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THE PHILOSOPHICAL\ ~_
Has TORY
AN D
MEMOIRS
OF THE
Royal Academy of Sciences at Paris: OR,
An ABRIDGMENT of all the Papers relating to Natural Philofophy, which have been publith’d by the Members of that Iujtrious Society, from the Year 1699 to 1720.
With many Curious OsservaTions relating to the Natura! Hiftory and Anatomy of Animals, &c.
Illuftrated with CoppER-PLATES.
“The Whole Tranflated and Abridged,
fe Ome NY MA RT ‘YIN, F.R.'S. Profeffor of Botany in the Univerfity of Cambridge ;
AN D
PPM RaAIM. CHAMBER S,.¥F. R. S. Author of the Univerfal Diftionary of Arts and Sciences.
VOL. Ul pee
“LONDON: Printed for Joun and Paut Krarron, in Ludgate-freet ; and Jousx Nourse, near Yemple-Bar. M.DCC.XLII.
coe a
OF sda
PAPERS contained in the AnRibGMEN? of the History and: Memorrs of the, 'RoYat, ACapEMy of SCIENCES, at Paris, for the Year Mpccvil.
In thee HISTORY. N the light of bodies produced by frifion.
I. On fire arms differently charged. WI. On flones, and particularly on thofe of. the ea.
IV. Of an extraordinary cure performed by 4 concert of mufic,
V. Of the mmutkiplination of puttdeules: .
VI. Of the circulation of ‘the blood in infects .
VH. Of worms voided by ftaal.
. MHL. Of the Iguana,..an American lizard.
IX. Of the difference of the milk of European
_ women, and Negreffes at Batavia.
X. Of au aurora borealis feen at Berlin,
XI. “Of @ new ifland wear Santerini.
XII, Of a new way of conftrufiing: the map of 4 country.
In.the MEMOIRS.
1. Obfervations on the quantity of rain, which feli at the obfervatory during the arte 17063 and on the thermometer Gitd barometer, by M. de la Hire.
NW. A machine to retain the wheel, which ferves to raife the rammer, to drive the piles, in
Vou. Il. N°? 24. B the
2 ‘A TABLE, &e.
the conftruttion of bridges, kays, and other works of this nature, by M. de ja Hire.
Ill. Of the irregularities of the apparent depref- fion of the horizon of the fea, by M. Caffini.
IV. Odbfervations on fpiders, by M. Homberg.
V. Of the effects of gunpowder, chiefly in mines, by M. Chevalier.
VI. A new confiruction of fiuices, by M. de la Hire.
AN
AN
ABRIDGMENT
i Ae all gael 2 Philofophical Difcoveries
AND
OU poe & VY AT TONS
TNT. es
History of the Rovat AcADEMY of
Screncesat Paris, forthe Year 1707.
I. On the light of bodies produced by friction ; tranflated by Mr, Crambers,
HE new phofphorus difcovered by M.
Bernoulli, and mentioned in the preceding papers, could not fail of raifing the curiofity of philofophers, and efpecially thofe of the acade- my, who had a fort of right to a difcovery made by one of its members. Among other expe- riments on this head, they came at length to the light which certain bodies yield, by rubbing in the dark; the refult whereof is as follows.
As moft of thefe experiments were only made on bodies which yield light the moft eafily, asa cat’s back when rubbed Vagaintt the hair in win- ter, or fugar, or fulphur “pounded, €fc. . there are certain conditions to be obferved.
tft, That of the bodies rubbed againft each other, one of them at leaft muft be tranfparent, that the light may be feen through while it lafis, which ufually is during the time of friction.
2 adly,
4 The History andMemorrsof the
adly, The furface of the two bodies muft.be plain, fmootn, and clean, that the contact may be the more immediate.
gdly, The two bodies muft both be hard.
athly, A great denfity, without a great degree of hardnefs, will alfo have its effect. Thus M. Bernoulli procures light, by rubbing an amalga- ma of mercury and ‘tin upon a looking-glafs.
5thly, One of the two bodies muft. be.as thin as poffible, that it may be the eafier heated by friction, and may yield a quicker, as well as brisker, light. This M. Bernoulli tried on little copper-plates of different thickneffes.
6thly, Gold rubbed upon glafs, appeared the fitteft of all metals to afford light; but no body yields fo exquifite a light as a diamond, which comes nothing behind that of a live'coal, briskly blown by the bellows ; nor is it any matter how thick the diamond ts.
Hence M. Bernoulli concludes, that Mr. Boy/e, notwithitanding all his skill in’ experimental philofophy, held a thing to be a kind of prodigy which was none, vz. a diamond of his, which yielded light when: rubbed in the dark, to which he gave the magnificent appellation of adamas ducidus, yet had not this any particular privi- ledge, unlefs that its brightnefs- continued a few moments after the friction, which we may add, was the foundation of part of Mr. Boyle’s efteem for it.
On occafion of thefe experiments of M. Ber- noulli, M, Cafint the younger made others on the fame head to the effect following.
1ft, A diamond, cut table-ways, “being rubbed on a looking-glals, yielded a light almoft equal to that of a live coal, and which even appeared
Jarger than the face of the diamond. 2dly,
Rovat AcApemy of ScIENCES. f
_2dly, A diamond, cut facet-ways, yielded a lefs vivid light.
gdly, A crown, and fome other pieces of fil- ver, yielded lefs light than the facet-diamond.
4thly, A copper double and a fol yielded very little.
