuus, upon the moft attentive exami- nation into the ftate and condition of bo- dy at reft; we4iave found it to be per- -feétly inert or inactive. Body in motion next demands our confideration. Suppo- _ fing a body once put in motion by fome agent or other, it behoves us to follow it ‘out, and inquire what happens to it on this change of its ftate. An extended, im- __-penetrable, inactive fubftance has recei~ ved a motion: Will it inftantly {top when the immediate influence of the active power ceafes? or will it perfevere in its new ftate? shed From what commonly happens in the motions of bodies, their gradual lofs of force and returning to a ftate of reft, peo- _ ple contract an early prepoffefion, and _ are ready to imagine, that reft is the proper ftate of body. But a diligent re- Be Vor. +t. M view 90 ESSAYS anp OBSERVATIONS view of all the circumftances foon difco- vers, that body is equally indifferent to either ftate, of reft or motion. Body at reft does not change its ftate of itfelf; no more does body in motion. A body at re{t requires no caufe of its continuance ; as little does a body in motion. ‘This _ property of body, by which it perfeveres in its ftate of reft, or of uniform motion, in a ftreight line, unlefs when forced to change it by fome external influence, 1s called the inertia of matter. We know not how motion is original- ly communicated at all ; we know nothing of the nature of motion or force, but by experience. We can define neither, the ideas being quite fimple. Natural philo- fophy however takes it for granted, that fuch a thing 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 ftop of itfelf; and that, to preferve it in mo- tion, a conftant exertion is neceffary, like that which produced it at firft? What argument can lead us to afcribe fuch an ativity PHYSICAL sno LITERARY. 91 a@tivity to body ? What fhould determine the body to ftop, if there be nothing to oppofe its motion? {Is there any experiment pointing that way? Yes, “ we ** may be defired to reflect on what a per- * fon feels within himéelf in walking, du- ~“-< —- s ve ** ring which a repeated activity is exert- “ ed to continue the motion *.” But this, furely, can only bg intended as an illuftra- tion of what is meant by the fuppofed _ activity of matter in 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 activity, fome- times more than we are mafters of, to ftop a begun motion in our bodies. How _ doth it appear, that the fame effo?t is ne- ceflary to be continually exerted, which was employed at the beginning of the motion? We find a certain effort neceflary , _ to begin a motion in our own bodies ; but, we fhould find no occafion for repeating it, were it not confumed or wafted upon _ other bodies. When we give ourfelves ee eS pares Pe ee one 8 Effay I, p, 22, 92 ESSAYS anp OBSERVATIONS one pufh forwards upon a {mooth furface, fuch as ice for example, there is no need for a fecond immediately ; and, were ‘there no attrition nor refiltance from the air, the motion would continue for ever. Ifa body fet in motion were to ftop, re- tard, or any way change its motion of it- {elf, that would betray an inclination or | tendency wf one fate preferably to ano- ther; it would no longer appear equally indifferent to either, in which alone paili- vity confilts, THE moft general law of matter we difcover by experience is, that every efle& continues 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 exi- {tence of matter? “ Motion is indeed a ‘ mode of exiftence different from all o- “thers, nor can we compare it to any, as thi ng that is not motion*.” But that is no reafon why it fhould change of it- felf, ® Effay J. p. 20, i we pofitively conclude its effects to be on- 4 PHYSICAL anv LITERARY. 93. felf, any more than thefe other modes,. If the continuation of motion bore a: mearer refemblance to the continu- ation of any other effeét, would that render it any plainer? Motion is an effea fui generis ; but we have an infinite _yariety of examples of its continuance. An active being prefles forwards a certain ‘quantity of an impenetrable ina¢tive fub- ftance: Is there not fome effect produced here? fomething then communicated to pat? The body is put in motion: Why | eught that motion to ceafe without a caufe? Action is neceflary to the produc- tion of motion, and no wonder if nothing can deftroy the effect of one action but _ another action. ‘The trite maxim, /ulata caufa, tollitur effedtus, is not to be fo literal- ly interpreted, as that an effect may not - continue, after its caufe ceafes to act. As we know fo little of the nature of that influence by which one being puts a- nother in motion, or by which it excites motion in itfelf; with what reafon can ly w 94 ESSAYS anp OBSERVATIONS ly momentary, when they vane bane ‘ihe pear to be fo permanent?) When motion is begun, in. any body, we attribute it to a certain action which we cannot pofti- bly explain; when a body continues in the motion which it has once received; it appears to be a neceflary confequence of that, action. We commonly indeed fay, thatthe body then moves on of itfelf,; but the only queftion in debate is, Whe- ther,there be occafion for a continual re- cruit of force, new imprefiions, new folli- citations to motion, like to what were at firft exerted by the moving power? UNLEss this account of the continu=- ation of motion can be fhewn to involve fome abfurdity, why fhould we feek for any other caufe of it, than the force im- prefled by the external agent? We may » be told perhaps, “ That motion is a con- *‘ tinued action;” and therefore body con- tinuing to move, is active. But is not - this either a begging of the queftion, or taking hold of the ambiguity of language to fupport it; inftead of explaining, why a motion once excited fhould ceafe of it- felf? a ry ¥ PHYSICAL ann LITERARY. 95 flf? No doubt, we commonly fay in the mechanical philofophy, that one body acts upon another by impulfe, and the other reals upon it. Nay, Sir Haac Newton himfelf {peaksof matter aGting by mertza, or vis imertie, which, tranflated literally, would feem to import an impotent pow- er, or active inactivity. Such terms can- not eafily be avoided, without introducing endlefs circumlocutions. If more accu- rate expreflions can conveniently be fub- ftituted in their place, it would be no dif- fervice done to philofophy. But we are ‘mot to: difpute about words, when the meaning is clear; or to confound things entirely diftinét, becaufe they happen fre- quently to be called by the fame name. ‘The true diftinGion between active force, properly fo called, and the vis inertia, feems to confift in this, that fome beings can begin motion where there was none before, either in‘themfelves, or in the bo- dy to be moved: In other beings, the motion, when begun from fome external . . . caufe, is continued for want ofa power to , flop it. The firft of thele may be proper- ly 96 ESSAYS anv OBSERVATIONS ly denominated active beings ; the other; even when in motion, have no proper acti vity of their own. THERE Can indeed be no aétion upon matter without a produdtion of motion, or at leaft a tendency to it. But it doth '-not therefore follow, that motion and adti- on are fynonymous terms. Why may not ‘an active being communicate motion to matter, without moving itfelf? Is not that every whit as eafy as felf-motion? But, whether the agent moves itfelf or not, it muft have a power of acting, previous to all motion; otherways it would be impoflible for matter or any other being to begin motion of themfelves, A due attention to this remark, will afford a di= rect anfwer to what hath been fo much infifted on, “ That motion is action.” Motion is not action, but the effect of an action. AcTiviTY miay be varioufly applied. An a@tion may be with-held by an oppo- fite and equal action, as in the cafe of two contrary preflures: Or, it may be em- ployed in deftroying the effect of fome former ¢ - PHYSICAL anv LITERARY. 97 former action, as when it ftops or retards a moving body. But the genuine. cha- facteriflic of an active being, is a power of beginning motion either in itfelf or a- nother, without the means of preceeding iY motion *, 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 ftop or retard another motion, And it will readily be admitted, that whatever active being cam thus begin mo- tion in another, without the means. of previous motion, will of courfé be able to _confume motion in another, without ré- ceiving any itfelf. WHEN one body ftrikes upon another and moves it, we commonly indeed call this an aGiion: Yet there is no “refem- blance between this mechanical commu- nication of motion, and the adtivity be- fore defcribed: This is conceived to be Vou... N an ® All mere mechanical communications of motion, are not properly action, but mere paflivenefs both in the a bodies that impell, and that are impelled, ‘Aétion is the beginning of a motion where there was none before, from a principle of life and aétivity. Clark’s Lett. to Leibnitz p. 227, 98 ESSAYS anv OBSERVATIONS an ation in a fecondary fenfe. It is on- ly a confequence of the firft a@tion. A motion once produced continues, till it be deftroyed by an equal and oppofite motion, er an action capable of having produced it. THE effe@ produced by an agent is a certain quantity of motion or force, which, like other effects, continues with= out any tendency to perifh of itfelf. This quantity of motion is always proportio- nal tothe real fpace defcribed by the whole quantity of matter; and that {pace ha- ving length, breadth, and thicknefs, is meafured by multiplying the quantity of matter by the length of {pace deferibed ‘by every particle, that is, by the velocity. If a body in motion ftrikes dire@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 fingle body had before the ftroke, for. then there would be an increafe of quan- tity of motion. And whence fhould that proceed ? Such an appearance as that would difcover an activity in bodies in- deed. : PHYSICAL aNp LITERARY. 99 deed. Upon the fuppofition of perfect inactivity, the quantity of motion muit al remain unchanged : And we here abftract entirely from elafticity, whofe effects pro- ceed from a real activity, and have no re- Jation to what is called the vis inertie.'To find the length of the {pace defcribed by the impinging body, we divide the {pace - py the quantity of matter, which is as it were the bafe. And, to have the length - of the fecond fpace defcribed by the two bodies conjointly, we mutt divide the fame {pace by the mafs of matter in both. As the divifor increafes, the quotient muil diminifh in the fame proportion. _ WERE we indeed to examine very mi- nutely the gradual communication of mo- tion from one body to another, we fhall find a real activity concerned in the ope- ration ; but then it is not of that fort a- gainft which we are now contending. It is that active force known by the name of the attraction of cobefion, which there takes place. When any part of a body is pulled or ftruck upon by any moving power, it would neceflarily be feparated from roo ESSAYS anp OBSERVATIONS from the other parts, were there no co= hefion. But, where there is a cohefion, that attractive force muft oppofe the mo- ving power, And, if either the cohefion be itrong, or the velocity of the moving power but fmall, ‘this , oppofition mutt continue, till fuch timeas all: he parts of the body have acquired one common veloci- ty. That part of the body which is im- mediately aed upon by the moving power, is firft put into motion; and, drawing the other parts after it, gradual- ly communicates motion to them, with- out ever getting beyond the reac!) of their attraction, or being broke afunder. Yet, it is {lll tothe moving power that the mo- tion of the whole body muft be afcribed ; because the attraction among the fmall particles being mutual, will oppofe the motion one way, as much as it promotes it the other; and fo can neither forward nor ob{ftruct the motion upon the whole. The attraction ferves only to conneét and Jink the feveral parts together. ‘The force loft by one body, is precifely equal to | what TSS ae 3 Sa - PHYSICAL snp LITERARY. ror what is gained by the other; the whole effe& or change, with regard to motion, being the fame as if it had been inftan- taneoufly produced. And there is no ar- gument to be drawn from hence, to prove the ative refiftance of one body at reft co another in motion, or the tendency of any body in motion to return to a ftate of reft.. | _ From the experiment of Mr Poleni we Jearn, that fpheres of equal diameters falling upon foft clay, make equal im- _ preflions, when the produéts of the quan- tities of matter into the heights from which they fall are equal; that is, when the quantities of matter multiplied by the fquares of the velocities are equal. As it is much eafier to determine when two impreffions are equal, than when _ they differ in any proportion of magni- tude, the velocities of the different bo- dies in this experiment are fo adjufted, in refpe&t of the quantities of matter, as that the impreflions may be equal. But, : from thence we conclude, that fuch im- preffions 102 ESSAYS anp OBSERVATIONS. preflions are always as the quantities of matter, and {quares of the velocities con- jointly ; and confequently, when the quan- tities of matter are equal, the impreffions will be as the fquares of the velocities. The fame experiment may be fhewn per- haps in a more fimple manner, by making pendulums of different quantities of matter to ftrike with different velocities upon a fmooth furface of foft clay ; the velocities being always afligned by help of a gradu- ated arch, as is done in the common ex- periments of the collifion of bodies, In this manner, likewife, the impreflions are found to be equal, 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 cer- tain impreflion. If you afterwards in- clofe as much lead within the fame ball, as to render it of double the mafs of mat- ter, you mutt give it a velocity fomewhat exceeding 14, before it make an impref- fion equal to the former one. If the bo- dy PHYSICAL -anp LITERARY. 163 | dy 2, receive only a velocity Io, the im- -preffion will be remarkably lefs. In the former method, the gravity or weight of the balls, continuing to act after they touch the clay, may contribute fomewhat in making the impreflions ; but, in the other way of proceeding, the impreflions muft be more exactly owing to the vis i= fita, or force acquired by the bodies in falling from the determined heights. | This experiment can eafily be reconciled with the old meafure of forces, accord- ing to which the forces of equal bodies are to be eftimated from the velocities fimply. But, in order to do this, we ought carefully to diftingnifh betwixt _ two very different kinds of refiftance, viz. that from the inertia of the matter, and the other from the force of cohefion. When an impreflion is made by a ftroke, upon the furface of any yielding fubftance, fach as foft clay, the refiftance to be o- vercome in making that impreflion pro- ceeds aloft entirely from the tenacity or — Any refiftance arifing from the inertia ros ESSAYS anp OBSERVATIONS: znertia of the fmall quantity of matter difplaced in forming the pit or cavity, is quite inconfiderable. The force of co- hefion or attraction amongtt the feveral particles of any homogeneous body is equal and conftant; and therefore muft produce an uniform refiftance to the mo= tion 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 mo= tion, and the fucceflive refiftance of 2 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, mo- ving with a certain velocity, be confumed by the refiftance from cohefion in a given time, the force of the fame ball moving’ with double velocity will be confumed in a double time; if the velocity be tri- ple, the time will likewife be triple; and the velocities muft always be proportio= nal to the times in which they are deftroy- ed. From whence it is manifeft, that a ball ftriking with a velocity as 2, muft make - PHYSICAL anv LITERARY, 105 make an impreffion fourfold of what it makes with a velocity as 1}; becaufe it continues likewife for double the time. In uniform motions, a double velocity and a double time muft always givea fourfold fpace: And the fame thing muft obtain in equably retarded motions; the {paces defcribed being exactly the half of what would have been defcribed by the uniform motions. But, though the im= prefiion be fourfold, the real effect, by which the force ought to be meafured, is ‘only double; for it has only undergone _ a double refiftance. For the fame reafon, triple the velocity makes a ninefold im- preflions And, in general, the {mall im- preffions made upon the furface of foft clay (or even upon marble) by bodies ftriking upon it, muft, caeteris paribus, be asthe fquares of the velocities. Thefe impreffions, made in oppofition to the u- hiform refiftance of cohefion, are no bet- _ ter meafures of forces, than the, heights. _ tg which bodies are thrown near the earth, in ‘oppofition to the uniform. power 1 of gravity. The heights are known to _ be as the fquares of the velocities. When Vout. O ; the 706 ESSAYS anv OBSERVATIONS the velocities are as 2 to I, the heights aréas'4to I. But the forces are ftill to be eftrmated, as 2 to: 1; fince the times which the uniform action of gravi- ty takes to deftroy them are in that pro-= portion. With a double velocity, and in a double time, the body arrives at a fourfold height. Wuat hath been here bdvhiorlt con= cerning the meafure of. forces, is not fo . much intended for the inftruction of thofe who have had leifure to attend, to this celebrated controverfy, as to enable every one who has the fmalleft acquaint- ance with thefe matters to judge for themfelves ; whether the common argus ments, when rightly underftood, be fufi- . cient for the decifion of the queftion ; or, whether there be {till occafion for a new - folution.cf the difficulties. The debate has been clofed long ago; after being . managed by the ableit advocates-on both fides: And the fubject is generally thought to be exhaufted, though no formal recon- ciliation hath hitherto been declared a- mong{t the parties, We are now told, ; ‘* That, Spent PHYSICAL anv LITERARY. ro7 ' “That, by a’ profufion of writing, the “ point! is rendered fo perplexed and ‘intricate, that there appears nota bet- “ ‘ter way tocome at the truth, than, ne- ““glecting the arguments on both fides, to “apply dire@tly to facts for a folution, “ as/one would do upon a point newly *« ftarted.” With this introduction or | preamble, is ufhered iz a new project for a treaty of peace among{t the Englith, French, and German philofophers. No mention is made of the Italians, the Dutch, and others, though they were - ~pretty deeply engaged in the quarrel. The reafon for which omiffion may pofli- bly be this, that the philofophers in Italy, » Holland, and elfewhere, chufe rather to preferve the appearance of neutrality, and act as mediators. A preliminary article being firft fettled, namely, to confider the feveral pretenfions of the contending powers, as fo many points newly farted, and that without any regard to their_re- {pective memorials, there arofe a necefli- ty, in the next place, in order to render the negotiation the more confiftent with . itfelf, to8 ESSAYS anp OBSERVATIONS itfelf, for /larting new facts likewife, or at leaft of new-modelling the old ones, The method in which the whole af- fair hath been conduéted, and = the jarring and oppofite interefts adjufted, will beft appear by an inftance or two. Itis faid, ‘‘ That, when a body is “ thrown up with a double velocity, and *confequently with a double farce, the ““reafon why it afcends four times its “ former height, is plainly this, that the “ counteraction of gravity, while it has a “ double force to ftruggle with, has but “halt the time, in any given fpace, to “produce its effect.” ‘Fhe natural meaning of which is, that if a body thrown up with any velocity, rifés 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 hap- pens always to be equably retarded, the real fact comes out to be very different. The _ PHYSICAL anp LITERARY. reg The body thrown up with the double ve- ‘locity rifes to triple the height of the firft body in an equal time, and to Z 7 of that height in half the time, Let the height to which the firft body rifes in any time » | be called 1 yard; the height to which the fecond body afcends in half that time is i yard and j. The former pofition, how- ever, as it was only taking a retarded motion for an uniform one, was pretty plaufible, and good enough to pafs upon Germans and other foreigners; efpecially if they were ftrangers to the Englifh Jan- guage. Another allowable artifice to de- ceive the adverfaries, is in endeavouring to make them believe,. that all the world .. that, “ when bodies move through ‘a fluid, or any foft matter, a double « force produces a quadruple effect.” . If _ the word effec? were taken in its moft 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 pro- duce any more than a double effect in its own ! 110, ESSAYS anv OBSERVATIONS « own direction. All.the world indeed;may know that, when a body ftrikes upon clay’ er other fuch {oft matter, a,double force may produce a quadruple impreffion, But _ then, this can only happen in fuch cafes where no other refiitance is worth the minding, but that arifing from the cohe- fion of the matter, in the manner above explained. When a ball moves through a fluid, the refiftance proceeds, almoft en- tirely, from the denfity or mertia; and, the denfity being given, this refiftance muft increafe as the fquares of the velo- city. In this cafe, it would bea vain at- tempt, to aflign any mieafure of the im- prefiions ; becaufe, it follows clearly from the demonftrations of Sir Ifaac Newton *, that the body would go on for ever. And furely, it requires not much abftract rea foning to «prove, that mere ertia, with- out the help of fome active power, like gravity, or the attraction of cohefion, could never totally confume any motion, or reduce a body from‘a ftate of motion to * Princip, Lib, II, Prop. y, et cors PHYSICAL anoLITERARY. rrr toa ftate of abfolute reft. Yet, after’ all, as every one has: héard;: that the refiftance of 4’ per fet and incompreflible fluid, was in’ the: duplicate ‘ratio ‘of ‘the velocities ; this was foundation enough for a lover of peace, to allert’roundly,) that the impref fions niade in a fluid’ were in’ that vatio likewife. © Greater ftretches might well be permitted for the accomplithment of fo defirable an end, as a compleat union and harihony amongtt philofophers. We EN one body ‘trikes upon another with a great velocity, the parts immedi- — ately impelled are fometimes broken off or driven ‘away beyond the reach of attrac- tidn, before they have time to draw the other parts after them with any obferva- _ ble force $ and the force of cohefion, ha- ving oppofed the impinging bedy for fo fhort a time, makes ‘no fenfible refiftance to it: “The attraction of cohefion ating ? without! interruption, any refiftance made} or arly motion comimunicated ‘by it, muft be ‘pradually: produted; and confequent* pA ly; ‘in @ very fmall ‘time, the effect will be fe. on fall, Of “this we have many t13 ESSAYS anp OBSERVATIONS 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 dif- charged 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 ef- fects are performed, let it be obferved, that, by means of a {mall thread or aload- | ftone, a confiderable mafs of matter may be gently pulled along a table ; whereas, if a fudden tug be given, or a greater force applied, the thread breaks, or the load- ftone feparates, without feeming at all to _ move the body. The nature of iertia. and refiftance has been fo much mifun- derftood, or mifreprefented, that it was neceflary PHYSICAL anv LITERARY. 113 neceflary to explain thefe phenomena from their true principles. In particular, it inight be thought, confiftently with the falfe notions advanced concerning the re- fiftance 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 imertia or refiftance to mo- tion in that cafe became ftronger than the power of cohefion. -PHILosopHERS have fondly perplexed themfelves with many fubtile queftions toncerning the communication of motion, and ‘have perfifted, with the utmoft anxi- ety, in a very fruitléfs inquiry, how mo- * tioncan pafs out of one body into ano- ther; as if motion was fomething that could be feparated from the moving bo- dy, and infufed from one. into the other, like water poured into’a phial. But, not- withftanding all the intricacy of this af- fair, it would appear to be ftill a greater myftery, if one body in motion wefe not to move another lying freely at reft. It 4s indeed only by experience that we learn : laws of the communication of motion. Vor.t P For 114 ESSAYS Any OBSERVATIONS For whoever fuppofed, that either the ge- neral or particular properties of matter could be difeovered in any. other way? How could it be known, whether body was penetrable or impenetrable, divifible er indiviftble, elaftic or non-elaftic, ani- mated or inanimated, but by trial? Sup- pofing, however, that we were informed before hand, that the body at reft was impenetrable, utterly inactive and foft, and had neither impediment nor tenden- cy to motion ; what would hinder us from foretelling exactly every circumftance that happens, when another bedy ofthe fame kind ftrikes upon it * ? WHEN a body in motion Ouida pio another at-reft, the one lofes as much mo» tion as the other gains, in the fame direc+ tion, This is ordinarily faid to proceed from a reaction of the body that acquires the motion. The effect is indeed. the fame upon the percutient body; there is the fame change of its ftate as if it had actually received an impulfe in the con- . trary * Philof, Eflays, PHYSICAL anv LITERARY. 115 trary dite@ica! This, for the fake of fhortnefs, wé may, and always do call, the effe& of rea@ion; but we can never imagine that there is any real active op- pofition of the body at reft to the motion of the other. The great difficulty com- plained of, is in ‘conceiving how the one body has its motion diminifhed by the {troke as much as the other is increafed, while there is no active repugnancy allow- ed in the one to the other. It would be ridiculous enough to fancy, that the mo- ‘tion of the one was a part of the motion of the other; and that the very fame _ motion could be transferred from the one into the other. “ As well might the “ magnitude, figure, or colour, of one “ body be imparted to another.” But this we may venture to fay, that, for aught appears to the contrary, it follows from ‘the nature of a paflive, extended, and im- penetrable fubftance, that motion is loft in one by producing it in another. It will be eafily admitted, that one motion “may deftroy an oppofite motion, and by _ that means lofe of its own. Yet there is ne 116 ESSAYS anv. OBSERVATIONS no lefs difficulty here, than in the com= munication of motion. If two pieces of clay oppofing each other with equal for- ces, had any real activity of their own, it might be expected, that, though they both ftopt at their firft meeting, this was only done by fufpending the effect of each other’s action; and that they would re- fume their former degree of motion, upon being feparated by a man’s hand. We find, however, that the motion of both bo- dies is irrecoverably loft by fuch a colli- fion. If then the force of one body i is loft or confumed by deftroying force in an- other, Why may not one body as well lofe 1 force by producing i it in another? Be- fides, were there any real active oppofition in the body at reft, to the body i in motion, 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 i it. : WHEN a horfe pulls a {tone forwards, it-is commonly faid, that the {tone pulls the horfe back, with a force equal to that with which the horfe pulls the ftone fore= wards. PHYSICAL anv LITERARY. 117 wards. But nothing more can poflibly be meant, than that the horfe lofes as _ much force as the ftone gains: And that, with re{pect to. the horfe, the effet is the fame, as if there was no ftone tied behind him, but that he was pufhed back with a force equal to that acquired by the ftone, The active force of the horfe’s limbs pref- fes 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 progreflion: It is only equal to what is impreffed upon the ftone. THE equality of action and Tea¢tion i in the cafe of preflures, is to be underftood in the fame manner. When a finger is preffed again{t any body, the body is faid to react upon the finger, as much as the finger is made to aét upon the body. If the weight of the body be fuftained by the preffure of the finger, there will be an active refiftance from the power of gravi- ty. And, if the figure of the body be vio- = ently kept i in a bent or comprefled ftate, there will be an active refiftance from the caule 118 ESSAYS anp OBSERVATIONS _ eaufe of 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 bo- dy really rea&ts, or actively bears againft the finger. The effect indeed upon the finger is the fame, as if the body actually preffed upon it; but that effec can eafily be accounted for, without having recourfe to fuch a fuppofition. 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 im- preffion, ‘as if the hard body was preffed again{t it; becaufe, when the parts that come firft into contact with the body have their motion retarded, the other parts will advance farther forwards. Ir there was any contradiction or ab- furdity in the common opinion of the communication of motion, this would be a fufficient reafon for rejeCting it, though jt were ever fo agreeable to the natural ap- pearances of things, But fhall we main- tain, that every particular body can only . be PHYSICAL anv LITERARYuitag be moved by! 4. power of its own; and fhall we deny, that motion is-communis cated by one-body to another, merely, ber caufe we donot underftand the precife manner in which motion is either convey ed or preferved? Why do we not, forthe 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, shan how it moves another? AN appeal has been offered to bis com> mon fenfeof mankind, as ready to declare in favour of the activity of matter. If the faéts be fully reprefented, the public judgment need mot be declined) . What= ever \obf{curity; the learned may. find in this fubject of the communication of mo- tion, a vulgar obferver will-be very little ‘perplexed about the matter.» When a ftone is thrown out of the hand, and continues 0 move when left to itfelf; ‘there’ is no fear, but “ every perfon, who has not ftu- “died philofophy,” will rather attribute ‘this to a force fome how imprefled upon the ftone, than to any aétion or operation ir " of 126 ESSAYS aNp OBSERVATIONS of the lifelefs tone. It will never enter ito his head, that thé ftone’ flies away with wings of its own. Such a’ perfon, judging from: firft appearances, that alk motion languifhes and decays, may, like- ly enough, be inclined to think that body rather affects a ftate of reft than a ftate of motion ; and that the impreffed force would not remain for ever: But he will never entertain the fmalleft doubt, but; that as long as the motion continues, it is only an effec of the firft impulfe. And, having once granted that motion can con- tinue one moment as an effect after the action of the moving power is over, the fame reafon muft remain for its continu~ ance the next moment of time, and fo on for ever. When we fee a body continuing to move with the felf-fame velocity which 4s received from the hand, is it not more natural to fay, that it does fo for want of a power or activity to ftop itfelf, or ‘to deftroy this motion, than to imagine the body to be no way détermined by the im- pulfe, but to be carried on with an equal force by a power of its own continually exerted PHYSICAL anp LITERARY. 12% exerted after the impulfe.; Such obfequi= ‘ous complaifarice of the'ftone, in imita¢ _ ting fo exactly the motion. of the hand, gnuft appear extremely | curious 3. efpe- éially if we confider what a violent op- ‘pofition it. is fuppofed to have made, be- fore it yielded to the motion at fir. It brings to, remembrance the man in the parable, who faid, he would not go, but ayent: Or perhaps it may be likened to a young fellow. learning to. dancé, who bends his, limbs but aukwardly at firft fetting out, till, being led; about for a while in the mafter’s hand; he can after= wards tontinue 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, if feems to be the higheft injuftice to refufe it the power of fenfatiom and confcioufnrefs: . FRoM experience and obfervation we learn, that body is equally indifferent to Motion and reft, And this indifference appears to be the:naturat confequence of the moft abfolute inaiivity. Body muft “Vo gE, ke Q. ul ean 122 ESSAYS snp OBSERVATIONS exift either in the one ftate or the other. But, fuppofing it once exifting in a mo- ving ftate, the continuance of the motion implies no activity in the body, any more than it requires activity to preferve a qui- efcent body in aftate of reft. And we | may, with equal ‘reafon, inquire for the caufe of the continuation of reft, as fora caufe of the continuation of motion. PHILasOPHERS have indeed entertain- ed various opinions concerning the conti- muation of motion. Ariftotle endeavour- ‘ed to explain it by means of a vehicle or the circumpulfion of fluid matter, hereby only evading the»queftion, as the fame difficulty returned, how the motion of this fluid continued. And many of the mo- derns have imagined reft to be the proper ftate of inactive matter, to which it natu- rally tended; and have afcribed the con- tinuance of motion to the conftant and_ immediate agency of the Deity, or of fome delegated intelligent power. How far the concurrence of the Deity is neceflary to the fupport of created be- wags in general, is perhaps impoflible for us PHYSICAL anv LITERARY. 123 us to dete:mine’: But, unlefs fome conti- nual influence 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, how- - ever, it could be demontftrated, that bedy cannot continue to move on ina ftreight line, by virtue of the firft impulfe, what more rational folution will be found, than to have recourfe to the efficiency of an in-— telligent principle? For tho’ it fhould be granted, that the continuation ef motion, and the communication of it from one bo- dy to another, cannot proceed from the énértia of matter 3 Will it therefore follow, that every atom of unintelligent and un-_ defigning matter is endued: with an acti- -vity capable of moving it with the greateéft order and regularity, as well as variety sand diverfity ; conforming itfelf 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 prefervation of motion with thofe o- , shee active powers employed upon matter, though 124 ESSAYS anp OBSERVATIONS though not effentially belonging to it, (fuch as gravity, attra€tions and repul- fions of various kinds, &c-), and refet ‘them all to an intelligent caufe, if there be herein difcovered the fame Signatures of thought and defign? THIs leads us to another fource of ob- - jeGions againft the inactivity of matter. ‘As the very refiftance which matter makes to an external force, and its prefervation of the motion received, have*been taken for fymptoms of adtivity, we need won- “der the lefs to find an activity fufpected in matter from its gravitation, and thofe o- ther inftances where motion begins in bo- -dies, without any vifible caufe. rie - Irmay be objected, “ That a ftone falls J* to the ground without any external im- “pulfe, fo far as we can difcover; and “ therefore dead matter begins motion of Grfelf? Such manner of reafoning would make fhort work of natural philo- fophy. Becaufe there are a variety of mo- tions, changes, and transformations, pro- “duced every day amongft inanimate bo- dies’; Is it ftraight way to be concluded, that PHYSICAL and LITERARY. 129 that thefe bodies move themfelves? The contrary of this appears in fo many in« _ flances, as gives good reafon to believe ‘it never happens in any cafe. We fee for certain many motions begun by anima- ted beings ; we obferve many bodies mo: wed by the impulfe of other bodies; and the mechanical caufes of fome motions, have through time been difcovered, which were not formerly perceived. Once ina day, it was found philofophy to maintain that fmoak and vapour mounted upwards of themfelves by a principle of levity, though now one might as well af- fert that cork rifes up of itfelf in water. Many phznomena were explained from an abhorrence of a void, which was fully _’as reafonable a paffion in a dead body as, the love of a center, or an inclination to meet with other bodies. The rife of ‘water in pumps was afcribed to a felf— — ‘moving power in the water, and the pul- fation of the arteries to a- power they had _ of dilating themfelves. The power of -Mmagnetifm bears fomerefemblance to that . | ef gravity ; the theory of it is. ftill imper- fect: 126 ESSAYS anp OBSERVATIONS fe&t: Yet there are a multitude of facts which indicate a mechanifm by means of fome effluvia; particularly the new me- thod of making artificial magnets by at- trition, and the well known experi- ment, in which an iron rod is prefented to a magnetic needle, the fame end being _ made to attract, fometimes one pole and fometimes another, by only changing the pofition of the rod, or inverting it upfide down; and much more by ftriking upon it with a hammer, or beating it againft the ground. Klec¢tricity is another more palpable inftance of the fame fort. That a fluid is concerned in producing the ap- parent attractions and repulfions, and other more aftonifhing effects of the elec- ‘tric globe, can hardly be doubted, how- ever difficult it may ftill be to defcribe the Jaws to which it is fubjected in its opera- ‘tions. Why then fhould it be accounted “‘ whimfical”. or unphilofopical to de- mand a caufe for the attractive power of gravity? Though all the mechanical ac- counts hitherto given of the caufe ‘of gravity fhould be found unfatisfactory, . may PHYSICAL ann LITERARY. 127 may it not ftill be owing to fome unknowh mechanifm, or the intervention of rhatter, ‘moving other matter? Or, though it were dhown to be impracticable by ‘any mecha- ifn’, whatever, as is not’ improbably ‘the cafe, why may we ‘not attribute it to the immediate agency of an’ Feet ative ‘being? : IT ‘may be urged further by’ way: of ob- jeGion, “ That a power of beginning ‘vi- . “fible motion is no more connected with my a power of thinking, than it ig with any “ other property of matter or {pirit. ” This. _ may poffibly be admitted in’a certain fenfe, viz. that chere may, for aught we know, exift fome fpecies of thinking beings, de- ftitute of the power of motion altogether. _ Oifters have very little of it. But, howe- wer this be, we know, with all the cer- _ tainty attainable in phyfics, that many 1 thinking beings have fuch a power 5 we fee them begin motion, a relative motion on the ground. When that motion is lott is 4 they renew it and vary, it again at every Mt Aftep. They not ool, begin new Motion, re but PS 4s" 128 ESSAYS anD OBSERVATIONS ‘ but deftroy old motion, at pleafure: 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 fubject) betwixt animated and inant- -mated beings, with refpeét to motion, namely, that the thinking being can de- termine the direction and quantity of its motion, which is a power incompatible -with dead matter; and confequently it will of itfelf remain for ever incapable of the leaft motion. Thus far therefore there is a connexion betwixt motion and think- ing, that a power of beginning motion feems neceffarily to infer a power of think- ing ; though we cannot affirm inverfely, ‘that a power of thinking muft infer a power of beginning motion. Burt, if the bare beginning of motion feems to require an intelligent caufe, the power of gravity, furely, has the highelt title to lay claim to that origin. The’ motions arifing from gravity are evident: ly of fuch a fort, as cannot, without the greatelt See eee - PHYSICAL any LITERARY. 129 gteateft violence to reafon, be afcribed to any blind-tendency betwixt the attracting bodies. This will beft appear upon fta- ting 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 near@ ly to the center of the earth, (or exactly ' ina line perpendicular to thé level, furface) in the fame manner a iron does towards the loadftone, or a feather to the electric tube. The attractive force of a ftone di- minifhes, the farther it is removed from the earth, according to a fixed rule, of as _ the fquare of the diftance increafes. A _ body placed by itfelf would move no way}; but two bogies run together. “A given: body is more attracted to a large quantity of matter than to aleffer. Is it then conceivable, that an unthinking be- ing fhould’ be endued with an aétivity which it regulates and varies in proportion to the fituation, diftance, and magnitude’ Of another body, whilft it is fuppofed to’ be not in the leaft influenced or ated up- on by that other body, or any other Vort, R being 130 ESSAYS anp OBSERVATIONS being whatfoever? If this thall be maintained, another queftion will arife. By what actions, or what ftronger lan- guage than this, can any man convince his neighbour of his own reafon or un- derftanding? It is prefumed, that a high- er degree of evidence will hardly be re- quired. in phyfical matters, than what we have for the life and exiftence 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 | obfervable in the apparent mutual ten- dency of bodies, we are naturally led to conclude, that gravitation is the effect of the continued and regular operation of fome other being upon matter; and that bodies are either drawn or prefled toge- ther by fomething external, A power fo conftant, fo regular, and withal fo uni- formly varied and diverfified according to different circumftances, can proceed from nothing but an intelligent caufe, either mediately or immediately exerted upon bodies. | WHEN PHYSICAL anp LITERARY. 