All the bodies, in the fore-mentioned experi- ments, were rubbed upon glafs,
sthly, The table- diamond, when rubbed on a plate of filver, yielded light.
II, On firearms differently charged; tranf- lated by Mr. Chambers.
M. Carré informing the academy of fome ex- periments made by a friend upon fire-arms charged in different manners, it was thought pro- per to verify them ; which M. Ca/fjini the younger, accordingly undertook.
He madea kind of machine, wherein was a piece of wood armed at one end, with a pretty thick plate of talc, whereon the feveral fhots were to be received. This plate was made move- able, fo as to give way, more or lefs, according as a greater or lefs impulfe was made on it; and at the fame time fhew, by the ftructure of the machine, how much it had given way.
Now from the experiments made by M. Caffini, it appears, aft, That the putting a wadding be- tween the powder and ball, renders the cfiore the greater: the reafon is evident, and accord- ingly we find it the common practice.
“odly, That ceteris paribus, thofe balls which fit exactly the bore of the piece have the greateft effect, by reafon, doubtlefs, that they do not come out fo readily, but give time for a greater quantity of powder to take fire.
"3 adly,
6 he History and Memoirs of the
gdly, That when the powder is rammed vio- lently down, the effort is no greater, but rather fomewhat lefs, than when barely preffed down.
4thly, That gun-powder caft upon the ball, diminifhes its effe¢t: the reafon may be, that the powder making its effort every way, that which is upon the ball muft needs give fome oppofition thereto, by acting counter to the motion which fhould bring it forth.
sthly, That this powder, though it diminifh the effe& of the ball, increafes the norfe.
6thly, That the fire of the powder under the ball, communicates with that over it, even though the ball be exactly fitted to the bore, and lodged between two waddings: this appears from the ereat increafe of noife.
sthly, That taking a ball fomewhat lefs than the bore, and putting but little powder under it, and a good deal over it, one may fhoot with a very great noife, but no fenfible effect. They who have purchafed fecrets for becoming invul- nerable, and have been fo cautious as to make trials thereof, have doubtlefs been impofed on by this artifice.
III. Upon flones, and particularly thofe of the fea; tranflated by Mr. Chambers.
M. Saulmon making a tour about the coaft of Normandy and Picardy, and the country adjoin- ing, had occafion to make fome phyfical re- flections which he communicated to the academy.
The Galets are a kind of pebbles, commonly flat, round, and always very f{mooth and polifhed, driven by the fea upon thofe coafts. It is eafy to conceive, that their figure and poltfh had arofe from their being long beaten and toft by the waves,
and
EEE
Royak ACADEMY of SCIENCES, 7
and rubbed one againft another ; but there are ftore of them likewife found out at land. M. Saulmon learned, that when they dig their cellars at Cazeux, abundance of thefe galets tumble in;
~ and that at Bruel, which is a league from the fea,
the fame thing had befallen: upon digging a well he further obferved, that the mountains of Bof- aueil, Broye, and Quefnoy, which are eighteen Jeagues from the fea, are all covered with ga- lets, which he alfo found in the valley of Cler- mont, in the Beauvaifis ; but obferved, that there were none on the top of the mountain, which is very high.
Among the ga/efs out at land, there are feveral whofe furface is very rough and irregular, befet with points; and what is more, this furface is a kind of bark, or rind, different from the reft of their fubftance ; yet this feems to be their natural ftate: for no external caufe can ever have invefted them with this rind, but may, on the contrary, have {tripped them of it; and fuch caufe may be a long and violent friétion. Add, That it is highly probable they are of the fame fpecies with pebbles, which have a like rind, confiderably thick, and of a chalky confiftance.
M., Saulmon makes no doubt, but that all thefe Jands were formerly covered by the fea ; a notion which had already been ftarted in the hiftory of 1706, with fome of the arguments which feem to prove it. To render it ftill more probable, at leaft with regard to the country where M. San/mon made his obfervations, he endeavours to fhew by the dif- pofition of the place, that when the feadidcover ir, the currents formed between the mountains with tHe feveral eddies of water, mutt neceffarily have thrown the greateft or leaft galets into the places where they are actually found; for it is obfervable,
ay se that
8 The YWisrory and Memoirs of the
that the greater and {maller’ kinds are’ not ufually intermixed, and diftributed fome on the one fide, and fome on the other. ft is evident upon M.. Saulimon’s fappofition, that the mountain, whofe top was free of galets, had rofe above the fea, ‘and confequently could not receive the driving ftones upon its top; but to determine by the laws of. motion of bodies circulating in, and witha fluid the feveral diftributions of galets that muft have een made in feveral places, would’'be both a “Beak aBy and a phyfiology of fo nice a kind, that we think it ought not to be attempted. We
fhallonly relate two y obfervations afterM .Saulmon: ‘The 1ft, Thata hole 16 feet deep, ' being dug - horizontally in the beach of Tre/port,. which is all ftony, difappeared in 30 years times that: the fear had eat this thicknefs of 16 feet into the’ beach. in. that time. Now fuppofing, «that: it always ae at that rate, it would dig 1000 fathoms, 1 4 league of ftone, in 12000'years 5 and‘izis ape from Lahey that the fea has really ad- vanced, or withdrawn, ina multitude of places; and that it has a general, though a very flow
motion, whereby it changes its bounds.
adly, Flints have not only a chalky rind, but their black and hard fubftance, which is properly the flint, may be fuppofed to have originally been no other than cha k, whieh had hardened by de- “ees, and changed its colour. M. Saudmon pro- duced fiints of different ages, fome whereof hada greater or Jéfs quantity ‘ot chalk ftill remaining in - their centre, while others had chalky veins “dif perfed through their black fubftance,. and carried all the indications of their having arrived at their blacknefs and hardneis by length of time. He even conjectures, that the fltnts, when too old, turn rotten; and that it is fuch as thefe we find with
RoYAL ACADEMY gf SCIENCES. 9 with their black fubfance turned reddith, lefs firm, and as it were rufty. All which feems
to tally with the fyftem of ftones arifing from . feeds.
IV. Of an =i oy cure performed by a concert of mujfick,
An eminent mufician, who was a great com- pofer, was feized with a fever, which ftill in- creafing, became continued. On the 7th day he fell into a violent delirium, having hardly any in- termiflion, attended with cries, tears, terrors, and a perpetual want of fleep. The 3d day of this de- lirium, one of thofe natural inftinéts which is faid to make animals feek for thofe herbs which are proper for them, made him defire to hear a little conceft in- his chamber ; it was with much difi- culty that the phyfician confented to it, They played to him the cantata’s of M. Bernier. From his firft hearing them tune their inftruments, his face afflumed a ferene air, his eyes were compofed, the convulfions entirely ceafed, he fhed tears of pleafure, and his fenfes were affected with the mu- fick in fuch a manner, ashe never felt before- nor fince the cure; his fever ceafed during the whole concert ; but as foon as it was ended, he relapfed. They did not neglect to continue the ufe of this unexpectediy fucceisful medicine; the fever, and delirium always fufpended during the concert and _Mmufick was become fo neceflary to hina, that in the hight he made a relation who. watched with him, both fing and dance, though her affliction made it difficult for her to comply with him. One night among the reft, when none but his nurfe was with him, who could only fing one miferable ballad, he was forced co be content, and even
re-
no Zhe History and Memoirs of the
received fome benefit from it, In fhort, 10 days mufick quite cured him, without any other affiftance, except bleeding in the foot, which was the fecond time this had been done, and was fuc- ceeded with a great evacuation. M. Dodart re- jated this hiftory, which he had well attefted :, he does not pretend, that this ought to ferve as an example or arule, but it is pretty curious to fee in aman, whofe very foul, if I may fo fay, was become harmony, by a long continued cuftom, how concerts by degrees reftored his fpirits to their natural courfe.. Ir is not likely that: a painter would have been’ cured thus by pictures; paint- ings have not fo great an influence as mufick over the motions of the fpirits, and no art im this re- tpect can equal it,
V. Of the multiplication of animaicules.
A philofopher, friend to M. Carré, who has been frequently mentioned in the preceding hi- itories, imagined from fome experiments which he had made, that animalcules feen in the water with a microfcope do not multiply therein, bur proceed from little invifible flies, which lay their egos inthe air. And indeed, as thele animals are a kind of little worms, 1t is natural enough, that, like many other. worms, they fhould all proceed from {ome of the winged fpecies 5 but the obferver was convinced of his miftake. He boiled water and dung, and filled therewith two phials of equal fize; when they were lukewarm, he put into one of thefe phials, two little drops of water taken out of a veffel, wherein the water was full of thefe little animalcules ; and $ days after, he found this phial Glled with an innumerable quantity of ani- mulcules, of the fame fpecies with thofe which
were
Royal ACADEMY OfSCIENCEs. If
were in the drops of water. There were none to be perceived in the other phial, though the dung might probably have produced fome. They had both been ftopped very clofe. The multiplica- tion of animalcules in water, is therefore hereby fettled; but more fo, if it is certain, that this phi- lofopher faw them couple; at leaft, it is certain, that he faw them joined two and two. Perhaps this was to fight; but, do they always fight by pairs ?
VI. Of the circulation of blood tn infects.
M. Lewenhoeck fays, That he could not obferve the circulation of blood in infeéts, and therefore imagines another way, by which he believes their life is maintained. But the philofopher, whom we juft now mentioned, who is well {killed in the ufe of the mifcrofcope, fays, ‘That he has diftinét- ly feen the circulation in the leg of a {pider.
VII. Of worms voided by ftool. M. Homberg fays, That a young man of his
acquaintance, who is in good health, has during thefe 4 or 5 years, voided every day by ftool, a great number of worms, about 5 or 6 lines long, though he eats neither fruits or fallads, and has made ufe of all known remedies, He once or twice voided above an ell and a half of a flat -worm, divided by joints, called the folium. It is hereby feen, how many eggs of infeéts there muft be in all that food which we leait fufpeét to contain any, which want nothing but the fto- mach; or, as I may call it, an oven fit to hatch them.
\
VIL.
12 The Pirate and Memoirs. of the
VI. Of the Iguana, an American disse |
The iguana is a kind of lizard found through all parts. of Americe, it is defcribed in Pi/o’s book, De utriufque India re natural (8 medica.. Mt is amphibious, it has two ftomachs, in one of which there is often a ftone, white on the outfide, and the infide very much like the colour of the Ame- vican bezoar. It has the virtue of expelling the ftone and gravel in the kidneys, and cures the fuppreffion « ofurine. Iris adminiftred. in very fine powder, with an equal quantity of the powder of nut-fhells, both together weighing a dram, ~in orange-flower water, if there is no fever, or fuf- picion.of an inflammation in the ureters, or in the bladder ; in which cafe it muft be given in white wine, mixed with parfley water, or pellitory of the wall, or fome other diuretick. It fometimes has effedt in an hour’s time, but at moft, in three hours. A Spanifo phyfician of Caraccas, having fent this:accoynt to M. DePas, a phyfician of Montpellier, who is with M. DesLandes, director ofthe Afiexto. company in America, and having related to, him many experiments which he had made with the ftone of the iguana, this letter has been, fent to.the academy.