131 WueEn motion is obferved to begin in any body, it mu{t be afcribed to one or other of thefe four caufes; 1. Some ex- ternal animated being; 2. An external inanimated being ; 3. A felf-moving ani- mated faculty; and 4. A felf-moving inanimated faculty.. Of the former three, there are a variety of manifeft examples, Of the laft there can be no certain exam- ple at all; and confequently we fhould make a bad choice in preferring it to the others: Such a fuppofition, namely the production 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, Tuar fomething may begin to exift, or ftart into being without a caufe, hath indeed been advanced in.a very ingenious and profound fyf{tem of the fceptical' phi- lofophy * ; but hath not yet been adopted by * Treatife on Human Nature, 3 vols. ofavo. This is the fyftem at large, a work fuited only to the com- prehenfion of Adepts, An excellent compend or fum- mary 132 ESSAYS anv OBSERVATIONS by any of the focieties for improvement of natural knowledge, Such fublime con- ceptions are ‘far above the reach of an or- dinary genius; and could not have enter- ed into the head of the greateft’ phyfiolo- gift on earth. The man who believes that a perception may fubfift without a perci- pient mind or a perceiver, may well com- prehend, that an a€tion may be performed without any agent, ora thing produced without any caufe of the prodution, And the author of this new and’ wonderful dé@rine informs the world, that, when he looked into-his‘own mind, ‘he could dif- cover nothing but a feries of fleeting per-~ ceptions; and» that from thence he con- cluded, that! hé himflf was nothing but a bundle of fuch perceptions. . Mr Baxter,’'in his Jnguiry into the na- ture of the Human foul, and likewife in his Matho, endeavours. to prove, that gravity cannot be aproperty inherent in matter ; from mary whereof, for the benefit of vulgar capacities, we of this nation enjoy in the Philofophical Effays, and the Effays Moral and Political. PHYSICAL ano LITERARY, 133 from this confideration, that, if body had afi actual tendency to fall’ down, it could not at the fame time refift the downward - motion by its zwertia. Which reafoning plainly fuppofes, that there is a real adtive refiftance arifing from inertia, And ‘in- deed, though he exprefsly intends to deny the fmalleft activity in matter, yet he e- _ very where {peaks of inertia, as a conatus or tendency effential to matter, by which it makes a violent oppofition to the pow- er of gravity, and other a@ive powers. This being a queftion of the utmoft im: portance, it may not ‘be amifs to offer an amendment upon that argument, which will free it from any inconfiftency, and place it on its true bottom, on which’ a: lone it can ftand-its ground. To prove then that gravity does not proceed from any internal ative force of any kind, ei- therin the earth or fuch bodies as fall to- wards it, it is only neceflary to affume one axiom, that no fubftance can actively | tend to move to two oppofite fides, at the ‘fame time. It is eafy to conceive that a body 134 ESSAYS anp OBSERVATIONS body may be pufhed or drawn to oppo- fite fides, by two contrany external forces: In which cafe, if they are equal, the body will remain at reft; if unequal, it will be moved to one fide, by the difference of the two forces. Thus, every part of a ftag- ‘nating fluid is preffed equally in every direGtion. But if a body adtively tend to one fide, it cannot actively tend to the o- ther at the fame time, that being a contradiction in terms. And, in fat, we fhall find it impoffible to make two fuch efforts in our own bodies, to move them wholly to two oppofite fides. Thijs being granted, it follows, that if the waters of the fea gravitate towards the earth by an active force, they cannot, at the fame time, gravitate by their own activity to- wards the moon, fo as to produce the tides, And, therefore, the gravitation in one or both cafes is owing to an external influence. The fame argument, if it fhall be found conclufive, may be applied to the attraction of the moon towards the earth and fun, in the conjunctions, and other PHYSICAL any LITERARY. 135 other fuch like cafes, The attractions betwixt {mall corpufcles will be fhown to proceed from an external caufe in the fame maoner. And hence it will follow, | that’ elafticity and the chymical effer« -vefcéncies, are not the refult of the a@i- vity of attra€ting particles. And for the fame reafon a body thrown upwards cans not move up by an active force of its own; for that would be oppofite to the active - force of gravitation, | Ir, in order to evade the foregoing ar- gument, 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 difference of the forces with which it would tend to each of thefe bo- dies taken feparately: This will at leaft afford another remarkable inftance of that exact regularity with which the power of gravity is varied and adapted: to the dif ferent fituations of bodies; and which it is quite inconceivable that blind matter fhould perform without the fuperinten- dence of an intelligent being. 3 } Ir 136 ESSAYS AND OBSERVATIONS ~ -- Ir has indeed been frequently afferted, that bodies move towards each other by virtue of a law originally eftablifhed. But _law, that is to fay, a mere abftract name er complex notion, which is no real be- ing, cannot impell a ftone, and caufe it to begin to move.. Law by itfelf, with fub- miflion be it fpoken, will avail nothing, unlefs either the fubjects of it have under- ftanding to yield a willing obedience, or they be compelled to it by external force. Ir the firft appearances of things are to be trufted, there is full as good reafon to affert, that the earth draws the {ftonep or the magnet the iron, as'that the flone or iron move of their own accord. Yet the fuppofition of one body drawing a= nother body at a diftance, without the ins tervention of other matter, is univerfally rejected ; and that merely becaufe of the natural impoflibility of the thing. _ ‘That a being cannot act 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 PHYSICAL Ano LITERARY. 137 it hot equally felf evident, that dead mat~ ter can never begin motion of itfelf; far lefs regulate its motions according to a law? If bodies are not fenfible of the neigh- bourhood of other bodies, of their quan- tities of matter, and of their precife dif- _ tance from them; 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 attra@ion and repulfion are of fuch a fort, as could not be exercifed by the bodies themfelves, without either diftin& perceptions of their own fituations and magnitudes with re-~ fpec&t to other bodies, or a régular fuccef= fion of -fome kind of clear peréeptions, correfponding to every variety of ftuation and magnitude, and all this accompanied with a memory and a power of comparing’ paft with prefent perceptions. It would therefore make nothing to the prefent purpofe to have recourfé to that extraor= _ dinary fubterfuge, made ufe of by Mr Hobbs on a like occafion, That all mat- weyo..l. - S ter 133 ESSAYS anp OBSERVATIONS ter is endued with an obfcure fenfe and perception, and wants only. the organs and, memory of. animals, And it hath never yet been alledged, that all matter is effen- ‘tially endued with a clear and diftin@ fenfation or confcioufnefs., If it fhould, we need be at no lofs for an anfwer. For, were that the cafe, why have we no per- ception of this activity that is fuppofed to be exerted by our own bodies in falling to the ground? Dr Clark, Wollaften, and. others, have fo fully proved that matter is. incapable of any degree of thinking, that it is impofii- ble to confute.their arguments, but by. fcornfully denying the force of all meta- phyfical demonfirations whatever. If matter thinks, then either thinking is, ef- fential to all matter, or it arifes from the modification, magnitude, figure, or mo~ tion cf certain parcels of matters But what can be more ridiculous than to i- magine, that matter is.as effentially con- {clous, as itis extended! Will it not fol- low from that fuppofition, that every piece of matter, being made up of end- lefsly | bs PHYSICAL any LITERARY. 139 defsly feparable parts, (that is, of pafts which are as really diftin@ beings, not- . withftanding their contipuity, as if they thad been at the greateft diftance one from another), is made up alfo of innumerable wonfcioufneffes and infinite confuGon? And farther, if every part of matter be felf- conf{cious, it would be a contradiction to fuppofe that any fyftem could be fo: The refulting fenfation or confcioufnefs at daft being but one diftin@ fenfation or confcioufnefs, {as is that of a mani), the fenfation or confeioufnefs of every one of the conftituent particles would ‘be the individual fenfation or con: feioufhefS of all and each of the reft. Ia the next place, the faculty of thiaking cannot arife from the fize, figure, texture, er motion of body; nor-can be deftroyed by any alteration of thefe qualitics: Be- caufe bodies, by aly change of thefé, Gn- ly become greater of lef, round or {quare, rare or denfe, tranflatéd from one place to another, with this or that hew direction, or velocity; or the like. All whith ide- __-@$ are quite different from that of think-— oll d i. i nS my 4 i140 ESSAYS anp OBSERVATIONS ing; there can be no relation between them, | Tuis fort of reafoning deferves at. leaft fome direct anfwer, and is not to be overthrown by any criticifm on the mean- ing of the word zmmateriality, This, as is learnedly obferyed, moft certainly ‘* comes out to be merely a negative term, ** comprehending every thing that is not ‘© matter.” And itis not to be doubted, that if other terms, fuch as zmmortality and zufinity, were but examined with the fame “ {ufficient 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; the only difficulty lies in difcern- ing the ufe and importance of them. But, if the reafoning fubjoined to thefe premif- fes “be found entirely conclufive,” the confequence muft be, that, in judging of the qualities of matter, we are in every cafe to rely upon the report of our exter- nal fenfes, and never to employ our rea- fon, / PHYSICAL ann LITERARY. 141 fon in comparing one thing with another, : $b order to correct our firft impreffions. | -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 refpect, than the greateft philofopher ; and Copernicus is to be regarded as a common enemy to mankind, “‘ for declaring war againft our # fenfes,” : THE grand queftion to be refolved in this controverfy, is not, whether we have clearer conceptions of material or imma- terial fubftances, as we are equally igno- vant of both; but whether the power of thinking, which is a known faculty of fome fubftance, be not abfolutely indivi- fible, and, as fuch, incompatible with the known properties of matter? The moft plaufible objeétion that can well be made dagainft this argument, arifes from the late obfervations made concerning the po- lypus, and other living creatures of that kind. Yet thefe, when duly confidered, . . will 142 ESSAYS anb OBSERVATIONS will be found entirely confiftent with the indivifibility and unity of thinking fub- ftance. They do indeed exhibit a. re- markable peculiarity in the manner of the propagation of thefe animals; and. per- haps give fome ground for conjeCturing, that a number of animals, of a fyftem of thinking beings, may probably be con= joined 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 different kinds, though they do not growor extend themfelves to any larger dimenfions upon feparation, Other ani- mals were known, which, upon Jofing 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 univerfe may proceed at prefent without any guidance or direction, will find it dif- ficult to affign to himfelf any good rea fon why it might not always; or from e= ternity, have done the fame. The excel- lency PHYSICAL anv LITERARY. 143 lency and perfection of the material world can be no evidence to him: of an original architect or contriver of all things: Since the higheft excellencies and perfections are acknowledged, even. by. every Theift, to exift without a caufe. But the inftan- ces of a wife adminiftration, and fuperin- tendence, prefented every moment.to.our view, {trike the mind in the moft forcible manner, Weare eye-witnefles, of provic: _ dence, but not of creation. The contem- plation of every part.of nature furnifhes us with irrefiftible proofs of intelligence, counfel, and.defign, fill employed in ac- tuating, moving, conducting, and govern- in g the univerfe, ‘ Nihileft.enim, quodyra- tioneet numero. moveri pofhit fine confi- “ lio, in quo nihileft temerarium, nihil va~ rium, nihil fortuitum. Ordo autem fide- “ rumet conftantia, neque naturam fignifi- “ car; eft enimplena rationis: Neque fortu- “ nam, quae amica varietati con{tantiam refpuit. Quae qui videat, non impie “folum, verum etiam indoéte faciat, fi Deos efle neget. Nec fane multum in: * tereft, utrum id neget, aneos Omni pro- 7 ae ** curatione, 144 ESSAYS AND OBSERVATIONS — cyratione, atque actione privet: Mihi e= “ nim, qui nihil agit, effe omnino non vi~ “ detur.” C1c. de Nat. Deor« lib. IL. cape 16. | ~ We obferve indeed, in various inftan= ces, a f{ubordination of natural caufes and effects, and a dependence of one thing upon another. To inveftigate thefe, is the proper province of natural philofophy. The philofopher’s bufinefs is, to learn the conftitution of things as they really are; and to fearch out the laws and order efta- blifhed in the material world, and by which it is conducted. The moft fuccefs- ful inquirers into nature have feen moft reafon to refolve all things finally into an incorporeal, intelligent, and powerful firtk - caufe: And have rejoiced in the perfua- fion, that they themfelves, and all parts of the univerfe, are the offspring, and un- der the adminiftration, of the fame great, wife, and beneficent parent. But they are not folicitous in hmiting the number of fecond caufes, far lefs in excluding them altogether, as fome over zealous friends . pat mA PHYSICAL any LITERARY, ts friends to religion have done. Plutrach, in recommending the philofophy of A- Py \ . * 8 _ flaxagoras, obferves, that fuperftition pro- ceeds from ignorance of caufes, and want of experience ; but that natural phi- _ Tofophy banithes all fuperftition, and be- _ gets in the mind a well grounded piety, — - with comfortable hopes. Many fruitlefs attempts have. former- ly beén made to explain all the phaenome- _ tia of nature, on mechanical principles a- lone. But it is exceedingly furprifing, that, in the prefent age, fo eminent an a- -ftronomer as M. Maupertuis * fhould a- gain revive exploded notions, and fug- _ gelt, that the planets may poffibly be re- tained in their orbits by the motion of a circumambient fluid, as an ultimate caufe. There is nothing more demonttrably cer- tain, than that gravity cannot arife from the preffure of a'whirlpool, or vortex of a denfe fluid, once put in motion, and con: tinuing to move round of itfelfjas M. Des mo Vou. . ¥ Cartes _ . * Cofmologie, ’ 4 = 146 ESSAYS axpb OBSERVATIONS — Cartes imagined. And it is needlefs at pre= fent to examine, whether it can be better ex- plained by means of a rare elaftic ether. If Sir Ifaac Newton endeavours in that manner to account for gravity, the attrac- tion of cohefion, the refleétion and refrac- tion of light, &c. it is only with a view to point out fome more general mechani- eal caufe, upon which all thefe powers may poflibly depend. He never could believe that his ether was pofleffed of a real activity of its own. The elafticity of that fluid, muft ivfelf either proceed from fome higher mechanical caufe, or flow immediately from fome vital intelligent principle, which muft be immechanical.’ The mutual repulfions betwixt one parti- cle 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 phaenome- na of gravity ; and muft confequently be regarded as the continual effects of thought and defign. Ir feems to have been far from Sir I- faac’s ia - _ PHYSICAL anv LITERARY. 147 faac’s intention, to afcribe activity to mat: ~ terin any fhape; though his meaning has been fometimes miftaken *, To do fo, rt would be a manifeft contradiction to. the primary laws of motion, delivered by himfelf in the beginning of his Princi- pia. e ACCORDING to Spinoza, one piece of ~ matter is moved by another, and that by ‘athird; and thus there is a progreflion _ of caufes and effects, in infinitum, all aGting - blindly, without intelligence and defign. Not to repeat here the metaphyfical argu- ment againft the poflibility of an endlefs feries of dependent caufes of any kind, it will be a fufficient confutation of this {cheme to obferve, that it fuppofes” that an infinite number of undefigning beings A ean continually produce the greateft or- _ der, regularity, ‘and harmony: Which is _ ho better fenfe than to fay, that, though . one fingle cypher be of no value, yet an ::. infinite number of nothings can amount al to . a ae me * Philoophical Effays, ps 119, 148 ESSAYS ap OBSERVATIONS to a real quantity. There is no other poflible method whereby to judge of the intelligence or wifdom of any being, but by its fenfible effects; and we may as eafily fuppofe one fingle lifelefs being to produce by itfelf the ordinary effects of wifdom, as that they can refule from the fucceflive action of an infinite number of them. BrCAUsE the world is often compared to a machine, it hath been imagined, that, when once fet a going, it may continue its Motions without any further interpofi- tion of the Author of nature, or any other being. If we attend, however, to any ma- ‘chines of human contrivance, we only learn, that all their motions'depend upon certain active powers, as gravity and ela- fticity. Thefe are employed by ingeni- ous artifts, fuch as they find them, to many ufeful purpofes in life. But it is. by confidering the effects of thefe powers in general, and without regard, to any particular application of them, that we muft determine concerning théir nature. ' And it hath been already attempted to fhew, se ‘ae Bet \ b i | _ fhew, that they are all probably derived : PHYSICAL any LITERARY. 149 _ from an aétive intelligence, either immedi- ately or mediately exercifed upon matter. A connection manifeftly appears amongtt dif- ferent parts of the fyftem of the world; and many bodies in it, though dead and inanimated, are not only moved and agi- tated themfelves, but communicate mo- tion to each other, according to a certain fixed and eftablifhed order, which is cal- - led the courfe of nature. »But there is no foundation in mechanics for imagining, that a lifelefs body, in confequence of a law promulgated fome thoufands of years , . ago, can move itfelf with as much regu- larity and variety, as if it was actually endued with thought and reflection. Tuts, to moft people, will appear an impoflibility, as much as to make a blind man to fee, whilft he continues blind. And there are few, but will at leaft ac- knowledge the contrary opinion to be fupported with fo high a degree of pro- ___ bability, as juftly to deferve the preference. _ “ Haec quidem, fi non vera, faltem veri- fimillima videtur.” . | | In 459 ESSAYS anp OBSERVATIONS “Iv is alledged, that the fyitem of the “‘ world would difcover more contrivance, “¢ if it went on of itfelf, without any con- * currence of the Deity.” That Mr Boyle gives any countenance to this opinion, cannot be pofitively concluded from his words. He does not fay, that brutesmat- ter moves itfelf, but that ‘it is managed ‘< by certain laws, and upheld by God’s “ ordinary and general concourfe.” The lefs power is exerted to produce a gi- ven effect, the mechanifm may juftly in- deed be efteemed the more perfect. But a machine going on without a movmg power at all, is a thing quite unheard of, And where would be the beauty of every body, every wheel moving itfelf, without _ a dependence of one part upon another? ‘There would then be no mechanifm at all. Let the machine be as grand and perfect as poflible, it muft ftand in need of a firft mover, not only to begin the motion, but to preferve it. If every part {ponta- neoufly moved itfelf, it 1s then no ma-= chine; fome other name muft be found for fuch an arrangement or fyftem of | things. ef it c . ee at PHYSICAL ano LITERARY. 155 — things. If all the motions and changes of bodies are performed immediately by thefe bodies themfelves, without the influ=’ ence of other matter, or any other power, _ there is an end of all inquiries into _ caufes and effects; philofophy muft be degraded to a bare knowledge of faéts, a hiltory of nature. THERE is an argument, in the form of a reductio ad abfurdum, brought againtt the received opinion of the equality of aétion and reaction, which had almof been overlooked. The fubftance of it is this, that as the preflure wndequaque is a confequence of the law of equal action and reaétion in fluids; fo the fame fort _ of preflure ought to be a property of fo- hid bodies likewife, if the fame Jaw be univerfally extended to all bodies, folids as well as fluids. For a ready anfwer to this objection, we need only recolle& the definition of a fluid, as diftin guifhed from a folid body. An undequaque- preffure can- _ fot obtain in a folid body; uinlefs the par- ticles of it did yield t6 any fi orce exereifed - upon them; and, in yieldi: dg, were eafily put t52 ESSAYS anp OBSERVATIONS put in motion amongft themfelves ; or, in other words, unlefs the folid body was converted into a fluid. A parcel of dry fand may bear fome fmall refemblance to a fluid; its particles may be moved more eafily amongft one another than thofe of a firm body, whofe parts are clofely united by attraction: Yet ftill there muft be a confiderable adhefion of the particles of fand, on account of their irregular fi- gures, and the inequalities on their furfa- ces. When a man applies his hand to a hole in the fide of a veffel of water, he fuftains a preffure from the tendency of the particles to flide down and make their efcape: But, when his hand is laid on the | fide of a fand+bank, there is no fuch pref- fure to be felt; becaufe the particles are intangled together, and fupport one ano- ther. Thus a body laid upon a rough in- clined plain, may remain fixt, by the res fiftance from attrition alone; whereas, if the plain be fmooth, fome other power becomes neceflary to hinder the defcent of the body. i "Fue Dart seek PHYSICAL anp LITERARY. 193 | THE mechanical ation and reaction of matter, or the changes, with regard to mo- tion and reft, which take place in the col- lifions of non-elaftic bodies, have been al- réady confidered, and were found to bé | intirely confiftent with the moft abfolute inertia. But, that real ations, and equal oppofite reactions, obtain in thé active powers of attraction and repulfion, is a- greeable to perpetual experience, and is no lefs certain, than. that thefe powers themfélves are eftablifhed in nature. We find the loadftone attracts iron; and that iton attracts the load{tone, with equal force; and, becaufe they attract each o- ther equally, they remain at réft when they come into contact. Ifa mountain, by its gravity, prefled upon the earth, and the earth did not react equally on the mountain, then the mountain would ne- ceflarily carry the earth before it, by its preflure, with a motion accelerated in in- jinitum. The fame is to be faid of a ftone, * or the leaft part of the earth, as well as of i a mountain. A mutual at traction too is io LE. 3 U obferved 154 ESSAYS anv OBSERVATIONS. obferved amongit the diftant bodies of the folar fyftem, _, WHEN a heavy body lies upon a table, and confequently acéts upon it with its whole weight, there muft be an equal re- action from the power of cohefion of the parts of the table, im order to fupport the burden, In the fame manner, if the bot= tom of any veffel fuftains the weight of a certain quantity of fand, it muft reac with a force equal to that weight ; other- ways it muft break or give way. The power of cohefion may indeed greatly exceed the particular weight which it hap- pens to counteract at any time: And the > fame table, at different times, may fup- port very different degrees of weight. But 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 barely fupports the body without beginning motion in it. If this needs any illuftration, we may fuppofe a man to have a weight hanging at his hand, while at the fame time he preffes that hand upwards again{t any fixed body, the force with -~> PHYSICAL anp LITERARY. 55 with which the hand adheres to, or is prefled againft the body, may be greater or lefs at pleafure ; but the force employ- ed-againft the weight, or that which di- rectly oppofes and counteracts it, muit exactly be equal to the weight itfelf. ’ ‘THE argument againft the law of ac- tion and reaction may. be made to con- clude with equal force againft the law of gravity itfelf; and, if it proves any thing atall, willeven prove it impoffible that all terreftrial bodies fhould be endued with weight. Mutatis mutandis, the rea- foning proceeds thus. Admitting the law of gravity, a fmooth level furface muft be the confequence. And, as the law is not confined to fluids, but is fuppofed to be an univerfal law of matter, a {mooth level furface muft not only be the confe- quence 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 fand, 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: 4 doubt ;56 ESSAYS anp OBSERVATIONS doubt betwixt thefe two oppofites? We are certain that a fmooth level furface is not a neceflary property of folids. The gravity ofa whole hill of fand, is but an affertion without evidence. Whatremains — then, but that we adhere to the former, and reject the latter, except as to fluids? And thus our author luckily, tho’ with- out intention, has furnifhed a very con- vincing argument againft the univerfality of this fuppofed law of gravitation. If a fmooth level furface is an effect of this law, it follows clearly, that this law takes not place in folids, at leaft not univerfally, asin fluids, 9 3 ART. ‘ PHYSICAL anp LITERARY. 157 Art. Iii. Pappi Alexandrini Collectionum mathemati- carum Libri quarti Propofitio quarta gene- ralior fatta, cui Propofitiones aliquot eo- dem fpectantes adjiciuntur ; ; Auctore MAT- THEO STEWART, 7 Academia Edinen- fi Mathefeos Profeffore- PROP. Iv. Lib. 4. Collect. Matth. Pappi Alexandrin. Sit [Tab. 1. Fig. 1.] circulus ABC, cujus centrum E, diameter BC, et recta linea -contingens AD, quae cum BC in punc- to D conveniat. Ducatur autem DF, et junéa AE, producatur ad G, et FKG et GLH jungantur. Dico KE ip- fi EL aequalem effe. . Fadtum jam fit; et ipfi KL parallela du- _ gatur HXM. Ergo MX eft aequalis XH; | ducatur etiam a puncto E ad FH perpen- i, dicularis 158 ESSAYS anp OBSERVATIONS — dicularis EN: Aqualis igitur eft FN ip NH: Erat autem et MX aequalis XH: Ergo NX ipfi FM eft parallela; et angu- Ins HNX aequalis eft angulo NFM; hoc - eft, angulo HAX; et in circulo font pune- ta A, N, %,H; eft igitur angulus ANH aequalis angulo AXH, videlicet angulo AEL: Et propterea in circulo funt puncta © A, E, N, D; rectus eft enim utergue an- gulorum EAD, END. Componetur autem fic. Quoniam u- terque angulorum EAD, END eft rectus, pundta A, D, E, Nin circulo erunt. Factum jam fit. Et ducatur DL pa- fallela re€tae AC, reétis CB, CF, CG oc- i | currens 176 ESSAYS ann OBSERVATIONS currens in L M, N; et ducatur LO paral- lela rectae AB, rectis CF, CG occurrens in GQ, P. 3 QuontaM eft rectangulum HAK ad rectangulum HBK ut quadratum ex AD ad quadratum ex DB, hoc eft, ut quadra- tum ex CL ad quadratum ex LB; et eft rectangulum HBK ad rectangulum OLP,, ut quadratum ex CB ad quadratum ex CL; erit rectangulum HAK ad rectangu- lum OLP, ut quadratum ex CB vel AC ad quadratum ex BL: Et, alternando, erit rectangulum HAK ad quadratum ex AC, ut rectangulum OLP ad quadratum ex BL. Rurfus, quoniam eft OL ad LM ut HA ad AC, et PL ad LN ut KA ad AC; erit [Zem- ad prop. 2-]| rectangulum OLP ad rectangulum MLN, ut rectangulum HAK ad quadratum ex AC, hoc eft, ut rectangulum OLP ad quadratum ex BL. Eft igitur re@tangulum MLN aequale quadrato ex BL, hoc eft, quadrato ex DL. Quod quidem| Prop. praec.] verum eft. CoMPoNETUR autem fic. Quoniam eft rectangulum MLN aequale[ Prop. praec-} | quadrato PHYSICAL anv LITERARY. 177 quadrato ex DL, hoc eft, quadrato ex BL, erit rectangulum OLP ad rectangulam MIN ut rectangulum OLP ad quadra- tum ex BL: Quoniam vero eft HA ad-AC ut OL ad LM, et KAad AC ut PL ad LN; erit rectangulum [per Lem. ad prop 2.] HAK ad quadratum ex AG, ut rectangu- lum OLP ad rectangulum MIN, hoc eft, ut rectangulum OLP ad quadratum ex BL: Et alternando, erit retangulum HAK ad reGangulum OLP, ut quadratum ex AG vel BC ad quadratum ex BL: Ef autem rectangulum -OLP ad rec- tangulum HBK, ut quadratum ex CL ad quadratum ex CB; quare erit rectangu- lum HAK ad re@angulum HBK, ut quar dratum ex CL ad quadratum ex BL, hoc - eft, ut quadratum ex AD ad- amet ex DB. Q.E.D. PROP. VI, Tab. 1. Fig. y, Sint duae rectae AC, BC, circulum con= tingentes in 4, B, et fit D punctum in _ reGta AB; fit recta EF, rectis AC, BC _, occurensin FE, F, et juncta CD in G; fi per puncdtum D. ducatur guevis recta oA Vou. I. Z circulo 1y8 ESSAYS np OBSERVATIONS circulo occurrens in H, K, et CH, CK jungantur, rectae EF occurrentes in L, -M; erit reciangulum LEM ad rectans gulum LEM, ut quacratum ex GE ad- guadratum ex GE, FaGtum jam fit. Per pun@um D ducas tur recta parallela reGtae AC, rectis CB, “CH, CK occurrens in N, O. P; per punce 4um.N ducatur recta parallela rectae EF, : redtis CH. CK occurrens ‘ia Qi; et per punctum F ducatur FS parailela rectae AC, re€tae CD occurrens in S. Quoniam eft re&angulum LEM ad rec- tangulum LFM, ut quadratum ex EG ad quadratum ex FG, hoc eft, ut quadras tum ex EC ad quadratum ex FS; erit,al- ternando, rectangulum LEM ad quadra- tum ex EC, ut rectangulum LFM ad quadratum ex FS: Quoniam eft rec- tangulum QNR ad quadratum ex CN ut reclangulum, LEM ad quadratum ex CF, et eft quadratum ex CN ad quadratumiex | ND, ut quadratum ex CF, ad quadratum © ex FS; erat rectangulum QNR, ad qua- dratum PHYSICAL anv LITERARY. 179 dratum ex ND, ut re@tangulum LFM ad quadtatum €x FS, hoc eft, ut reangulum — LEM ad quadratum ex EC. Quoniant véro éft LE ad EC ut QN ad NO, et ME ad EG ut RN ad NP, erit [per Lem. ad prop. 2.] rectangulum LEM ad quadra= tum ex EC; ut rectangulum QNR ad rec- tangulum ONP; quare erit rectangulum QONR ad rectangulum ONP, ut rectan- gulum QNR ad quadratum ex ND: Eft igitur rectangulum ONP aequale qua- drato ex ND. Quod quidem | per Prop. 4.| verum eft. Componetur autem fic. Quoniam eft reCtangulum ONP aequale quadrato ex ND, erit reCtangulum QNR ad rectangu- tum ONP ut rectangulum QNR ad qua- dratum ex ND; et quoniam eft LE ad EC | tt QN ad NO, et ME ad EC ut RN‘ ad NP, erit reG@tangulum LEM ad guadra- tum ex EC, ut reclangulum QNR ad rec- _tangulum ONP, hoc eft, uf®reGtangulum - QNR ad quadratum ex ND. Quoniam ¥ero eft rectangulum QNR ad quadratum "Ss a CN, ut rectangulum LFM ad quadra- tum ex CF, et eft quadratum ex CN ad quadratum 180 ESSAYS anp OBSERVATIONS — quadratum ex ND, ut quadratum ex CF ad quadratum ex FS; erit rectangulum QNR ad quadratum ex ND, ut rectan- gulum LFM ad quadratum ex FS; quare erit retangulum LEM ad quadratum ex EC, ut rectangulum LFM ad quadratum ex FS: Et, alternando, erit rectangulum LEM ad rectangulum LIM, ut quadra- tum ex EC ad quadratum ex FS, hoc eft, ut quadratum ex EG ad quadratum ex PO) EDs ~ PR OVP ao NET Tab. 2. Fig. 10. Sit recta AB circulo occurrens in A, B, et in ipfa fumatur punctum C, et du- catur CD circulo occurrens in D, E, et AD, BE jungantur fibi. mutuo occur= rentes in F ; ducatur CG parallela rec- tae AF’, rectae BF occurrens in G: Si per punctum C ducatur quaevis recta circulo occurrens in H, K, et FH, FK jungantur, rectae CG occurrentes in L, M>; erit rectangulum LGM aequale quadrato ex CG, FaCtum . _ = _ RE ee ete x | } PHYSICAL ann LITERARY. 181 -Fa@tum jam fit. Jungantur CF, et oc- currat recta CH rectis AF, BF in N, O; per puactum O ducatur redta’ parallela rectae CG, vel AF, reétis FL, FM, FC oc- currens in P, Q. R, et rectis AB, DE in my 1 Quoniam eft easels LGM aequale quadrato ex CG, et eft rectangulum POQ | ad quadratum ex OR, ut rectangulum LGM ad quadratum ex CG; erit refian- gulum POQ aeguale quadrato ex OR: Et eft rectangulum HOK aequale reCtangulo EOB; quare erit rectangulum HOK ad retangulum POQ,, ut rectangulum EOB ad quadratum ex OR; et quoniam eft HN ad NF ut HO ad OP, et KN ad NF ut KO ad OQ, erit (perLem. ad prop. 2.) rectangulum HNK ad quadratum ex EN, - ut rectangulum HOK ad rectangulum POQ , hoc eft, ut reGangulum ECB ad quadratum ex OR: Eft autem quadratum ex FNadrectangulum AND, ut quadratum ex OR ad rectangulum SOT ; quare erit rectangulum HNK ad re@tangulum AND, ent rectangulum EOB ad rectangulum » | Et quoniam eft retangul um HNK ' aequale 182 ESSAYS anp OBSERVATIONS aequale reCtangulo AND, erit refangu= Jum EOB aequale reCtangulo SOT ;_ qua- re erit OB ad OS ut OT ad OE, hoe eft, érit BG ad GC ut GC ad GE: Eft igitur angulus GEC aequalis angulo GCB, hoc eft, angulo BAD; quod quidem verum eft, quoniam pundia A, B, E, D, funt in cir- culo. Componetur autem fic. Quoniami ~ punda A, B, E, D funt in circulo, erit angulus GEC aequalis angulo BAD, hoc | eft, angulo GCB; quare erit BG ad GG ut GC ad GE, hoc eft, eritOBad OS ut OT ad OE: Eft igitur re@angulum SOT. aequale rectangulo EOB, hoc eft; reCtangulo HOK; quare erit rectangu- lum HOK ad quadratum ex OR, ut rec= tangulum SOT ad quadratum ex OR, hoc eft, ut rectangulum AND, vel HNK, ad quadratum ex FN. Quoniam vero eft HN ad NF ut HO ad CP, et KN ad NF ut KO ad OQ, erit reftangulum HNK ad quadratum ex FN ut reGtangulum HOK ad rectangulum POQ ; quare erit relangulum HOK ad rectangulum POQ , wt PHYSICAL anp LITERARY. 183 ut retangulum HOK ad quadratum ex OR ; eft igirur rectangulum POQ aequa- Je quadrato ex OR: Et quoniam eft rec- tangulum LGM ad quadratum ex GC, ut rectangulum POQ ad quadratum ex OR, erit rectangulum LGM aequale qua- drato ex GC. Q.E.D. PROP. VI. Tab.2. Fig. tt. Git recta AB circulo oceurrens in A, B, et - 4n AB fumatur punctum C, ducatur CD circulo occurrens in D, E, et jun- gantur AD, BE, fbi mutuo occurren- tes in F; per punctum C ducatur quaevis recta circulo occurrens in G, H, et FG, FH jungantur, rectae AB eccurrentes in K,L; erit retangulum KAL ad -rectangulum KBL, ut qua- dratum ex AC ad quadratum ex BC. - FaGum | jam G fs. Ducatur CM parallela 2 aectae AF, rectis FB, FK, FL occurrens in __-M,N,O; et per punctum-M ducatur pa- 4 . rallela t f 4“ 4 ws 184 ESSAYS anp OBSERVATIONS | rallela rectae AB, rectis FK, FL occurrens in P.Q. Quoniam eft rectangulum KAL ad rec tangulum KBL, ut quadratum ex AC, ad quadratum ex BC, hoc eft, ut quadratum ex FM ad quadratum ex BM; et eft rec- tangulum KBL ad rectangulum PMQ ,ut quadratum ex FB ad quadratum ex FM; erit rectangulum KAL ad rectangulum PMQ,, ut quadratum ex FB ad quadra- tum ex BM, hoc eft, ut quadratum ex AF ad quadratum ex CM: Et, alternan- do, erit retangulum KAL ad quadratum ex AF, ut rectangulum PMQ ad quadratum ex MC. Quoniam vero eft PM ad MN ut KA ad AF, et QM ad MO ut LA ad AF; erit (per Lem. ad prop. 2.) rectangulum _PMQ ad rectangulum NMO, ut rectangu- ium KAL ad quadratum ex AF, hoe eft, ut retangulum PMQ ad quadratum ex CM: Eft igitur rectangulum NMO ae- quale quadrato ex CM. Quod quidem (per Prop. praec.) verum eft. Componetur autem fic. Quoniam eft rectangulum NMO aequale quadrato ex MG, erit reCtangulum PMQ ad rectangu- lum |" PHYSICAL AND LITERARY. 185 jum NMO ut re@angulum PMQ_ad qua- - dratum ex MC: Quoniam vero eft KA ad AF ut PM ad MN, et LA ad AF ut QM ad N 0; erit reQangulum KAL ad quadra- et am 1 ex bce ut TR PMQ ad sea Mc, hoe sie: ut sida < FB ad quadratum ex BM; 3 et eft) ngulum ~PMQ: ad ‘rectangulum, sre ut quadratum ex FM ad qua- tu 1 ex FB; quare erit rectangu-’ \L ad retangulum KBL, ut eft I FM ad quadratum ex: BM, R quaestsio’ eX AC ad d quadra- on. Ix, Tab, 2, Fig. L23:: a circulo, occurrens in A, B, Ra eS pettig 186 ESSAYS AND OBSERVATIONS rectis AF, BF cccurrens in.G, Hi, et junc- ta FC in K: Si per punctum C du- catur quaevis recta circulo occurrens in L, M, et FL, FM jungantur, rectae GH occurrentes in N, O; erit rectan- gulum OGN ad rectangulum OHN. ut guadratum ex GK ad quadratum ex BAK 5 (A226, | Factum jam fit. Ducatur per puactum C parallela rectae AF rectis FB, FL, FM oc- currens in P, QsR 3 et per punctum y du- catur parallela rectae GH rettis FL, FM occurrens in 5, T, et ducatur HV paral- lela rectae PC rectae FC occurrens in V. — Quoniam eft rectangulum OGN ad rec= rangulum OHN, ut quadratum "ex GK, ad quadratum ex HK, hoc eft, ut qua~ dratum ex FG ad quadratum ex HV; erit, alternando, rectangulum OGN ad qua- dratum ex FG, ut rectangulum OHN ad quadratum ex HV: Quoniam eft reCtan- gulum SPT ad quadratum ex PF, ut rec- tangulum OHN ad quadratum ex. HF, et eft quadratum ex PF ad quadratum ex PC, ut quadratum ex HF ad quadratum ex PHYSICAL anv LITERARY. 187 ex HV, erit reGtangulum SPT ad quadra- tum ex PC, ut rectangulum OHN ad qua- dratum ex HV, hoc eft, ut reCtangulum 4OGN 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.] rectangulum OGN ad quadra- tum ex FG, ut reGangulum SPT ad rec- tangulum QPR; quare erit reangulum SPT ad reGtangulum QPR, ut rectangu- lum SPr ad quadratum ex PC. Efi igi+ tur rectangulum QPR aequale quadrato ex PO. Quod quidem [per Prop. 7.] ve rum eft, ; Componetur atitem fic, Quoniam eft rectangulum QP aequale quadrato ex PC; erit reGangulum SPT ad re@angu- dum QPR, ut rectangulum SPT.ad qua- dratam ex PC: Et quoniam eft NG ad FG ut SP ad PQ, et OG ad GF ut TP ad PR, erit reCtangulum OGN ad qua- dratum ex FG, ut reCtangulum SPT ad ns rectangulum QPR, hoe eft, ut re@angu-" lum SPT ad quadratum ex PC. Quoni-' _ am vero eft recangulum SPT ad gquadra- tum ex PF, ut reGtangulum OHN ad qua- dratum 188. ESSAYS ANp OBSERVATIONS — dratum ex HF, et eft quadratum éx FP ad quadratum ex PC, ut quadratum ex ex HF ad quadratum ex HV> erit ‘rec- tangulum SPT ad quadratum ex PC, ut rectangulum OHN ad quadratumex HV: © Quare erit rectangulum OGN ad quadra- tum ex FG, ut retangulum OHN ad quadratum ex HV: Et, alternando, erit — reGtangulum OGN ad retangulum OHN, ut quadratum ex FG ad quadratum ex HV, hoc eft, ut quadratum ex GK ad quadratum ex HK. Q.E.D. sa SCS Bor ee Ie Propoftione ante dictae in fectionibus quoque conicis obtinent. Idque reputanti Sequen= q tia obfervata funt theoremata, a quibus — alia etiam multa deduct kale | THEOR. ft. Sint [Tab. 2. Fig. 13 J ise certae \AB, CD, fectionem. conicam con- tingentes inA, C; et A,C jungantur; fic — ‘quaevis recta, rectis AB, CD, AC occur rens - B, D, E, et fectioni in F, G fama wy whee ‘a EOR. 2. Sit [Tab. a». Fig. tad: recta fectionem conicam: contingens in A, recta CD feétioni occurrens: in.€,:-D | pene 3 et aime AG, AD; occur- & ; Brit : «3.In ‘abe 20 “Figs al a - tione conica ieiestbistes duae. reCtae AB; y sae cet jungantur AC, BD; si ‘oceurratgne x ket AB, Dy 2 AC, BDA in i ft? f pet fue Theorem. L2 190 ESSAYS asp OBSERVATIONS | Ut finem faciam; theorema unum tantum fubjiciam, obfervatione quidem haud indignum; et quod etiam in fectio- nibus conicis; paululum mutatum, obti- net; unde alia, a nullis, quod {ciam, ferip- toribus geometricis obfervata, deriventur. Sit AB diameter circuli {Tab. 2. Fig. 16. 