[X. Of the aiferenceof of the nuilk of European
qvomen, and / Negreffes at Batavia.
M. Homberg fays, that European women who go to Batavia, cannot fuckle thejr children, their milk being fo fale that they will not take it; whereas, the milk of the Negreffes, though their diet is the fame, is {weet and pleafant as ufual 5 therefore they fuckle the children of the Dutch
2 and
Rovar AcAvemy of SciEncts. “13 and Engi.’ He himfelf,’ who was born at Ba* tavia, was fuckled by a d/ack. He thinks it probable, ‘that when the Europeans are carried into fo hot a climate, being not made for it, thoté veffels which in them are defigned to filtrate the milk, dilate too much, and give paffage to thote falts which are not intended to enter into the com- pofition of this liquor; bur that the women of thefe hot countries are, by their firft formation, ficted to generate good milk; that is, either that the filtring vefftls are naturally lefs, and do not afterwards dilate more than is neceffary, or are of a firmer texture, and lefs capable of dilatation; or fomething, in fhort, equivalent to this,
X. Of an aurora borealis /een at Berlin.
M. Leidnitz fent an account from Berliz, to
M. PAdté Bignon, that March 6, between 7 and ‘ro in the evening, there was feen in this city, and in the neighbouring country, an aurora borealis, which was fomething like that mentioned by M. Gaffendi, in the lite of M. Pierefc. There were two luminous arches, one of which was higher than the other; both directly northward, their concavity turned downward; their chords parallel with the horizon. The fuperior arch was interrupted; ftreams of light went from the one’ to the other, which jut appeared, and vanifhed away.
XI. Of a new ifland near Santerini.
M. De la Lanne, conful in Candia, fent word to the conful of Tunis, that two miles from the ifland cf Santerini, which is feventy- miles from Candia, a new ifland was perceived; which, at firft
: ab-
14 The History and Memoirs of the
appeared only Jike a little veffel, but increafing dai'y, it becameas big asa large fhip. It is fur- rounded with many other little iflands; and there continually proceed great flames from it. This novelty is the more furprifing, the water being in this place more than 60 braces deep ; the fubter- ranneous fires muft therefore have ftrange force to throw up fuch a great heap of ftones fo high, through the fea. As in fome parts of Santerini, and of fome other iflands of the Archipelago, the foil wholly confifts of pumice ftone, it is very likely, that thefe new iflands are formed of thefe light ftones. M. de Chajtuetl Gallaup, a gentle- man of Provence, of great erudition and. merit, has done me the honour to communicate this to me, of which he.was informed by a letter from Tunis, which letter faid, this account was con- firmed by the captain and failors of a fhip newly arrived from the Levant to Sufa, in the kingdom of Tunis, who were all eye-witneffes of the truth of what M, De /e Laune had written.
XH, Of a new way of conftructing the map
of a country.
The great expence which attends the conftruct- ing the map of a country geometrically, the length of time which it requires, and the {mall number of thofe who are capable, or who will take the pains to execute this work, are the reafons why few maps are conftructed geometrically ; yet no others are abfolutely certain. Provided fuch cannot be had, M. Chevalier propofes another methed, which is not far fhort of the geometrical exactnefs ; yet may be put in_ practice without any geometry, requiring only care and attention.
The
RovAL ACADEMY of ScIENCES. 15
The arch of the horizon taken between the point where the fun rifes or fets, at any day what- foever, and the point where it rifes or fets, when it is in the equator, is called the amplitude. Ic is then, at firft view, that the amplitude is greater in proportion to the diftance of the fun from the equator, or has a greater declination ; and it 1s alfo feen from the different pofitions of the fphere, that the more obligue it is, or the higher the pole is elevated for any place, the greater is the amplitude, all the reft being equal. The decli- nation of the fun, and the elevation of the pole, are therefore the two elements whereon the fize of the amplitude seeds and tables of the va- riation of the amplitudes are conftructed accord- ing to that of their elements,
‘I fuppofe the place where I am, for example Paris, to be in the centre of a pretty large circle defcribed on a paper, and divided into 360. As I know by the tables, that the folftitial ampli- tude, the greateft of all at Paris, is 37 degrees omitting the minutes, I take on my circle for the equinoctial amplitude, or 0, the point where its divifions begin, and the 37 degrees following an- {wers to the folftitial amplitude. This {pace of 37 degrees anfwers tothree months, and I divide it according to the table of amplitudes, to each day of 3 months, or rather from 5 to 5 days, becaufe the amplitudes have not any fenfible * teration from one day to another. I do the fam for the amplitudes of the other g months of ie
ear.
I alfo fuppofe that the radius of my circle re- prefents an extent of two leagues, and I divide it into 8 equal parts, which are coniequently of a quarter of a league each, and through each of thefe divifions I defcribe circles concentrical with
3 the
16 The History and Mremotks of the
the firft. M. Chevalier calls the papers, where- on thefe figures are, chaffis, or frames.
This done, on any day whereon the rifing or the fetting of the fun can be obferved, I have two wires on the frame dire€tly perpendicular, one at the centre, the other at the outward circle, which anfwers to the day pitched upon, I place the frame exactly horizontally, and turn tt in fuch a manner, that at the moment of the fun’s rifing or fetting, the fhadow of the two wires is upon the fame right line, and I fix it faft in this fituation. Tt is certain, that all the divifions of the outward circle will anfwer exactly to thofe of the horizoa, that the goth degree, for example, afteran equi- noctial amplitude, is a pole, &c. in a word, that the frame is well rectified. Then if I am in a place high enough to furvey an extent af two leagues round, I direct a rule, which can be moved round the centre, exactly to a fteeple, at what place I pleafe; and I am certain, that this fteeple is in refpect to Paris, in the pofition determined by the rule, tothe fouth-eaft, for ex- ample, and confequently it muft be defcribed in my frame on this line. It remains to be known at what point ; now it is fuppofed, that I know pretty well the diftance of al] thofe places which are within two leagues of the place were I dwell, and this knowledge is more familiar in the coun- try, where the frame will be moftinufe. As it is divided into quarters of leagues, I place the fteeple according to its known diftance, either upon one of the concentrical circles, or between two circles, and cannot fall into any confiderable error therein.
What I have done in relation to Paris, M. Chevalier would have 30 or 40 perions do round about Paris, at 2 leagues diftance at moft from
one
RoyAL ACADEMY of SCIENCES. 17
one another, each of. them in relation to the place where they dwell ; not that each fhould be obliged to make a frame, that work requiring the hand of a geometrician, but they being once made by an artift, copies may be fent to 30 or 40 perfons, who will then have only the trouble » of laying out the lines of neighbouring places, as has been faid, and few are incapable of doing this. The 30 or 40 little maps being made, they mutt. be returned to the geometrician, who underftands how to put them together, and there- by compofe a map of the country round Paris. Asthe fame frame is to be fent to all thofe de- fiened to be employed, it is fuppofed, that the amplitudes are the fame, as to places which are but little diftant, which is only fenfibly true. Nor can this method of conftructing maps be ufe- ful, except as to a little tract of Jand; and it is proper, that the city, or principal place, on which alone the amplitudes are regulated, fhould be in the middle of that tract of land which is to be deferibed, that fmall errors of particular places "may compenfate for one another.
It fhould feem, that without making ufe of amplitudes, the frame might be rectified by means of the meridian of the place, which is commonly known in the country ; but it is only known in a grofs manner, and if it was neceffary
to find it more exactly, few would fucceed in
it. The method of rectifying by amplitudes, when the frame is quite finifhed, is more cer- tain, and has no difficulty in it. Not but the other may alfo be ufed with fuccefs.
It may be obferved, in the method of the am- plitudes, that anerror, which may be imperceiv- able in a little tract of Jands will be lefs fo if the work is performed in a tract of lefs latitude,
won. iib. N°, 24. C or
18 The Wistory andMemorrs of the
or in a time nearer to the equinoxes, for in thefe two circumftances, there is lefs difference in the amplitudes of different places. The latitude is the circumftance which makes leaft difference in them; and as in France it 1s pretty extenfive, the operations near the equinoétial ought fo much the more carefully to be obferved there.
To have given here in general the fpiris of M. Chevalier’s method is fufficient. As a geome- trician muft of neceffity be at the head of the work, he will eafily imagine what alterations certain particular circumftances require, and fa- cilities which may be contrived for the operators. A bifhop, who has a genius for the fciences, may in this manner conftruét a map of his country, by help of his clergy, who will hardly be fenfible themfelves, that they are making geometrical o- perations. Many ufeful things, and fome which appear difficult, would almoft execute themfelves, if they who are in place, would give a firft mo- tion to them.
AWN
AN
ABRIDGMENT
rT rH &
Philofophical Memoirs
OF THE
RovALt Acapemy of Sciences at Par/s, for the Year 1707.
I. Obfervations on the quantity of rain, which fell at the obfervatory during the year 1706, and on the thermometer and baro-
meter, by M. de la Hire *.
HE obfervation which I have long made
_on the quantity of water which falls on the earth during each year, the refult of which I give in the memoirs of the academy, at the be- ginning of the fucceeding year, have excited ‘many curious perfons, in different parts of the kingdom, to do the fame in the places where they dwell. Some of thefe obfervations have al- ready been given in our memoirs, and have been compared with thofe made at Paris; but the moft confiderable is, that made by the marfhal de Vauban at Lifle, in Flanders, during ten years fucceffively, which I related fome time ago, and from thence concluded, that there is a little more rain in Flanders than at Paris.
* Jan.8, 1707.
C2 Her
20 The History and Memoirs of the
Here is the continuation of thefe obfervations, which were made here during the preceding year, in all the fame circumftances, and in the fame manner as thofe of the foregoing years: The height of water which fell at the obferva- tory, was in
Lines. Lines. Van: 8: July 13 Feb. 1534 Aug. baa March x2 Sept. FO April + — Qétob. 19% May 23% Nov. 17 June ore ec: 3005
Quantity of water in the whole year 8 3 lines
2+, or 15 inches, 3 lines 3
This has been a very dry y year, if the quantity of water, which has fallen, is in general confi- dered, which commonly ufed to be between 19 and 20 inches: ‘but ic muft be looked upon as one of the wetteft years, if it is confidered that the greateft rains commonly happen in the months of Fuly and duguff, with ftorms, and that this. year it did not rain in both thefe months toge- ther much more than 18 lines.