17.] pofitione dati, occurratque retta CD ipfi normalis in dato puncto C; non fit autem C centrum circuli, et datum fit punctum D in recta CD ; ditque quadra- tum ex CD majus rectangulo ACB, ff fit punctum C intra circulum; fi vero ex- tra, fit quadratum ex CD minus rectan- gulo ACB; producatur DC ad E, aot fit CE aequalis ipfi CD-; dabuntur duo puncta F, G extra rectam DE, ut, fi ab ipfis infletantur rectae FH, GH ad punc- tum quodvis H in circulo, rectae DE oc- currentes in K, L, erit fumma quadra- torum ex DK, EK ad rectangulum DLE in ratione data. ART. pHYSICAL any LITERARY. Io ART. Vv. af the Caufe of rhe Variation f the Obliqui- “ty of the Ecliptic, by Cotrw M'Lavrin, “fate Fellotw of the Royal Society, and --Profeffor of Mathematics in’ the Ui never= S y of all HE frida aftrodbneds in Peru, and’ Dr Bevis at London, arid others elfe- ied. have: endeavoured to determine the obliquity of the ecliptic with greater accuracy than former aitronomers had attained to. The refult of their obferva- tions makes it to be now about 23° 29/ 281, It had been for fome time reckon- ed'23° 29''29%; and before that, 23° 29% 30"; and, “by fome antient aftronomers, Ig or 20 minutes greater. Meff. Caffini and Bradley had found it to vary a little : And this has given occafion to a notion, Ee _ 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 | 19% ESSAYS anv OBSERVATIONS | it has been gradually rifing, till now it contains an angle with this plane of 66° 30° 31’; and that, in a long period of time, it will become perpendicular to this plane ; when we fhall have'every where a continual fpring throughout the year. The Chevalier de Louville and M. Godin pretend even to compute the period of this motion; the former having gone to Marfeilles to meafure the variation of this obliquity from the time when Pitheas mea~~ fured it at the fame place 2000 years ago; he found it diminifhed by 20’, and thence eftimates the period of this motion to be above 2 millions of years. M. Godin has fince found, that, from the year 1655 to, 4734, it decreafed 55”, by comparing an obfervation of old M. Caffini’s with his ‘ewn, and thence deduces the period to be 1944000 years, And hence fome authors: have endeavoured to explain: feveral: old Egyptian and Babylonith traditions, con-: cerning the fun’s having rifen twice in the weft; and have taken occafion to indulge: themfelves in feveral {peculations. - PHYSICAL anv LITERARY. 192 _ Twave formerly feen a piece that was printed many years ago, but never, I think, publifhed ; containing a fy{tem and _akind of liturgy for the Pantheifts or Spi- by nofifts; wherein the author warmly e- Ms eet this notion, coucerning the varia~ . 3 tion of the obliquity of the ecliptic, and ~ endeavoured to improve it, for fupporting his favourite principle of equality; ima- ‘gining, that, in the compafs of this pe- riod, the ftate and phenomena of all pla- ces on the earth would be upon the whole equal ; an opinion that feems to fuit the _ patrons of a blind and abfolute neceflity: _ But, whatever be thought of this continu- al and regular diminution of the angle in which the ecliptic and equator interfect each other, it is certain that fuch an equa- ~ Jity would not be the confequence of it. Places of the earth would ftilf have their , peculiarities: Fhe people at the equator - would have their days and, nights con- | ftantly equal, how great or fmall foever _ the obliquity of the ecliptic were ; for this a neceflary confequence of their defcri- J A Bb bing 194 ESSAYS anp OBSERVATIONS bing a great circle of the carth by the di- urnal motion, that is always bifected by. the boundary of light and darknefs, which, is likewife a great circle in confequence of a neceflary truth. The poles would haye their fix months day and fix months night, as now; with this further fineularity, that, when the axis lay in the plane of the ecliptic, the heat muft have been far more intolerable at the poles than is now known in any part of the earth, or could be known in any other part of it, during this long period: For the fun mutt have then con- tinued ten days together within 5° degrees of the zenith of the poles, without any: intermiffion of night, or abatement from a lefler elevation, at which altitude he ne- | ver continues above 40° in the equino*ti- al days at the equator; a peculiarity as fingular as it would have been fatal to the polar regions. ‘The prefent obliquity of the ecliptic gives evidently great relief to the equatoreal regions ; as by it the fun is carried to both fides of the zenith dus ring the year, and is not permitted to dart conftantly : | PHYSICAL ann LITERARY. 195 conflantly perpendicular rays upon them, It is to it likeways the more northern touintries owe their Lalas iis Marvels two Siesta or very little more, while the fun’s almoft continued and inceflant action ripens fruits, which the heat of our ~ fan, much lefs theirs, on the 1oth of March, thé equinottial day, could never be able to accomplifh. Thus it ferves for diminifhing their heat at the equator, where it was ufeful to leffen it; and for increafing it towards the polar regions, where it was proper to ftrengthen it. But a regular and continued variation of the obliquity of thé ecliptic would ruin fome parts of the world, and difturb 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 fup- port this doctrine, from old fables of E- _ gyptian or Babylonifh priefts delivered i) ¢ to Herodotus, that feem to. have flown | from their vanity. What is {hewn by Dr Shaw in his travels, concerning the | gradual 196 ESSAYS avy OBSERVATIONS gradual rifing of the furface of the land of Egypt, from the annual fediments of the Nile, feems to afford a much better argument againit their boafted antiquity | in Egypt, than any thing that can be drawn from aftronomical obfervations, to fupport a vanity fo univerfal, that we need not go very far from home to find abfurd enough inftances of it. As for what is faid of Pitheas and other ancients, their wrong notions concerning the re- fractions, and the imperfection of their inftruments, render any conclufions on fo nice a fubject, drawn from their ob- fervations, dubious. We ought to fhew more regard to the modern obfervations brought for this doétrine, than to repre- fent them in a level with the fables vent- ed by the priefts of Egypt. According to feveral modern obfervations, the obli- quity of the ecliptic 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; and, from his errone- ous opinions concerning the refraction of cl PHYSICAL and LITERARY. 197 of the atmofphere, made the mean di- {tance of the moon lefs by 4 femidiames ters of the earth than it really is. It is true, Mr Caffini’s obfervation in 1655, compared with late ones, makes it vary at the rate of 55’. in 79 years. Let us therefore fee, if.a variation, fuch as that arifes from Meff: Caflini’s and Goden’s obfervations, be not a confequence of principles already eftablifhed in the folar fyftem ; and offer fome hints of a method by which it may be afcertained whether this be the jait folution of this queftion, and how, from a proper feries of obfer- vations, made with great exactneis, an - improvement and correction in geogra- phy and navigation may be deduced from. this inquiry, by bringing the theory of ' the earth’s motion in her orbit, and fappofes the tables of his declination to 3 t particularly what relates to the declina- tion of the fun, to greater perfection. | This will be the more ufeful, that the u- fual methods of taking the latitude of places by the fun’s meridian altitudes, be i % ig8 ESSAYS anp OBSERVATIONS be perfectly juft ; whereas there is ground to doubt of their precifenefs. MaTHEMATICAL inftruments in ge< neral, and fuch particularly as ferve for aftronomical purpofes, have been, of late, brought to an exaétnefS never known in former times. Hence fome minute mo- tions, or inequalities of motions, in the heavens, may be difcovered, that have hitherto eftaped the moft diligent obfer~ vers: They had difcovered indeed fome motions that are very minute or flow, fach as the preceflion of the equinoxes 5. but this was owing to the continual in- creafe of the effects of thofe very minute motions, whicli, though infenfible in one revolution, become very manifeft in ma- ny revolutions. Motions of this kind are eafily found, and are accurately de- termined, by comparing’ diftant obferva= tions. But theré are other minute mo- tions which are hard to be difcovered: Thefe which do not grow up to be fenfi- ble in a number of revolutions; their effect in one part deftroying their effect in another part of a revolution, Of this kind PHYSICAL anp LITERARY. 199 kind is the motion lately difcovered by Mr Bradley, which, on this account, lay fo long concealed from aftronomers. Of _ the fame kind is the motion of the fixed ftars, that ought to-arife from the paral- lax of the earth’s orbit. And of this kind I fufpect the variation of the obli- quity of the ecliptic to be. To proceed therefore to what I take ta be the caufe of this motion, Sir Haac Newton has found, that the fun and planets gravitate all towards each other mutually ; that it is neither the fun, (ac- cording to the Copernican fyitem), nor the earth, (according to Ptolomy), that V is the centre of the fyftem, or fixed point ;: but the centre of gravity of the whole fy- ftem, , That the {un therefore moves a- bout this centre; and that, when Jupiter and Saturn, the two biggeft planets, are in the fame right line, on the fame fide -of the fun, the centre of the fun will be almoft a diameter of the fun, diftant from this fixed point. Hence, though we fup- _ pofe the earth to move always in the plane, the fun will appear to have different 200 ESSAYS anp OBSERVATIONS different declinations at the time of the folftice: And, as the obliquity of the e- cliptic is determined always from the declination of the fun at the folftice, it will therefore appear to vary, but not in a manner that will accrefce and produce any fenfible change in our feafons; but it will increafe and decreafe a little with- in fimall limits, and its variation will principally depend on the pofition of Ju- piter and Saturn to the fun and earth, and will nearly return to the fame mag= nitude, when thefe return to the fame po- fition with refpect to one another and to the folftice. Jupiter has moft effect in producing this variation; and, if it be found to have a connexion or depen-— dence on his pofition to the fun and earth, it will be an indication that this is the true caufe of the phaenomenon. Was the orbit of the earth perpendicu- lar 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. Sup- pofe (Tab. 2. Fig. 18.] BEF to reprefent the orbit of the earth in fuch a cafe, C the PHYSICAL anv LITERARY. 201 the common centre of gravity of the fun and Jupiter, which we may confider as centre of the earth’s orbit, becaufe of the minutenefs of the earth compared. with thefe, T the folftitial point, PTp the axis of the earth, IS the right line joining the centres of the fun and Jupi- tet; which ve fuppofe perpendicular to the orbit of the earth, while the earth is in the folftite T. Then, if Jupiter be at t, 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 ati, and the fun at /, the angle PTS will be the complement of this declina- . tion, and thefe would differ by the angle ST/, which, (becaufe CS is nearly equal to a femidiameter of the fun), might a- mount to 32’. But, becaufe the angle contained by % the orbits of Jupiter and the earth is . fmiall, the right line CS is feen very ob- liquely from the earth, and the variation 3 of the obliquity thence arifing is fmall, Pathe angle CTS is nearly to’ the inclina- - tion ‘of Jupiter’s plane to the ecliptic, 2s vot, J]. | Ce the 202 ESSAYS anp OBSERVATIONS © the femidiameter of the fun tothe diftance of the earth from the fun: Or the angle CTS is about =; of that inclination ; therefore ST/, 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 difcover- ed by aftronomers. But, fince it may exceed one minute, it appears that it is of moment to have this theory profecu- ted farther and afcertained: For an error of a minute, in a matter of fuch moment as the declination of the fun, which is an element in moft queftions in aftrono- my, geography, and navigation, is not to be defpifed; efpecially now when fo great exactnefs in thefe matters is defi- red, and, I believe, may be obtained, Such a variation, however, can have no fenfible effe& on our feafons; and there feems to be no ground to apprehend, that our year will degenerate into a perpetual {pring in any period of time; which, af- ter all, would be far from being an ad- vantage to us, or to the inhabitants of the earth in general, Art. PHYSICAL anp LITERARY. 203 : | Art. V. Concerning the fudden and furprifing Changes obferved on the Surface of Jopiter 5 Bo:ly ; . by the fame. HERE have been more fudden and furprifing changes obferved on the furface of Jupiter's body, than on any o- ther planet in the fyftem. Caffini has ob- ferved feveral belts rife on his body in one hour’s time; and fpots, in very different forms, are often feen upon him. I could with that the pofition of his fatellites were well confidered when thofe changes hap- pen: For, fince Jupiter has four moons, fome of which are much nearer to him than our moon is to the earth ; when they are all in conjunétion or oppofition to one another, very great tides muft be pro- duced in the ocean there, if there be any ; and there is ground to fufpect that thefe Bh fudden 204 ESSAYS anp OBSERVATIONS © fudden and great changes on his furface are owing to tides analogous to thofe we call {pring-tides. Further, the velocity with which Jupiter revolves on his axis, and the greatnefs of his body, muft con- tribute to the greatnefs of thefe tides, and of the inundations produced by them. st IN Jupiter's fyftem, the theory of gra- vity difcovers itfelf in fome particulars more manifeltly than in any other part of the general fy{tem. Jupiter i is the only body that is, to fenfe, {pheroidical ; the axis being lefs than the diameter of the equator byys. Poflibly we may, by far- ther obfervations, difcover the effects of the tides likewife ; or rat her may learn, that effects already vifible and known proceed from them. THE aétion of the fatellites. upon one another produces {ome irregularities. in their motions ; ; and from this it as fup- pofed that their eclipfes do not anfwer ac- curately to the times com puted from the tables. Butthere is another fource, I be- lieve, of their irregularities. Jupiter's (oa! PHYSICAL anp LIT ERA RY, 205 figure. differs confiderably from a fphere ; and the gravitation towards him is not _inverfely z as the fquare of the diftance from his centre. Now, this variation from the " ~ yegular courfe of gravity may produce fome inequalities in their motions. And, _ in order to judge of thefe, I have com- Hit puted the law of gravity towards {uch a fpheroid as Jupiter; and will fubjoin fome theorems on this fubject. Ir 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 obferved. Such an eclipfe could hold but | for; a fmall time: But, as it is not diffi- cult to compute nearly the time when they ey , ought to happen, it would be worth while - to look for them; fince this might con- tribute to render their theory more per- feét ; which is of fo much ufe in afcer- taining the longitudes of places. If it be _ found to be a phaenomenon that pafles a prer quickly, becaufe of their fwift.-mo: nes, pons, it may be the more ufeful, provi- " ame pit.can ‘be feen, PS No ih, 206 ESSAYS anp OBSERVATIONS No phaenomenon feems more extraor- dinary, relating to Jupiter, than that, ac- cording to Caflint, fome of his fpots re- volve in lefs time than others ; the dif- ference amounting to 4°. This is a phae- nomenon, of that kind, of which it is per- _ haps beft not to attempt any explication, till the fame be confirmed by more ob- fervations. | Ir is worthy of our notice, that, from feveral phaenomena, aftronomers con- clude the fatellites to revolve on their axes, in the fame time that they revolve © around their primaries; by which means the exceeding great tides that would be produced in them are avoided. Thofe arifing from their various diitances from the primaries, in their apfides, may be fafficient for agitating their waters. The tides that would be produced in our moon, fram this circumftance alone, ought to be confiderably greater than the tides produced in our ocean; and pof- fibly, by a careful attention to the limits of thofe black parts of the moon which formerly | PHYSICAL anv LITERARY. 207 formierly were confidered as feas, but, be- caufe of cavities difcovered in them with better telefcopes,. are fufpected by many to be only large planes, fome decifion of this queftion might be obtained.. Water is of too great importance, in natural o- perations, to fuppofe haftily any planet to be deprived of it; though we muft alfo allow that the variety of nature is not to be limited by our conceptions. 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 diftance from the centre increafes: ‘But the gravity in the plane of the equa+ tor decreafes in a higher proportion than that in which the {quare of the diftance increafes. Tae om. HU, Ler b denote the femidiameter of the equator, ¢ the diftance of the focus of the generating 368 ESSAYS anv OBSERVATIONS ; generating ellipfe from the centre, @ the diftance of any body from the centre of the fpheroid in the plane of the equator ;. and the gravity at the diftance d, will be to the gravity at the diftance 6, as*— a i ; 3¢ ge* : 3c° 9c* ; i A ; 143 +07 ke. tor +t Se &e. | ART: PHYSICAL anv LITERARY. 209 Art. Vi. Obfervations on Thunder and Electricity, by EpenEzER Macrait, M.D. HE experiment propofed by DrFrank- lin, to prove that lightning and the electrical fire are the fame, has often been repeated with fuccefs both in England and abroad; fo that the moft noted e- jeGtrical experiments have been perform- ed by fire drawn from the clouds. Dr Frankwin fart difcovered, that fharp points attract and difcharge the e- leGtrical matter moft copioufly ; and from thence fuppofes, that a very fharp point- ed rod, fixed to the extremity of the top- maft of a fhip, with a wire conducted down from the foot of the rod round one of the fhrouds, and over the fhip’s fide into the fea, would filently lead off the electrical fire, and fave the fhip from thunder in hot countries ; and that, by a _ Vor. 1. Dd fimilar 210 ESSAYS aNp OBSERVATIONS — fimilar method, buildings might be pre- ferved. So ufeful a propofal deferves to be ex- amined: Variety of experiments may give hints for new improvements. For this reafon the following obfervations are communicated, though not fo compleat as might be withed, being the refult of one trial only, Ir feldom thunders in this lashes clime. In June 1752, there feemed to be fome thunder at a diftance from Edin- burgh ; ; but, from the beginning of July to the beginning of October, we had _no- thing almoft but continual rains. The Jatt fammer was uncommonly warm and dry; and yet we had only a few claps of thunder at Edinburgh, one evening: And my attempts for making any of thofe ex- periments were entirely unfuccefsful till Saturday's night September 15. when we had a very great ftorm. I ufed a round iron-rod, two tenths of an inch diameter, about eleven feet long, fharpened at one end; the other end was inferted into a glafs-tube; and that tube y ftood » \ PHYSICAL anv LITERARY. 211 ftood in a. common alafichettle, which [held in my hand. | 4 ufed alfo another rod about. three feet long, fharpened in like manner at one end; which ftood with the other end in a glafs-tube; which. was ftuck in the ground: I began upon the Calton-hill. THE lightening and.fire.in the air a= bounded 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 ina {mall 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 ftands. upon glafs or rofin; or like that which appears upon any fharp point, when prefented to an electrified gun-barrel, but in greater quantity: Ltouched the long rod with my finger; but had no fparks. from it. _ The fhort rod was accidentally taken out, of its tube, and yet continued to burn and blaze as formerly, In like manner the flame a] 912 ESSAYS anp OBSERVATIONS | flame continued upon the end of the long rod, though 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 attracted by my hand, and vanifhed, I went from the Calton-hill to the Caftle-hill, at the other end of the town; and, in paffing ‘through the ftreets, no fire appeared upon either of the rods: But almoft immediately when I got clear of the houfes, upon the open hill, the point of the longer iron-red took fire. In the dark, I had: loft the tube belonging to the fhorter rod; and the point of it did not catch fire when the longer one was kindled. Perhaps I did not wait long e- ~ nough far a proper trial; for I foon touch- ed the flame upon the long rod with the fharp point of the hort one, and then it alfortook flame and continued burning, as before, without any further dependence upon the longer one. I held the fhorter rod by the fharp ‘end, and approached the blunt end of it to PHYSICAL any LITERARY. 213 to the flame, upon the point of the lon- ger rod; then this blunt» end catched the fire, and the fame upom the points of the two rods ‘continued rather’ ftronger, than on the fingle one before, fo long:as Tkept them incontad, and:the’fires with> in three or four inches of one another: But; when I'drew them farther afunder, the flame upon the extremity'of the blunt rod vanifhed: “This happened as often as I tried it; and it is evident, ‘that, ia like manner, I could have got the fire’ to fix upon the points ‘of a great many rods, and fo have had them all “Aaming togé- ther. | Once or twice, a flail of lightning _feemed to’ dart direGly againft the point of the signal ba the’ sia as’ T aii ning, but it a ea to fhine again, when the hghtning was patt. ‘-Tuoucn it rained much in time of thefe obfervations, yet the fire upon the ends of the rods did not go out until ic became fo heavy, as if it were pouring ashe out of funnels. © 7 oe AFTER 214 ISSAYS and OBSERVATIONS - AFTER this I went home for fome time; refolving to comé abroad again when the ftorm was more tolerable; but it continu- ed to rain all night, fo violently, that I was obliged, with regret, to leave feveral experiments to the chance of fome future opportunity« % I beg leave to add a few remarks rela- tive to this fubject. Ir feems plain that the glafs-tubes were not of great ufe upon this occafion, and that by being wet, they conducted the e- leGtrical fire nearly in the fame manner as the iron rods. ) Ir is probable, that thunder-gufts in cold or boifterous weather are apter to ftrike, becaufe the fire is more condenfed. IN warm weather the lightning expands itfelf more as it flies; and, by expanfion, lofes its vigour. Peruaps there is one fimple and eafy way of protecting. mafts and {pires from thunder, viz. to fix horizontally, upon the highefl parts of them, a flat round piece of wood, of a foot diameter, or more, PHYSICAL and LITERARY. 215 more, in order to prevent thofe blazing fires from fixing upon them, by the at-- traction of the fharp points, Tuis ftorm pifled dire@tly 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 fixty miles to the weftward; _ but no thunder heard. At Glafgow, _ there was very much lightning, and a few diftant taint claps of thunder, On the road from Belford to Berwick, it lighten- ed inceflantly; but two claps of thunder only were heard, and thofe very faint: Upon the whole, there i ig reafon to think, that the ‘fire of this ftorm {pread over. the breadth of 130 miles, at leaft. It began, at leait, as far fouth as Liver- pool, and went off upon ‘the so at Inver- nefs. | On September 3. there were a great ‘deal of ftreamers, which rofe nearly from the fame point that the thunder after- wards came from ; and gradually worked north, till they defcended below the hori- zon. The air had a thunder-like appear~ ance 216. ESSAYS anp OBSERVATIONS | ance for feveral days before this ftorm; and, for fome nights after it, the ftreame- ry vapour appeared equally diffufed, muddy, inert, and languid, and not vi- brating any variety of colours; as if the. more volatile parts had been confumed. It is highly probable that lightaiag and the aurora borealis are of the fame mate- rials, In hot countries ftreamers are not feen, or but rarely; becaufe they are’ kindled into thunder and flathes of light- ning: In cold countries ftreamers abound, and it feldom thunders. The ftreamers have ferved to predict thunder to follow next day, in fummer; and they have been alfo feen.to break out into flafhes of lightning. Thunder difturbs the mo- tion of the magnetic needle; and it has been lately found in Sweden, that ftreame ers do the fame. Thus thunder, electri- city, magnetifm, and the aurora borealis, appear all wonderfully related; and ma- ny things remain undifcovered in this vatt field, which is but juft newly open- ed. As PHYSICAL anp LITERARY. 217 “As it is probable that the height ‘which fome philofophers have affigned for the - ftreamers in the atmofphere, is by feve- ral hundreds of miles too much, it were to be wifhed that people in various lati- : ‘tudes would carefully obferve their alti- tude, at different times of the night; that, by comparing fimultancous obfer- vations, this matter may be determined with more certainty. But, becaufe proper inftruments are not always at hand, it will be of ufe to ynark the time when any principal range Becomes vertical, or the time when the higheft part of the range feems to touch any remarkable ftar. | ‘THESE vapours commonly aflemble, ee at. firft, in a broad lucid yellow vein, flowing flowly eaft and welt. By degrees : the vapours accumulate and turn bright- er, and, by their mutual collifions, are at laft kindled and {plit into thoufands of revolving cylindric columns, fhewing a variety of colours, but principally red and green, and the red appears to be un~ Bia) rmoft. Thus they are fcattered thro’ | * VoL, I. Ke the 218 ..ESSAYS anp OBSERVATIONS the fky, and beccme faint in their co- lours; then they coalefce and revolve, and are fcattered again, or continue flafh- ing hither and thither thro’ the air, in a thin luminous vapour. that feems to be compofed of a grofler and more volatile kind, and people imagine they fometimes hear a faint crackling noife, Ir is probable that the fhining of the fea is a phenomenon nearly related to thofe above; namely, That it is owing to fome volatile oily fulphureous matter. that arifes from the fea, and floats upon, its furface when the evaporation is fmall 5 ‘as is the cafe at Jand with the zgnes fatuz,, and thofe fiery fparks which often appear, when you tread in marfhy or mofly low grounds, in damp weather, We may even. fuppofe that thofe particles are often car- ried down to the earth and fea from the. fky, adhering to the particles of rain, hail, or {now, and continue floating there till they are evaporated again. Tuese things are agreeable to what obfervations J could make, and I leave them to be examined by thofe who have better opportunity. ART. ey | } | s | i LITERARY. 221 _ Thad occafion to {ee it again on the 23d of Oétober laft,, in travelling from Glaf- gow, northward. .yWhen | had afcended a very little out of the fog; fo that my fhadow was projected amongft it; the fun being behind, and almofi ona level with me; there was. a double range of colours, - jike thofe of the rainbow, tormed round the fhadow.. The colours of the utter- moft range were broad and very diitiad, and about two feet diltant trom: the thas dow every where ; then there was a dark- ifh interval, and.after that another nar- rower range of colours, clofely furround- ing the fhadow, which was very much contracted. Havine feen no account ig this ale nomenon, I fhall:now venture to offer my - conjectures. As the fun is a broad lumi- nous furface, the fhadows of bodies muft be furrounded with a penumbra occafi- __ oned by the different direction of the rays _ proceeding from each verge of the fun and Hi from the center; this becomes very fenfible _ when you are upon iome eminence with . ; the 222 ESSAYS anp OBSERVATIONS | the fun near fetting, and your fhadow projected a good way on the other fide. WHEN one has travelled for fome time in the mift, his cloths become, as it were, erufted over with particles of dew or hoar froft, and the rays of the fun are refract- ed in paffiing through them, The rays which proceed from parts near each verge of the fun form the exterior and interior bow, if I may call them fo, and the rays that proceed from parts near the centre form a bow ‘in the middle. 3 THIS agrees with the account of that phenomenon by Don Antonio D’Ulloa 5 but when there are only two bows, it would feem that they are forméd only by the rays proceeding from each verge, which occafioned the darkifh interval a= bove mentioned, and the great bending of the rays by refraction occafioned the fhadow to be contracted. | Ir would feem that this phenomenon. was feen on the mountains of Peru always accompanied with the white bow above defcribed ; but the above obfervation fhews they were not neceffarily connected. ART. PHYSICAL anv LITERARY. 227 ArT. VII. Of the Meafures of Scotland, compared with - thofe of England, 4y James GRAY. HE ftandard pint jug in the cuftody of the burgh of Sterling, is made of brafs in form of a fru- fium of a cone; it weighs near fixteen averdupois | pounds. It appears, by its make, to be very old, \ and has two fhields in re- | ‘lievo upon its fide, with rude figures upon them, | as reprefented in the _ margin. Its dimenfions, as near as could be ta-’f ken from a veffel of fuch | rude workmanfhip, are, — Viz. * 224 ESSAYS aNp OBSERVATIONS — Inches, Mean diameter of its mouth, Ais Mean diameter of the bottom, Sts 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 10O 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 yreigh 26180 troy grains. ; | Ar the fame time, a veffel which was made to contain accurately, one hundred cubic inches, was filled with the fame wa- ter: And, after feveral trials, which did not differ one grain from one another, its content 1m water was found to weigh 25318 troy grains. Tue ftandard pint jug therefore con- tains 103%9%. cubic inches; and each cu- bic inch of water with which the jug was filled, weighs 253735 troy grains. THE ftandard Sterling jug in the cu- ~ ftody of the dean of gild of Edinburgh, likewife PHYSICAL and LITER ARY. 225 likewifé made of brafs, and weighing a- Bout 204 averdupois pounds, having thd arms of Scotland and of Sterling tharked in relievo upon its fide, was in the fame _ manner filled with water ; and its content was found not to differ from that in thé cuftody of the burgh of Stirling, above a fiftieth part of a cubi¢ inch, Perhaps it may not be improper to obferve, that, notwithftanding the rlicety of thé beam, and the fmall furface of the mouth of the velfel, 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 degreés both above and below temperate in the thermometer ; | and that no difference was to bé foiind be- / tweeri fpring and river water; nor even dda rivet water when clear, and when e - fomewhat difcoloured after a fpeat. By ad. parl. of r9. February 1618, a- | “hent polite the meafures and et of Ff THE 226 - ESSAYS anp OBSERVATIONS . THE Englifh wine gallon contains, ac- cording to the Guild-hall ftandard, 224 cubic inches; but, according to ftatute, 231 cubicinches. The Englifh ale gallon, both according to the Exchequer ftandard and ftatute, contains 282 cubic inches. The Winchefter bufhel, according to act of parliament, 1697, and ratified in the firtt year of Q. Anne, contains 2150722 cubic inches. Therefore Cubic Inches, The Scotch pint contains - 103.4 ‘The Englith wine pint, accor- ding to ftatute, contains - 28% The Englifh ale pint contains - 35% The wheat firlot contains - 2197,3+4 The bear firlot contains - 3205,£4 The Winchefter bufhel con- tains « - - 2150742 AccorpDINnG toatt of parl. of 19th Fe- bruary 1618 above mentioned, the Scotch pint jug contains, of the clear running» ‘water of Leith, three pounds and feven “ounces of French Troas weight, ordained — to PHYSICAL anp LITERARY. 227. to be.the weight of Scotland ; whence the Scotch pound is equal to 76 16 Troy grains, or 1542 ounces Troy. | By an accurate comparifon of ftandard weights made at London (Vid. Philo/aph. Tranfact. N° 470.) the Averdupois pound was found equal to 7o0o Troy grains. Therefore ‘Troy Grains, Te Troy ounce being equal to 480 The Scotch ounce is equal to 476 “The Averdupois ounce is 4374 | : Englifh Inches. ‘Tue Scotch foot is - 1298 The Englith foot is - =e _, The Scotch ell, according to the © ftandard of Edinburgh, is e- ae gual to =: - a , a ~The Englifh ell is - 45 The Englith yard is - 360 B . Englifh Feet. | 7 THE Scotch milecontains 5952 ‘3 _ The Englifh mile contains rst : _ The Scotch acre - 5653537 fquare. us The Englith acre contains 43 A fquare. ART. 228 ESSAYS snp OBSERVATIONS ART. IX. A Differtation on the Sexes of Plants ; by CHARLEs ALstTon, M, D. King’s Bo- tanifi im Scotland, Fellow of the Royab College of Phyficians, and Profeffor of Medicine and Botany in the Univerfity of Edinburgh. aT’ ef a fmalleft, and apparently moft def- picable productions of nature, are not fo barren, but that they are capable, both to invite our fpeculations, and to re- compence them. Even Pliny ¢ould fay, “ Rerum natura nufquam magis quam in “minimis tota eft *.” For how much foever the coeleftial bodies declare mag- nificence 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 think, that the eye of a fly isa mOre » LM Xi. Ce 2 _ PHYSICAL anv LITERARY. 229 _ more curious piece of workmanfhip than - the body of the fun, at leaft as far as ap- pears to us *. Hence "FHE exquifite ftru@ure of flowers, e- {pecially of the moft minute and fcarcely’ _vifible duft of the apices, commonly the {port of the winds, has engaged the at- tention of the learned both of this and the preceeding age: And yet no body has been able to determine, with any certain- ty, whether it is abfolutely neceflary to the fecundity of the feeds, or excrementi- tious only, which is the fubject of the following i inquiry. _ ANIMALS and vegetables refemble one another in fo many things, that not only _ fome of the ancients, but even of the mo- a derns alfo, feem to be at a lofs how to diftingpith them, or fix the limits of each of thefe kingdoms +; yea, and to reckon ‘analogy a fufficient proof, that fuch pro- me pethes as are generally obfervabie in the one, a. © Vid. Boyle’s works, fol. edit. yol. 4. p- 428, and gol. 4s P- 523- + Vid. Tyxocin bot, ps 3. 230 ESSAYS anp OBSERVATIONS © one, do belong to the other alfo. Thus Empedocles and Anaxagoras feem to have reafoned, when they maintained, that both fexes were conjoined in plants ; that they were animated, yea and fentient beings, capable of pleafure and pain, de~ fire and averfion, &c *,. * «© Vita et in animalibus et in. plantis effe deprehenfa “eft. ANAxaGoRAs itaque et EmPevocces defiderio ** plantas duci aiunt; fentire item, ac triftitia volupta- ** tequeaflici, afirmant, Et Anaxacoras quidem, a- ** nimalia ipfas effe, et voluptate ac dolore moyeri, do- *¢ cnit; E foliorum fcilicet defluvio, et ex incremento, *¢ iftud colligens, _EmPpepocues vero fexun his admif- ** tum effe arbitratus eft. Eodem modo Prato quoque * appetitu folum illas duci, ob vehementem {cilicet fa- ** cultatis altricis neceflitatem, affirmabat. Quod fi ** conftet plantas yoluptate ac dolore affici, tum fentire ** quoque rationi erit confentaneum : Et ubi hoc confti- ‘* terit, tum appetitu quoque duci; fi quidem fomno re- J ficiuntur, et vigiliis excitantur, rationi confentaneun> eit. Ad cundem modum fi quaefamus, an fpicitum « ducant, et fexuum mifionem habeant, an contra fit H ‘* multam fuper hoc ambiguitatem, et quaeftionem pros ** lixam excitabimus,—Cum in plantis reperiatur, quod ** unaquaeque fpecies mafculum genus habeat et femel- ** Jum, et omnino quod mafculum eft afperius ac durius « rigie | PHYSICAL anp LITERARY. 23% J thall follow the philofophers no fur- ther; my defign being only to inquire into the rife and progrefs of the dodtrine concerning the fexes of vegetables among botanifts ; and whether it.is fupportable by experiments, or a mere hypothefis, SB Odd THEOPHRASTUS, the greateft, as well as the eldeft of the Greek botanifts whofe works have been preferved, can beft ex- plain, why fome plants of the fame kind were called females, and others males, by them. I know fome reckon Crateva more ancient, and cotemporary to Hippocrates, ~ onthe authority of fome epiftles. fathered [ on the old man, and annexed to his works, et But the learned have proven thefe letters E ae ‘ > « rigidiufque, temellum debilius et feecundius ; quae- rendum rurfus eft, inveniaturne haec duo genera fi- ** mul commifta in plantis effe, ut Empepocves dicit. Id quod ego fane ita habere non arbitror.” Thus _Arisrotre de plantis, lib. 1. c. 1, et 2, See alfo _ Fragmentum Gatenr in Pratonts Tim#uM, c,2 Et _ Tibrum de hiftoria philofophica Gausno adfcriptum, fab - finem. #32 ESSAYS anp OBSERVATIONS to be fpurious; and that Crateva lived not before Mithridates, whom he ¢om- plimented with the name of a plant, as Pliny * informs us, As for Hippocra- tes himfelf, I find in him a conyza femina, but no other plant ealled either male or female. 2. BuT ‘Theophiaftus, who fucceeded Ariftotle in his fchool, in the 14. olym- piad, very frequently mentions the fexes of plants. Thus gas de cies, fays he, iat To sedsoryevav, Ta Usv aves, Ta de by &e. “ But **it is faid, that of plants of the fame * kind, fome flower, others not; as of the palm-trees; that the male bloffoms, * not the femiale, which about the famé time puts out the fruit. Plants there ‘* fore of the fame kind are thus differ-. ‘* enced, as alfo all fuch as cannot perfect - “the fruit.” + And elfewhere +, “‘ The ‘¢ moft common diftinétion of trees, is in- *< to female and male, whereof the one is ** fertile, ® Lib. 25. ¢. 6. + Hilt. lib, 1. 22. t Hil. lib, 3. 9. / PHYSICAL anp LITERARY. 233 «¢ fertile, but, the other barren, in fome. ‘‘ But, when both are fertile, the female carries the faireft fruit, unlefs fuch be “ called males, for fo fome call them.” And almoft all the plants which he di- ftinguifhes into male and female, are e- qually fertile in both fexes, as abies, filix, cornus, tilia, cupreffus, ciftus, conyza, &es Even palm-trees he divides into fructife- yous and barren; and the fructiferous a- gain into female and male *: So feems not much to have regarded analogy, in the diftinétion of fexes, except it be in one fpecies of the palm-tree. _, But of this famous tree he fays Ts unlefs the /patha be cut from the male, - and, while it retains the down, flowers, and duft t, be fhaken over the fruit of the female, it will never ripen, but fall off; which this fprinkling prevents. © &* For the male, adds he, of both the fig VoL. Gg “ tree * Hift. lib. 2, c. 8. } Hii. lib. 2.6.9. $ Kopsoprase / 234 ESSAYS anv OBSERVATIONS - ‘tree and the palm-tree, is of ufe to the S¢ female, car’ n ev stv patkte, ij dz nar Grr TeoTOVE “ but, in the one* there is, qua/i coitus ; in ‘‘the other it happens after a different “‘manner.” And elfewhere ** + That “ the fruit will not continue on the fe- ** male palm tree, unle's the flower of the ‘Smale with the “7% be fhaken over it, *©as fome affirm, ‘is certainly fingular: «For though there is an evident reafon ‘* for caprification, which it fomewhat “ refembles ; yet none can be affigned ** for the effect of this fprinkling.” And, left it fhould hence be inferred in gene= ral, that female trees were of themfelves infefficient for fructification, without the affiftance of the males, he obferves, that in order to fuch a conclufion, this ought ta appear, not in one or two jnftances f, but in all, or the greateft part of the fes males, tiv yap ougiv wT xpivome! Ts yevy. Of this tree more afterwards, 4. D1Qe * viz. Palm-tree. + Cauf, plant. lib. 3. c. 23. t As here in the fig-tree and palm- tree, Pe, * vu PHYSICAL anp LITERARY. 235. .4. DioscoripEs, who lived under Nero, has a male and female mandragora, abrotanum, mercurialis, anagallis, arijtolo= chia, cifius, filex, peonia, polygonum, tithy- malus. verbafcum, and an arundo femina: ‘But, without any regard to analogy or to their fertility or barrennefs, does he call them {o ;* for his mercurialis-mas car- ries the feed, and the femina is barren; and the male of all the reft, equally fer- tile with the female. The fame may be faid of Galen and the fucceeding Greeks ; none of them, fo far as I have obferved, mentioning the {exes of the palm-tree. 5. PLINY, who flourifhed under Ve- {pafian, fays. indeed, “* Arboribus, imo po- “* tius omnibus quae terra gignet, herbif. “ que etiam, utrumque fexum efle, dili- “ gentiflimi naturae tradunt: Nullis ta- “men arboribus (palma) manifeftius. “Mas in palmite floret, foemina. citra “ florem germinat tantum, f{picae modo *.” “But, when he comes to mention par- ficular plants, excepting what he has * L, 13. Cc. 4. “< from 236 ESSAYS anp OBSERVATIONS from 'Theophraftus of the palm-tree, he tranfereffes analogy as much as Diofco- rides : His mercurialis mafculus being the feed-bearing one; and his other male and _ female plants the fame with thofe of The- ophraftus and Diofcorides. Hence it ap- pears that the palm-tree is the only in= ftance, among the ancients, where fexes are attributed to particular plants, on ac- count of fertility or barrennefs : Other plants being called male or female, on va- rious and very different accounts, and for diftinGtions fake only. 7 6. IN a word, from Theophraftus down to Czxfalpinus, who died at Rome in 1603, the analogy between plants fand animals, with regard to fexes, feems to have been entirely neglected. But Cxfalpinus * fays exprefsly, “ Fructum ferunt, non vero “florent oxycaedrus, taxus; in genere ** herbaceo mercurialis, urtica, cannabis : * Quorum omnium fteriles mares vocant, “* foeminas autem fruétioferas. In eo ta- “men genere foeminas melius provenire 66 et : * De plantis, i, I .c, 3. _ Oy PHYSICALann LITERARY. 237 ¢ foecundiores fieri aiunt, fi juxta ma- ” yes ferantur; ut in palma eft animad- ®verfum: Quafi halitus quidam, ex ma “re efflans, debilem foeminae calorem * expleat ad fructificandum.” Sect. Il, 4. Bur of late it has been maintained by not a few, that there is as real a diver- fity of fexes in every fpecies of plants, as in every fpecies of animals; and, firft of all by the celebrated naturalift 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 Royal Society November 9. 1676, after noticing the fecondary ufes of the duft of the apices, which he calls globulets or {mall particles within the thecae of the attire, he adds, “ But the primary and chief ufeis fuch as has refpettito the plant itfelf, and fo appears tobe very great and neceflary ; becaufe © even thofe plants which have no flower or foliature, are yet fome way or other " © attired 5 238 ESSAYS anp OBSERVATIONS * attired; fo that it feems to perform its ** fervice to the feed, as the foliature to the © fruit. In difcourfe hereof with our learn- “ ed Savilian profeffor, Sir Thomas, Mil~ *‘ lington, he told me, he conceived that * the attire doth ferve as the male for the -“ generation of the feed. I immediate- ly, replied, that I was of the fame opi- *‘ nion; gave. him fome reafons for it, and * anfwered fome objections that might ** oppofe them.” WHETHER, as fome pretend, this com- pliment paid to Sir Thomas Millington, fhows him to be of this opinion before our author, I leave to the learned to de- termine; for my part, 1 think, the words cannot bear-it. And Mr Ray * gives it for Dr Grew, without naming Sir Tho- mas. 8. Dr Grew then proceeds to give the fum of his thoughts concerning this mat- ter; and plainly afferts, as his opinion, that, when the attire or apices break, or o- pen, the globules or duft falls down on “govathe ® Hift. p. 17. PHYSICAL any LITERARY. 239° - the feed-cafe or uterus, and touches it with a prolific virtue; not by entering: bodily, or-as to its grofs fubftance, but only' by communicating to it fome fubtle and vivific efHuvia *. 9g. AmMonG the firft who adopted this dottrine, was Mr John Ray, that great natural hiftorian ; at firft indeed only as probable +, but afterwards as proven by many arguments, which are‘collected in the preface to his /ylloge firptum Europea- rum extra Britannias nafcentium, printed — at London 1694, in 8vo: Whether thefe arguments fufficiently prove the doctrine will be confidered below. to. In 1695, Rudolphus Jacobus Ca- merarius, profeffor of botany and medi- cine at Tubingen, publifhed there an epz- flola de fexu plantarum, in I2mot: This I have not feen, but only an abftra&t of it in the appendix to Mifcl., nat. cur. Dec. 3 - -@ See Grew's anat. fol. p. 171, ~ $ Vid. R, Bilt: ps 18. _. . $ Reprinted Francoturti, 1701, in 4to, Lin. bib, bot. 373, 240 ESSAYS anv OBSERVATIONS: 3. an. 3- for 1695, and 1696, by M. B. Valentini. Here, the generation of plants to be analogous tothat of animals, he en- deavours to fhew in eight particulars’; the aft of which he calls the palmarium and ponderofiffimum argumentum: And it is this, “ Certum: éft,” fays he, “ad animalium * senerationem copulam utriufque fexus “ exigi: Quae in plantis adeo quoque ne- * ceffaria eft, ut fi vel maris apices, vel foe- “ minarum ftyli, vel utraque deficiant, “ nulla proles fequi poffit: Ut in frumen- * to turcico, cui juba praemature refeca- * tur, et mercuriali, marea foemina fepa- “rata, conftat.” But then he propofes three objections againft his own dodtrine, which are ftronger than all his arguments for it; yea, the third plainly confutes it: And they are thefe, as Valentini delivers them: “ 10, Plantae dantur apicibus co- “ piofis, aft nullo ftylo praeditae; adeo= “que mares fine foeminis, ut in equifeto, “ lycopodio, &c. 2do, Videtur e contrario “ fibi obfervaffe foemininum fine pretenfo “ virili femine. 3fi0, Mercurialis, fpina- * chiae, by PHYSICAL anv LITERARY. 245 * chiae, et cannabis foemellas folitario, “ abfque yicini maris contagio excultas, “ plurima granula feminaque foecunda :- Beesanille vidit: Et haec in caufa erant, cur haec. omnia cum alana's oppoliti * formidine proponat.” 11. In, 1703, Mr Samuel Morland laid ‘before the Royal Society, fome new ob- fervations on the parts and ufe of the flower in plants *. Here, he fays, “ Dr “ Grew falls fhort, in that he iuppofes “the farina only to drop upon the out- “ fde of the uterus, and to impregnate “the included feed by fome fpirtneus “ emanations, or energetical imprefs.” So he paraphrafes prolific virtue and fu5- tle vivific efluvia. He then propoles .a more probable hypothefis, as he thinks, viz. “ That the farina is a, congeries of «“ © feminal plants; one of which mutt be *¢ conveyed into every ovum or feed, before “it can, become prolific.” He has the honour, I believe, of being the inventor of Vouk... Hh. this mi - * Philof. Tranfa&- No 287. 942 ESSAYS anv OBSERVATIONS this hypothefis; but is fo far from ma- king it probable, that the ftructure and pofition of the parts of fomeof the flowers he inftances, which are all the arguments advanced by him for it, fufficiently con- fute it; e. g. corona imperialis. For allow- ing for once, which however cannot be allowed, that the ftylus is always hollow, and that rain might wath the duft, or wind fhake it down this cavity, into the heart of the feed in ere€t flowers, What muft become of pendulous flowers, fuch as the crown imperial? here the farina muft be wafhed or fhaken upwards. 12. As for Wald/chmidii differtatio de Jexu plantarum, Kiliae 1705, 4to, and Ga- —kenbolzii differtatio de vegetabilium indole cognofcenda, Helmfladi 1706, in 4to, men- tioned by the learned Heifterus, in his praefatio in epifiolam Burckhardt, Helmfta- — dii 1750, in 8vo; I know nothing about them : But I have no reafon to think, that they have been more fuccefsful in demon- ftrating the fexes of plants than Camera- -rius, “ qui, omnium planiffime, fexum . * plantarum PHYSICAL anp LITERARY. 243 plantarum expofuit ”’ As the fame pro- feffor Heifter * teltifies. 13. In 1711, Mr Geoffroy prefented the Royal Academy at Paris with * obfer- « vations on the ftruclure and ufe of the “* principal parts of flowers;”’ wherein he attempts to prove, that the duit of the a= pices really impregnates the feed. And, after advancing almoft all that had been {aid on this fubject by Grew, Ray, Came- rarius, Morland, without mentioning them, he afferts, 1mo, That, the germ is never to be feen in the feed tll the apices fhed their duft. And, 2do, That, if the fta- ‘mina be cut out before the apices open, the feed will either not ripen, or be bar- ren, if it ripens: In proof whereof he gives two experiments that he made, one on the mays, by cutting off all the ftami- na before the apices opened; and the o- ‘ther on the mercurialis, by training up feparately fome of the feed-bearing plants by themfelves. The confequence was, fome of the ears of the mays aborted al- _ together ; _ ® Pref. p.70, 244 ESSAYS anp OBSERVATIONS — together; others ripened a few feeds; as did alfo the mercurialis plants: Both which fcemed to be foecund. “ Perhaps, “fays he, the duft of the apices, brought “from fome other place by the wind, fer- “‘tilized thefe few feeds: That this is not “impoffible, we have a fine inftance in “ Jovianus Pontanus, preceptor to Alphon= *“fus King of Naples, who, in a poem, | “tells us, that, in his time, there were two “palm trees, a male cultivated at Brin- “ des and a female in the woods of Otran- “to, which carried no fruit for many “years. Butat length, being elevated a- “bove the other trees of the foreft, fo “that it could fee the male palm-tree of “ rondufiam, it then began to bear good “fruit in abundance. No doubt, becaufe “then it began to receive the duft of the “ ftamina, carried by the wind from the “ mule palm tree, over the other trees of the ‘“ wood*.” ** Seb, Vaillant * tam eleganter defcribit, “ut neminife hac re dubium fupereffe | “ poffit” Ita autem cl. Vaillant, ‘‘ Quo- ** ties acciderit, ut in eadem ftirpe flores “ gerantur fimul, quorum hi foeminina ** cantum, illi autem mafculina et foemi- “ nina conjuncéta, organa cingunt, arrectio * tumorque organorum mafculinorum “in his tam fubito contingit, ut lobuli * gemmae flofculofe cedant illorum im- ** petui, atque hinc inde femet expandant, ** mirabili mehercle velocitate, et extem- * plo quam violentiflime fazcundam ex- * plodant, omnemque uno impetu ejacu- ‘‘lentur genituram, diffufa nimirum pul- _ verulenta nubecula, {pargente quaqua- “* verfum foecundationem arvi genitalis. ** Vix venereus. hic ludus abfolutus eft, ‘* quin illica florum labia, aut lobuli, ad _ ** fe invicem accedant eodem quidem ** quo a fe mutuo recefferant, celeritatis ‘* impetu, veteremague ita formam ftatim ** renovent: Apparatum hunc artificio- ** fum facili fpeCare datur in parietaria, * Sed * Jn lib. deftrudtura forum, “PSL , my PHYSICAL ann LITERARY. 26r “ Sed accedas opportet hora facra veneri; ‘aurora eft quae favet his cgngreflibus ; ‘* ubi vero agere renuunt {atis opportune, ** aciculae apice, leniter modo, ftimulus. “In hermaphroditis, ubi duo fexus con- “‘ jun@i habentur, multum abeft ut tan- **to impetu explodatur. Plerique enim ** flores, praecipue nutantes, in quibus “ piftillum obliquum intra ftamina pofi- ‘*tum habet a¢tum generationis floribus ‘“ claufis exercent, dum ftigma adhuc in- ** tra medias antheras continetur.” Thus Mr Gefner:®. 22. ALLow me here to obferve, in the firft place, that this artificial apparatus + _was feen and defcribed by John Bauhi- nus, long before Vaillant was born {, and tran{- © Dif. p. 86. _ = Tout cette mechanique, Vaill. - } “ Parietariae flofculi conferti circa caulem ex foli- “ orum alis, floccos coccinei ferici imitantur, primulum §* e nodulo emicantes: Poft fe ftamina oftendunt obfcure, *« ex albo purpurafcentibus apiculis involuta, quae fi “ ftylo evolvere coneris, fubiultum excuffo pulvere cum impeto, fpedtaculo jucundo, fe expandunt repanda, in medio feminis rudimentum circundantia.” J.B, 2 Pp 976. / ‘262 ESSAYS AnD OBSERVATIONS © tranfcribed both by Morifon and Ray in their hiftorigs of plants, though Vaillant mentions none of them: And, fecondly, that this feems to afford a ftrong:argu- ment again{t the impregnating virtue of the duft of the apices. For, according to Linnzus himfelf, “ parietariae herma- * phroditi, flores duo continentur involu~ “cro plano hexaphyllo. Calyx mono~ " phyllus, magnitudine involucri dimi-~ “diati, Stamina filamenta quatuor, “ calyce longiora, illumque expandentia. “ Foemineus flos unus, inter hermaphro- ** ditos ambos intra involucrum; cum ¢a- “lyce ut hermaphroditi *.” Now, fince the ftamina of the hermaphrodite flowers, as well as the germen of the female flower betwixt them, are contained in one com- mon involucrum, and the apices do not eject their duft until, by the {traitning, or ftretching out of the formerly crooked ftamina, the common involucrum is burit open, and the apices raifed in the air; fince no fooner do they find them- — felves * Gen, pl. P- 494. ‘PHYSICALiann LITERARY. 263 felves free, and erected highenough a- bove the involucrum, than immediately, by a fort of explofion, all the duft is en- tirely, 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 re-- fume their former figure*; does not all _ this thew, that the’ duft is not by nature defigned to imprégnate the feed, but to be carried away by the winds, left it fhould infe& it; by'falling on the ftig- _ ‘mata ;’and that’ autopfia teaches the quite contrary to what Mr Gefner alledges. 23. “Ira fefe in plantis habere, (fays “M. Whalbom) didtitat’ primo oculos. _ “Flore florefcente, “et polline antherarum “ volitante, quod ftigmati pollen inhzreat, ** prima fronte obvium eft.” But it is not im ' at ink re betty 3 PAO | _ # Ita (quidem, adds Mr Vaillant), ut diffcillimum | _ ™-foret credere, flores hofce ullam vim paffos effe, nifi 4h ye! ipfe aQum hune vidiffet oculus, vel adhuc cerneret i caduca fceleta magnanimorum heroum, aliquamdia We eae in campo confii@us, ubi apluftrium inftar, jos ie ** cularios experiuntur lufus volitantis zephyri.” |. ¥ Amaen, Acad, 1.p. 90, | | | 264 ESSAYS and OBSERVATIONS at allobvious, far lefs does the eye fee; that generation is thus accomplifhed ; for this duft as often befpatters the petala, &c. Neither does what he adds concerning the florefcentia. violae tricoloris, gratiolae, iridis, campunalae, et fyngenefiarum, in the leaft favour him. For, though all he fays were true, thefe make but a very inconfiderable part of the, vegetable king- dom. Yetthey feem rather to make a- gainft him. For, in thefe compound flowers, which he calls fyngenefiae, the “ antherae * funt lineares, erectae, lateribus coalitae “in cylindrum tubulatum. Stylus fili- * formis erectus, ftaminum longitudine, ** antherarum cylindrum perforans; ftig- , “ma bipartitum, laciniis revolutis, pa- tentibus.” Lin. Gen. pl. Pp. 370 To which if we add, that thefe antherae fplit, and emit their duft, on the outfide, not infide, of this cylinder, while the ftigma — is commonly pretty far above it; What — can reafonably be inferred from this ftruc- ture, but that nature defigned this duft fhould be thrown away. as ufelefs, if not. hurtful to the ftylus?: AGAIN, PHYSICAL anv LITERARY. 26¢ - Acarn, the ftylus of the campanuia is : commonly much longer than the ftamina, and briftly a little above them, as it were _ to hinder their accefs to the ftigma. The ftamina of the iris are hid under the cut- fide of the fegments of the ftigma, the ‘depreffed petala being frequently bearded . or hairy under them. So no plants could be here more improperly alledged ; for, by the ftru€ture of their flowers, it is evi-_ dent, that the follinis illapfus fupra fiig- mata nuda is impoffivle: Nor can Mr Wahlbomdeny it: “ Campanula (fays he) ‘a caeteris in eo differt. quod pulvis la- “teri hifpidi ftyli adfigatur, et exinde es per certos canales ftigmati communice- “‘tur tris particularum nobis oflendit _ © ftru@turam ; ftigmata enim fefe dilatan- “tia; antheras omnino operiunt; illum ** tamen ad petala referunt fitum, ut, au- ““ra fubeunte {tigmata, pollen per rimas ~*illorum aicendat.’’ What eye ever faw ethete canales, or rimae, with the pollen - *rifing in them? how, or why: rife to the > fli ma thus fituated ? = VoL. I. L1 - As 266 ESSAYS anp OBSERVATIONS As for his obfervations on the viola trico- lor, 1 pafs them, becaufe nothing to the purpofe; and alfo too fmutty for Britith ears. But let us hear what the great Lin- naeus by himéfelf fays. 24. “ GENERATIONEM vegetabilium * fieri, &c. (fays he) confirmat oculus. * Pollinem intrare germina credidit Mo- *rilandus ; ejufdem effentiam extrahi, * mediante fligmate madido, ftatuit Vail- * Jant: Pollinem aceris rumpi in humore ** vidit Bern. Jufliaeus: Omnem pollinem - “in humore explodere auram feminalem, — confirmat Needham *.” But Morland’s opinion is fully confuted by Vaillant, who maintains only that the vapour, or vola- tile fpirit of the male duft, enters the tra- chiae of the ftylus; but not a word caf I find in his difcourfe, concerning the at- traction of the eflence of the duft by means of the moift ftigma; and, although it fhould all burft in moifture, I do not fee how it thence follows, that it thus fends out an aura feminalis; efpecially, fince it does * Phil, Bot. p. 91. PHYSICAL anv LITERARY. 267 does not appear, that the ftigmata muft neceflarily be moift in order vo fertility 3 and it is obferved by Mr Walhbom*, That, “in omnibus fere floribus confpicitur, “ quomodo, aére humido, flofculos com- plicant, ne aqua pollen attingat.” 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 antherae bear to the ftylus. “Ex proportione quoque (fays Gefne- “ rus) f, verofimiliter judicamus, cum, * pro magnitudine et numero feminum, * ipfa quoque ftamina majora fint vel “ numerofiora.” But that this is evi- dently a miftake, will appear to any one Tae ams bo that will take the pains to compare Lin. naci monandriae with his polyandriae ; or the cannacorus with the prunus, and other ftoned fruits : The fyngenefiae have five ftamina for one feed, and that not feldom * Amaen Acad, 1, pe 93, ay Differt. Pp. oI. 268 ESSAYS anp OBSE? VATIONS ~ _feldom a very finall one: ‘The umbellife- rae, as many for two feeds, &c. y ‘tra fede in plantis habere didctitat fecunda proportio: Plerumgue ftamina et piftilla eandem ferunt altitudinem, ut eo melius ad ftigma pollen, mediante vento. accédat; in guibufdam vero non, wb: fingularis obfervatur proceflus foe- cundationis *.” But plerumque dilti- tat uhit. efpecially fince there are a great many genera, where no fuch propértion or tingular procefs takes place, as in al- moil all the floiculofi, femiflofculofi, ra- diati, liliacei, caryophyllei, &c. and of the fix plants inftanced as fingular. in three, viz, dianthus, nigella, and paffiflo- ra; the pittilla, any curvature notwith- fiancding, continue high above the ttami- na ft. “ ‘Yuis argument is thus explained by Linnxus. “ Proportio: Stigmata fefe flec- 6% 6s ee ce «6 65 * tere ad antheras, dein exferi ex diantho, ‘* pafliflora, * Wahlbom. Amaen acad 1, p, 90. + See Pontedera for more initances, Anthol. k 2, Co 8» U ; * vi A PHYSICAL anv LITERARY. 269 e ** pafliflora, nigella, patet. Piftillum ubi ““breviflimum, connivent antherae fupra “ftigmata: Saxifraga, parnaffia. Con- “mivent dum efHant pollinem antherae “in celofia. Comprimit corolla digitis “antheras ad ftigmata in teucrio *.” Here not a word of proportion confirm= ing his fcheme; no inftance of it; but only reafons for inequality. No matter, therefore, whether it be fo. in thefe or not. 26. THE third argument is, “ Ex loco * (taminum et piftilli, non leve argumen- “tum petere poffumus ; nam in plerifque “* plantis, floribus hermaphroditicis prae- “ ditis, ftamina ambiunt ovarium, et ea ** ratione ut maxima pars geniturae ad “ ftigma accedat ;” Gefnerus +. Can the {tamina furround the ovarium, in the mo- nandriae, diandriae, &c.? But this needs no anfwer ; neither what he adds con- | cerning the pif/iili fabrica, and anthera- rum matcries, which is nothing to the purpofe. ; ) * Tertio, * Phil. Bot. p. 91. 7 Differt. p. 9. 270 ESSAYS anp OBSERVATIONS © _“Tertio, /ocus. Etenim ftamina plerum- “ que piftillum ambiunt, ut ventorum ope “ {emper quidquam pulveris attingat ftig- “mas” Wahlbom *. But the learned author cannot but know, that the ftami- na ftanding round the piftillum can never prove the neceflity of the duft’s falling on the ftigma of every plant, in order to its foecundity ; efpecially when this is not al- ways their fituation. He adds, “ Mone- *¢ ciae flores mafculi plerumque fupra flo- ** res foemineos collocantur, ut pollen eo ““ melius in piftillum decidat ;” and in- ftances ricinus among others: But, fure I am, the ricinus vulgaris B. p. has all its female flowers above the male flowers ; the fligma of the uppermoft being com- monly fome inches above the neareft fta- mina. . “Locus. Nunquam piftilliferae {ponte “nafcuntur fine ftaminiferis in eadem “terra; prodeunt ex eodem femine am- “bae;” Linneus ft. But this cannot be ‘proven. Yea, Camerarius aflerts the con- trary. * Amen, Acad. 1. p, 91. f Phil. Bot. p. 91, PHYSICAL ann LITERARY. 271 rd trary *. But, granting it true, it proves nothing, confirms nothing. 27- ARGUMENT 4. “ Ex tempore quoque vegetationis harum partium concludere * datum eft: Namgue in antheris, ftami- “na farinam foecundantem eo tempore * continent, quo piftillum viget, deinde, _ “ excuffo pulvere, peracta foecundatione, “ perit ftamen ; fuccus copiofior in piltil- *Jum devolutus eficit ut fructum ma- “ turefcat ;” Gefnerus +. But the fta- mina fpinaciz, mercurialis, cannabis, mays, jumiperi, viol martiz, &c. fhed their duft commonly before their ftigma- ta are vifible. - Quarto, tempus. PR1 Mum hic attenden- * dum venit, quod ftamina et piftilla una ** proveniant, exceptis tantum pauciflimis, “ Alterum, quod ubicunque flores maf- “culi diftincétis a foemininis gaudent “ thalamis, aut in eadem aut diverfa plan- “ta, et ub: mafculi flores nec perpendicula- _“ riter fupra foemieos erecti funt ; ibi, flo- _“ refcentia ante foliorum exortum pera- 4 “* gatur, * See No, 10. fupra, ¢ Differt, p. 91, 272 ESSAYS anp OBSERVATIONS - “oatur, necefle eft; ne, foliis interveni- *‘entibus, inhibeatur foecundatio: Ex. “or, in moro, wvifco,. mercurial perenni, * &c;” Wahlbom *, How juftly thefe three are inftanced, any body may judge. But, fince he admits of exceptions as to the firft notandum, and many other plants emit the flowers before the leaves, this argument proves nothing. “Tempus. In declinis, flores ante ger- * minationem foliorum plerumque pro- *deunt, ne folia tegant piftilla ; falix, “ populus, corylus. &c.;” Linnzus f. Here, as commonly, we find plerumque, and an imaginary reafon. 28. ARGUMENT 5. viz. pluvie: “Fit *¢ inde ut, dum pluvia eluit pulverem fta- “‘minum, germina piftilli decidant, aut ‘¢in fructus nafcantur abortivos, ut ftil- “lant vices, percoquantur, marafmo ex- ** arefcant, locum concedant infectorum ‘* nidis et eorum evolutioni ut fruges u- ‘* ftilagine pereant, et quae funt alia vitia. ‘* Sedulo itaque natura ubique folicita <_fuit, * Amen. Acad. 1, p. 92. } Phil. Bot, p. 91. PHYSICAL ann LITERARY. 273 “ fait, ut genitura illibata ad piftillum ‘s perveniret.” Gefnerus *; But how does “it appear that {uch are the confequences, of the duft’s being wafhed away by rain? ‘Has too much moiftureno bad effects, af- ter the {tamina have fhed their dufts? Does it not frequently rot the plants? &c. e Quinto pluvie, In omnibus fere ~ *floribus confpicitur, quomodo, urente “‘fole; fefe expandant; vefpertino: vero ‘* tempore, et acre humido, flofculos com- as plicent, ne aqua pollen antherarum at- ** tingat et coagulet, quo facto, ad ftigmata *« efflari nequeat; at ftigmate, mirum fane! ** femel fcecundato, nec vefpere, nec plu- ‘via ingruente, fefe contrahant flores ;” Wahlbom +. But our author knows, that many plants clofe their leaves in the night or in rain; as the acacie, mimofe, &c. that many open their flowers in the night, and ~ fhut them when the fun is hot; as fome cerei, ketmiz xyla, lychnis no¢tiflora, mi- me Vou. I. M m rabilis 4 amis Differt. Pp: 9t- + Amen, Acad. 1. p. 93. 274 ESSAYS anp OBSERVATIONS rabilis peruviana, &c. * Does not the paflion-flower keep open in the night as well as day, untilit fhut up for good and all, and that whether it be fun-fhine or rain? He adds, ‘‘ Secale florens antheras ** filamentis infidentes exferit, quo tem-= ** pore, fi pluvia cadit, pollen congloba- “tur, hincque annonam difficilem augu- *‘ratur agricola, nec immerito; grana ‘* enim imminuuntur exinde, quod pleri- ‘** gue flofculi abortum paffi fint.” That fecale, triticum, many gramina, planta= gines, pimpinellez, &c. thruft out the a- pices on pretty long ftamina, when in flower, I deny not; but, that rain, at that time, caufes fcarcity of any of them, I never obferved: And, altho’ it were granted, that this commonly hap- pens. how does it appear that rain caufes — the floiculito abort, or this abortion cau- © fes {carcity of fecale? Since, at the fame — time, the other plants are fufficiently fer- tile, yea, the manner of flowering in fome of | * «* Mirabilis eft planta quae tam fpeciofos flores, nocti *¢ atrae objicit,, et fereno dici fubtrahit.” Lia, H. Cli&, P- 54> shal PHYSICAL anv LITERARY. 275 of thefe plants feems to afford an argu- ment, not contemptible, againft the fex~ wal fcheme. For, in fecale and triticum too, there are three flamina for one ger- men, both included within, and well co- vered by the fame hufks (be they a co- olla or calyx, or both, no matter here) before the flowering time. Now, if the duit be neceffary to the impregnation of the feed, and, in order to this, it muit fallon the ftigma, Why is not this accom- plifhed before the covers open? Why are the ftamina fo long? ._Why do they thruft out the apices fo far from. their fligmata, and throw out, if not all, at leaft the greateft part of their duft, in the common air? Does not all this look as if _ this duft was not defigned by nature for the impregnation of the feed? as is of- ten noticed. . “ Pluvie (fays Linnzus) * combibunt ** pollen, ut in ftigmata cadere neqneat; ** hortulanis notiflimum in drupiferis, (fo “‘ he calls the amygdalus, perfica, pruaus, _ “ armeniaca, cerafus; laurocerafus, &c.) et ‘* pomiferis, ‘Phil, Bot, p. ore 26 ESSAYS anp OBSERVATIONS “‘pomiferis. Agricolis deteftabilis in “‘agris fecalinis (why not alfo triticeis?) *‘fumus idem etiam facit, abforbendo “* humidum ftigmatis.” So the ftigmata muft: neither be wetted nor dried. But this is fully an{wered above. Non caufa pro caufa is here very frequent. 29. THE fixth argument, which the fexualifts triumph in as a demonftration of their doctrine, is taken from the cul- ture of the palm-tree. ‘ Inftar omnium peo cucrytn efle potett (fays J. Get “nerus *) modus quo feecundatio palmae + dadtylifere, ad obtinendos dadtylorum ** fructus maturos, apud Perfas inftitui- vy eae a cl. Kempfero, in his locis, an- ‘ notatus.” It would be too long. to tran{cribe all that modern authors have faid concerning this tree. The reader may, if he pleafes, confule John Leo Te Pr ofper Alpinus tf; Hadgi Muttapha Aga I, Engel- * Diffect. p. 85. t Harris colle&. vol, 1, P. 347. ! t De pl. Aeg p. 24 | T. Juh. p 69, PHYSICAL anp LITERARY. 277 Engelbertus Kaempfer *, Pere Labat {, Chrift. Got. Ludwig. +, &c. : 30. THESE authors are agreed only in this, that the date-bearing palm tree has no flowers: And, unlefs the flowering or male palm-tree be faficiently near, or the duft of its apices be fome how conveyed into the fpatha 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 ob- ferve, that, without the influence of the male, the female will either be barren, or caft her unripe fruit, according to the an- tients and Alpinus; that the dates will want ftones, be harfh, and not eatable, except by camels and cattle; Hadgi. ** Omnia fua fructuum rudimenta, inde- -¢* clinabili abortu dimittunt ;” Kaempfer. ‘¢ In frudta pulpz loco adeft cortex durior, ‘* ficcus, adftringens, officulum vel nul- “Jum vel tenue ;” Ludwig: Which are all contradicted by Labat. ‘s - SHeelr * Amen, exot, p. 706. z+ Voyage aux ifles de L’Amerique, Hague edit. tol, 1 Part 2. p. 209. $n J. Gefner, diff. p, 86. 278 ESSAYS axp OBSERVATIONS 31. “Ir is pretended, (fays that reve- rend 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. I am for- ry that I cannot fubfcribe to this opinion of the naturalifts; but it is a moft certain experiment, diretly oppofite to their fentiments, that hinders me; for we have -a date-tree befide our monaitery in Mar- tinico, which carries fruit, though fingle: ‘Whether it is male or female, I know not; but this I know tor 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 necef= fary to render this tree fruitful, as natu- ralifls pretend.” He fays indeed alfo, that the ftones of the dates of the iflands awill not grow; fo that thofe who would raife palm-trees are obliged to plant the Barbary dates ; and that dates do not ripen fo perfe@tly in Martinico and Guadaloupe, as they do in Africa, in Afia, or even in | St PHYSICAL anv LITERARY. 279 St Domingo “ For, although our dates, fays he, become foft, yellow, and as it were lufcious, and in a word, appear per- fe€tly ripe; yet they {till retain acertain fharpnefs, which fhews they want at leaft fome degree of maturity.” Thus Pere Labat. Lc. Jo. Bauhinus * relates, that he faw only one date-bearing palmtree at Mont- pelier: “ Centefimum annum fuperare *creditur (fays he) et vulgo ibi perfua- “fum, ante grandem aetatem fructum “non proferre, et vix ante quinquagefi- “ mum annum, ut quidem, perhibebant.” Hence Pontanus’s fiction is eafily account- ed for, if ‘there be any truth in it; and perhaps fome others, particularly con- eerning the amours of thefe trees; for which fee Pliny , and Caffianus Bat ‘fus t. 39. But I cannot omit the opinion of Herodotus, the moft ancient author, who has 4 © Hil. 1. p. 360% De TL iz .c. 4. }$-In Theoph. p. 103. 480 ESSAYS anv OBSERVATIONS has left any thing concerning the ufeful- nefs of the male to the female palm-tree ; “In Babylonis agris, (fays he,) palmae ** magna ex parte fructiferae proveniunt ; * ex quibus non folum cibum, vinum, et * mel conficiunt, fed etiam eodem modo “quo ficus curantur. _Palmarum enim, *quas Graeci mafculos vocant, fructus © “ palmis glandiferis alligant, ut earum * fruétum maturet culex fubiens, ne ex “ arbore is defluat. Ferunt enim palma- “rum mares * culices in fructu, quem- “admodum caprifici.” Thus Herodot, as rendered by Bod. a Stapel?. Who elfewhere | quotes a famous traveller for fuch a culture of this tree, as confirms Herodot’s opinion ||- Acatit e * aves + In Theoph, p. 115. FPL TOR. t{ ‘“e Agricolae etiamnum, ut refert doctiffimus Guit- ® tanD, in Arabia, Agypto, Mefopotamia, Judaea, «* Phoenicia, et tota Syria, volentes, cavere ne foeminac ‘© aut fterilitatis noxam incurrant, aut frutum, quem ‘* aliquando imaginatione Jibidinis, ut ita dicam, con- ** cipere folent, ante maturitatem amittant, ita ordi- © nant r ” say ° PHYSICAL ann LITERARY, 281 Acai, Joan. Veflingius, who was long in Egypt, differs not a little from Alpinus, as to the culture of palm-trees there: ‘‘ Caufa tam foecundi proventus (fays he) in telluris habitudinem refe- “‘renda eft, arenofam fcilicet et falfam, _ “plantae huic gratiffimam. Vidi his “‘Jocis, in palmarum veluti fylvis, terram * copiofiffimi nitri calida nive late con- * fperfam, vel aquis Nili, vel rofcida noc- “tium humiditate fervidiore fole peru- *““ftis. Nec opus hic maritali cinere pal- “mae effoeminatae vigorem incitare. “ Flantibus enim ab auftro per £thiopi- WoL, I. Noa ‘am, ** nant utriufque fexus palmas. ut mares eo faltem inter- * yallo a foeminis diftent, quo pulvi-, ventorum flati- f s* bus a foliis mafcularum fublatus, in foeminarum folia -“incidat; idque fatis ad foecunditatem, et fraétus ma- ** turationem facere compertum eit Sed mirum didu! ** quod fi qua procul a mare abftiterit, ut neque pulvis, *** neque aura, odorve ejus, ad eam permeare poflir, _ “*S excogitaverunt coloni fuxem a mare religatam ad Sen: foeminam ufque producere; atque ita quafi waritali - * 7 ’ ® ** vinculo copulatam, mafculi virtute clanculum per = Fi \ : ® funem irrepente, foecundam fieri, quae prius in ea _ © fterilefcebat folitudine.” It is ealy to conceive how es. ~ infects may creep along a rop. but not how a powder or Guft can be thus conveyed from one tree to another. 282 ESSAYS anp OBSERVATIONS “am, et fteriles Arabiae defertae campos _“ urentibus, ventis ; ingens nitrofi pulve- “ris fublata vis, abunde cacumina pal- “marum vegetat—Meminique fic onu- ftum fuifle dactylis fais unicum race- “mum, ut eum attollere a terra prae *“ pondere vix fuftinerem*.” And Alpi- nus himfelf is obliged to own, that the fruitfulnefs of the palm-trees in the deferts of Arabia, is not owing to any artificial culture, but to the winds carrying the duft and flowers of the male to the fe- male f. Is it probable, that nature has left the fertilifing of fo ufeful a tree.to | the uncertain motions of the air? BesipEs, that great and curious bo- tanift Tournefort, after mentioning the opinion of Theophraftus, Alpinus, and o- thers, concerning the male palm-trees, adds, ‘ Cum in Hifpania Baetica, palma- ~ “rum feraci, a prudentioribus viris de * hac re {cifcitarer, certum nihil accipere “potuie De lupulo certius loquor. In ** horto * Vefling in Alpin. c. 7. p. IY. + V.- Alpin, de plant Eg. p. 25. PHYSICAL anv LITERARY. 283 “orto Regio ParifienG luxuriat frudj- “bus quotannis onuftus. Qui vero flo- “ribus gaudet, non occurrit nifi in infu- “Tis Sequanae et Matronae, longe diftan- “tibus: In horto Regio tamen femina “ profert” *, Ditirts: dhjection again{t 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 fta- “ miniferis, alter piftilliferis; idque quod “fructum vulgo vocant, eft calyx tantum eucates et elongatus: Hinc humulus, hei foemina, nec foecundata, co- “nos tamen proferre valet. Hoc Tour- “ nefortium decepit, ne fexum plantarum “ agnofcerit, quum lupuius (foemina) in « horto. Parifienfi luxuriabat, fructibus * quotannis onuftus; qui vero floribus. “gaudebat (mas) non occurrebat nifi in. “infulis Matronae et Sequanae multum il ee dantibins T+ Idem fit in moro et bli- 6s to, _* Int. p, 69; + Tournefort, Hag. p. 69. bl oy ~ si 3 eae ~ 284 ESSAYS anp OBSERVATIONS ~ *‘'to,; cujus baccae calyces funt fuccu=** “lenti ; minime pericarpia, feu ovas TIA. © 34. For Iam at a lofs to find where- in ‘Tournefort was deceived. He gives an accurate defcription, as well as elegant figures, of the parts of the flower and fruit, as ftanding on different plants, without which the character of the hu- mulus, i Linnaci Genera Plantarum + is not. very intelligible to a beginner. But he calls. the enlarged calyx, fructum : The cones he calls frudfus; and fo they: are in the moft proper fenfe of the word. Linnaeus himfelf in his fundamenta bot. - teaches, that “ effentia fructus in femine “‘ confiftit” |]; and in his Philofophia Bo- ranica **, * fru€tus ex femine five peri- “ carpio, five non tectum fit, dignofcitur.” No matter therefore, whether ye call thefe cones calyces elongatos, or fructus, if they contain . * Amaen. acad. 1. p. 99- t Vid. T. p. 535. t. 399. t P. 477. | § 83 SF 56, PHYSICALAnD LITERARY. 285 contain feeds: And ‘Tournefort exprefsly adds,“ In horto regio femen profert;’ which Mr Wahlbom is pleafed to omit, for what reafon I {hall not fay: , As for’ the morus and blitum, I fee not.why their baccae fucculentae may not be cal- led frudtw alfo ; efpecially fince Linnaeus * gives, blicum a pericarpium ; and de- feribes a pericarpium to be “ vifcus gra- *‘vidum feminibus, quae matura dimit- * tit’ +: And confequently Walhbom and he don’t well agree. But, to return to the palm-tree, 35. ‘*SExTo, Palmicolas palmarum “ fpadices miafculos divellere, eofdem- “ que fupra foeminas collocare, memo- “riae mandarunt Theophraftus, Plinius, “ Alpinus, Tournefortius, Kaéempferus, “ alii: Quo neglecto, dadtyli acerbi, et *‘ nucibus deftituti, fiunt ;” Wahlbom ¢. This is anfwered above (No. 31.). Then the author gives a long paragraph out of Kaempfer * Gen. pl. p. 5. t Phil. Bot. p 53. £ Amaen, Acad. I, p, 94. 286 ESSAYS anv OBSERVATIONS Kaempfer*; as does Gefnerus +,'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 credible in each, according to their principles, viz. ‘‘ Nemus foecunda- — “ri univerfum poteft ab una phoenice “ florida ;” Gefner., ‘* Singulare quod “ fpadices exficcati ad thalamos apti funt, * et in annum pofterum, falva virtute, af- * fervari poffunt;” Wahlbom. {36. ‘* PALMICOL: notiffima Theophra- “ flo, Plinio, Kaempfero, aliifque. Piftaciae © “cultura in Archipelago; Tournefortius, 7 “ Caprificatio veterum, et adhuc in Archi- “* pelago, per infecta.” Vid. differt. noftr. de ficu; Linnaeus{. Neither Theophra- ftus, Pliny, or Kaempfer, relate the cul- ture of palm-trees, as frém their proper knowledge ; and are contradited. by an eye witnefs, Pere Labat. As for the culture of piftacia in the Archi- * Amaen. p, 706. t Differt. p, 85. tPhil. bot. p. 92. PHYSICAL anp LITERARY. 287 Archipelago, for which Tournefort is al- ledged, I cannot find any fuch thing in his works. Such a culture, indeed, is mentioned by the editor of M. Geoffroy’s Materia Medica *, 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 culture of the piftacia, either in Sicily or the Archipelago, | it feems to be very modern, and founded on the imaginary impregnating virtue of the duft of the apices , and no doubt, the terebinthus will foon be treated the fame Way; it can do no harm; though it is not _very probable, that, deficiente tali impreg- natione, fructus abortiant in this tree, more than in the palm-tree. 37. CONCERNING caprification, if you 4 confult Theophraftus +, Pliny +, and Tournefort §, or Pontedera ** only, who - quotes _ * Tom. 2, p. 417. t De cauf, pl. 1, 2. c. 12, Rhas.e ry Bo - § Voy. let 8. _ -¥# Anthol. 1, 2, c, 33. 34+ 35¢ - 288 ESSAYS anp OBSERVATIONS - quotes all the three, together with the learn- ed differtation ourauthor refers to, which Ttake to be Cornelii Hegardt Hiftoria na- turalis et medica ficus *; it will be eafy to judge, whether it is at all probable, that the fig-infe&ts carry the du‘t of the caprificus to the unripe figs, and thus’ impregnate the feeds t. 38. IF * In C. Linnaei, Amaen, Acad, vol. 1, p. 213. 243. a Se Cupido ficus nobis dicitur, quem antiqui pfenem feu infefum vocarunt ficarium; et Pontedera, Anthol, 172. defcripfit, eltque fpecies ichneumonis. Hifce ich. neumonibus jam mutatis, alifque infrudtis, tempus adeft, quo caprificus, feu ficus mas, florefcit, i.e, farinam e- dit antherarum; tunc ichdeumones e caprifici cavitati- bus, farina, molitoris inftar e mola fua prodeuntis, ob- dudti evolant, et conjugibus acquifitis de ovis pariendis foliciti funt: Hine ad fingulos@Groflos tran{volantes, cae vitates ficus foeminae, dolii inftar, clavis ferreis vel fpicu- lis feu piftillis ab omnibus lateribus intus completas, in- trando, non poflunt non farinam illam, qua contecti funt, excutere. Patet igitur hoc modo, ficum hanc foe- minam facillime impregnari ” Thus Mr Hegardt, A- maen. Acad, I. p. 231. A fine appendix for Pontanus’s . poem! But, According to Pontedera, ‘¢ Ficarii culices, forma ad vefpas, nafcendi’autem modo ad mufcas, accedere mihi videntur, Ur primum grofli crandiufculi faci apertum . fun- *- ~ ys _ PHYSICAL ann LITERARY, 289 38. Ir it be ftill alledged; that the in foecundity of the date-ftones of Martini- mVor:;T. Oo co ;fundum oftendunt, ingrediuntur foemellae, et ex infimo ventre producta tuba, foeturae in frumentis nidum exca- vant, et ovula deponunt. Nafcuntur in his vermiculi, qui deinde nymphae evadunt immobiles, durae, corpore _ oblongo, capite cum dorfo luteold, caetera primum albae, mox nigrae, Perforato deinde nido, exit animalculam, ' plerumque nondum pinnis explicatis. Egreffum ftatim feneftam deponita capite incipiens, .Tunc flavum cerni- tur, quod tamen mox exficcatum nigrum evadit. Dum vero involucris fpoliatur, hue et illuc revolvitur; ‘et propterea apicum pulvifculo, quo tota pomorum cavitas repleta eft, infarcitur, quippe molliufculum. Quare.e groflis egreflum, et fole.exficcatum, pulvyerem difcutit ad hunc modum : Stans quatuor anteriorious pedibus inni- titur, et duobus poftremis abdomen, lumbos, pinnas, pul- vere mundat, itesum atque iterum cruribus detergens ; deinde quatuor pofterioribus fefe liberans duobus an- terioribus caput, dorfum, et cornua purgat: Quem- admodum feles et . aja elegantiora. animalia fo- lent. Tunc, depofito onere, evolat.”’ Anthol. p. + 174. And, p..175, he adds, ** Hujufmodi animalcu- }- u _ pus perpetuum non eft, ferotina roma -non caprifican- PRMS.perp F Pp Be cas: praecociorum in macro folo, et in aquilonio, lis tota grofforum caro et frumenta corrumpuntur, In fativae vero ficus pomis, haec animalcula nunquam inve- ni: Num veroad haec volent ignoro; fedulo boc mihi inquirenti, nullum fane in fativis ficubus apparuit. _Ne- - ane enim Italia caprificationis indiget, fed fine groffis fa- vae ficus fua coquunt poma, In Graecia hoc culturae ip 290 ESSAYS anp OBSERVATIONS: co demonftrates the foecundating virtue of the male duft; I anfwer, by no meana: For Pere Labat does not fay that he tried them; but, in general, that the date-ilones of the French iflands would not grow; and it can fcarce be fuppoted there were no males among all their palm-trees. _ Be- fides, in ipfa Graecia ulla fit caprificatio. Pomum caprifica- tum bonitate inferius eft non c-prificato et infuavius, Hinc illi qui in Graecia ficus venundabant, quo faclius emptores allicerent, guxe a vephyetsee iterum atque ite- ‘rum clamitare folebant.” And, after explaining the ufe of caprification, he adds, ** Quare conclucen’um, eaptificatinnem in Graecia ob externas caufas eff: necef- fariam, nequaquam ob ficus naturam, cum alibi pom coquant non caprificata. Eadem etiam de caufa palmas in quibufvam regionibus efle caprificandas, in aliis mi. nime ; id autem per culices fieri, non vero per affedtio- nem, quam apices embryonibus communicent, fatis de- monitratum elt” ‘See Anthol |] 2. c. 34. and 35. p, 172s &c. Now, fince M. Hegardt’s Cupid, or Miller does * not zo abroad, till well brufhed, and freed of the duft ; fince there is no caprification in Italy; and fiuce. this notwithRanding, he and Linnaeus alfo sdffirtn; * Ficus in Hollandia quotannis prolici e feminibus, vel fruéu la~ terato terrae commendato, fruétu tamen illo ex Italia allato.” Amaen © Acad, 1. p. 233. Exam. Epicris. p, 16, &c ; [leave it to the reader to determine, whether caprification affords an argument tor, or again{t the fex- ves of plats, > - a PHYSICAL anp LITERARY. 291 fides, many things concerning 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 Pontedera’s cu- lices. rather than of the male duft, for a= ny thing yet appears. 1 39. ArGuMENT 7. “Septimo, flores * nutantes. Cum pollen mafculus, ple- * rumque aé€re {pecifice gravior, difficile -** furfum tenderet; apud plerafque plan- * tas, piftillum longius gerentes. florem “ nutantem fecit Creator, ut ftigma eo “ melius attingat pulvis; e. gr in galan- *‘ tho leucoio, cyclamine,. narciffo, fritil< “laria, campanula, erythronio, ~ &c. ;” ~Wahlbom *, “Flores nutantes gaudent _ “piitillo, ftaminibus longiore, ut cadat * pollen in ftigma: Campanula, leucoi- - “um, galanthus, fritillaria;” Linnaeus +. I readily grant, that the pollen ma/fculum, or pulvis apicum, is heavier than air, it be- Sa ing _ * Amen. Acad. 1, p. 95. { 4 Phil. Bot, p. 92. 