Dry years are always advantageous to the corn in this country, the greateft part of the land be- ing moift and cold ; for the weeds do not then crow, of turn the corn up.
As to the heat, I compute it by the thermo- meter, called the Florence thermometer, which is fixed in a place expofed to the air, but fhaded from the fun. It is at the 48th degree of its divi- fion in the bottom of the caves of the obferva- tory, where I fuppofe the air to be in a mean ftate of heat, and it begins to freeze when the li- quor in the tube falls to 32 degrees. The loweft
i which
Royat ACADEMY of SCIENCES. 21
which the thermometer fell at the beginning of this year, was to 20 4 degrees Fan. 213 but it almoft immediately rofe again to 30 degrees, and the froft was but inconfiderable, and of Jittle continuance ; and in the firft 8 days of February, when the cold is commonly moft fevere, the ther- mometer always f{tood at about 30 degrees. The gth of this month, it was at 45 degrees, which is almoft its mean ftate; the remainder of the month it was always near 30 degrees, which indicates a little froft. As to cold at the end of the year, it was inconfiderable, for it only froze Dec. 21, the thermometer then falling to28 4. There fell only a little fnow Fed. 4.
Though the cold was not great, nor of long continuance, the heat on the contrary was very confiderable, and lafted long; for the thermo- meter. almoft always ftood at near 60 degrees in the 3 months of June, Fuly, and Aug. The hotteft day was Aug. 8, wherein the thermome- ter was at 68 degrees about the fun’s rifing, which is the time when I always obferve it, and wherein the air is the cooleft of the day. This very day, at 2 in the afternoon, which is the time when the air is hotteft, the thermometer rofe to near 82 degrees; whence the heat is known to have been very great, fince the thermometer rofe to 34 degrees above the mean ftate; and had it fallen as much below it in the winter, it would have come to. 14 degrees, which commonly in- dicates the greateft cold that we ever iuffer in this country. |
In thefe fort of obfervations regard ought to be had to the wind, which partly caufes heat and cold, therefore I alfo give much attention to that. Inthe month of Fan. the wind was al- ways eafterly, inclining fometimes to the fouth,
C 3 ant
22 The History and Memorrs of the
and fometimes to the north. At the beginning of Feb, it was welterly ; and towards the end of the month northerly. In March, it was pretty changeable, chiefly in the weft, but little in che eafl, and paffing by the north. In April, at the beginning, towards the north-eaft; and at the end, in the weft. In May, the weft wind prevailed. In June, it was almoft always near the fouth and weft. In fwly, at the beginning and end, near the weft ; and in the middle near the north, In Aug, it was almoft always weft, inclining a little to the north, and very often to the fouth ; which contributed much to the great heat. In Sept. al- moft always fouth-weft. At the beginning of O. alfo fouth-weft ; and at the end, near fouth- eaft. In Nov. the wind was almoft always fouth, and a little thereabouts; but chiefly weftward. In Dec. almoft always fouth and fouth-weit.
The prevailing wind this year, was fouth-wett, as it is commonly in this country, becaufe of the neighbourhood of the fea; but this fouth-weft wind has always been very violent.
There were fome ftorms this fummer ; but the moft confiderable happened Fuly 27, in the morn- ing, with thunder; which did much damage in many places.
The barometer which ferves me for the weight of the air, is always placed at the top of the creat hall of the obfervatory. March 10, the quick- filver rofe to 28 inches, tr line. Dec. 22, 1t fell to 26 inches, 9 lines: the difference between thefe 2 heights was therefore 1 inch, 4 lines $, which is pretty hear as ufual; but it feldom falls fo low, except with a very high foutherly wind of long continuance, as it was then. I have frequently ebferved, that the quick-filver has been very high,
though
Royat ACADEMY of SCIENCES. 22
though the wind has been foutherly, which is contrary to the common rule.
The tube of the barometer which I always make ufe of, is very flender and long ; and I fufpect that there is a little air therein, which I cannot get out; for I have another, whofe tube is of a middling fize, wherein the quickfilver always ftands more than three lines higher. Light is feen in the yacuum of thefe barometers when the quickfilver is agitated ; and one of them is that wherein M. Picard, of the academy, who was the firft that obferved it, made his firit obferva- tion on the light in the vacuum of barometers. We have alfo other barometers, conftructed in a manner different from the common ones; in which, even air has been fuffered to enter, yet they alfo give a light.
I alfoobferved, Dec. 31, of this year, 1706, the declination of the needle, 9 degrees, 48 mi- nutes, weftward, with the fame needle of 8 inches, Jength, and in the fame place where I ufed to ob- ferve it every year, as I have related in preced- ing years.
Il. 4 machine to retain the wheel, which Jerves to raife the rammer to drive the piles in the conftruétion of bridges, kays, and other works of this nature, by M. de la Hire*.
The rammer, or beetle, which is ufed to drive preat piles, is of 1000 or 2000/). weight ; and Is commonly raifed by a roller, which -compofes a part of the crane or engine, which is to raife great weichts.
* June 1, 1707.
Ga This
24. The History and Memoirs of the
This rammer runs freely between two grooves, that the whole force thereof may fall on the head of the pile which is to be driven. But as the com- mon rollers of engines are moved by 4 arms fixed to them it is difficult and tedious to turn them, which hinders the work; therefore a great wheel is fixed to this roller of 10 or 12 feet in diameter, as there is to great cranes, that men by walking or climbing in this wheel, may caufe the roller to turn more eafily and conveniently, as may be feen in the figure*.