292 ESSAYS avp OBSERVATIONS © ing often heavier than water; and alfo, that fome flores nutantes have the piftil- . lum longer than the ftamina; but cannot allow the reafon'to be “ ut cadat pollen in “* figma:” For thus it muft fall on the back of the ftigma, when the ftylus is there thickeft, -or fall by it quite, when there flendereft; and, in neither cafe, can’ this have ready accefs to the feed. Again, in many genera of plants, not only in dif- ferent {pecies, but even on the fame ftem, foe flowers hang down, others ftand e- rect, others horizontal, while the piftil- lum and ftamina bear the fame propor- tion to one another: e. g. fome fpecies of the narciflus, campanula, lilium, &c. And although every /los nutans had the pi- ftillum longer than the ftamina, yet it could not thence be inferred with any probability, that the defign of the great Creator, in thus forming them, was what our authors alledge, unlefs every erect flower had its piflillum fhorter than the {tamina. which is far from being fact, as is proven above *. 40. AR- * Vid, No 25. / PHYSICAL ano LITERARY. 293 . Ao. ARGUMENT 8. “Videte et ad- ‘‘ miremini folertiam, quam Natura adhi- “bet in plantarum aquaticarum, quae farinam foecundantem habent, floribus. * Tempore florefcentiae, flores fpecifice ** leviores redditi, ultra aquae fuperficiem © attolluntur, ut in acre foecundatio fat, “nec humiditate diluatur genitura: Dum “vero fub aqua flores adhuc recondun- tur’ fubmerfi, folicite per petalorum **commifluras clauduntur, apicibus ver- ‘* fus ftigma inclinatis, et verfus interio= “ra tantum farinaceis, exteriori fuperfi- ** cie membranacea et lata; ut in nym- “‘nhaea et affinibus apparet ;” Gefne- rus *, R ““OctTavo, fubmerf, Plantae haud “ paucae caule fub aqua latent; inftante “vero florefcentia, enatant flores, ut “nymphaea, &c.’ Aliae vero’ fub aqua ** omnibus fuis partibus occultantur; ut “myriophyllum, ftratiotes, potamogeto- ‘* nes plerique, qui omnes, fub florefcen- “tia, fpicam flores fupra aquas ‘exferunt, “ deinde * Differt. p. 92. Saye 294 ESSAYS anp OBSERVATIONS. _ ’ , > “ deinde iterum. peracta florefcentia, de- “© mergitur fpica;”, Wahlbom*. | , _ “Flores fubmerfi adfcendunt fub flo- *¢ refcentia:,. Nymphaea,,. {tratiotes, my- * riophyllum. potamogeton,.hydrocharis, “ valifneria ;” Linnaeus t. ALTHOUGH fome aquatic plants blow only above the water, it cannot be proven that all do fo: Yea it is certain, that ma- ny fubmarine ones fructify under water, But, granting all the alledged facts, it by no means follows, that the defign of na- ture is to procure the better accefs of the duft to the ftigma; but rather that it may be difperfed in the air. For fince, under water, the flowers “ folicite per pe- “ talorum commifluras clauduntur, api- «¢ cibus verfus ftigma inclinatis, et verfus © interiora tantum farinaceis;” the duft, or its aura feminalis, muft there have much eafier accefs to the fligma, than it can have, when the ftamina are feparated and expofed to the winds; efpecially, if it # Amaen Acad,1. p. 96, + Phil. Bot. p. 92. a PHYSICAL 4nv LITERARY. 29¢ ee \ it be true, as Mr Vaillant has it, that, in _ hermaphrodite flowers, and fuch, accord- ing to the Sexualifts, is the nymphaea, and fome other aquatics, the duft is not thrown out.at once with fuch violence, as . itus where the.fexes are feparated: *‘ Sed ac- s* tum generationis (adds Mr Gefner) flo- ‘¢ ribus claufis exercent;.dum {tigma_ad- ‘‘huc intra medias antheras. contine= eue*.’: 41. 1 mention thefe two learned aus thors, though I have the misfortune to differ from them, not only becaufe they are recommended by Linnaeus, efpecially Vallaint, of whom he fays, ‘* primus cla- “re fexum expofuit f.” but alfo that I may help them to a better inflance. than the parietaria, of the fudden explofion of the duft ‘of the apices in»barren flowers: _ It is the common flowering nettle, or ur- * ticavurens maxima, B. p. 232. ¢; for one 6 can- “)@ Vid. n. a1. fupra, > Bib, bot. 173. { That is for a fpecimen of botanical fuperfluity ; ur- tica foliis cordatis amentis, cylindraceis, fexu diftinétis, mas, ‘ \ 296. ESSAYS anp OBSERVATIONS cannot obferve this ftinging nettle fora few minutes, in almoft any of the fum- mer-months, if the fun fhines, efpecially before noon, but he muft fee many little clouds of duft, thrown with a fort of ex- plofion out of the burfling apices, which foon difperfe and fall down. This, how- ever, being a fingle inftance, and, by me, not obferved in fpinacia, mercurialis, can- nabis, or any fuch barren plant; no ge- neral conclufion can be drawn from it. “42. Arc. 9. “ Nono, Syngenefia fru- ““ftranea. Flores compofiti variis mo- « dis fabricati funt—Polygamia fruftra- “© nea foeminis exfultat. maritatis, totum ““ difcum > occupantibus; -flofculi vero “< foeminei radium conftituentes, ob de- << fectum fligmatis, abundante licet dif- “‘ci pulvere, familiam propagare neque> “-ynt;’ Wahlbom *, I omit. the reft, ) fince — “mas, Fl. lap. p. 299.3 urtica foliis oblongo.cordatis, dioi- ca, H, Cliff. p. 440; urtica dioica foliis oblongo-corda- tis, Fi. Suec. p..282.3 urtica mafcula, Syft, Nate 333.3 urtica perennis, 'Amaen, Acad, 2, 25.99. * Amen. Acad, 1. p. 96. & \ 4 PHYSICAL anv LITERARY. 297 fince Linnaeus * fays only, ‘‘ fyngenefia “* fru{tranea: Ubi ftigma deeft, ibi nulla *‘ foecundatio: In radio centaureae, he- “* jianthi, rudbeckiae, coreopfidis.” But, in the radius or corona of all thefe flow- ets, the ftylus is alfo wanting, as well as the fligma; which may be many ways neceflary to the ripening the feed. It does not therefore appear that this proves or confirms the foecundating virtue of the duft. -.43. ARGUMENT Io, is a very exten- five one. ‘“ Ita fefe in plantis habere dic- * titat, decimo, omnium. florum genuina “ confideratio. _Brevitatis caufa nonnul- * los tantum hic examinare lubet ;” Wahl- bom +. And, for brevity’s fake alfo, I hall 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 cart be proven only by anas general induction; which is, altogether impracticable. Based Pip cosy 44. Bor * Phil. Bot. p 92. ‘fT Amaen. Acad. 1. p. 97 298 ESSASY any OBSERVATIONS 44. But fince Malpighius, whom I reckon one of the moft genuine contem- plators of flowers, obferves, * that, “ Tur- “ gentibus orbicularibus corporibus qui- “bus ftaminum capitula replentur, exfic= * cataque continente capfula, foras pro- * deunt globuli minimi et difperguntur ;” and that this exficcation does not, cannot well happen, before, by opening of their covers, the ftamina be expofed to the free air; and fince, in fact, the apices do not fplit, at leaft generally {peaking, fo far as IT have obferved, until their covers open, it appears to be a more natural inference, that this duft is not defigned to fall on the ftigma, or to impregnate the feed *. And, confeguently, that “ Omnium flo- “rum genuina confideratio nec didtitat, “ nec confirmat, generationem vegetabili- “um fieri” in the manner the fexualifts pretend. 45. ALTHOUGH I have already, per- haps, been too tedious, and faid enough to * P. 63. edit. in gto. ¢ Vid, No. 40. fupra, PHYSICAL anp LITERARY. 299 . to overturn the modern doctrine of the fexes of plants; yet there ftill remain fome arguments for it, which I cannot pais. For Linnaeus fays, “ Antherasefle ‘< plantarum -genitalia mafculina, et ea- rum pollen veram genituram, docet ef- “ fentia, praecedentia, fitus, tempus, lo- “ culamenta, caftratio, pollinis ftructura : “Stigmata, germini ubique adnexa, efle * senetalia foeminina, probat effentia, “ praecedentia, fitus, tempus, cafus, ab- “ fciffio *.” Which in Phil. Bot. +, and Sponf. Pl. ¢, are explained: But con- firmed only, either by miftakes, or by falfe confequences. ‘Thus, “ Situs: Didynamiftis ftamina adfcen- © dunt fub corollae labium fuperius, quo “et fe piftillum flectit.” But in the de- feription of his clafs 14. or didynamia, ** Antherae fub labio fuperiore faepius “reconditae §’. And, concerning the fi- tus, - | * Lin, Fund, Bot, § 143. 144: tT P. 90. “ov t P. 84. § Vid, Lin, Gen: pl. pe 261: 300 ESSAYS anp OBSERVATIONS tus, he adds, “ Moneciae pleraeque flores “ ftamineos fupra piftilliferos gerunt: Zea, “ricinus.” But the flores ftaminez are be- ‘low the piftillifer1 in ricinus. What he fays of tempus, is an{wered above ; of ca- ftratio, below: And what he obferves of the /oculamenta antherarum, and pollinis ftructura, teach nothing, but the author's conjectures, 46. But, whether thefe arguments be conclufive or not, cafiratio florum moft certainly demonftrates the ufe of the /a- rina fecundans, and confequently the fexes of plants. ‘‘ Veritatem hanc pro- * bat caftratio, Si antheras alicujus plan- ‘‘tae uniflorae auferamus, et, ne aligua “© alia ejufdem fpeciei adfit, curemus; a- «* bortit fructus, vel faltem ova profert *‘ fubventanea; quod adeo certum, ut ‘* quifque nullo non fucceflu id experiri *¢ gueat ;” Wahlbom *, “ Caftratio: «¢ Melonis flores ftamineos qui diligenter ** auferunt, fructus non obtinent,. Tuli- ** pae folitariae, fi auferantur antherae an- * te * Amaen, Acad, 1, p. 86. PHYSICAL anv LITERARY. 301 * te cafum pollinis, fterilis evadet ;” Lin- nzus * ~ So the winds feem here to forget their duty. © But, granting all here alledged, it proves nothing. kor plucking off the pe- tala may have the fame effect: “‘Saepius ‘© avulfis floris foliis,, antequam hiarent, “5 in tulipa praecipue, expectavi an ftylus “* incrementa caperet; et interdum ejuf- ** dem incrementum remorari obfervavi, “‘ quandoque quaédam femina, abfque **noxa, debitam fortita fant magnitudt- ““nem;” Malpighius t. Wounds alfo, in otherways néceffary parts, may be the caufe of fuch barrennefs, by depriving the feeds of their proper juices, &c. Ne- verthelefs there is reafon to deny the fa@: For furely M. Wahlbom did not make the experiment in every fpecies of flowers: _M. Geoffroy’s mays ripened fome feeds, tho’ caftrated {: And I made the trial in tulips, nullo cum fucceffu. Thus, 47- ONE year, obferving two ftrong has growing together, in an aitalte furrounded * Phil. Bot. P. 90. and 92. ; t Oper. p. 70. t Vid. Mem, Acad. 1711 302 ESSAYS anp OBSERVATIONS. furrounded with a tall and thick quick- ‘fet hawthorn-hedge, I cut down two or three more tulips, which ftood at fome diftance from them, fo as to leave none within that inclofure, fave the two I men- tioned ; out of thefe, gently opening the petala, I plucked all the ftamina with: their apices ftillintire. The confequen- ces of this too rude caftration, was a cen- fiderable extravafation of the juices, in | the bottom of the flower, and a fudden decay of the ovarium or fruit, which ne- ver increafed, but turned yellow, fhrunk, and withered. In order to difcover whe- ther this abortion was owing to the wounds, or to the want of the duft of the apices. I fuffered thefe two tulips to re- main in the place where they were: And next feafon, withthe fame precaution that no other tulips fhould flower within the inclofure, IL opened the petala, and took out carefully, not the ftamina, but only all the apices; which prevented any fen- fible bleeding of the parts. This more gentle caftration, they bore perfectly well; the ovarium fuffered nothing in either of : them, - PHYSICAL any LITERARY. 363 them, but increafed, and came to matu- rity, quite full of feeds. See alfo Gar- dener’s Dictionary, article mpi anv near the end. 48, Tuus I think I have ‘igisiany an- - fwered all the arguments for the fexes of plants, taken either from the ftructure of flowers, or experiments of any confe- quence that I could meet with. But, fince no fmall ftrefs feems ftill to be laid on the analogy between plants and animals, as much favouring this doctrine, I muft beg leave, a little to confider it alfo, al- tho’ it is certainly true, to ufe Mr Need- ham’s words *, that the method of rea- foning by analogy, is but too apt to lead us into miftakes ; and therefore we ought to be very diffident of confequences de- ‘duced this way: For mere analogy, found- ed on faéts, and extended by conjecture, however plaufible, can, at moft, but fur- nifh motives for a reafonable doubt, and further inquiry. - 49- ‘‘ OMNE vivum ex ovo; per con- *fequens etiam vegetabilia: Ovum, non ian §* foecun- # Phil, Tranf, No 49°: 304 ESSAYS anp OBSERVATIONS - ** foecundatum germinare, negat omnis ‘* experientia ; adeoque et ova vegetabi= ** lium ;” Linnzus *. — I {hall not here en= quire, whether either of thefe propofitions are certainly true; 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 vegeta- bilia ex ovis, et per confequens etiam vege- tabilia: If vivum do not include vegeta- bles, the confequence does not follow- The fame holds. in the fecond, and feve- veral others of his aphorifms. 50. In how many things foever plants and animals may agree, certainly they do not agree in every thing. ‘* Ad fummum, “* (fays Theophraftus) | non omnia fimi- ‘‘ liter atque in animalibus accipi debent « ‘“ Nam (in plantarum genere) vis undi- ** que germinandi habetur ; quoniam et “‘undique animatum eft.” And Malpi- ghius t, ‘* In vegetantibus, ubi non eft ** tantus * Fund, bot. § 132.—150. t De hift. pl. 3. c. 1. } Anat, pl, p. 76. , ait | | PHYSICAL anv LITERARY. 305 « tantus organorum apparatus, et cuili- “ bet fenfibili particulae, omnia infunt «« guae in toto deprehenduntur: Nulla in- “* tercedente gene atione, abfcifli quicun- “€ gue rami frequenter in novam fobolem ** excrefcunt; vel naturae minifterio, de+ *< ciduae minimae et compendiariae plan- *‘ tulae, a tenellis furculis fub feminum “‘ {pecie, propagationem quocunque anno ** perpetuant.” Hence many plants are much better and eafier propagated by cut= tings, 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 bulbous roots but gems? And fach Czefalpinus obferved on the leaves of the moly ; as they are frequently feen on the ftalks of tulips, lilies: And it is. to buds that the increafe of many trees is owing. 51. Now, what is a bud? How does m it differ trom a feed? ** Differt foboes a ** femine, ut foetus vivens ab ovo; femen “enim tanquam ovum ett, in quo eft prin- Vou. I. Qq * cipium 306 ESSAYS ANp OBSERVATIONS | *€ cipium vitale, at vita nequaquam; fo ** boles autem vivit, primo quidem juxta ‘* parentem, ut ejus germen, poftea vero _“ per feipfum, propriis radicibus ex terra ** humorem trahens ;” Czfalp. de plantis *: And Malpighius t, ‘‘ Gemmez funt velut ‘* infans, feu foetus ita cuftoditus, ut fao ** tempore auctus, in furcuium excrefcens, **tandemova promat. Erit igitur pro- “* babiliter femen quafi gemma pendula et ** decidua, alieno germinatura folo.” And although the learned Petrus Lofling, in his treatife called Gemme Arborum t, or ra- ther the publifher himfelf, is pleafed to fay, ‘‘ qui gemmam fibi reprefentant ut *‘alterum femen, fallunt et falluntur ||;” yet his defcription of a gemma feems not altogether to agree with this notandum: For § he fays, ‘* Gemma eft pars plantae ** radici infidens, quae occultat fquamis, ‘* foliorum rudimentis, embryonem futu- ae rae FI LADs Be Co) Se f Anat. Flant, p. 39. 77. f~ Amaen. Acad, 2. p. 182, 224. J P. 195. note k § P. 185 1 2aee oe. commen ie ae PHYSICAL anv LITERARY. 307 ‘rae herbae.’”’ And below *, he explains what he means by radix thus: ‘‘ Hae gem- “© mae infident, vel radici fub terra recon- ** ditae, vel radici /upra terram in truncum ““ramofum affurgenti; illae, ubi carnofae “©fuerint atque magnae, du/bi nomine © veniunt, &c.” And elfewhere 7, ‘** Gem- ** mam proinde concipio inftar herbae in ** compendium redaétae, teétae, et’ con- *“tractae fua inter extrema folia, ut ab "2 . e . ° ° 3 * aeris injuria confervetur ; cui herbae ni- ** hil amplius deeft, quam vis fe exten- ** dendi, eam autem calor demum exci- **tat.” Is not this as applicable to feeds, asto gems? ‘Semen, (fays Linnzus) t¢ “* proprie, novum vegetabilis rudimen- “tum, humore rigatum, vefica tunica- “tum.” 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: Since Linnzus owns, “‘ Generationes plantarum 3 66 ex ‘ * P. 186. TP. 192, * Linn, Phil. bot- p, 54, s 308 ESSAYS anp OBSERVATIONS _ © ex femine et gemma effe coevas *; and ‘* semmas, proinde ac femina, in fe con~ ‘* tinere primordium plantae t ;” it comes to the fame thing for our purpofe. For, 52. Ir gems contain the primordia plans tarum, they contain the moft eflential part of feeds; becaufe the /eminis effentia confiftit in corculo t; and the corculum is nothing but the movae plantae primordi- um |. Now, fince buds or gems are co- ‘ pioufly produced by numberlefs plants, and often break out of the {mootheit part of the bark, efpecially of pruned trees; and, fince the fmalleft part of a plant may be made to grow and emit gems, whether it be naturally fertile or barren, male, fe- male, or hermaphrodite, does it not cleare - Jy follow, that neither difference of fex, nor ilapfus pollims antherarum fupra fig- mata nuda, are neceflary to the produc- tion of the primordia plantarum, the effence of feeds, as wellas of gems; and thatno imagined * Phil, Bot, p. 88. + Gem. arb, Amaen, acad. 2. p. 185, $ Phil bot. p, 56. : l) Ibide p. 54. . ¢ PHYSICAL anp LITERARY. 319 ART. X. Remarks on chemical Solutions and Precipi- tations, by ANDREW PLUMMER, M.D. _ Fellow of the Royal College of Phyficians, and Profeffor of Medicine and Chemifiry in tke Univerfity of Edinburgh. * “8 HAT I may not give the firft in- ftance of breaking in upon the or- der and rules eftablifhed in this fociety, I fhall lay before you, at this time, fome mifcellaneous obfervations on the folu- tions and precipitations which frequently occur in the profecution of chemical in- quiries. I fhall lay down thefe remarks by way of propofitions, and, after each, fhall mention the facts or experiments which gave occafion to the remark, or which confirm and illuftrate the propofition. ALTHOUGH many of ‘the inftances which I am to adduce are common, and well known to every one verfant in che- 3 mical * January 3. 1738. 320 ESSAYS anv OBSERVATIONS ~ mical experiments; yet, as the hiftory of © chemical folutions is very extenfive, and as many fingular conditions and appear= ances are to be obferved in the achons of various folvents upon the bodies which they diffolve; it may poffibly be of fome advantage, to any one who {hall afterwards undertake to give a rational | and fatisfactory account of the caufes which produce fuch effects, and of the laws by which thefe caufes act in parti- cular circumftances, to have in his view a great many inferior axioms or ca- nons, comprehending! as many particu- Jar inftances as poffible: Becaufe thefe may enable him to afcend to more gene- ral canons, and at length to the ultimate phyfical caufe; and again, from thence to explain the phaenomena in particular inftances. | By /olution is here meant, the fepara- tion and divifion of a folid body, or of a thick and confiftent mafs, by means of a fenfible fluid, into parts fo fmall, as to difappear and be equally difperfed through 7 the fluid, . “THAT ¢ - pRYBIENY AnD LITERARY. 321 Peat liquor which makes’ the fepa- #ation of parts, I call the Jolvent; or, in’ e {tile of the chemi‘ts, the menjiruum. aq muft take the liberty to make one preliminary remark, before I defcend to particulars: For, if theaffertion of certain cheinitts was well founded, it would, in| a great meafure, fuperfede any ‘farther in’ quiries. vi f, ‘Tue notion of an univerfal menftrus um, capable to diffolve equally every Bo-’ dy to which'it is applied, appears repug= nant to the nature of things, and to’ thefe limited’ aidan which we blac 1m! ‘i Known Bodies.” ; TY fliall not tindertake, in this place, ‘to’ addiicé and examine the bold affertions’ ahd’ ‘high pretenfions’ of fome chemilts’ to" the difcovery of an univerfal folvent ; becaufe it would exceed the limits which T propofe to myfelf, and perhaps afford Tit : pester titienert orinftr udlion: Bur fia ibe allowed’ to doubt of ‘the pofibility of “ah univerfal’ folvent, until more certain Vidences aré “produced than what Have Vou. I. gig © hitherto 322 ESSAYS anp OBSERVATIONS hitherto appeared. For, as there is a vaft — variety of bodies which differ much from one another in denfity, folidity, and tex- ture, in the bulk, fhape,and compofition of the conftituent particles, in the degree of force with which thefe cohere among themfelves, and in the number, fize, and figure of the pores or interftices betwixt the folid parts, it is fcarce conceivable, that any one liquor can be endued with powers correfponding to all the various circumftances of fuch 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 endued with different qualities, in different degrees, to feparate the particles of fo many different folid bodies ; and daily experience fufficiently confirms the truth of this conclufion, There is perhaps no body, natural or artificial, but there may be found a men- ftruum proper to diffolve it: And, though fome liquors are known to diffolve feveral bodies which differ in many refpects ; yet even thefe folvents, which are allowed to a y PHYSICAL anv LITERARY. 323 PHY! to be moft extenfive, are found incapable of diffolving a great many other bo- dies. Il. Tue denfity, folidity, hardnefs, fixednefS, and other manifeft qualities of bodies, can afford us no certain mark or ndication of the qualities of the liquors requifite to diffolve them, if experience is wanting. Neither can we conclude, from the ftrength, fharpnefs, or corrofivenefs of liquors, difcovered by their effects on the human body, the fitnefs of fuch li- " guors to diffolve different fub{tances. 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 diffolved by liquors moft harmlefs to the human body; as vinegar, juice of le- mons, a folution of tartar, rhenifh wine, nay, moift air: Whereas quick-flver, whofe particles are fo mobile, eafily fepara- ble and diffipated by a moderate heat, and tin, which is very foft and eafily melted, re- quire more corrofive menftrua. Coral, and fome of the hardeft gems, will be better diffolved 324 ESSAYS snp OBSERVATIONS,, difflolyed ina weak vegetable acid; than Sap | in;a much ftronger one ofthe mineral kind. Oleum vitrioli, fpivitus nitri, or agug fortis, the moft: ponderous, and corrofive of the acid liquors, cannot diflolve beess wax or crudefulphur, which will readily relent in thé mild and foft oil of olives; fal.tartari, or olenm tartari p. d. is almoft equally corrolive, with regard to the hus man body, as.aqua fortis: Yet the folvent powers of thefe liquors, with refpect to other fubftances, are moft oppofite. IU. THE ifitnefs of a liquor to diffolve aicertain bedy, cannot be certainly learn- ed.from the agreement of that body in feveral properties. with another which wé know ‘can be. diffolved in that liquor, Neither can we fafely conclude, that two liquors, which nearly refemble one ano- ther, will mutually diflolve all the fame bodies. a) Wer m veet with sb te NaC of iiinges in chymifiry, to make us cautious in drawing fuch conclufions, Well re¢tified fpirit of wine makes a very compleat folution ~ ae PHYSIC AL anpLITE RARY. gag folution of colophony or any of the com; mon rofins ; but there are feyeral fubttane ces which have a. great affinity to rofins, as lacca, copal, amber, ulphur, which, Deing digefted with highly rectified fpirit of wine, wall {carce give a tincture to the fpirit ; that is, thefe bodies remain either altogether, or: for the far: greater part, _-gndiffoluble in that liquor, unlefs they are previoufly prepared and difpofed.to a fo- lution, by the interpofition of another bo- dy, asa fixedjalkaline falt, &c. . Diftilled | vinegar will readily diffolve copper, lead, iron; but it would be rafh to conclude, that, the fame liquor will .alfo diffolve gold, filver,, antimony, whatever agree+ ment we find between \thefe, bodies and the,former..,, On the other hand, aqua fortis, and agua regia appear to be ‘much of the fame nature; and) the former,; by awery {mall change, may be.converted in- to the latter; yea, further, they diffolve equally. feveral bodies, as copper, iron, {pelter, tinglafs : Yet, it would be erro- - Reous to conclude, that, whatfoever body one / 326 ESSAYS and OBSERVATIONS one of thefe liquors diffolves, the other would diffolve the fame; for aqua fortis diffolves filver and not gold, and, vice vera fa, aqua regia diffolves gold and not fil- ver. ; , IV. THE folvent power of fome liquors, with refpect to certain bodies, may be in- created, diminifhed, or deftroyed, by a wery fmall and almoft imperceptible change of the liquors, I put two grains of gold into a drachm of fpivitus falis marini, and fet the glafs on warm fand ; after fome hours, I could obferve no fenfible 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 /piritus mtr? 5 af- ter fome time, I found the liquor had af> | fumed a bright yellow, or golden colour, and the gold quite diflolved ; for there re- mained only a few white particles at the bottom, which were probably filver. Thus the very fmall addition of /piritus mtr: very much increafed the folvent power of ‘the /piritus faks marin, It is known, that : PHYSICAL anv LITERARY. 3247 that oleum vitriol: poured on quick filver, and kept in the common air, orin a very gentle heat, does not corrode or diffolve it; but, if they are brought to a heat ex- ceeaing that of boiling water, then the fo- lution takes place. Mr Boyle teftifies, that, by his care to rectify or de- phlegmate aqua fortis very much, he ren- dered it unfit to diffolve filver, While aqua fortis is diffolving copper with a brifk motion, if a little alcohol is poured in, the folution will be flopt. ‘V. Some bodies, which we know can be eafily diffolved in certain liquors, may be fo changed by the fire, or otherways, that the fame liquors will not afterwards dif- folve them. On the other hand, the fire - genders fome bodies fit to be diffulved in ~ certain liquors which could not be diffol- ved in them before. | THE oil of vitriol, as I faid before, af- filed by a proper degree of heat, readily enough diffolves quick-filver: But when quick-filver is, by long digeftion in a. mo- _derate heat, deprived of its fluidity, and * _ turned $08 ESSAYS anv OBSERVATIONS turned into a red calx, or has been’ firft diffolved' in aya fortis, and afterwards, by evaporation and calcination, freed from the acid, and reduced: to a red pow- der; if either of thefe red‘ powders, -T fay, is digefted with oit of vitriol; and made to-boil, this liquor will not now diffélve the mercury, or fo much as change its. colour. On the other Rand) tho’ fpir. fal. mar. is not efteemed a proper men~ ftruum of quick-filver in’ the immierfive way, but when applied’ to it in form of vapour in fublimation ; yet, if this ssh is poured upon the réd precipitate’ mer cury, it prefently changes its colour’to’ white, and‘ quickly diffolves it, Again, fpir. fal. mar. readily diffolves’ clean and: frefh fileings of iron: Yet, if thefe’ are’ frequently moiftened*with water, and by trituration and calcination turned’ to a’ crocus; fp. fal. mar. poured upon this, raifes an. effervefcence indeed, buat does! not feem to make a folution ; for the iron’ lies at the bottom not fenfibly diminithed, and the colour of the liquor is not chai ged. te *£ _ . . PHYSICAL anv LITERARY. 329 ged. Some ores, as they are taken from the mine, tho’ they appear pretty rich and ‘clean, yet will not readily diffolve in the fame menftrua which are fit to diffolve the pure metals, until the ores are roaft- ed, wafhed, and fmelted. The calces of lead and tin will more eafily diffolve in fpirit of vinegar, than-the thin plates or Shavings of the fame metals. ; VI. Some liquors which diffolve feve- ral different bodies, while they perform the folutions, feem to act in a different manner upon each body, require different helps, and diffolve different quantities _ of each, THIs is very remarkable in the action _ of oil of vitriol upon iron and quick fil- ver: To make oil of vitriol diffolve iron © fuccefsfully, it muft be diluted with a quadruple quantity of water; when the clean fileings are put into this liquor by degrees, there arifes a ftrong ebullition and effervefcence, with a confiderable heat and thick fteams of a penetrating fulphu- reous fmell, which are apt to kindle and 7 Vor.I. Ts make 330 ESSAYS anp OBSERVATIONS make a fulminating noife upon the ap- proach of the flame of a candle; and, laftly, one ounce of oil of vitriol thus diluted will diffolve an equal weight of pure fileings of fteel: But, when oil of vitriol is employed to diflolve quick fil- ver, it muft be ftrong and well dephleg- mated: Whenit is poured upon the quick- filver, it raifes no inteftine motion or heat ; it does not begin to corrode or diffolve the quick flver, till there is fuch a heat applied, as will almoft bring the liquor to boil ; and even then the folution goes on flowly and quietly: Laflly, to diffolve one ounce of quick filver, it requires, at leatt, three ounces of oil of vitriol; and yet the quick filver will not be entirely fufpended in. this ponderous liquor. EVEN water, tho’ it diffolves all kinds of falts, yet it does not act upon all of them with the fame eafe ; that is, the fame quantity of water cannot diffolve an equal quantity of each falt, in the fame time, or with the fame degree of heat; for an ounce of cold water will foon diffolve half an ounce of falt of tartar; but half— an HY SICAL and LITERARY. 333 Ain ounce of crude tartar cannot be dif folved 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, hew water being added to fupply the wafte. Even that compound falt, made of the fixt falc and chryftals of tartar, which, from its folubility, with refpe@ to common tartar, gets the name of tar- tarus 5[abalet, requires little lefs than ten times its weight of warm water to diffolve it fully. VIL. Some bodies can be diffolved in liquors of very different qualities, but in different proportions, with different helps, appearances, and effects. Common fulphur or its flowers dif- folve in any oil, but more eaftly, and in greater quantity, in a thick, mild, ‘ex- ; preffed oil, than in a thin, hot, aromatic, - diftilled oil, “When flowers of fulphur are digefted with oil of olives, or lint- feed, it becomes a thick balfam : Three’ ounces of oil will diffolve one ounce of ’ fulphur ; 332 ESSAYS any OBSERVATIONS fulpkhur ; and any fmall part of fulphur which remains has the appearance of melted fulphur. But, when the flowers are digefted with zthereal oil of turpentine, fix ounces of oil will fcarce diffolve one of fulphur, and what remains is not like the fulphur in the former cafe ; for, if the veflel is cooled gradually before the bal- fam is poured off, the fulphur appears al- moft like nitre when it chryftallizes, or a vegetating falt branched out into long. flender flalks. Sulphur likeways diffolves in fpirit of hartfhorn, but {till in lefs quantity, and with a fmaller degree of heat. And it is to be obferved, that the " unrectified or oily fpirit will diffolve more fulphur than the clear and pure fpirits ‘Fo make fulphur foluble in water or {pi- rit of-wine, it muft be melted, then mix- ed and incorporated with a fixed alcaline falt, by which means it will moftly dif- folve in warm water, and give a deep and ftrong tincture to {pirit of wine. THE calx of lead, litharge or minium, diffolve in diftilled vinegar; but more fully PHYSICAL anv LITERARY. 333 fully and quickly in aqua fortis diluted with fix times its weight of water. The folution of lead in fpirit of vinegar, be- ing evaporated flo ly to a due conftft- ence, and then removed to a ‘cool place, never fhoots into. fair diftinét chryftals ; but thickens, ‘as it were, into a faline mafs, like coarfe fugar, fomewhat moitt ;. and, with difficulty, can, be brought to a tolerable whitenefs: But the folution in diluted agua fortis, treated in the fame manner, gives large, folid, fhining, white chryftals, regularly fhaped- The calx of lead or miniumwill likewifediffolve. by digefting or boiling in oil of olives or’ ' lintfeed; but, as it diffolves, it thickens into the confiftense of an unguent or plaifter. _ Goon aqua fortis or aes nitri path ajgolve about an equal weight of quick- filver ; and the folution is performed with a great commotion, heat, and, thick red fmoke: Strong -oil of, vitriol’ diffolves fcarce a third part of its weight of quick- sy ilver ; and the folution is made in a flow Divs ct amds $44 ESSAYS anv OBSERVATIONS. and imperceptible manner, and requires the affiftance of a great external heat. THE manner in which the acid of fea- falt is applied to quick-filver, in order to’ diffolve and be united to it, is ftill more éxtraordinary : There are two methods practifed, but both depend on the fame’ principle, and produce the fame effect. For, either the quick-filver is rubbed in a marble mortar with green vitriol cal¢ined’ to whitenefs, decrepitate fea falt, and a fmall proportion of dry falt-petre, till the’ quick-filver is extinguifhed and difap~ pears, this mafs is put into a fubliming: ‘glafs { a gentle hieat is made at firft, and : gradually increafed ; in the beginning a's rife white fteams ; if ‘thefe are collected, they condenfe into a liquor, which proves a weak aqua regia ; then there will fublime a white fhining chryfta“line body, which’ ¥s a vitriol of quick filver, and goes un: der the name of mercurius fiblimatus cor~ rofivus: That the quick-filver is here dif- folved by, and united to’ the acid of fea: falt, with a fmall quantity of the nitrous acid, is evident; becaufe the fame mate— rials, PHYSICAL anp LITERARY, 33g. rials, without the addition of quick-filver, properly treated, yield a good aqua regia which diffolves 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 de- crepitate fea falt, and fublimed as before: ere likewife the acid of fea falt, with a portion of the nitrous, is joined to the _mercury; for, one way of preparing an aqua regia, is by pouring aqua fortis upon decrepitate fea falt, and drawing off a li- \quor by diftillation, which is in effect done in this cafe; only the acid incorpo- rates with the quick filyer into a vitriolic ; form. VIIL THE folvent powers of certain mer fir ua are not deftroyed in the act of - folution, but can be exerted on other bo- dies ; and the mexfirua, feparated from the _ diflolved bodies, may retain or recover all their former qualities.” ¥ Tuts property of feveral folvents will be found to obtain in many more inftan- ces than is seine y imagined. Many 309 folvents, 336. ESSAYS anp OBSERVATIONS: folvents, when they are actually diffolving bodies, excite a ftrong and remarkable effervefcence, with a great expanfion, hifling, bubbling, heat, and {moke ; 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 generally imagined, that, from this ftrug- gle or action and reaction betwixt the bo- dies, the particles of the meufiruum are broken, their points blunted, and their ficures changed, by penetrating into the pores of the folid body, by disjoining and dividing the parts very minutely. But, I fhall endeavour to make it appear, from experiments, that the active particles, of moft liquors, 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 cha- racters of thefe liquors: That, tho’ they have diffolved feveral different bodies, have entered into many compofitions, and have paffed thro’ a great variety of forms5 . yet, 7 = Nr : PHYSICAL ann LITERARY. hee yet, after all, moft 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 through all the fucceflive changes; fo that it may be . doubtful whether art can intirely change the nature of fome of thefe folvent li- quors. f To begin with fome familiar inftances toconfirm our remark. Water can dif- folve a certain quantity of any falt; yet, when it is fully impregnated with one falt, it will ftill diffolve a portion of an- other falt, though not fo much as the {ame quantity of pure water would do. From fea water, by evaporation and chryftallization, are procured three di- ftinc&t falts, befides other fubftances, as the ingenious Mr Brown has obferved, viz. the muriatic, or falc for common ufe, the bitter purging falt, and a fiery calcarious falt, different from the other two; yet fea-water will diffolve, at the fame time, a pretty confiderable quantity _ of feveral other falts, as fugar, falt am- moniac, falt-petre and falt of tartar ; and, Savor. I, Uu after 338 ESSAYS anp OBSERVATIONS after it has diffolved fufficiently of two or more of tbefe falts, it will, even then, diffolve fome more fea falt, and ftill more of the Epfom or Glauber’s falt. Hence, by the way, we find fuch a varie- ty of mineral or medicinal waters, impreg- nated in various proportions, with diffe- rent falts, vitriols, metals, earths, &c. The acid of fea falt-which has diffol- ved quick-filver, and chryftallized with it in the fublimation of corrofive mer- cury, will diffolve the metallic or reguline part of antimony into a liquor, called butyrum antimont; and this will after: wards diffolve gold. Diffolve filver in a- qua fortis, when the folution is finifhed, add to it fome crude falt ammoniac, in | powder, and fet the veffel in hot fand; the filver will all fall to the bottom: Then pour the clear liquor into another glafs; this will be found a good aqua regia fit to diffolve gold, regulus antimonu, &c. There is another noted experiment which evidently illuftrates and confirms the re- mark. If fine copelled filver is diffol- ved in proof agua fortis, and the folution is PHYSICAL anp LITERARY. 339 is diluted with an equal quantity of diftilled water, it will continue clear and lympid, without» any — precipita- tion: If then a piece of polifhed cop- per 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 gra- dually off, by the copper falling down, and the iron is diflolved in its place: Af- ter allowing a fufficient time for the folu- tion of the iron, and precipitation of the copper, put into the folution a piece of, lime-ftone; the aqua fortis immediately works upon it with frefh vigour: Laftly, add fome falt of tartar, or oleum tartari, p.d.; this precipitates the {tony matter, and renews the effervefcence. This feems to finith the work, and quite to abforb -the acid, and deftroy all its folvent, __ powers: Yet even here the acid only lurks and conceals itfelf by its ftri€@ union with . 340 ESSAYS anv OBSERVATIONS with an oppofite falt. But art can again produce it to view, and reftore all its former powers. If, in this procefs, five or fix ounces of /pir. nitri, or aqua fortis, » were employed in the beginning, and, after the laft ftep, the liquor is diluted with fome more water, {trained through brown paper, fully fatiated with the al- caline liquor or falt, and then flowly e- vaporated and chryftallized: There will be procured a falt perfectly refembling common falt-petre, in the fhape of the _chryftals, explofive quality, and other marks. This factitious falt-petre then may be employed in place of the com- mon; and I diftilled fome ounces of a falt, made much in the fame way (for I imagine the intermediate fteps will make no alteration) with oil of vitriol, inGlau- ber’s manner, and obtained a ftrong fmoaking fpirit, which anfwers all ‘the characters of Glauber’s fpirit of nitre, and diffolves the fame bodies; and there- fore may run through the fame courfe, over and over, without’ any change, un- lefs that it may be gradually wafted, fome part PHYSICAL ann LITERARY. 341 part of it being diflipated in every ope= ration. xe I found the fame thing hold in other acid liquors, as fpirit of fea falt, fpirit -of vinegar, the acid of tartar, &c. which I joined to alcaline falts, and recovered the acid by diftillation. Thefe, and fomeo- ther experiments of the like nature, which _Thave not yet’ had leifure to confider in their full extent, I fhall take another op- portunity to lay before the fociety. In the mean time I fhall proceed to make fome Remarks on Precipitation. By precipitation is meant the parting or feparating the {mall particles of a dif- folved body from the folvent liquor by means of a third body, folid, or fluid; which is therefore called the precipi- tant. THERE is indeed another manner of ‘Parting the diffolved body from the fol- vent, which is fometimes, though lefs Properly, called precipitation; when, by drawing 342 ESSAYS anp OBSERVATIONS drawing off part of the folvent liquor by evaporation or diltillation, the diffolved body falls down gradually 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 a change. Remark I, ALL precipitations do not happen from the oppofition of an alcali to an acid; but there are different means of. precipitating different folutions. It is certain, from experience, that whatever bodies are capable of being diflolved in any acid liquor, may be pre- cipitated from it by an alcaline falt or liquor. On the other hand, any body that is diffolved in an alcaline liquor may be parted from it by the addition of an acid. This then is a pretty general me- thod of precipitating : However this op- pofition of acid and alcali is not the fole caufe of precipitation; for many metals and metallic fubftances, diffolved in their proper acid menftrua, may be precipita- ted PHYSICAL ano LITERARY. 343 ted by other bodies that are not alcaline, fome by plain water, fome by neutral falts, natural or artificial; fome by an- other metal, fome by another 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 alca- line liquors are not the only folvents; for water, ardent {pirits, oils, and feveral com- _ pound liquors, neither acid nor alcaline, diffolve a great many different bodies, which likeways may be feparated from them by precipitants of different quali- ties. Therefore an acid and alcalido not | always concur to make a precipitation. 1. Tue weakening or diluting folu- tions, by a liquor fpecifically lighter than | the folvent, is not the fole caufe of preci- _ pitation, SoME, who would account for precipi- tations upon mechanical principles, con- tend, that diminifhing the {pecific gravity of the folvent liquors is the caufe of all Precipitations: But this, although it ob- taims in fome inftances, yet, in many more, 344 ESSAYS anp OBSERVATIONS more, it will be found contrary to expe- rience. If any falt is diffolved in water, and if fpirit of wine, a liquor fpecifically lighter than water, is added to the folu- tion, no precipitation will enfue. WHEN filver is diffolved in good agua fortis, the folution may be diluted with fair water to any degree you pleafe; yet — the particles of filver continue fufpended in the liquor, though rendered fpecifically — lighter: Whereas, when the thinneft and lighteft parts of the folvent are carried | off by evaporation, the filver falls down. in the fame manner, a folution of quick- filver in aqua fortis, a folution of gold in agua regia, of lead in fpirit of vinegar, © and fome other folutions of metallic fub- — ftances, may be diluted with fimple wa- ter without precipitation. Further, fome- times a liquor fpecifically heavier than the folvent is added to the folution, whereby the fpecific gravity of the compound lie quor is increafed; yet the particles of the diffolved body are no longer fufpended 3 in it, but fall to the bottom, quite contrary to this hypothefis. When rofin of jalap is’ diffolved 7 | YSICAL and LITERARY. 345 liffolved in: highly reétified fpirit of | vine or alcohol, if water, which is fpe- ally heavier than the fpirit, is pouf- sd in, the refinous particles can no longer: Wbe fuftained. The fablimate corrofive ae: ercury can be diffolved in lime water Der common water: Upon pouring in ofl of vitriol, a very ponderous acid liquor, the mercury fabfides. Coral diifolved in fpirit of vinegar will be thrown down by the fame oil of vitriol. Thefe int ftances naturally lead us to another re- ‘mark. "TIL. Some bodies diffolved in one acid xe liquor may be precipitated by anotheracid. aye. ‘To the two former examples of this ae of precipitation, I fhall add fome | ers. Silver, diffolved in aqua fortis, ee be thrown down, if /pir. fal. marini is put into the folution: On the other hand, a folution of gold in agua regia - fufers a precipitation by the affufion of zr. nitri, ‘That corrofive acid liquor, Valea butyrum‘antimonii, is kiown to be Pa folution of the metallic part of anti- a * in aqua regia: If we pour into it Vou... xX & Spits ‘ Mi | 346 ESSAYS anp OBSERVATIONS fpir. nitri, after a pretty heise effervef cence, we fhall find a metallic powder at the bottom. | IV. Some metals diffolved in an acid — liquor may be precipitated thence by another metal or metallic, ftony or cal- carious fubftance, capable of being dif- folved in the fame menftruum. UNDER the head of folution, I had oc- cafion to adduce a well known inftance, to fhow that a menftruum having diffolved one body, will fucceflively diffolve feve- ral others in a certain order. I am obli- ged to mention the fame again, as a con- firmation of the prefent remark. If pure filver is diflolved in proof agua fortis, 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 fole inftance of this way of precipitation: Others may be found. The fublimate corrofive mercury may be juftly looked upon as a folution of quick-filver in the acid of fea falt or aqua regia, brought in- to ‘ y 4 % ' 4 | F ; -. WE meet with a great many inftances " PHYSICAL anp LITER ARY. 347 | foPehryfaltine or vitriolic form by fub- tion: When this corrofive mercury “Gs mixed with an equal weight of com- antimony, and thefe rubbed toge- ther, left to moiften in the air, and then diftilled ; there happen fuch changes to this mixture, as evidently fhow a real pre- - cipitation of the quick-filver by the re- guline part of the antimony; for the a- cid forfakes the quick-filver, and diffolves the regulus, which makes the butyrwm an- timonii; and the quick-filver, freed from the acid, is by the fire incorporated with the fulphur of antimony into a_ black powder like Ethiops minera/is, which may be fablimed into the cinnabaris antimonii, Quick-filver diffolved in aqua fortis may likeways be precipitated by another me- _ tallic body, as zinc or bifmuth. V. Some bodies diffolved in their pro- per menftrua may be precipitated thence by feveral bodies of different quali- See temsiliey to confirm this remark. [- fhall | 348 ESSAYS snp OBSERVATIONS - fhall mention a few examples, in which the greateft variety obtains. Pure filver being diflolved in good aqua fortis, and the folution diftributed into fix or eight _ gilaffes. we may make as many precipita- tions by different precipitants ; for folu- tions of fea falt and crude falt ammoniac, fpirits of fea-falt, vitriol and falt amma- miac, a fixt alcaline falt or its lee, and a piece of copper, will, each of them fepa-_ rately, make a precipitation of the fil- ver. avila oti : QUICK-sILVE R,diffolved in aqua fortis, © may be precipitated by a folution of fea falt, by a folution of crude falt ammoni- ac, by freth urine, by fpirit of faltammo- — niac, by o/. tart. p. d. and by zine. ) REGULUs of antimony, diflolved in aqua regia, will be precipitated by plain water, by a folution of falt-petre, by {pirit of ni- ~ tre, and, by the alcaline liquors, fixt and — volatile. | VI. THE matters precipitated from the fame folution, by different precipitations, differ from one another in feveral remark- able qualities. | Bs WHEN - sr a. ae ea wee << wy « > - _ PHYSICAL anv LITERARY. 349 | WHEN either a muria of fea-falt, a for ution of falt ammoniac, or fpirit of fea fale, (for thefe three have nearly the fame effects), is put into a folution of filver, it becomes milky, and, as it were, cruddled, and,at length,awhite powder fubfides tothe ‘bottom: This powder, being wafhed with warm water and dried, is foft and impal- pable; its weight exceeds that of the fil- ver diflolved by more than one fixth part. 'This powder comes much fooner to fufion than filver, but does not recover the ap- pearance or properties of that metal; for it looks like a piece of yellowifh glafs, femi opaque and brittle, yet bending or yielding a little, whence it gets the name of /una cornea, or horny filver; and it is with great difficulty that it can be redu- _ ced to true malleable and ductile filver. _ WHEN a plate of copper is put into 2 folution of filver diluted, the furface of the copper is immediately covered, as it were, with a coat of filver; this becomes gra~ dually thicker, and appears tufted, fpun- _ gy,.and loofe: Upon fhaking the plate, _ large pieces of this cruft fall off, which € either 350. ESSAYS anp OBSERVATIONS | either rife to the top, or fwim about in the liquor for awhile, till, difcharging many bubbles of air, they grow heavier, and fall down in form of a white powder: The filver being in this manner feparated from the liquor, then wafhed and dried, is nearly of the fame weight with the fil- — ver diffolved; and, when melted, runs into a lump of pure malleable filver, without any confiderable lofs, Ir an alcaline liquor, as /pir. fal. am- moniaci, or ol. tartari p. d. is dropt into a_ folution of filver, it excites. a ftrong ef- fervefcence, which will be renewed when more of the alcaline 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 pour- ed in, the frothy matter diminifhes con- fiderably in bulk ; and there is left a pow- der of an afh colour, which, being dried, a little exceeds the weight of the filver diffolved. THE - PHYSICAL ann LITERARY. 351 _ ‘THE precipitations of mercury fhew fiill a greater variety, at leaft, as to their _ effets, being ufed as medicines. If fea i falt, diffolved in a good quantity of wa- ih ter, is put into a folution of quick-filver P in aqua fortis, it turns the clear and lime | _ pid folution turbid, opaque, and milky ; at length the white matter fubfides, which. : being feparated from the fluid, wafhed _ and dried, remains a very white powder, and a little exceeds the weight of the - quick filver diffolved: But it is to be ob ferved, that the muria does not precipi+ tate all the mercury; for the liquor, thus _ feparated from the white powder, is known. _ to have the effects of a cofimetic or deter- _ five mercurial water; befides, if ol. zart. | p+ 4. is dropt into this liquor, a {mall |. quantity of a brown mercurial powder will be precipitated. Phyficians know that this white precipitate is a pretty ac- tive and brifk medicine, and produces "greater effects, even in a fmaller dofe, | than calomel; but is more mild and trac- table than the merc. fublim. corrofinus: For, “when this laft is fomewhat tempered. by | Ser 352. ESSAYS and OBSERVATIONS” Spir. fal. ammon. it becomes a medicine mauch of the fame nature with the pré= — ceeding white precipitate: A folution of crude falt ammoniac and /pir. fal. mar. have the fame effects on the folution of quick filver, as the muria has. IF a little frefh uriné is put into a fol | jution of quick-filver in agua fortis, there will likewife happen a precipitation: But the powder is not white, but of a — pink or flefhy colour; it appears pretty bulky, and has acquired a little additio« nal weight. This precipitate is not ufu= ally prefcribed’ by phyficians: But M. Lemery pretends that it is milder than the white, and only operates by ftool. IT would appear then, that, in many inftances of precipitation, the particles of the diffolved body are increafed in denfi- ty and fpecific gravity; by reafon that fome parts either of the precipitating matter only, or of the compound, madeé ~ up of the folvent and precipitant, are ve> | ry firmly united to them, fo that they ; cannot longer be faftained in the liquor, But, in other cafes, where the matter pré- cipi- ther caufe of sirectpitatioi which may obably be, that there is a greater aff- nity betwixt the precipitating body and g the folvent, than betwixt this and the bo- if ly diffolved ; whence, from the difpofi~ tion of thefe bodies to unite, they fhake off, or drive away from them, the parti eles already joined to the folvent. ‘ 354 ESSAYS anp OBSERVATIONS A phe Ser Experiments on Neutral Salts, compounded of different acid Liquors, and alcatine Salts, fixed and volatile ; by the fame. * & T a former meeting of the fociety (January 1738), I read fome re- marks on chemical folutions ; the laft of which gave me occafion to mention fome experiments, in which I was then employ- ed, but had not finifhed: And _there- fore, at that time, I could not confider them in their full extent; or have a juft view of all the confequences that nvarte be drawn from them. I now proceed to relate the experiments, and to obferve how far they may be ufe= ful to extend our knowledge. I prepared a parcel of factitious, or (as the chemifts are pleafed to call it) rege~ nee * June 7. 17396 a — Pa ' _ PHYSICAL anv LITERARY. 355 nerated nitre, in this manner: I took two ounces of an extemporaneous fixed alca- “dine falt, made of equal parts of nitre and tartar ; ; I diffolved this falt in warm wa- _ ter, filtred oan folution, and poured 1 into ‘ a mati the alcaline pea was ae ta ba _ tiated with the acid, which required one ounce and a half of the {pirit of nitre. From this faline liquor, by evaporation and chryftallization, I procured two oun- ces and a half of falt, when it was all collected and well dried. The chryttals were long, flender, and prifmatigal ; the falt had a pretty mild and cooling tafte 5 and bits of it put upon a burning coal | made it fparkle and give a bright flame. WE may obferve by the way, that the compound falt exceeded the weight of the fixed falt by half an ounce or 240 grains; _ this additional weighr it procured from the fpirit of nitre: Therefore one ounce and a half, or 720 grains of the {pirit of ‘nitre which I ufed, contain 240 grains. of “true acid, which is capable to fatiate four times its weight of alcaline fixed {alt, I 356 ESSAYS anv OBSERVATIONS. I put two ounces anda half of this fac- titious nitre into a fmall glafs retort, and poured upon it one ounce of oil of vitriol, which immediately begun to raife an e- bullition with heat and red fumes; a re- celver was inftantly joined to the retort with pafte, the glafs fet in a fand fur- nace, 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 remained at the bottom of the retort a cake of white folid fale, which being dif- folved in warm water, the folution’ filter- ed, and part of the water again exhaled, fhot into chryftals; and thefe being all carefully collected, weig ghed two ountes, twenty two grains. Tur fpirit obtained in this manner was fiery, active, and conftantly emitting red fumes ; it diffolved filver, kindled with oil of cloves, and agreed in all other cha- racters with ftrong fpirit of nitre. The ‘falt which remained in the retort when purified and chryftallized, no way refem- bled PHYSICAL anp LITERARY. 357 bled falt-petre, or the falt employed in this operation, in the fhape of the chry- _ ftals, tafte, or other properties; for thefe oe chryftals were polyhedras, having feveral triangular faces and folid angles; their tafte is rough, bitter, and fomewhat a- ftringent; they do not readily melt or fparkle in the fire, as common or factir tious nitre does. Imade another factitious falt, by im- pregnating a felution of the fame alcaline fixed falt with fpirit of fea falt, pouring it in by degrees, till there appeared no ef- fervefcence, and the liquor tafted briny. Four ounces and a half of this fpirit were employed to fatiate two ounces of the fix- ed falt:; When the two faline liquors were duly proportioned, there appeared, before evaporation, a great many fmall grains | of white falt at the bottom, which, as as well as the liquor furrounding them, had the true muriatic tafte. THE falt obtained out of this liquor, had the genuine figure of the common fea falt; but the chryftals were fmaller, more hard, white, and opaque: The falt is not alto- 358 ESSAYS anp OBSERVATIONS altogether fo pungent as what we com- monly ufe; but more agreeable and cools ing, yet without any acidity. This falt, 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 falt into a {mall glafs retort, and poured upon it two ounces of {trong fpirit of nitre, which occafioned an ebyllition with heat and fmoke. I proceeded to the diftillation, with a fire gradually increafed ; when the. veffels were cooled, I found in the recei- ver, two ounces four drams and a half of an acid liquor, of a faint greenifh colour, which fmoaked much when the vellels: were fir{t 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 filver in aqua fortis ; it made it white and cruddled, and at length a white powder . fell down. I poured a {mall quantity of it upon a few grains of filings of gold; with the affiftance of a little heat, the fpi- ‘Tit a - ce caees? te aw PHYSICAL any LITERARY. 359 tit pretty quickly diffolved it, leaving on- ly a few particles at the bottom. From thefe characters I think we may conclude, ~ that the acid liquor, produced in this o- " peration, is a true agua regia: I chufe ra- ther to call it fo, than fpirit of fea falt ; becaufe I found it had a greater and quicker effect in diffolving gold than the plain fpirit of falt-had ; therefore it is pro- bable, that a {mall quantity of the nitrous acid had accompanied the acid of fea falt. THERE remained in the retort a cake of folid white falt, like melted nitre, or /a/ prunellae: After it had been diffolved in warm water, the folution filtered and eva= porated, there appeared many regularly fhaped chryftals,long, flender, and prifina« tical, of the nitrous kind; which being removed, and more of the moifture ex- haled, the chryftals which formed were not fo large nor fo regularly fhaped as _ the preceeding, but the whole appeared _ like a mafs of white falt coarfely powder- | ed: However I could difcover, among thefe chryftals, fome that a a quadran- - gular 360 ESSAYS ANp OBSERVATIONS - gular bafe, but long fides, like two cubes joined, others varioufly compounded or - broken: Even this part of the falt had the cooling nitrous tafte ; and part of it put upon a live coal fparkled and excited a bright flame like falt-petre. Acatn, I took two ounces of that neu= tral falt, called tartarus folubilis, the’ pre~ paration of which is very well known; in this compofition, the native acid of white tartar, or the chryftals of tartar, is impregnated with an alcaline ley, or o/. tart. p. d. from the union of thefe in due proportion, arifes a mild neutral falt, 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 {mall glafs retort; and poured upon it one ounce of oil of vitriol, which raifed a bubbling and ef- fervefcence. In diftillation there came o~ ver fix drams of liquor, of a brownith colour, with a little oilinefs upon it: Its tafte was four, but difagreeable and em- pyreumatic; it had an unpleafant fmell, but not very ftrong or pungent; it effer= vefced; : 4 PHYSICAL anv LITERARY. 361 yefeed with alcaline falts fixed or vola- tile: In all which properties it agrees with acid liquér drawn by diftillation from crude tartar, which is commonly called its fpirit. I obferved, in dittilling this. mixture; that there came up fome vola= tile falt, but in very fmall quantity, which. fpread itfelf upon the neck of the retort, in very finé and ‘fubtile ramifications : The upper part of the body of the retort was fullied with fome thick black oil; - and the faline matter at the bottom wag of a dirty afh colour, like tartar half burnt. I poured warm water into the re tort, and left it on hot fand, to diffolve thé falt; I found it neceflary to pafs this folution through a filter, and there re- ‘mained 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 zartarus folubilis than was fufficient: . _ Fo overcome the acidity, Idropt into the liquor fome ol. tart, p. d. till the effervef- cence ceafed ; and then, by evaporation and chryftallization, I procured a falt, in Vor. tI. Zt every 362 ESSAYS aNp OBSERVATIONS every refpect like the tartarus vitriolatus, as ufually prepared. Upon two ounces of the fame cari. fo~ lubil. 1 poured one ounce of ipirit of fea falt; made after’ Glauber's,) manner} by ditullation there. was produced a liquor of the fame kind with that of the pre= ceeding experiment. The remaining falt indeed was not diffolved nor chryftallized ; but, from.its tafte,and by its precipitating a folution of filver in a7. fort. it appeared to be of the miuriatic kind. AFTER this, ] made an experiment on another neutral falt in which the acid of vinegar is united to the alcaline falt.of tartar, which is commonly known by the name of tartarus regeneratus, 1 took one ounce and an half of falt of tartar, and poured diftilled vinegar upon the dry falt at feveral times, fhaking tie glafs fre- quently, till fifteen ounces of the acid were employed: The veflel was then fet on a fand-bath, and the liquor gradu- ally infpiffated till there remained four ounces 27 grains of a moift, greafy, faline fubftance, of a brownifh colour, like | coarfe PHYSICAL ann LITERARY. 363 coarfe fugar. I did not think ic for my prefent purpofe to beftow more time and pains to bring this falt toa greater degree of whitenefs and drynefs ; but I putit in- -to 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 limped acid liquor, which, in tafte, refem- bled diftilled vinegar, but was more {trong, The faline maifs left in the retort being diffolved in warm water, the folu- tion filtred and evaporated, the chryftals could not be diftinguifhed from the or- dinary ¢artarus 6 aha ca in fhape, colour, or tafte. To fatisfy myfelf, “ie a volatile alia line falt or {pirit may likewife be difen- gaged from an acid to which it has been united, and reftored to its former ftrength and qualities, I made the following expe- _riment. I took eight ounces of that com- pound faline liquor, which is defcribed | in our College Difpenfatory under the ti- tle of Spiritus Mindereri; it is made by pouring diftilled vinegar upon volatile fal- 364 ESSAYS anp OBSERVATIONS — fal-ammoniac, until the falt is diffolved and fatiated by the acid. This neutral - faline liquor, however, will not chryftal- lize or coalefce into a dry folid falt, nor will the volatile alcali feparate from the acid, by a fimple diftillation, but they rife together. I put eight ounces of this fpirit into a bolt head; and, adding half an ounce of dry falt of tartar, I prefently tted a capital and receiver to the body, | luted the joinings, and fet the veffels in a fand heat; in a little time a white vo- latile falt fublimed into the capital, which was foon wafhed down by a watery va- pour into the receiver. This liquor being tried, was found equally ftrong, pungent, clear, and volatile, as the beft fpirit of fal- ammioniac: The faline maiter left in the body was of a greyifh colour, foft and greafy to the touch, and would hardly dry or chryftallize, refembling tartarus regencratus. I need not confirm this by any further experiment ; becaufe it is known to every body, that the volatile falt and fpirit of fal ammoniac are sata by adding a fixed : | : PHYSICAL ann LITERARY, 365 fixed alcaline falt to the crude fal-ammo- miac: Now, as we can prepare an extem- poraneous or artificial falt, by impregna- - ting the volatile falt or f{pirit of fal-am- - moniac with the fpirit of fea falt, we have no reafon to doubt, but, by means of a fixed alcaline falt, we may again dif- engage the volatile falt or {pirit from the acid. BuT it.may be of more importance to difcover what kind of acid is joined to the volatile alcali in the common or crude fal-ammoniac: For this purpofe I. made the following experiment. When all the wolatile falt and fpirit are drawn off from crude fal-ammoniac by the addition of a fixed alcaline falt and water, there remains a faline mafs; which, when diffolved in warm water, the folution {trained and e- vaporated, the chryftals very much re- femble thofe of fea-falt, in fhape, tafte, and other diftinguifhing characters of that falt, ‘efpecially when it is well depu- _ rated and carefully chryftallized. This falt, however, has been dignified with the title of fal febrifugum Sylvii, 1 put three ounces | 366. ESSAYS anp OBSERVATIONS ounces of it into a retort, and poured in ' one ounce of oil of vitriol, and as much water. In-the diftillation, the receiver was filled with white fumes, which con- denfed into a liquor of a pale colour, fomewhat turbid at firft, of which 1 had near three ounces. The liquor had all the appearances of the fpirit diftilled in Glauber’s manner, from common fea-falt; and, when fome of it was dropt into the folutions both of filver and quick-filver, it turned them both milky, and made a white precipitation From all which I have no difficulty to conclude, that the acid contained in crude fal ammoniac is of the muriatic kind, or the fame which js produced from fea falt, But whence this acid fhould proceed, is a matter of © greater intricacy ; fince we are affured that no fea-falt is neceffary to, nor employed in, the preparation of that fal-ammoniac which is brought to us from Egypt. Tas queftion I fhall not undertake to difcufs, as being foreign to my prefent -purpofe ; but fhall fubjoin fome remarks. on the experiments above related, or de- duce PHYSICAL ano LITERARY. 367 duce fome corollaries which feem natural- ly to arife from them.) | 2 lTue acid fpirits, as thofe of vitriol, nitre, fea falt, vinegar, &c. are faline li- quors, or fluid falts, made up of the very ° minute particles of an acid falt, and/a'cer- tain proportion of phlegm or water. Il. THE particles of thefe acid falts can- not be brought to, unite, among them- felves, by chryftallization or fublimation, fo as to appear in the form of a folid or - dry falt: But they readily lay hold-on the particles of certain metals or femi-metals, ¢alcarious ot abforbent earths, or oppofite faks, fixed, or.volatile, which ferve them us the bafis; and, joined, to thefe, they affume a chry-ialline form. WW. Wen any of the acid liquors are joined, in due proportion, to any alcaline falt, whether fixed or volatile, the parti- cular acrimony and pungency of both, as fo our fenfes, and their power of diffol- _ ving certain bodies, in a feparate ftate, are ignite deftroyed, at leaft, overcome and ee ed, by their union. . y IV. WHEN 368 “ESSAYS Ano OBSERVATIONS ~ IV. WHEN an acid liquor has diffol~ ved a metallic body, and is united to it; the folution and the vitriol made of it are frequently more acrid and cotrofive, with refpe& to the human body, than the acid by itfelf. Ido not affirm this uni- _-verfally : But we have inftances of it in the folutions and vitriols of filver, quick- filver, copper, antimony. . Ve WHEN the fpirits of nitre or fea falt are joined to falt of tartar, or pot-afh, and chryftallized, the chryftals affume the peculiar fhape and molt remarkable properties of the natural falt from which the acid fpirit was originally produced. Confequently there appéars to be fome affinity betwixt the native fixed bafes of thefe falts, and the fixed falts of plants. VI. Tue artificial vitriols compounded of the fame acid fpirits and metallic par= ticles, do not refémble the originak falts ; but the vitriols of different metals, or me- — tallic bodies, have different fhapes, though ~ they are joined to the fame acid falts. ; VIL. Tue acid falts, though combined — with the alcaline, into mild neutral falta, yet PHYSICAL anp LITERARY. 369 yet are not fo changed by this union, but, when they are again artfully disjoined, they may exert the fame powers and pro- duce the fame effects as before their uni- on: Therefore we may conclude, that the figure, bulk, and denfity of the acid par- — ticles are not changed, though the liquors may differ fomewhat in ftrength from the greater or fmaller proportion of phlegm, or water accompanying the real acid. . VIII. ONE acid which has been united to an alcaline falt may be fet at liberty, or expelled from its cohefion with the al- - caline falt, by another acid of a different \ origin, But this does not happen indif- criminately ; for the oil of vitriol expels any other acid, but cannot be diflodged _ by any of the reft. A volatile alcaline falt is expelled from its union with an acid, by a fixed alcaline, but not contrary- ways. | ) ae Wid. Generad . - 370 ESSAYS anp OBSERVATIONS General Scholium. | WE can have no other idea of a folid or confiftent body in general, as diftin- guifhed from a fluid, than that the parts of a folid cohere together by fome power which retains the particles in their fitu- ations with refpect to one another, and makes them to refift 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 fo- lid body, as a lump of falt-petre, in fome. hours, makes fuch a change upon the lump, that, it wholly difappears, if the glafs is fhaken a little ; that is, the falt is divided into particles, fo fmall, that they efcape our fight, and are equally diftriz buted through the liquor, and fufpended jn it: When we obferve this, I fay, we cannot but conclude, that the particles of watcr are endued with a power capable to PHYSICAL awn LITERARY. 97: to overcome the force by which the par- ticles of falt-petre cohered with one ano= . ther: Ir a known quantity of cold water has diffolved as much {alt petre as 1t is capa- ‘ble.to hold, in this folution, the water is _ to the falt as 53 to 1 ; (in fcealding wa- ter, the proportionis as4to1.). If then % of the water is wafted by evaporation, ~ many of thefmall particles of nitre, being brought into contact, join together, and form chryftals in thape and other proper= ties refembling the nitre which was dif= folved in the water. It follows, there- fore; that the particles of nitre mutually ‘attract one another; when the interpofing — ‘matter is removed; the diftance betwixt them very much diminifhed, and no fu- perior power acting upon them; and, when in contact, they cohere with a cer- tain degree of force. Again, it appears, that the particles of water do attract the -particles of nitre more ftrongly than thefe jaft attract one another; and, confequent- Wy, overcome their cohefion, and fufpend - there 372 ESSAYS anp OBSERVATIONS their mutual attraction. Laftly, it is evi- dent, from the above appearances, that though the parts of nitre which fwim in the water are fo fmall, that they are not perceptible fingly, even when viewed through a pretty good lens; yet they mutt be fimilar to one another, and re- tain the properties of real nitre. LET us next confider the effects of an- other liquor, upon the fame falt- petre. Ir oil of vitriol is poured upon a par- cel of nitre, there happens likewife a fo- Jution, but with appearances different from thofe in the former; for this is ac- companied with a confiderable inteftine motion and expanfion, {moak and heat, and produces a much greater change on the nitre: For, by the help of external heat and clofe veflels, there rife from the mixture copious red fteams, which are condenfed into a corrofive acid liquor, ve- | ry active and volatile; and there is left a white faline mafs, no way refembling ni- tre. From what has been faid formerly of this experiment, it appears that the oil of vitriol PHYSICAL AND LITERA RY, 373 vitriol makes a more minute and fubtile divifion of nitre than what fimple water ean do; that the fluid acid: fale of the oil of vitriol attracts one part of each real particle of nitre, viz. the fixed and alcaline bafis, while this fame vitriolic acid feems to repell another part of nitre; that is, the acid and volatile part, which attraéts,; or ~ _is attracted by the phlegm or: watry part of the mixture, is eafily raifed up in va- pour by heat, and turned into a faline a~ cid liquor. Ir may be juftly queftioned, whether this is an ultimate divifion of nitre, or a feparation of it into its moft fimple prin-< ciples or firft elements. It is very hard to find an experiment that can give full -fatisfaCiion in this point; for there are certain bounds fet to art as to the divi- fion of bodies: But, if that part of nitre which unites with the acid of vitriol into a neutral falt is the fame with nitre fixed by deflagrating with charcoal; or if it is no other than that falt which can’ be extracted from the remains of the diftil- lation 874. ESSAYS anp OBSERVATIONS jation of nitre with bole; then we have fome reafon to conclude, that this part of nitre is mot a fimple elementary mat= ter: Since fixed nitre can, by frequent fo- lutions 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 folvents act no otherways upon their proper objects than water does upon nitre or any other falt, by diffolving the cohe- hefion of the larger particles which com-. pofe the body, without refolving the par- ‘ticles into their primary elements, WHEN fpirit of nitre or aqua fortis is poured upon pieces of filver, the appear- ances plainly point out that there is an attraction betwixt the particles of the fol- vent and the filver; and that there is like- wife 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: For there is a remarkable motion and agita- tion in the liquor ; the furface of the filver foon: 7 PHYSICAL anp LITERARY. 37¥ {oon 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 hquor is carefully taken. off. from the top, even before half the filver: : is diffolved, and dropt into a muria of "fea falt, it will give evident marks that it contains a portion of filver. When all the metal is. diffolved, the folution be- comes clear and limpid, and all is at reft. Thefethings evidently fhew, that fuch me- tallic particles as are freed from their co- hefion by the faline parts of the men- _ ftruum recede with them from the filver, _and are fucceeded by other acid particles . to perform their payt of the operation, un- til all the parts of the folvent are equally charged with particles of filver. _ THE attractive force between the fa- line particles of the fpirit of nitre and the. filver muft be fuperior. to the pawer by which the particles of filyer attract one another ; for it diffolves their cohefion, _feparates them, and keeps them fafpended in a fluid which has only about one tenth | part 376 ESSAYS Anp OBSERVATIONS part of the fpecific gravity of filver: Yet thefe particles, thus fufpended, 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, firft, 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 cohefion among the particles of filver, and bring the mafs to a ftate of fluidity, fo that the particles may eafily move and flide one upon another while that degree of heat lafts; but fpirit of nitre produces the fame or rather a greater effect. In the next place, though fpirit of nitre is of — itfelf pretty volatile, yet, when it has dif- folved 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 flow- ly, PHYSICAL anv LITERARY. 377 dy, unlefs the fire is confiderably increa- fed; and, after feveral hours, the matter has ftill the appearance of a very moiit falt, which is very corrofive, and, in bulk and weight, greatly exceeds the filver that was diffolved. When the fand-heat - can make no further change on the mais, put it into a crucible, and fet it in a pretty brifk and clear fire: This expells the remaining moifture and fuperfluous acid; after this the matter melts like wax, and, when cold, is turned toa hard fubftance; the cauftic quality of which, _ the increafe of weight above that of the filver, and its aptnefs to moiften) thew, 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 inti- mately incorporated with the filver. Now, when a piece of this hard ftony fubftance a is put upon a piece of well kindled char- _ Coal, and blown a little, it makes an ex- _ plofion with a fparkling and flame, like a. j En Piece of common fale petre; the faline matter is confumed orturned into a fame or fmoke, and the pure filver is left on ee Vou, I. Bbb the 378 ESSAYS anp OBSERVATIONS. the coal, By the way, this may be fome fort of proof, that the volatile acid part of nitre is not more a fimple elementary | matter than is the fixed part. | NorwiTHsTanpinc what has been thewn, concerning the ftrong attraction between the particles of fpirit of nitre and thofe of filver, and the difficulty of fepa- rating them by the force of fire; yet, if a piece of clean copper is put intoa folu- _ tion of filver in fpirit of nitre, the faline particles moft readily fhake off the filver, and diffolve the copper: Which fhews that the particles of copper have a ftrong- erattractive power, with refpect to the fpi- rit of nitre, than the particles of filver have; which difference of attraction will probably arife from the different bulk, 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 falt, and fixed falt, each of which attract {pirit of nitre more ftrongly than filver does, and the laft more than the preceed- “ing. ; HERE PHYSICAL anv LITERARY. 379 HERE then we have a feries of bodies - from filver to falt of tartar, whofe attrac- tive powers, with refpect to the fame fa- line liquor, are continually increafing ; but, whether uniformly or in any certain proportion, is not eafy to determine: There may be found a body which at- tracts the acid of nitre more than the firft, and lefs than the fecond, and fo through other degrees; which can only be afcer- tained by a great variety of trials. As the falt of tartar, or any ftrong fix- ed alcaline falt, is the ftrongeft attracter of the nitrous acid, and throws down or feparates any other body that has been diffolved in it ; fo it likeways attracts e- very other acid, and disjoins it from whatever it has diflolved: Therefore we | 4 may confider that falt as a ftandard 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 fixed alcaline falt are joined _.to the three different acids of nitre, fea- falt, and vinegar, and, if oil of vitriol is poured 380 ESSAYS anp OBSERVATIONS | poured upon each of thefe faline mixtures or compound falts, the vitriolic acid will attract, or be attracted more ftrongly by the alcaline falt than the other acids, which wiil be driven from their places ; and the acid of vitriol will be fo firmly” united to the fixed falt, that no other a- cid or known body is capable to {feparate- them, 2 Acarn, If fpirit of nitre is poured up- on acompound faline liquor, or falt made of fpirit of fea falt and falt of tartar, and upon another made of {pirit of vine= | gar and the fame falt of tartar ; the fpirit of nitre, by its fuperior or attractive power, will join itfelf to the alcaline fale, and drive away the other acids, but is not able to refift the ftill greater force of the vitriolic acid. LasTLy, If {pirit of fea falt is poured upon a compound of fpirit of vinegar, or any other vegetable acid and a fixed al- caline falt; this will be more ftrongly at- tracted by the acid of fea falt, than by the vegetable acid which will be expelled: ~ But PHYSICAL anv LITERARY. 381 But the fpirit of fea falt may likewife be diflodged by the acids of vitriol or nitre. In moft folutions, precipitations, and _ ‘other operations by which the texture of Dodies are much changed, there are fome appearances, fuch as an expanfion and * bubbling, the production of an elaftic fluid like air, and a commotion fo great, as to produce fome remarkable degree of heat, and in fome cafes f{moak and flame; Which appearances, I fay, plainly difca- ver, that the finall particles of bodies are endowed with fome very active powers, capable to introduce certain motions tend- ‘ing to union or disjunction, attraction or, ‘Fepulfion. ys | ‘THAT many parts of matter are en- - dowed with an attractive power tending ‘to union and cohefion, may be deduced ‘from the inftances already mentioned : : And many more might be brought, from occurrences in chemiftry, 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, demonftrated by the great- Fe Sh eft 382 ESSAYS anp OBSERVATIONS eft philofophers of the laft and prefent age. ‘The curious experiments of the in- genious Dr Hales, in his Avaly/is of the Air, and the furprifing experiments on electri- city, now fo much in vogue, may fatisfy us, that particles of the fame nature and qualities with thofe of air and light, may bejoined to particles of a groffer nature and attractive quality, in various mafles of matter, to fome adhering more loofely, to others more firmly connected. For fome time, they may lie concealed without ma- nifeft motion or action, their repelling or elaftic power being overcome or balanced by the attractive force of the {urrounding corputcles, till, by certain concurring cir- cumftances, as external motion, heat, moifture, the addition of other matter, gc. the attractive force is diminifhed, or the repelling increafed: Then they are roufed, as it were, into action, and difco- ver themfelves by great and remarkable — effects, in changing the texture of the maffes to which they were united. Such - changes we daily fee happen in fermen- ae —_— lations, — PHYSICAL ano LITERARY. 383 tations, putrefactions, effervefcences, fo- lutions, accenfions, explofions, &’c. _ THEsE principles of motion in matter, are not the vain fictions of men merely fpeculative in philofophy, but evidently qeduced from obfervations and experi- ‘ments on a great variety of bodies in ma- ny different circumftances; and every one, who reflects upon the moft ordinary oc- currences in the works of nature and art, will be convinced of the exiftence of fuch caufes, and find that they are fo univer- fal and unalterable, that they can only be referred to the firft caufe, that is, ¢ to the will of the Supreme Being. ART. a oF = tor a sii iee se — pie ign Se Rot cay ey i, 5 a ae i+ = S' ~ Dal z- . 4 ra 2 ~ . P . oo Ps ire * a . ; ‘ s 384 ESSAYS anv OBSERVATIONS © ArT, XI. Experiments and Obfervations upon the Hart fell Spaw, made at Moffat 17503; and an Account of its Medicinal Virtues, fo. far as | they have hitherto been difcovered from Ex- perience; by W1LL1AM HORSEBURGH, M, D. | i HIS Spaw fprings from the Hartfell mountain, about three miles north of Moffat; and is commonly called Wil- — liamfon’s water, from Mr John Williamfon who difcovered it in 1748, and who has Ses reed been at a good deal of pains, and fome expence, to make it acceflible, by mending the road, clearing away the dirt about the fpring, and fitting it with a {pout, that it may be more conveniently taken up. | THE water on which I made the fol- lowing experiments, had been taken up three PHYSICAL ann LITERARY. 385 three or four days from the fpring, and _- ‘was contained in bottles well corked and waxed ; it was taken up on the 26th of Auguft, after a very rainy feafon. 1. [r was quite clear and pellucid. 2. Ir had a fharp, aluminous, ftrong chalybeate, and ftyptic tafte. 