In conftructing a great ftone bridge at Moulins, in Bourbon, after anew manner, by the direétion and plan of M. Manfart, furveyor of the build- ings, they are obliged to fink great piles, more than 20 feet deep, to get a good foundation; it is therefore neceflary to make ufe.of a rammer of 2000 /b. weight. But as the great wheel which is apply’d to the roller, on which the rope of the rammer winds in proportion as it is raifed, is large, enough to receive in‘ it 4 men on a row, who climb up together on the crofs bars, or rounds, which form the breadth of this wheel, and almoft always to keep them in at the heighth of the axis or roller, to make the greater effort, this wheel muft be ftopped every time the rammer goes down ; for the weight of the men within it being no longer {topped by the weight of the rammer, would carry the wheel fwiftly round ; and the men therein might be thrown down, and perhaps killed ; therefore they are obliged to ftop this wheel with a hook faftened to a rope, and fixed to fome appointed place every time the rammer is letdown. ‘This is very troublefome ; befides, it may happen, that the hook or rope may break by the force of the men’s weight on the circum-
* Plate I. Fig. "1, ference
Roya ACADEMY of SCIENCES. 25
ference of the wheel, and then the labourers run the rifque of their lives.
But the men in the machine have not only this to fear; for fometimes the defcent of the rammer, or the hook, by which it is fupported, or the rope which is made ufe of, may break on a fudden in raifing it; and by thefe unforefeen accidents the labourers are in great danger, as has fometimes happened.
This obliged one of the king’s chief architects, who has the direction of this edifice, to propofe to me laft winter, that I fhould find out fome re- medy for all thefe inconveniencies, and make it fo eafy, that corpulent men, who are moft com- monly employed in thefe works, may receive no hurt by any negligence, or inadvertency whatio- ever: This is what I thereupon contrived, and which is to be executed.
I firft confidered, that in all accidents which may happen to this machine, the rope which holds up the rammer, entirely flackens; and con- fequently, a piece muft be fixed in the timber work of the machine itfelf, which falling between the fteps or rounds of the wheel, and being capable of refiftine any effort whatever, may retain it when the rope of the rammer is flack ; and on the contrary, this piece muft difengage itfelf from
thence when the rope is tight.
For this purpofe I made a fquare A BC* of either wood or iron, much wider than it is thick, forked near the end C, which is a little bent. In this forked part I fixed a lutle roller or pully, fo that the cable or rope of the rammer, may move freely in this part, paffing under the pulley. To the other branch of the fquare AB, near the
Oy ies:
angie
26 The History and Memoirs of the
angle B, I fix a ftrong pin D, or a bracket of the fame thicknefs as the branch of the fquare. To conclude, in the end A of this branch BA, a hole is bored that an iron pin may be put therein,
In the compofing this engine, there are two pieces EF * mortifed parallel to each other, which help to ftrengthen it; there isa fpace of 4 or 5 inches between them, in which I faften the fquare ABC, and fix it to the mortifes by a pin placed at the end A, but in fuch a manner that it has not too much room to play on the fides, which de- pends on the diftance between the mortifes, and on the thicknefs of the branch of the fquare.
Directly under thefe mortifed pieces goes the great wheel of the roller, which carries the ro of the rammer; and the machine is difpofed in fuch a manner, that when the cable GH, which comes from the top of the engine to the pully H, to be afterwards turned on the roller, is tight or ftrained; it holds up the fquare, paffing through the pully at C, fo that the bracket of the fquare D, does not touch the rounds of the wheel. But as foon as the rope GH flackens, the weight of the {quare itfelf, and the weight which the rope adds to it, by refting on the forked part, makes it turn upon the pin at A, and fall into the fellows of the great wheel ; and the bracket D falling immediate- ly between the fteps or rounds, retains the wheel in this ftate, it being impoffible for it to turn; for the branch AB of the iquare, being faftened be- tween the mortifed pieces, can bear a very great effort.
But when the cable or rope of the roller is again ftrained, to fix the rammer to it, the fquare im. mediately rifes, and the bracket D dilengages it-
py Figs a:
felf
RoyvaArt AcADEMY of SCIENCES. 29
felf from the rounds of the wheel, which is then at liberty to turn round and raife the rammer.
This machine is very fimple and convenient, and may fave the livesof labourers and workmen employed in this bufinefs, and without any pre- caution, »
Ill. Of the irregularities of the apparent de-
prefion of the horizon of the fea, by M. Caflini* ; tranflated by Mr. Chambers.
After examining the 1ft obfervations of the ap- parent depreffion of the fenfible horizon of the fea, made by father Laval, in his obfervatory at Marfeilles, fnding them different at different times, I defired him to continue his obfervations, to fee whether this difference would ftill continue equally irregular,
The telefcope of the inftrument which he ufes, is raifed 144 Paris feet above the level of the fea, according to a levelling made by himfelf; which 144 feet high give the direét ray, which razes the furface of the fea an inclination of 13! 14”.
The leaft apparent depreffion obferved by father Laval, at this heighth during this winter, was 11’ 46”; and the difference between this height, and that of the direct ray, would be 1’ 28”; which might be owing to the greateft refraction of the vifual ray, which razed the furface of the fea. — But the greateft apparent depreffion obferved by him was 14! 30", which exceeds that of the direct ray by 1/ 16”; and this contrary to the rules of refraction, which fhould diminifh this inclination inftead of increafing it. :
® June 28, 1707.