3. It cruddles with foap. 4. Its f{pecific gravity to that of Ane - nan river water (which is eiteemed 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 {pirit more thaa river-water. 6. Wien boiled with an equal quan: | tity of new or {weet piled it does not |. cruddle the milk.. 9. Wirn fyrup of violets, it gives a “faint green. 8. WiTH powder of galls, it prefently _ became blue, and turned gradually dark- er, till it became of a deep purple, and ‘then of an ink colour: It does the like Vor. I. Cee . with 286 ESSAYS anp OBSERVATIONS with an infufion of tea, though not in the fame degree as with the galls. Q- WHEN oleum vitrioli, or /piritus vie | trioli, is dropt into it, no effervefcence, or change of colour, is produced. | 10. WiTH oleum tartari per deliquium, it made no effervefcence; but light green clouds gathered, and were fufpended, in the middle of the water; and a great number of {mall air-bubbles, like parti- cles of quick-filver, appeared adhering to the bottom of the glafs, to its fides, and, — ‘upon the furface of the water, multitudes of the like air-bubbles were intermixed with the green clouds: After ftanding a- bout an hour, a great many of the air- bubbles difappeared, and the clouds in the middie of the water grew thicker, and of a darker green, and afterwards preci- pitated. I1- AN aqueous folution of /accharum Saturni, turned it a little whitifh, but net fo much as it did the river-water; and ~ much lefs than it did the river-water, — when there was a very little fea falt diflol- ved PHYSICAL anv LITERARY. 387 ved in it; in all thefe three trials, a white powder precipitated. 12. On September rift, I poured a cho- - pin or Englifh quart of this water into a clean white ftone-bowl; and covered it with a piece of paper, to keep out the duft. On the 2d, there was precipitated a brown powder, like brick duft; and, on the furface of the water, there were many fhining fpangles of a copper-like colour. On the 3d, there was more of the brownifh powder at the bottom; all the parts of the bowl, which were covered’ with the water, were tinged yellowith; a pellicle covered the furface of the water, and all the fpangles were gone. On the 6th, the fharp aluminous tafte | was pretty ftrong, but the chalybeate tafte much weaker ; there feemed to be no 3 more of the brownifh powder at the bot- tom than there was on the 3d ;. the yel- < oer fubftance that adhered to the bowl _was alfo thicker, and had a fmooth oily | look ; 3 the pellicle on the top had now ac- quired the thicknefs of writing-paper; it : wag 388 ESSAYS anp OBSERVATIONS was eafily taken up, as it adhered to any thing put into it, and was of a golden colour: [took up as much of the water as filled a wine glafs ; and, with powder of galls, it immediately ftruck a blue. On the 13th, the dharp aluminous tatte ftill remained flrong, but the chalybeate was fcarce to be diftinguifhed; the quan: tity of the precipitate, and the pellicle on the top, were much the fame; but the yel- low fubftance, adhering to the bowl, was , rather more: Into a glafs of this water, I dropped fyrup of violets ; it turned of 4 faint green: To another glafs of the fame, I put powder of galls; it immediately ftruck a blue tingture, but not fo deep as on the 6th. On Otober oth, it had a more alumi- nous tafte than the frefh fpaw water; the chalybeate tafte was fcarce to be diftin- -— guifhed ; the precipitate yellow fubftance adhering to the bowl, and the pellicle on the furface, much the fame as on the 13th ult.; the water was as limpid as on the firft day; fyrup of violets changed its co- ' Jour to a deeper green than before, aad, with PHYSICAL ann LITERARY. 389 | with powder of galls, it immediately gave a blue tincture, . 13. I boiled a chopin of this {paw wa- tér, in a clean tin pan, till there remain- ed of it only one fourth part; it turned of a yellowifh colour and was muddy: When this was cold, and the okry flakes precipitated, it had a harfher and more aluminous tafte than the frefh fpaw wa- cer, or than that which had been fo long expofed to theair (12.). To a glafs of this, I put powder of galls; it changed yery flowly, and, after it had ftood about eighteen hours, it exhibited a faint blue. 14. IN a clean tin pan, over the fire, I evaporated a chopin of the fame fpaw water, till there remained only about one ounce and a half; this I immediately | F - poured into a china tea-cup, and, when | gold, filtrated it: The filtrated liquor was _ clear and limpid, and had a ftrong chaly-- beate tafte; this was evaporated by a fand-heat, in a wide-mouthed glafs; there — was left a falt of a whitifh brown colour, “ t _ which had an aluminons and {trong cha- _ Tybeate rough tafte. The whitifh brown colour 390 ESSAYS anp OBSERVATIONS colour of the falt was owing, I believe, to its having been a little fcorched at the bottom of the glafs; for, when I after- wards gently exhaled the water before the fire, the falt was of a pure white. 15. A little of this falt put into a glafs of water, made the water of a yellowifh colour; and, in a little time, it began to feparate into {mall yellowifh coloured flakes, which, growing gradually larger. and thicker, precipitated; after {landing a night, the water was quite clear, with a few detached imall flakes, floating clofe to the fides of the glafs ; the water had the original tafte of the {paw, but rather {tronger, I poured off the clear water, half into one glafs, and half into another: Into the firft poured off, which was the cleareft, I dropped fyrup of violets; after ftanding a little, it gave a faint green tincture: To the other half, I added powder of galls; it flowly changed to a violet colour, then to a purple, and, after ftanding all night, it was of a very dark blue, inclining to black: Into the remaining water, with the fediment, PHYSICAL any LITERARY. 391 fediment, 1 dropt fyrup of violets, and ftirred all about; it caufed a tincture of a deeper green than the clear water: All thefe three mixtures, which did not ex= _ ceed an ounce anda half, I poured into a - chopin of common water ; and the whole _ became of a deep violet colour. 416. Tuts falt, after of. tartari p. d, has - been dropped upon it, and then diffolved in a little water, yields a deep green. 17. THE falt of this fpaw, after it is burnt on a hot iron, exhibits the like phenomena (15.), and always lofes its a- luminous tafte. 18. Furs falt turned moift and bub- bled on a hot iron; and, when calcined ima crucible, it became of a purple co-~ lour, exactly like that of the vitrio/i Mar- tis calx rubra; and there was a manifeft at- _ traction of feveral of its particles by the | magnet. “19. NEITHER the falt nor earth of this fpaw make any effervefcence with /piri- | tus vitrioli, oleum vitrioli, or oleum tartari, -p. 4. when by themfelves, or when dilu- ted 7 392 ESSAYS 4np OBSERVATIONS ted with water; nor does the falt emit — any fumes with o/. vitrioli, 20, A glafs of this water, into which ten gutts of o/, tart, p. d. were dropped, and another glafs of the fame water, turn- ed, with powder of galls, to a faint vio- _ let colour; being mixed together, produ- ced exactly the colour of old red port- wine. Experiments made on the fame Spaw Water, taken up OXober 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 ftanding all night, there was a little, and but very little, tendency -to green. 23. WITH ol. vitriol, no effervefcence, or change of colour. 24. WITH Ol, tart. p. d. no effervefcence; but the like clonds appeared as (10,), tho” ; in fmaller quantity, and of a yellow co- lour, with fcarce any green, . 26. WiTHa PHYSICAL ann LITERARY. 393 2g. WiTH the folution of Saccharum Saturni, it gave a little milkinefs; but - {earce to be diftinguifhed. 26, WiTH powder of galls, it changed very flowly ; and, after ftanding a night, he: it exhibited but a faint violet colour; fome= | thing inclining to purple. 27, A chopin of it, evaporated in a clean tin pan, yielded a very white faline fab- ftance, of a fharp, aluminous, chalybeate and {tiptic tafte. » 28. A chopin of this {paw water, taker ‘up from the fpring, after a long rainy feafon, yielded of falt, nine grains; and of earth, fomething more than one grain: The like quantity taken up after three weeks of dry weather, gave of falt, bute _feven grains ; andof earth, about half a grain: The hke quantity taken up after between five and fix weeks of dry wea- ther, afforded of falt, only five grains and PR FETT NT aT Le Ot 1: —— ae ahalf; and of earth, about a quarter of a grain. _ 29. THERE is another fpring, about | forty feet from this, which feems to be z of the fame kind; for it has the like taite; _ Vor, I, Ddd and, 394 ESSAYS anp OBSERVATIONS and, with fyrup of violets, powder of galls, ol. vitrioli, ol. tartai i, p. d. and the folution Of faccharum Saturni, it exhibits the like _ phenomena. From the preceeding Experiments we may ob-~ Serve, 1. THAT this fpaw contains a princi- ple of iron, which is volatile; for its cha- lybeate quality is much weakened by boil- ing (13), or even by being expofed for fome time to the air (12), 2. If contains an iron principle, which is fixed; for its chalybeate quality is not entirely deftroyed, by being expo- fed to the air (12), nor by boiling (13), nor by evaporation to a drynefs (14,15), nor by burning the refiduum (17)3 and, when its falt is calcined a fufficient time, it is attracted by the magnet (18 ), 3. i9 feems, by turning green with fy- rup of violets, to contain an alcaline prin- ciple, which is likwife fixed; fer neither by being expofed to the air, nor by eva-= poration PHYSICAL anv LITERARY. 395 ‘poration to a drynefs, nor by burning the tefiduum, does it lofe this quality. _ As neither the water nor its falt or: earth, make the leaft vifible effervefcence, with /piritus, or ol. vitrioli, either by them- - felves, or when they are diluted with was ter; 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 ftood fome time: But this I imagine rather to be a proof, that there is in common water an alcaline principle, viz. abforbent earth ; for rain-water, or fnow-water, have not the leaft tendency to green, with the faid fyrup } oe 4. 17 feems to contain a very little fea- fait (lefs than common water) by its pre- | cipitating the folution of faccharum Sa- turni (11.)- e, 5. IT feems to contain fome portion of a alum, _ « From thetafte of the fpaw water, as eat comes from the {fpring, which is re- a ‘markably aluminous. _ | & FROM 396 ESSAYS anp OBSERVATIONS» &- From its tafte becoming more alu-' minous, when part of the water is exha- led, by being expofed to the air for be- tween five and fix weeks (12.). . y FRom its tafte after three fourths of the water was evaporated, which was more harfh and aluminous, than that of the frefh fpaw, or than that which had been fo long expofed to the air (13.) ®. From the aluminous tafte of the fale Ceas'a7s); « From its falt {welling and rifing into a blifter on the hot iron (18.). ¢- From this falt lofing its aluminous tafte when calcined a fufficient time (17.), which alfo happens to alum, when treat- ed in a like manner. THE nitrum murale, it is true, alfo fwells and rifes in blifters on the hot iron ; like- ways borax, and the purging falt of Scar- borough water: But the mitrum murale dif- fers from this falt in tafte, and, when cal- cined, falls down into a loofe powder, like lime; which this falt did not do, though calcined for a confiderable time in a {trong fire. Borax PHYSICAL anv LITERARY. 397 Borax likeways differs in tafte from | this falt, and vitrifies in a moderate heat in afew minutes; which this falt did not, after being calcined in a {trong heat for a i confiderable time. This falt has not the | bitter penetrating tafte of the purging 1 ‘Scarborough fale, neither jts purging quality, | I don’t, however, pretend that all thofe marks amount to a demonftrative proof _ that there is alum in this water, but only to a great probability: For, to be fure of it, we muft fee the alum chryftallifed, which is not eafily done *, and requires, _ for that procefs, a greater quantity of fale than I had, | __ Ir may be objected, that, when equal | guantities of this water and new milk were ie, boiled together, the milk did not curdle le (6.); therefore there can be no alum in 4 it. This objection is {pecious; its vali- dity, however, like that of many other a panes which have very plaufible appear- ; - ances, ___* # Vid. Shaw’s Inquiry into Scarborough water, part 1. -s $4. Art, 43. 398 ESSAYS anp OBSERVATIONS ances, can only be determined from. ex- periment : Wherefore I diffolved in wa- ter a greater proportion of alum than there is, or feems to be, in this fpaw; and, when equal quantities of this folu- tion and frefh milk were boiled:together, the milk did not curdle. 6. THis water contains very little earth, it gives not the leaft fign of it, when . ol. tart. p, d.is dropt into it; but the lit- tle it contains feems to be of the white calcarious kind: And though okry earth is commonly allowed to be a conftituent principle in chalybeate waters, yet I am of opinion, that no fuch thing exifts in ~ them ina found, natural ftate; and that it is never to be found till the acid, or whatever it is that diffolves the iron-prin- ciple, 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 difolvent of the chalybe- ate principle remains united to it, that is, as long as the water continues in a found {tate, okry earth is never to be found in it. The _ PHYSICAL awn LITERARY. 399 ‘The earth, therefore, of this kind, which is left in the filter after evaporation and _ filtration, is owing to its diffolvent prin- _ ciple being loft in that procefs. And I have reafon to believe, from éxperiments _ which I have made, that, by repeated fo- e ‘lutions, evaporations, and filtrations, the by pureft and moft genuine ¢ryitals of viiri- olum Martis may be all reduced to an o- kry, or bolar earth } efpecially if the folu- tions be made in common water. 7. THE quantity of mineral principles in this water varies, and is lefs after a dry feafon, than a wet one (28); an un-. ufual circumftance, which probably pro- ceeds from this caufe, that the water, in a wet feafon, rifes higher in the veins which e : . . > e ” _ contain the mineral principles, and con- | quantity of thefe principles along with it. a “Whence it is likewife evident, that expe- riments made on this water at different times, will not always exactly correfpond, | 7 but will vary more or lefs, in proportion tothe mineral contents of the water. 8. THE tenth experiment feems to be an 400 ESSAYS anp OBSERVATIONS © 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 be- comes green. And, though there is no vifible effervefcence in this experiment (10.), yet the many air-bubbles genera- ted, feem to be the effe&t of the alkali’s uniting itfelf to the acid, which kept the chalybeate principle diffolved, and which chalybeate principle, being now by the o/, tart. difengaged from its diffolvent, ap- pears in the form of green or yellow clouds; and at laft is found, at the bottom of the glafs, under the form of a fubtile okry, or bolar earth. Ir may perhaps be faid, that, fince there is probably alum in this water, the air- bubbles are generated by the alkali’s uni- ting itfelf to the acid of the alum. To deftroy this fuppofition, I diflolved alum in water,and that ina greater proportion than it can be in this fpaw, and then dropt into it o/. tart. pd. ; there enfued no effervefcence, or fenfible change upon the PHYSICAL anp LITERARY. 401 the water; but a few air-bubbles gather- edat the bottom of the glafs; nothing, however, in comparifon of what appeared »vhen the o/. tart. p. d. was dropt into the fpaw; and no more than what formed upon dropping o/. tart. p. d. into a glafs of pure river-water. g. As chalybeate waters, in feveral par- ticulars, refemble a folution of vitriolum Martis in water; hence many may have been induced to think, that thofe waters contained a vztrzolum Marti, fach as is prepared by art: But fome of the lateft; / and moft learned authors, as Hoffman, Boerhaave, &c. are ofa contrary opinion ; and for a very good reafon, becaufe no | witriolum Martis could ever be found, upon “evaporation of chalybeate waters. The experiments, however, made on this fpaw, -feem to prove that it contains a fixed vi- _ triol of iron; for it not only turns green . upon the addition of o/. tart. (10.), but | Tikeways, upon evaporation, there is a falt VoL. I. | Eee I 7 402 ESSAYS anp OBSERVATIONS | Tdiffolved, in a chopin of fountain- water, vritriol, Mart, gr. xv. and in every. y refpect treated it as I had done the Hart- 4 fell fpaw water, viz. it was evaporated over the fire, till there remained about. two ounces; this was filtrated, and ex- haled, in a wide glais, before the fire: ‘There was left in the glafs gr. xiff. of a light yellowith coloured falt, and in the filter a dark-brown earth. With this falt, I repeated all the experiments I had made with the falt of the Hartfell fpaw; | and I had the pleafure to fee, that they correfponded in every thing, without any. ~ material difference: Only the falt left up- on evaporation of vitriolum, Martis did not rife in a blifter on the hot iron, and, when diffolved in water, gave, with pow- der of galls, a redifh tincture inclining to purple; whereas the falt of the Hart- — fell {paw, being diflolved in water, with galls, {truck a blue. The reafon of which I take to be, that there is a greater pro- — portion of acid in the compofition of the falt of the Hartfell fpaw, than there is in — the vitriolum Martis; for, if you add an alkali, PHYSICAL snp LITE RARY. 403 . alkali, as ol. tartari, to the blue tincture produced by the {alt of Hartfell fpaw, ic changes tv a redifh; and if an acid, as ol, vitrioli, is added to the vitriolum Mars tis, (e. g..if to a folution of two, three, or four grains of vitriolum Martis in eight j ounces of water, be dropt one gutt. of o/s ‘witrioli), this; with powder of galls, though ’ indeed it changes but flowly, will give a blue; not.a redifh tin@ture; and again, if the acid is weakened, by dropping into this blue tin@ture o/. tartari, the blue will change to a redifh.. And this conjecture feems to be confirmed by the following experiment, viz. 1f vitriol. Mart. be burnt ona hot iron, till it becomes quite dry; and of a yellowifh brown, and diffolved | in water, it gives much the fame redith | purple with galls, as before it was burnt; 1 af this burnt /al Martis be powdered, and the dry powder wrapt up in a fingle pa- per, and left in a room without a fire, _ for three or four weeks, it will become | _-moift, and, when diffolved in water, {trikes with galls no more the former colour, but a blue; which; I prefume, is owing to the 404 ESSAYS anp OBSERVATIONS the deidum vagum, which it has imbi=- bed. . | Sgrine therefore the falt of Hartfell fpaw has all the properties of vitriolum Martis, 1 cannot fee why it may not be allowed that this fpaw contains a native, fixed vitriol of iron: And it is the only water (I know of) which has been dif- covered to contain fuch a falt. _ In the Philofophical Tranfactions, No. 245. mention is made of two mineral wa- ters, which yielded a real fixed vitriol of iron, one near-Eglingham in Northum- berland, the other near Haigh in Lanca- fhire; but thefe waters were found by Dr Cay, who made particular inquiry into _ the matter, not to be mineral fprings, but drifts made for the draining of coal-pits 5 and that the vitriol found in thefe waters was owing to their running over marca- fite beds, which had heen expofed for fome time to the air. I was fufpicious that fomething of this kind had communi- cated the vitriol to the Hartfell fpaw; but Mr Williamfon, who difcovered the {pring, affured. me, that the water, on | which PHYSICAL ann LITERARY. 409 which I made the preceeding experiments, _had run over nothing at all, after its exit from the fpring, but was taken up: by himfelf immediately as it iffued out of the rock. Dr James Hunter, Phyfician in Moffat, afterwards fent me fome of the fame water, which he received into bot- tles, by applying their mouth to the ori- fice of the vein in the rock from which it iffued; and from it I obtained cryftals of vitriolum Martis, which were of a paler - green than the artificial. {n Auguft 1752, this fpaw, with fy- rup of violets, {truck no green tincture. Wit ol. tart. p. d. it immediately turned green; and clouds of a deeper greem and more in quantity than in Auguft | | _1750, were formed, and that much foon- er than in the preceeding experiments, . WiTH powder of galls, it fcarce chan- _ ged its colour; and, even after ftanding - fome time, it exhibited but a faint blue. ' _ Twas at a lofs for the reafon of its giving fo faint a blue with galls; when, at the fame time, I knew, by its immediately turn- x 406 ESSAYS anp OBSERVATIONS turning green with the ol. tar?. together with the quantity of the clouds that pre- fently formed, and the deepnefs of their green, that it was very {trong of the cha- lybeate principle: I therefore fet the mix- ture before the fire, to fee what change a little heat would produce; and, when I obferved that a fmall heat had no effect, I gradually increafed the heat, till bubbles appeared on the furface of the water; but this oceafioned no change on the colour of the water, the faint blue remaining much the fame. I then conjectured, from tle water 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 : Ard, to difcover whether my fufpicion was right, I dropt into the fame glafs, containing the water and powder of galls, one or two gutts (I do not remember which) of ol. ¢art.; and, haying mixed. it by ftirring, it immediately produced a very deep blue. | From this experiment, I think it ap- pears, that a water may be very {trong of a , ey m PHYSICAL anp LITERARY. 4°7 of the chalybeate principle, and yet dif- _ gover very little of it by the common ex- periment with galls; fo that it may be proper always to try it with the ol. zart. alfo: For the ftrength of the iron princi- ple is as the colour and quantity of the - douds formed by this oil; that is, if the clouds are of a light yellowifh colour, and. fmall in quantity, the chalybeate princi- ple is weaker ; if they are of a dark brown and more in quantity, it is ftronger; if they are of a green colour, the deeper the green and more in quantity, the ftronger is the chalybeate principle; which I have found to correfpond with truth, by re- peated experiments, not only on this {paw, but on folutions of vitriolum Martis, _ of different ftrengths, in common water : _ But, how far this will hold in chalybeate waters that are volatile, I have had no - opportunity to try- » | took a chopin bottle of this water, ry three months after it had been carried fif- q ty fix miles, and poured one half of it in- [ to another clean chopin bottle, and then |: ~ corked them both very tight ; the one - bot- 4o8 ESSAYS anp OBSERVATIONS bottle I fhook frequently and ftrongly for | two days; the third day I tried both, with powder.of galls and ol. tart. p. d.; . with the galis, both gave a very deep blue; but the water which had been fhaken with the o/. zart. rather yielded a fainter green, than that which had not: I let both bottles ftand corked up as before for ten or twelve days longer, without fhaking ; then tried them again with the galls and o/. tart. they both {truck much’ the fame deep blue, though not fo deep as at firft; and, with o/. tart. the water which had not been fhaken gave a green, though fainter than at firft; the other {carce offered any green; the clouds form- ed in it were fewer, and of a lighter yel- Jow, than thofe of the other, From which it feems, that fhaking fomewhar weakens the chalybeate principle of this water, though not much nor fudden- ly. } THIS water feems to belong tothe clafs of the aquae Martiatae; for it effervefces -' not with acids, like the acidulz and ther- , mae; neither is its volatile iron principle | fo rf » ey os | , = “ PHYSICAL and LITERARY. 409 fo volatile as theirs: Hence, in general, it may be faid tobe aperient and ftrength= as ening, both when-ufed internally and ex- ternally: Whence it muft be of ufe in dif> eafes where the folids are relaxed, and the - blood too watery and weak. But altho’, when the principles of a mineral water are known, we may, from analogy, de- duce its virtues in particular difeafes ; yet, as this method is not fo certain, no rea- foning being equal to experience, I I thall confine myfelf to the laft alone ; though it is to be prefumed, that there have not been yet fufficient opportunities of difco- vering all the virtues of a water fo lately found out... However; it has been obfer- _ ved to be of great ufe in curing itchy, hot; - tettarous, eruptions, old obftinate ulcers ~ and-fores, internally ufed, and externally Breen: It one west been of great f the ger fey obftridtion of the menfes ; a i. albus § ; gleet ; ; theamatic pains ; mb, ty Fft ever ‘ 410 ESSAYS anp OBSERVATIONS even when they have been further advan- ced ; in preventing mifcarriages ; and, in refloring health, when the conftitution has been impaired by long illnefs: All which will appear from the following hi- flories, moft of which were wrote down from the patients own mouths, and at- tefted by the phyfician or furgeon who attended them *. BEFORE . * There were given in to the Society, with this paper, twenty two well attelted hiftories of patients cured of the above mentioned difeafes, by means of the Hartfell {paw ; which it was thought proper to omit, fince they would have fwelled this: article to a bulk too great for a work of thiskind. But, as the good effects of this wa- ter in confumptions of the Jungs are fomewhat extraor. dinary, 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 Glendinning, wife to Mr Robert Glendinning, fchoolmafter in Moffat, aged 51, was, on the 20th of December 1750, attacked with pains in her right fide; acon(tant fharp pricking pain under the middle of the breafi-bone ; a hard, tickling, dry cough; thirft, diffi. eulty of breathing, and frequent gripes in her guts: All which fymptoms increafed, till the firft of January 1751, when fhe began to fpit, with diffculty, a little thick . grofs PHYSICAL anv LITERARY, 411 BEFORE one enters upon a courfe of the water, it will be proper to cleanfe the _ prime vie, by an emetic and a gentle _ purge or two; unlefs forbid by dome par- | ticular grofs matter, In the beginning of February, the {pit- ting was fo extremely tetid and ill-tafed, that it made her often vomit: She frequently walhed her mouth with falt and water; but ftill felt a tafte and fmell which fhe thought .refembled that of ftinking flefh : She now be- came very weak and emaciated; had heétic fits and night-fweats: Which fymptoms continued increafing till the middle of April; about which time (having tried mo medicines before) fhe began to drink the Hartfell dpaw, to the quantity of halt an Englifh pint every morning. She had fearcely ufed it a week, when her breathing became much eafier: After a fortnight, the : {pitting loft the fcetid fmell ‘and ill tafte; and, in three weeks, fhe was perfedtly free of the pain of her breaft, cough, fpitting, difficulty of breathing, hedic fits, and R 4 wmorning fweats: And has continued ever fince in good health, ; _. 2. Mrs Halliday in Barntympan, aged 28, of a ple- _ thoric habit, complained, in the beginning of September ' 4750, of a pain under the upper part of her breaft-bone, which frequently darted to the point of her right fhoul- _ der; apainin her head and neck; her breathing was ‘Mot quite free, and fhe could not lie upon her right fide, _ About the middle of Odtober, fhe began to fpit florid | blood, which continued three weeks, at the rate of a ee | fpoonful 412 ESSAYS anv, OBSERVATIONS ticular circumftances of the patient : Or, if the patient’s body has been long coftive, | and the excrements hardened,: emollient eS may be ufed. Such as are ple- “4 tharic, {poonful every day ; then {topped 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' relations had been car- ried off by confumptions of the lungs, fhe applied to Mr Jehniton furgeon-apothecary in Moffat, who, find.. ing the {pitting of blood increafing, and her pulfe pret- ty full and frequent, ordered her to be blooded, to take the deco?um tamarindorum of the Edinburgh Difpenfa- tory, and to {wallow four of the following pills thrice a-day. R. Extra. cort. Peruvian. drach. ii. balfam. Peruvian, jerup. i. pulv. cort. Peruvian. q-f. ut fi mala, ex cujus Jingul. drachm. formentar pil. xii. The blooding and decoction were repeated as often as they feemed neceflary ; and the pills were continued ten weeks . without fuccefs: For, foon after fhe left off ufing them, fhe began to cough up purulent matter with blood, Whenever the {pitting diminithed, her breathing became very dificult ; and the pain of her breaft increafed, with a particular forenefs all along the breaft-bone when the coughed, . She drank goat’s'and ewe’s whey, from the beginning of June, tothe end of Auguft, without any fenfible be- nefit ; for fhe continued ftill to fpit blood and matter: Soon after this, fhe was attacked with fudden flufhes of heat ~ PHYSICAL anp LITERARY. 413 thoric, or have their veffels full, fhould Jet a little blood, \ Tuis water may be drunk at all times of the year : Though I prefer the fummer or warm months; becaufe perfpiration is then ‘freeft, and the operation of the water, as an alterative, is aflifted by the warmth of the weather: Befides, this fea- fon is more conyenient for the ufé af ex- ercife, and the patients are lefs apt to catch cold. The propereft time of the day for drinking it, is, when the ftomach is moft empty, as in the morning, fafting, before heat. and morning fweats, which increafed till the mid~ dle of January 1752; when fhe was become feebier, was advifed to drink the Hartfell {paw in fmall quanti- 4 -ty3 but, finding it fit.eafy on-her ftomach, fhe drunk * san Englifb pint of itdaily, During the firft week after * drinking the water, the expectorated dark, blueith, pu- ‘ _much emaciated, and often faintifh, At this time, fhe trid ftuff, without blood ; and found her breaft much eafier than it had been any time from the beginning of “her illnefs. Soon after, fhe began to breathe freely ; . and, afier having drank the water fix weeks, was per~ featly recovered : Since which time, fhe walked, or ra- ther run, three Scotch miles in an hour, without being either hurt, or much fatigued by it. 414 ESSAYS anp OBSERVATIONS before dinner, and fometimes in the even- ing. Some patients have a cuftom of drinking it with their victuals: But: I don’t approve of this ; as it may retard, or, in fome meafure, hurt digeftion. THE quantity to be drunk is to be de- termined by the age, fltrength, and other. circumftances of the patient ; They ought to begin with a {mail dofe at firft, and in- creafe it gradually : Such 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 drink an Englifh pint a- day; a pint and an half, or two pints, which is about a Scotch chopin, and is the largeft quantity ufually drunk of this water in twenty fourhours. If the wa- | ter fhould be uneafy on the ftomach, the ‘patient may mix with it an equal quan- tity, or lefs, of new milk, or fuch a pro- portion of it as may be found moft convenient: It may aifo be proper to warm the water, As CES. \ | PHYSICAL anv LITERARY. 415 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 fhows that there is no great ftrictnefs requiréd in thefe matters: And, indeed, fuch as have any tolerable degree of health and ftrength, need not much recede from their ordinary way of living; though temperance in eating, a moderate ufe of wine, and gentle exercife, is what - all infirm people fhould conform thém= felves to: But, fuch as are very weak, and much emaciated, or that labour un- der dangerous difeafes of the lungs, or abdominal wifcera, muft obferve a very firi& regimen; their diet fhould confift of what is lighteft and eafieft of digeftion, _fuch as new milk, broths, panadoes, thin jellies, frefh eggs, chicken, veal, fowls, &e.; and a little wine may be allowed, when not prohibited by the circumftances of the patient; moderate exercife may be proper for fome, and reft for others; they 7 mutt avoid the night air, fitting on the ' grafs, and every thing that difcompofes _ the mind. Uror 416 ESSAYS Anp OBSERVATIONS Upon the’ firft ufe-of this water; fome complain that it makes them fick; others that it makes their head giddy; but thefe inconveniencies almoft always proceed from their having taken too large a quantity: The dofe is therefore to bé diminifhed ; andif, ina fmaller quantity, it fhould be uneafy on the ftomach, chew- ing cinnamon, or caraway feeds; or com- fits made of them, are frequently ufeful; or any other aromatic, moft agreeable to the patient. It fometimes occafions gripes, when the inteftines are weak, on account of its coldnefs ; it ought therefore to be warmed ; the beft way of doing it, 1s 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 water, till it acquires a fuffi- cient degree of heat. On its firft ufe, it fometimes purges fuch as are troubled with a diarrhea; but that is to be re- ftrained by a gentle emetic, or by giving fome guts of the ¢inc#. opiz in every dofe of the water, or rather fome little time before it; or three or four grains .of the pile PHYSICAL anv LITERARY. 417 pil. ‘ Matthei may be given at bed-time, and as much, if requifite, in the morning: It will be convenient likeways to warna the water. But it oftener occafions co- ftivenefs; for which it will be proper, now and then, to give a little /a/. Glaub, polychr. manna, or cream of tartar; or, which perhaps is preferable to any of them, the purging falt of Scarborough water. If, upon catching cold, any fe- verifh fits fhonld arife, the ufe of the wa- ter 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 {trength will permit, and whofe veflels are full of % blood and juices, fhould let blood. _ THERE is no determining precifely how - long it fhould be drunk; the advantage E the patient reaps from it muft decide | - that: Some have ufed it only twelve days, others three weeks, others four, others fix, | dome two months, and others many | months; and yet they have all been fo ph: appy as to meet with acure: So that, in general, as long as there is any pro- myOL, I. G ge {pect 418 ESSAYS anp OBSERVATIONS fpect of its working a cure, its ufe fhould be perfifted in; and, though the patient may think himfelf well, I am of opinion he fhould not immediately difcontinue its ufe, but gradually diminifh the quantity, and leave off by degrees. Some recom-= mend 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 : DePrETt, then fuch helps et be called in as the cafe requires. ~ As to the external ufe of this water : The practice has been, to wafh with it, when warmed, itchy, hot, tettarous erup- tions, and old obftinate alcers, two or three times a-day 3 and, in. fome cafes, during the whole day,to keep linen cloaths wetted in the fame water, applied to the - parts affected, which method has been very fuccefsful: But it muft be remark- ed, that the water was always ufed inter- nally alfo, in the fame cafes, Ir feems proper to obferve, that, as this water, put in bottles, well corked and | waxed, PHYSICAL anv LITERARY. 419 waxed, may be carried to any diftances - and will keep good a long time, longer than either the. Pyrmont water oF | Liege fpaw: People living in any part of Gredt Britain, ‘or even beyond feas, may | feap almoft the fame benefit from it, as thofe who refide in its neighbourhood: 420 ESSAYS anp OBSERVATIONS ArT. XIII. Of the various Strength of different Limes waters, by ROBERF WuyttT, M.De~ . F. R.S. Fellow of the Royal College of Phyficians, and Prof:{for of Medicine inthe Univer/ity of Edinburgh. | “Y HE 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 appeared, that ime- water acquired a confiderable addition of ftrength by being poured on quick-lime newly taken from the fire; and that the firft water got off quick-lime was fen- fibly ftronger than the fourth and fuc- ceeding ones *. On * Effay on the virtues of lime-water, &c. Pp. 33-39. 4 ; ® ps h- thing is affirmed of oifterfhell lime, PHYSICAL ano LITERARY. 43t On the other hand, my worthy friend and colleague, Dr Alfton, having obferved, feveral years fince, that quick-lime conti- nued to communicate its virtues to water much longer than any one before hadima- gined ; tells us, that he found, afterwards, by experiments, that halfa dram of ftone- quick lime yielded forty ounces of lime= water; and that, after a pound of the fame quick-lime had afforded five hun- dred pounds of lime-water, the water procured from it was as ftrong of the lime as ever *, Hence he imagines, that, as water can only be impregnated to a cer= tain degree by quick-lime, fo this will happen equally, whether the quick-lime be frefh from the fire, ar has had five hundred times its weight of water poured on it before; provided the water be al= -fowed time enough to extract the virtues of the lime f. And further affirms, that the ® Philofoph, Tranfact. vol. 47. p+ 266, and Differ- tation on quick-lime, &c. p. 4.5 & 6. where the fame $ Diflert. on quick-lime, p, m1. & 53. : 4i2 ESSAYS anp OBSERVATIONS the ftrength of lime water cannot be in- creafed by flaking new made lime init; becaufe the water can take up no more of the lime than it had before * As thefe experiments and cohabitors appeared inconfiftent with what [had ad- vanced, the Doctor has endeavoured fur- ther to weaken the credit of my experi- ments, by fome arguments drawn, chief- ly, from the imperfection of the hydro- ftatical balance, and from the nature of quick-lime and its water. In order, there- fore, to know whether I might not have been miftaken in what I had faid, con- cerning the ftrength of different lime-wa- ters, I thought it neceflary to make fome new experiments ; am account of which I beg leave to lay before the fociety. I, (a2) Havine got from my ingeni- ous friend Mr James Gray, a cylindrical copper-veffel ending in a narrow neck, which contained exaétly 100 cubical inch- es; I filled it with the fountain-water of this city, and, by means of a very nice balance, * Differt. on quick-lime, p, rr — Sy PHYSICAL anp LITERARY. 493 pilance, found it weighed 25326 Troy grains * , befides the weight of the veffel itfelf, ahieh amounted to 13055 grains. - (b) ¥ poured upon 90 grains of calci- ned oifter-fhells, newly taken. from the fire, and reduced to a powder, 96 ounces, or five hundred and twelve times their weight of boiling water. After 92 hours, during which time the infufion was fre= quently ftirred and fhaked, F decanted off the clear water, and filtered it through a piece of a very thick linen-eloth doubled ¥ ; by which means it was rendered freeof any crufts, and equally pellucid with fountain water. With this lime: water, I filled * According to’ Mr Gray’s experiments, the water which this. veflel contains, only © weighs 23518 grains, i. 6. twa grains lefs than we have made it, This ‘difference may. have arifen from. our having put ; a few more drops of water into the veflel than Mr Gray did. But although, in weighing fluids with “this veffel, one might err fix times more than this, yet it would not affe& the point we have in view, which is not be 4 cis * _ to determine with the greatelt accuracy the different | fpecific gravities of different lime- waters, but piss to thew that they are e different. 424. ESSAYS AND OBSERVATIONS | filled the above veflel, and found its weight to be 25356 grains *. (c) Mowpay, at feven in the evening, ¥ poured upon a pound of calcined oi- fter-fhells, 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 as above, filled the veflel with it; it weighed 25397 grains. (d) Tusespay at mid-day, I poured feven pounds of the fingle lime-water, (¢) upon one pound of calcined oifter fhells, newly taken from the fire, ftirring them well for fome time after ; at three quar- ters paft fix in the evening, | decanted off, and filtered as above, the clear ‘lime-wa- ter ; and, having filled the veffel with it, found its weight to be 25457 grains, HENCE it appears, that 100 cubical inches of the lime-water (4) exceeds, in weight, that quantity of fountain water by * The oifterfhells made ufe of in this, and the follow- ing experiments, were got fram among the rubbifh on the fouth fide of, the Caftle of Edinburgh, and were quite free of any fea falt. PHYSICAL asp LITERARY. 429 by 36 grains: (c) Exceeds it by 77 rainy and (d) by 137 grains. Tue fpecific gravity therefore of the weak lime-water (6) is to that of foun- ae tain-water nearly as 704 to 703. The fpecific gravity of the fingle lime-wa< ter (c) is to that of commion water, near- ly as 329 to 328; and the double lime- ‘water (d) is in fpecific gravity to water nearly as 186 to 185. Ir is ‘obfervable that the fpecific gras “¥ities of the fingle and double lime-waters (c) and (d), are confiderably lefs tham the fpecific gravities of the fingle and double lime-waters (4) A. and B. mentioned; p.39. and 40. of my Effay on the virtues _of lime-water, &c. But, if it be confider- ed, that, in making the latter, a much \ defs proportion of water was added to the i guick-lime, than in making the former; it will appear that this difference of their _ fpecific gravities does not infer any thing a ‘againft the accuracy of the hydroftatic “balance; but clearly fhews, that the firength of lime- water varies according to Vou. I. Hhh the 426 ESSAYS ann OBSERVATIONS the quantity of water poured on the quick-lime., _ Ir may be worth while to obferve, that the fpecific gravities of the lime-wa- ters, (>) (c) and (@) did not differ more than their taftes. he firft was weakeft and leaft difagreeable; the fecond was ftronger; and the third ftill ftronger and fomewhat pungent. Further, while the double lime-water (d) gave, in a few mi- nutes, a copper-colour to filver, the weak: lime-water (2) produced no fenfible change upon it. II]. Havine 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- water, one 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-{poonfuls of the lime-water (4); two’ — and about one third of (¢) ; and one and ax * Effay on the virtues of lime water, p. 47. in rs PHYSICAL anp LITERARY. 427 a half of (d), to give it the full gun-pow- der colour. Thefe experiments, though not fo accurate as thofe made with the balance, yet clearly demonftrate a remark- able difference of ftrength betwixt the a- bove lime waters. 3 Ill. TwENTY grains of falt of tartar _ ‘being mixed with eight ounces and two drams of the weak lime-water (), after ait had ftood five days on the lime, the mixture became immediately white and turbid, and fgon precipitated a white powder; which, being feparated from the water by filtration, and dried, weighed 23 gr. THE fame quantity of falt of tartar, mixed with eight ounces and two drams of double lime-water, that had ftood _ eight days on the lime, became confidera~ bly thicker and whiter than the former ; and afforded rather more than 7 grains of white powder. : THE fame quantity of falt of tartar be- _ ing mixed with eight ounces and two _ drams of the double lime-water (d), which had -428 ESSAYS AND OBSERVATIONS — had ftood 24 hours on the. lime, gave eight grains of a white powder. Ir was obfervable, that thefe three lime-waters retained the tafte of the lime, after being mixed with the falt of tartar, and this equally after precipitation, as be- fore it. 3 cw ey ler precipitated by thefe different lime waters proceeds 3 Ci SINCE the earthy pow wholly, or almoft wholly, from the wa- ters, and not from the fixed “alcaline falt. * Thefe experiments fhew, beyond doubt, that double lime-water may con- tain thrice as much lime, as lime water made by pouring on quick lime, 512 times its weight of water. IV. 1. Monpay 24th» December; at eight in the evening, I poured upon a dram - * ‘What proves this, is, that the calcarious matter pre- cipitated by mixing falt ‘of tartar with hme-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 falt. Thus 12 grains of falt 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 18 grains of the falt. PHYSICAL anv LITERARY. «429 dram of frefh calcined oifter thells, redu= ‘ced to a powder, 520 drams of boiling water. 2, AT the fame time, I poured, upon a pound of the fame calcined thells, 8 pounds of boiling water. | ' 3. Tunspay, at eleven before noon, I poured fifty ounces of the lime-water a. N°, 2. on nine ounces frefh calcined oifter- - hells; and, at eight in the evening, I fil- tered, through brown paper, thefe three esters, and put fixteen ounces of each of er into a bafon by itfelf; 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 No. 1. afforded very near four grains, No.2. near 12 grains, and No. 3. rather more than. 13 grains. ALTHOUGH thefe three lime-waters had, at the time they were filtrated, quite ¥ loft their tafte; yet, obferving that No. % Bs and 3. became turbid when mixed with 430 ESSAYS anp OBSERVATIONS with falt of tartar, I added eight grains. of this falt to twelve ounces of thefe two waters; and the white powder which was precipitated, when dried, weighed juft one grain and a half. Havina filtered the lime-waters of No. 2. and 2. into the fame bottle, before I fufpected that any thing of the lime re- mained in them, it became impoflible to know, which of them afforded moft of the calcarious powder precipitated by the al- caline falt; or whether it did not proceed wholly from No. 3.3; in which cafe, fix- teen ounces of it muft have contained 17 gr. of the earthy part of the lime, and No. 2. only 12 gr. SincE No. 2. and 3. were not quite free of the hme, although they had ftood expofed to the open air 19 days, and had loft above ; by evaporation; it follows, that the fureft way of knowing the quan- tity of calcarious earth, contained in lime- water, is to evaporate it, as Dr Langrifh did*: And, if it be objected to this, thar all water affords fome-earth, when evapo- rated, * Phyfical experiments on brutes, p. 11. * bod 4 - PHYSICAL ann LITERARY. 435 rated, the quantity of this may be de~ termined by experiment; though, in ma- “my waters, it may well be neglected, on account of its fmallnefs. Ir has been argued, that sciteie: muft, after many repeated affufions of water, yield as ftrong lime water as at firft; becaufe, as long as there remains any virtue in the lime, the water will ex- traé 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 agree: For, though there is undoubtedly a certain de- gree of ftrength which lime-water can never exceed; yet, in order to communi- eate to water this degree of ftrength, fla- _ked lime may not only be infufficiens, ‘but repeated additions of quick lime may be neceffary ; unlefs perhaps a very fmalk proportion of water is poured upon ite eae refh from the fire, yields its virtues more eafily, than when weak- ened by: long expoftion to the air, or by ‘many affofions of water: ‘The water muft “extra@t the virtues of the latter; while the former, by a fort of explofive force of 1ts- 432 ESSAYS anp OBSERVATIONS - its own, quickly impregnates the waters” ; Nor is it to be wondered at, that quick= t 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 extra more of the virtues of tea or coffee, than cold water, The only difs ference is, that the menftruum in the lat- ter cafe acts more powerfully; while, in the former, the fubftance to be extracted af= ~ fords its finer parts more readily, and in greater abundance: Upon comparing the experiménts No. 1. with thofe of No. 3. and 4. it appears, that the difference between the fpecific gravities of different lime-waters and common water is much more than the weight of the calcarious matter contained in thefe lime-waters: There muft, there- fore, be fomething elfe befides this earthy matter, which quick-lime communicates to water, by which its weight is increa- fed*, Perhaps quick-lime may alfo, in fome * As lime-water, after its earthy part has been preci- pitated by an alcaline falt, continues to tafte ftrongly of the . + § 0 ; ) , ¥ / . / PHYSICAL anp LITERARY. 433° fome other way unknown to us, alter the ‘fpecific gravity of water. But, whatever may be in this, it is evidently unreafon- “able to deny that lime-water is asanuch fpecifically heavier than common water, as the hydroftatic balance, or other accu- rate experiments fhew; becaufe we cannot account for this excefs of gravity from any thing we know of the contents of lime-water. This is no lefs unphilofophi- cal, than if one was to doubt of univer- Vo Baily Line pre: fal the lime ; 3 it follows, that, befides this earth, it contains fome more active and fubtile part, to which its tafte and virtues are chiefly owing: For we know that the calca- * rious matter of lime-water is perfectly infipid and void ie of any other virtue, than what. all abforbent earths pof- fels. This a€tive and more fubtile part of lime-water bs feems to be feparated from its earth by the alcaline falt, : “which ftrongly attracts and embraces it. And hence, _lime-water, mixed with falt of tartar, does not lofe its tafte of the lime by being expofed to the open air. Does not . folution of a fixed alcaline falt in water, poured on : iquick- -lime, feparate this fubtile a€tive matter of quick- ] Time from its earthy part, by ftrongly attraQting it ? “And do not foap-leys confift of water and fixed alcaline © : “fale, united with this active part of quick- lime, withoyt any, 0 or almoft any, of its earthy part? 434 ESSAYS anv OBSERVATIONS fal gravity, becaufe philofophers have hi- : therto attempted, in vain, to account for ~ it. If we miftake not the matter much, P the contrary has always been the opinion © of mankind, viz. that every well attefted 7 fact is to be believed, although we are ig- | norant of its caufe, or cannot {hew the particular way in which it happens. ENouGH, it may, perhaps, be thought more than enough, has been faid, to fhew 7 that the firength of lime-water is very different, according to the different quan- tities of water poured on quick-lime: | However, I mutt 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 tq $ fuch as drink lime-water, with a view to 5 the cure of the ftone, it is of no fmallim-_ portance to know, how it may be prepa-~ red, fo as to have the fureft and fpeedieft effects. And, as lime-water, injected into | the bladder, will undoubtedly diffolve a {tone lodged there ; itis evident, that, af- ter the bladder has been accuftomed to _ the weaker lime-waters, or to thefe even. foftened ” : ss ‘30 PH YSICAL anp LITERARY. 435 _ foftened with a little fweet milk, the if _ folution of the {tone may be much haften- ed, by injecting fuch as are more ftrongly ; impregnated with the virtues of the lime. Wi1TH regard to the lithontriptic pow- ers of oifter-fhell and ftone-lime-water, I fhall only fay, that, as ina variety of ex- periments made during the courfe of. ten “years, I had always obferved the fuperior efficacy of the oifier-lime-water, [thought it to no purpofe to make a new trial: Any | one, who doubts on which fide the truth as, may eafily fatisfy himfelf. But, in «making the experiment, the calculi fhould Be oo 4 - a +s either be immerfed in a large quantity of lime-water, or elfe it fhould be renewed _ upon them every three or four days. \ j “ ; AR‘T. 436 ESSAYS anp OBSERVATIONS ArT. XIV. Of the antheluintic Virtues of the Root of the P| Indian Pink, being Part of a Letter from Dr Joun Linine Phyfician at Charless ) town in South Carolina, to Dr RoBERT Waytt, Profeffor of Medicine in the Uni- verfity of Edinburgh. ra” HERE is a plant, commonly cal~ led, by the Carolinians, Indian Pink, which grows in this province, the root of which is ufed as an anthelmintic, _ and was firft communicated to the Eng- ith by the Indians. . THE root is either given in powder, or an infufion is made of it in boiling water But the powder is moft effectual. When’ I give the powder, I add fome rhubarb (2 fufficient quantity to keep the belly open), and a little of fome of the effential oils, as the of. rut. fabin. or abfinth. Toa child of three years of age, 12 grains of the’ — root | ee ae ee ee a ee PHYSICAL and LITERARY. 437 root in fubftance is a moderate dofe: And I repeat it morning and evening for fome days; ordering, at the fame time, a pro- per regimen. When the root is given in infufion, 20 grains of it make-a fufficient dofe for a child of the fame age. Ir has an advantage above all other anthelmintics 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 infufion with a little milk, and a fufficient quantity of fugar, in place of _ tease Though it does not always fucceed -in-expelling worms; yet I have obferved, that children’s complaints were remarka- bly relieved after having taken it for fome _ days. . pi ~ I fhall only trouble you with one fhort hiftory, where I gave it the other day with fuccefs. Iwas fent for toa Negro-child about four years of age, on the feventh day of a continual fever: And, as I fu- _ fpected that the fever was kept up by the : - ‘irritation of worms, I ordered the follow- ing, 438 ESSAYS anp OBSERVATIONS ing, that morning; E. aq. theriac. drach. ii. aq. font. unc. iifs. pulv. rad. anthelmie (for fo I called the Indian pink) tart. rege- nerat, ana fcrup, i. pulv, croci anglig. gr. vs facch, g- f~ M. fumat coch. unum fecunda qua- que bora, _ Next morning, I ordered a re- petition of the fame; and, in the after- noon, when the child had a ftool, 30 large worms, the /ereies, were at once voided; and, that afternoon, the fever went intirely off, and did not return. Next morning I repeated the fame mixture; and, that day, the child voided g more of the fame kind of worms, WHEN too great a dofe of the powder or infufion is given, it has fome ftrange effe&ts, which appear very foon after the dofe is taken. Children become vertigi- nous, complain of a pain in and over their eyes, and the mufculi addudtores and ab- ductores oculorum feem to be greatly af= fected, from their irregular actions ; while the other mufcles of the eye, fo far as have had an opportunity of obferving, re- main unaffected. Thefefymptoms, how- ever, foon go off; and their removal may be bs > yes > een, we ee : ufual be occafioned by the blood accu- ‘ ; mulated . Effay on vital and — motions, &c. p. 176. &e, soz ESSAYS anp OBSERVATIONS mulated in the pulmonary veflels. And to this it is owing, that refpiration is not only flower, but fomewhat deeper in time of fleep, than in a waking perfon at re{t in a horizontal pofition. IN comatous and apopledtic cafes, where all the feelings of the body are much more impaired than in ordinary fleep, refpiration is not only much flower and deeper than ufual, but fometimes, after expiration is finifhed, a paufe of 15, 20, 30, or more feconds will inter- vene, 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 infenfibility which at- tends thofedifeafes of the head; and which opium never fails to produce, when taken too liberally ; are we not hence led to conclude the lefs remarkable change of breathing which happens in fleep, to be owing * Effay on the vital and involuntary motions, &c. Ps 1940 PHYSICAL anp LITERARY. 503 owing partly to the fenfe of feeling in the lungs being then fomewhat diminifhed, though in a much lefs degree.than in thofe morbid eafes? To conclude with fumming up what has been faid in a few words: ‘In ordinary fleep the fenfibility of the heart and lungs fuffer fo {mall a diminution, that their motions will be very little more affected by it, thanthey would be from the hori- zontal 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 and lungs will be more obfervably altered. And, in the moft profound fleep, occafioned by opium or a morbid ftate of the brain, where a general infenfibility reigns over the whole body, the pulfe will become much more remarkably flow and full, and refpiration flower and deeper. ART. 504 ESSAYS anp OBSERVATIONS | ArT. XX, Remar ks on the Intercoftal Mufcles, by ALEx- ANDER Monro, F. R. S. Profeffor of Anatomy in the Univerfity of Edinburgh. “* AUVRY * thewed the mifappli- cation of Mr Bayle’s propofed de- monftration of the action of the internal intercoftal mufcles, from his inattention to the ribs not keeping in the fame paral- lelifm: when they are raifed; as when they are deprefled, becaufe of the greater mo- tion of the lower than of the higher ribs ; and he took notice of the fame demon- ftration, proving equally that the anterior part of thefe internal intercoftals muft ac in infpiration, as Bayle would have their pofterior part to act in expiration: But neither he, nor any other writer of my acquaintance, has applied this demonftra- tion of Bayle’s, which, granting the pa- rallelifm # Anat, raifonn, part 2, chap, 14, PHYSICALAnp LITERARY. sos rallelifm of the ribs to remain the fame, igs a good one, to account for the defect of the internal intercoftals between the fpine and the angle of the ribs, and for the deficiency of the external intercoftals from where the ribs begin to turn up-~ wards to the flernums; a fa& which ana- tomifts are now all agreed in. The ap- plication of the demonitration to this pur- pofe, is the intention of this paper. (WLET AB’ (figs 1s Tab.‘viil’) ‘be the f{pine, CD the fternum, EFGH, and IKLM two ribs ; then EK and GM are lines in the dire@tion of the external intercottal mufcles, and FI, and HL are in the di- rection of the internal intercoftals.—Now, fays Bayle, if both ribs rife, the angle FEI mutt be enlarged, and its hy SuLHeHeane FI, the fibres of the internal intercoftal, - muft be longer: Whereas mufcles gene- rally are fhortened when they a&.—Near to the fpine, where the ribs cannot be brought nearer at one time than another, this reafoning is juft; and therefore the internal intercoftals are not placed nearer - to the fpine than where the motion of the Vet. ait | ribs 506 ESSAYS anp OBSERVATIONS ribs is large enough to allow the lower 1ib to approach fo much to the one above it, as to do more than compenfate for the elongation of the hypotheneufe of the an-~ gle FEI, z. ¢. the internal intercoftal is only to be found farther forward than the angles of the ribs. NeAR to the fternum, the cartilages cannot be brought nearer ; and therefore, when they are raifed up, HL, the fibres of the internal intercoftal may be fhorten~ ed, becaufe the angle HMI. 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 raifing the ribs; and there- fore no external intercoftal mufcles are placed at this forepart of the thorax. | . PHYSICAL anp LITERARY. 507 AERO ot ES The Cure of a fractured Tendo Achillis ; Jy the fame. | Cer predeceffors were either not fub- ject to the breaking or tearing the tendo Achillis, or it was miftaken for a - {prain, or fome fuch other difeafe, by phy- ficians and furgeons; for it is rarely ta- ‘ken notice of in books ; and the oldeft and beft practifers here aflure 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 confider- able number of people of this country, of whom I know fixteen, and feveral of thofe have broke the tendons of both legs ; amongft the reft, I have been a fufferer this way; and, upon a comparifon with my brethren in affli€tion, my cure is the moft compleat of any I know; there be- ing neither pain, flifinefs, weaknefs, nor obfervable gc8 ESSAYS anp OBSERVATIONS | obfervable fhriveling in my left leg where the tendo Achillis was broken: Whereas moft of the ether gentlemen have fome of thofe uneafineffes, and feveral have all of them. Cn this account, I think it my duty, for the benefit of future patients, to make my method of management as pu- blic as} can; which probably will be beft done, by communicating it to your fo- ciety. WHEN my tendon was torn, it cracked as loud as if I had fuddenly broke a nut under my heel; which the company be- lieved had happened: And I had fuch a fenfation as made me imagine that the heel of my thoe had ftruck a hole in the floor; which is the feeling that feveral. have had as well as I: While others com- plain as if they had received a {mart ftroke with a ftone or cane on the part.-= I fufpeéted 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 fcot ftrongly ; and, as foon as I was put in PHYSICAL anp LITERARY. 509 in a feat, prefied down the calf of my leg with my other hand: In which po- - fture I kept them ull Meff. John Douglas and James Ruflel furgeons of this place came; and, after being fatisfied of the rupture, by prefling their fingers into the hollow between the two ends of the ten- _ don, they applied compreffes, anda bend- ed board on the upper part of my foot and fore part of my leg. which they kept . as near as they could, in a ftraight line, by a tight bandage made with a long roller. This drefling became foon too uneafy for me to bear, and the board was liable to fhuffle, whatever care was taken in the application of the bandage: There- fore I changed it for the following com- pound one, confifting of two pieces. (See Fab. viii.) 4 hah Fig. 2. Is a foot-fock or flipper A, of double quilted tiking; 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 EL, with pye-holes MM on each fide, through _ which a lace, fig. 4. is to be paffed ; and, . with g10 ESSAYS anp OBSERVATIONS 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 pye-holes are here reprefented on one fide, either of which is to be uféd according to the thicknefs of the leg. Havine then wrapped foft flannel, fmoaked with the fumes of benzoin, round my foot and leg; I put on, as in fig. 5. the foot-fock A, and calf-piece L, and bringing the ftrap C, through the buckle N, I could by it extend the foot, and pull down the calf to what degree I thought fit, and there fecure it with the buckle. Rader! Tu1s bandage anfwering my intention quite well, I wore it night and day, drawing the ftrap tighter when I inclined to fleep, and relaxing it when I was fully awake and on my guard; at which time, likeways, I placed my foot on a ftool, in the pofture reprefented at S, and frequent- ly fhifted the calf-piece or made the la- cing of it loofer, to prevent the fwelling of my foot, which it was in danger of occa= PHYSICAL anpb LITERARY. 5t! occafioning, when it became too tight, by being drawn down by the ftrap.——— After a day or two, I found my toes un- eafy, from the foot-fock prefling them ; and therefore undid the fowing of it at the toes, fromd, to d; and have caufed it always fince to be made open there, for others who ufed it. Dvurine two weeks, I made no moti: on nor effor: with my foot ; but was car- tied ona chair, running on caftors, from one part 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 mo- tions; but always {topped the flexion of the foot, or extenfion of the leg whenever I felt the leaft uneafinefs : Frequently | continued thefe motions for half an hour together, with the difeafed limb; but kept the other as much at reft as I could. Wuey 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 g12 ESSAYS anp OBSERVATIONS THE void between the two ends of the divided tendon became infenfible in few days, except that a foftne(s was felt there, more than any where elfe; but this part turned gradually thicker and harder, tll 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 fofter, for fome years pait; fo that, at prefent, it is much lefs perceptible than formerly. Some weeks after the accident, I be- gan to pour cold water on my leg and foot, caufing them to be well rubbed im- , mediately after; but the water, inftead of ftrengthening the member, as I expect- ed 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 wn- guentum altheae, or fome fuch greefy ftuff, to proteét the fkin from excoriation by the friion. ‘This manoeuvre was con- tinued till I began to employ the limb freely . BEING - PHYSICAL ann LITERARY. 513 Bene 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, however, 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 narrow but ftrong: The ends BB, are thin, broad, and concave, adapted to the convexity of the foot and forepart of the leg. ‘Lhree ftapples CCC, ftand up from the forepart of the iteel, one being in the middle of each of the broad ends, and the third in the middle of the ftalk. All the _ fteel, except the ftapples, was covered with _chammoy leather ; and the concavities of BB were well buffed, as the fofter rupture- bands commonly are. : AFTER I had put on my fhoes and flockings, 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 forepart _ of the leg : Then one ribband, or a thong - Vou. I, a | Saas of 514 ESSAYS anp OBSERVATIONS of leather, fig. 7. 8. was put round the foot, and another round the leg, to pafs through the two ftapples near the ends of the machine, and there fecured with traps or buckles, but without being drawn ught. A third ftrap or rib- band, fig. 9 having its middle D, applied tn the hollow of the foot. immediately before the heel, had its ends paffed on each fide of the feot, through a finus or noofe EE, of a fourth thong of leather F, that came round the quarter-heel of the fhoe, to be afterwards put through the middle ftapple; where, after thefe ends GG were drawn as tight as was thought convenient for extending the foot, they were fecured with the buckle, or with knots. See the application in fig. 10.— I wore this machine always in the day- — time, for five months: Though, as it is inconvenient, by fhuffling 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’ m- | 1 4 : : Y) } “Wi Uy pp WWW 77 YY) YY Yy Ups Ys Wi WY <= — ‘i it i AN NY ANC y= \\) | OTE i ! i jpdAinananaase { { ae man a PHYSICAL ann LITERARY, 515 inftead of it, without inconvenience. All that time I never walked the {treets, but was carried in a chair,—=.In going down ftairs, I always put the difeaied leg firft down at each ftep; and, in co- - ming up, 1 putthe found leg foremott, by which I fhunned the ftretching and re- tearing of the new fouldered finew, which, I knew from what others had tuffered, might have made the cafe worle than it ‘The habit I had got of walking after this manner in ftairs, be- - came fo much a fecond nature, that | 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 make. Dur1nG all that time too, I mounted my horfe atthe right fide inftead of the deft one, that I might fhun the rearing my whole weight, by the force of the 3 weak- was at firft 516 ESSAYS anp OBSERVATIONS weakened gaftrocnemei mufcles ; and, to prevent the accident of ftraining them, in cafe the horfe tumbled, I kept the left foot deep in the flirrup. In walking up hill, I put that foot a-crofs; and, in fhort, guarded againf{t shi other ftretch- ing {tep or motion. Own comparing the fize of the calfs of the two legs at prefent, the left one is a _ little {maller than the right one, efpecial- ly in the morning; but fo little, that it is f{carce perceptible: ‘Through the day, the difference becomes lefs. ‘the Tendo Achills that was broken is, as moft o- ther tendons cured after breaking, confi- derably thicker and harder than the other; ‘but one mutt be told it is fo, belore! he “i% can siti it BY the Ke ArT. kL) as PHYSICAL aNp LITERARY. 517 ArT. XXII. An pine of the Difeafe called Mill-Reek by the Miners at Leadbills, i in a Letter from Mr JaMEs WiLso N; Surgeon at Dury: deer, to ALEXANDER Monro, P. A, N obedience to your defire, I fend what I have ‘obferved concerning the difeafe which the people at Leadhills call the Mi/l- reck, and which all the inhabitants there are fubject to; but it moftly feizes, and violently affects the men whofe daily buii- nefs 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. "Iw the flighter flage of this difeafe, an uneafinefs and weight is found about the ftomach, efpecially near the cartilago. enfi- -formis; and fometimes it appears like a cholic in the inteftines. The fpittle of the oye bib asta MARES Dek: 518 ESSAYS anp OBSERVATIONS fick is fweet, and fomething of a blueith colour, refembling what one obferves when he chews lead. The pulfeis alittle low ; the fkin is all over cold; and a clammy {weat frequently breaks out.——The legs become feeble with a prickling numbnefs ; and there is a debility and lazinefs in all the body. The appetite goes away, and they do not digeft what food they take, ——Sometimes a diarrhoea makes a cure; but, if it continues too long, itis very hurt. ful ble to go about and to work. ) In this ftadium, the fick are yet a- But, if thefe fymptoms continue long, and {pirituous liquors are drunk with an empty itomach, or after working lead, the difeafe comes to its fecond ftage: In which, to the former complaints, are ad- ded a fixed pain in the ftomach and guts, efpecially in the lower part oi the abdo- men, extending itfelf from the one os «eum to the other. —-~ ] he patients become ve- ry coftive, with the fenfe of fomewhat gnawing their intel ines; and the pulle turns quick with heat on the fkin. Giddinefs, with vehement pain, feizes the head 5 OE PHYSICAL anpb LITERARY. 519 head ;' which is fucceeded by an infenfibi- lity and delirium, like madnefs of the worft kind; in fo much that. they tear their own flefh, and bite their hands; the extremities tremble, and are convulfed: At laft, they fall low, the pulfe intermits at e- very 3d or 4th ftroke, and they die ina coma or apoplexy. THE reek or fmoak rifing from the melting lead, is believed to be the caufe of this difeafe; becaufe the melters, who are moft expofed to the fmoak, which comes out often full in their faces, are moft fub- ject to this difeafe, the Mill reek ——The people here fay they have feen birds, in a calm moift day, attempting to fly through the {moak of fuch a chimney, fall down dead. - Cattle, which pafture. near to mills, are often killed; and there/ore fhepherds take great care to keep their fheep at a diftance ;_ which, if not by the {moak, muft be hurt by the grafs, which I often fee made blue by the fmoak fal- ling onit. And other animals fuffer from the water impregnated with the fumes, or with the lead wathed in it. | THE 520 ESSAYS AND OBSERVATIONS THE fymptoms in them are very like to what men fuffer. Dogs, in the laft flage, lie either dull and ftupid, or bite and {natch at every creature that comes near them: Nay, they will gnaw and tear up the ground upon which they lie, after they cannot raife themfelves on their legs. THE people at Leadhills are fo averfe to opening of dead bodies, that I could never prevail upon them'to allow mie to open any who died of this difeafe. But, in a dog who had it, J found fludge * lying on the inner coat of the {tomach and inte- {tines 5; and, in feveral parts, it was turned to a crutt. The guts were much in- flamed in fome places, and in others a morufication was begun with holes thro’ them. His foeces were very hard ; and, where they were of little quantity, the coats of the guts were thick, and the paflage through them lefs. Ir * The fine particles of lead which fubfide flowly in water, in which lead has been wafhed. -‘PHYSICALanp LITERARY. 528 Ir proper medicines are given in the firft ftage of this difeafe, the patient gene- rally recovers. If it goes on till giddi- nefs begins. the fuccefs is doubrful; and, when the cure is delayed to be attempted a little longer, the difeafe almoft conftant- ly proves mortal. If the work people at Leadhills would ufe the following precautions, they might _ fave themfelves from this difeafe, at leaft would have it very mild. I. No man ought to go to work fafting ;, and he ought to take oily or fat food: The Englifh mill-men on this account hold much better out than our countrymen. A glafs of {weet oil pure, or mixed with a little aqua vitae, would be a good morning - draught. | IL Pu ysre fhould be taken fpring and hharveft, and whenever any effects of the reek are felt. | ~ TI. ARDENT fpirits ought to be drunk very fparingly ; and ought never to be ~~ taken in time of work at the mill, or im- Vou.l. Uuu mediately 22 ESSAYS anp OBSERVATIONS. mediately after it. They increafe and fix the bad effeéts of the leady {moak. 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 lodging, to change his working cloaths for others, and cool gradually : By which he would prevent catching cold. In this ae ticle they are very carelefs. vote VW. IumevraTéery after coming from work, the aliment thould be moftly liquid, as broths, VI. Low and poor diet makes them more liable to ‘be affected, and lefs able to "undergo a cure: Thefe workmen ought to feed on good meat ; i 18 WHEN their bufinefs can allow, they fhould go out of the reach of the reek, to breathe an untajnted air, and to take vidtuals free from lead. But] muft caution the labourers at Leadhills not to take long journeys: They are more hurt by travelling one Gay than by working two,- ‘ THE cure of this difeate depends prin- cipally PHYSICAL ann LITER ARY. 523 cipally on cleanfing the primae viae: And, therefore, after blooding fuch patients, if they are plethoric, I give them a vomit of émetic wine or tartar; which muft bea dofe double to what would vomit another perfon ; ; otherways it would have no ef- fect, 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 finely powdered vitrum antimoni ready ; of which he gives half a drachm for a dofé; and, ~ during its operation, warm water is to be drunk plentifully. If the vomit ope- rates well, and purges brifkly too, the patient is in a fair way of recovering ; which a fecond, but a milder dofe of ipecacuanha with fome fartar emétic mix- ed, often makes compleat: But, if the emetic neither vomits nor purges, the pa- tient is generally worfe for it; and a ftronger dofe fhould be given foon. If it vomits, but does not purge, a ca- thartic of the antimonial kind, or of jal- lap and mercury, in greater than ordina- ‘ , ry 524 ESSAYS anp OBSERVATIONS ry quantities, ought to be given: And, during the time of purging by the eme= tic or cathartic medicine, the patient _ ought to drink warm broth plentifully.— The vomits and purgatives ought to be repeated at proper intervals, till the unea- finefs in the {tomach and guts, from the’ difeafe, is gone.——If thefe medicines o- ver-do, an oplate may be given at night; but this is to be adminiftred fparingly, left it bring or increafe cottivenefs, which is the worft thing can befal the patient: At the fame time, emollient, anodyne, and laxative cly{ters, are frequently to be in- jected for emptying the guts, if the pur- gatives do not their duty. WHEN blood or matter are paffed with the foeces, the emetics and purgatives are to be abftained from, till, by healing, bal- famic, but laxative clyfters, wah mild food,. this appearance ceafes. WuHeEN the belly is much fwelled, e- mollient fomentations fhould be often ap- plied to it; but, if the madnefs is begun, little elfe can be’ done, than to endeavour to PHYSICAL np LITERARY. 525 to keep the patient quiet during the peli time he has to live. ‘SomeETr™Mes it happens, that, after the complaints of flomaech and_ guts are gone, a prickling pain and feeblenefs re+_ ‘ main in the legs, much like to a rheu- matifm; for which, friction. with a coarfe eloth or flefh-bruth, is neceflary. If that fails, ung. nervinum with ol. terebinth. mix- ed, is to be rubbed on every night, be- fore the fire; after which, the member If thefe - pains are violent, or the feeblenefs re- fembles palfy. blifters 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 com pleated, that they remain afterwards © _ emaciated, weak, and as if they were hec- tic, with a giddinefs in their head: And fometimes they chat to no. purpofe, or feem hypochondriac. In this condition, the patient should go to the country, to _ ride on herfe-back fome miles every day ; is to be wrapped in flannel. and, 526 ESSAYS AND OBSERVATIONS and, at the fame time, fhould take bit- ters with bark and fteel. If the giddi- nefs continues, I have given, with fuccefs, . pilul. de myrrh, with a {mall proportion of camphor. End of the Frrst VoLumeE. NG Des, A. Adtion and re-adtion in matter, pag. 37: and 153: Adtive being (what) 96. : , Aether ( Newtonian ) not the caufe of gravity, 54. Alum, contained inthe Hartfell Spaw, 395, and 402, Gee Alfton (Dr Charles) - differtation on the fexes ot plants 228. Anaftomofs (none betwixt the uterine and Rapadary vef ~ fels, 473> Attraéion and repulfion, not.owing tovany aétive power in bodies, 133. Aurora Borealis, the matter of it, the fame with lightning and electricity, 217. : = Baxter (Mr) gn error.of. his, with regard tothe Inertia of matter, 132. ‘ Bodies, indifferent to reft or motion, 12%. / Cc. _ Caufes, the abfurdity of an infinite feries of them, 147. Circle {ome properties of it demonftrated, 164, Ge, Conic feétions (fome properties of. them) 188. Confumption of the lungs cured by wishin Spaw, 408. ae ah ea D. RS Deity, his continued concurrence, no argument againft the perfeation of the world, 1 50. Dennifton (1 (Mr George) his account of a cure performed by ' an alterative mercurial medicine, 440. Py eee E. : Ecliptic, the caufe of the variation of its obliquity, 191. Eleéiricity, obfervations on it, 209. Epidydimis, compofed of a fingle tube, 453. F. Farina. ot plants, conjeftures concerning its ufe, 314. ec. _ Foetus, its fituation in the womb, 476. © Force of a body in motion, pb pcg to its velocity, 72 - Force of bodies in motion, 1601. &e, Fra@ure of the Tendo Achillis, its cure, 450. Ge. G. Gravity (of) 47- =. a power inherent in matter, 58. —— the refemblance betwixt it and magnetifm, 125. ————owing to the continued and regular operation of an — intelligent caufe upon matter, 130. Theorems concerning the laws thereof ranares Ju- aan 207. Gray ( James) of the meafures of Scotland, compared with thofe of England, 223. Grew (Dr Nehemiah) the firft who asain that female plants were impregnated by the farina of the male, 237, H. Hartfe!l Spaw, Experiments and obfervations upon it, 384. — ftrongett ina wet feafon, and weakeft in a dry one, 398. ha — what difeafes cured by it, spi and 409. Directions how to ufe it, 413. Heart, its motion flower in fleep. and why, 493. Home (the Hon. Henry) on the laws of motion. 1. Horfeburgh (Dr William) his experiments and obfervations on the Harifell Spaw, 384. IN D-E X he Immateriality, the meaning of it, 140. ‘Ympulfe, (an analyfis of it), 33. Inertia of bodies, remarks on it, 34. ——of a body at reft, 85. &c. ——-of a body in motion, 89. &c. Jupiter, changes obferved on his furface, 203., L Lead, a remarkable difeafe produced by it, 517+ - Lime-water, of its various ftrength, 420. Linneus (Carolus) his arguments ig favour of the fexes of plants, 250. refuted, 259. &c. Lining (Dr John) on the anthelmintic virtues of the root of the Indian Pink, 436. MacLaurin (Colin) on the vation of the obliquity of the ecliptic, 191. ————on the fudden changes in the furface of Jupiter, 203. MacFait (Dr Ebenezer) his obfervations on thunder and ele&tricity, 209. ———— his account of fome phacnomena in foggy weather, 219, Magnetifm, owing probably to fome effuvia, 125. © Matter, whether endued with a power of motion, 6. ——— incapab'e of thinking, 138. Maupertuis, a notion of his refuted, 145. Meafures of Scotland and England compared, 224. Menftruum, (an univerfal one) by no means probable, 321. Mill-reek, a difeafe common among thofe who work inlead+ mines, its hillory and cure, 517. ° Monro, (Alexander) his defcription of the feminal veffels, 447» ————— his additional obfervations on gravid uteri, 481. Vou. 1. Xxx f ‘Hh ‘p> CE se Monro, (Alexander P, A.) his remarks on the intercofal mufcles, 447. chillis, 450. Monro, (Dr Donald) his remarks on gravid uteri, 455. Morland, (Samuel) his opinion concerning the impregna- tion of plants, 241. Motion, the laws of it, 1. - feveral definitions of it, 3- and 4. ——— acontinued ation, 24. . ——-—— the continuation of it, owing'to a power in matter, 25+ ——-— the communication of it, 29s ——— the force of bodies in it, 68. ——— remarks on the laws of it, 1, and 79, —___— not a¢tion, but the effects of action, 96. _——-~ the communication of it, 93, 99. ——— a body in it will continue fo for ever, 119, -———— of its continuation, 122. —— 2 power of beginning of it, infers a power of think- “ing, 129. Mulcles, (intercoftals) remarks on them, 504: : N. Newton (Sir Mfaac) does not afcribe activity to matter, 146, Pappi (Alexandrini) propofitio generalior faa, 1575 Pink (Indian) its root a good remedy again{t worms, 436, Plants, of their fexes, 228, ——conjeatures about the ufe of their farina or duft, 314. Placenta, not always ,fixed to one particular part of the womb, 475- Plummer (Dr Andrew his remarks on chemical folutions and precipitations, 319. ae —— his experiments on neutral falts, 354. on the cure of a fra@ured tendo A- Mm. NG. Dr Es X& Poleni, his experiment of balls falling upon foft clay, ror. Polypus, the phaenomena of it, confiltent with the indivi- © fibility and unity of a thinking fubftance, 141, Precipitations (chemical) remarks on them, 341. 2 08 Geet jamntiyn Tt . Quick-filver, injected into the epidydimis, 447. Ri shy ¢ Rainbow, formed round one’s fhadow in the eg 2236 Re-action, equal to action, 117. Refiftance in matter, the effect of an active power, 23. ———of a fubfiance perfectly ina@ive, $2. ce Refpiration, flower in time of fleep, and why, 499» ; Pe BE Salts (neutral) experiments on them, 354, Sinufes of the womb, a defcription of them, 486. Solutions (chemical) remarks on them, 319. Soap-leys, their component parts, 483. Sleep, the difference it makes on refpiration and the mo- tion of the heart, 492, Streamers, of the fame materials with lightning, 216, Stewart (Dr John) his remarks.on the laws of motion, 79. Stewart (Matthew) Pappi Alexandrini propofitio generalior Satta, 157« Subftances, material and immaterial, what, 12, lee T: ' Thinking, has no.relation to matter, 139. Theophrattus, his account of the fexes of plants, ke C5 Thunder, obfervations On ity 209. U, - Uteri (gravid ) remarks on them, 455, and 481, their thicknefs, 471. ‘ ary Uterus, its igure when impregnated, 468. os in DE XX ‘4 Vis infita, or vis inertia 18. Vis infita, and vis inertia or ref iftentie, different powers im matter, 26. Vitriolum Martis nativum, found in the Hartfell Spaw, 400. Venereal lues, cured by large dofes of an alterative mercu-. rial medicine, 440. ; Ww, Whytt (Dr Robert) on the various ftrength ‘of different lime-waters, 420. * his account of the difference between refpiration and the motion of the heart, in fleeping and waking per- fons, 492. - Wilfon (Mr James) his account of the Mill-reck, 514. a To the BOOKBINDER. Place Tas. I. fronting ; page 192 i.— 203 — ll 452 IV. V, VI. VIL— 468 ——V 1. —_—— een sig pies — oa a = Fee ioe FP haees rishi betas Sit spe bstisee