We
28 The History and Memoirs of the
We have already noted from feveral other obfer- vations, that a part of the furface of the fea, con- tiguous to the fenfible horizon, confounds itfelf as to fight, with the heaven itfelf; and that on this occafion, the apparent circumference of the fen- fible horizon falls in the fea within our fight. The vifual ray directed to this apparent circumfe- rence of the horizon of the fea declines; therefore on this occafion, from the direct ray which razes the furface of the fea, towards the lower fide, con- trary to the inclination which the refracted ray raifing this furface ought to have,
Having communicated this remark to father Laval, and he not having occafion to diftinguifh this difference by ‘any fenfible fign, it is evident how difficult it is co diftinguifh it; and how liable to error the method is of finding the magnitude of the diameter of the earth, by obferving the tangent of the fea without this circum{pection,
It appears by father Laval’s obfervations, that this difference between the feveral apparent de- preffions of the horizon of the fea, viewed from the fame place, does frequently exceed a 5th part of the leaft apparent inclination ; fo that one might be deceived in this method by a sth part of the femi-diameter of the earth.
I have endeavoured to reduce the difference be- tween the apparent inclination of the refracted ray, which razes the furface of the fea, and the real in-
clination of the direct ray, to certain rales; and it is evidently of great importance to examine, what degree of exaétnefs a method is capable of, to pre- vent any expectation of more than it can afford.
By the multitude of obfervations made by father Laval, we learn, 1{t, That when we attempt to determine a diftance, ora fmall height, upon the furface of the fea, by a fingle obfervation of the
depreffion
RoyaL AcADEMY @f SCIENCES. 29
depreffion of the horizon, we can only be fure of being within } of the truth; and accordingly this is pretty nearly the difference found between the height of the obfervatory at Mar/eilles, as taken by obfervations made at Mar/eilles, and the real height found by levelling, the former being 175 feet, and the latter 144. 2dly, That having fe- veral obfervations of the apparent depreffion of the fea, made in the fame place at different times ; and taking a medium between thefe obfervations, we fhall have the inclination nearly equal to that of the direé&t ray, which raifes the furface of the fea, which may ferve to determine the height and diftance, by the common method, to a tolerable exactnefs. 3dly, That the variation of the appa- rent heights of the fea bears no uniform relation to the variation obferved at the fame time in the barometer and thermometer, which feems to con- firm what we have frequently obferved, that the air which caufes the refraction, is of a different nature from that which balances the weight of li- quors in vacuo.
We have frequently obferved the apparent de- preflion of the fenfible horizon of the Mediter- ranean fea, from an elevation 6 times greater than that of the obfervatory at Mar/eilles, and con- ftantly found it 42 min. without any fenfible dif- ference between one time and another, which fhews, that the refraction is much more variable at moderate heights, than at very large ones,
IV. Odfervations upon fpiders, by M. Hom- berg; ¢ranflated by Mr. Chambers.
The colour and figure of an extraordinary kind of fpider, which I met withal, among the tube- roics in a garden at Toulon, raifed my curiofity to
€X-
30 The History and Memorrs of the
examine this; and afterwards all the other kinds of fpiders I could find in. I made ufe of a mi- crofcope for the difcovery of certain parts which the naked eye cannot diftinguifh, and have pro- cured defigns of them larger than the life, to reprefent them fuch as they appeared thro” the mi- crofcepe.
I fhall here only give the defcription of 6 prin- cipal kinds of thefe infects; to which, all the reft J have met withal, may be referred.
The 6 kinds are, 1ft, the domeftick fpider ; or that which makes its webbd on the walls, and in the corners of rooms. 2dly, The garden fpi- der; or, that which makes its webb out of doors, ufually of a roundifh figure, and a loofe texture, in the centre whereof the animal lodges all day. 3dly, The black fpider; found in caves, cellars, and holes of old walls. 4thly, The wandring fpider, which does not lie ftill in its neft like the other kinds. sthly, The field fpider with long legs, ufually called the fpinner. And 6thly, The raging fpider, or the famous tarrantula.
By the way it may be proper to begin witha general defcription agreeing to all the kinds of {pi- ders ; and afterwards to note the particular cha-
racters of each: nor fhall I enter into a minute account of the ftructure of all the external parts of this infect, but confine myfelf to_.what is not ea- fily difcoverable by fimple infpection, and with- out the help of a microfcope.
The whole body of the fpider may be divided into the anterior part, the pofterior part, and the paws or legs; the anterior part contains the thorax and head; the pofterior, the belly: thefe two parts are faftened together by a choak, or very narrow rim. Inthe generality of fpiders, the an-
terior part is covered with a hard fcaly cruft, and the
5
RoYAL ACADEMY Of SCIENCES. 31
the pofterior, with a foftfkin; the legs arife from the thorax, and are hard like the reft of it. ‘This ftructure is very different from that of diverfe creeping and flying infects; for inftance, the maids*, and others, whofe belly and thorax adhere to each other by their whole extent without any choak, or contraction, tho’ their thorax be invefted with a hard cruft, and the belly with a foft fkin, yet their head adheres to their shorax by a very narrow choak; again ants, wafps, and moft flies have their thorax and belly faftened by a choak, and their head and ¢horax by another.
All fpiders are covered with hair, their hard, as well as their foft parts.
They have eyes on various parts of their heads, of different fize and number, and differently placed; but all of them without Palpebrz, or eye- lids; and covered with a hard glofiy tran{fparent cruft.
In the fore-part of the head is a kind of double -claw, or gripe, like that of a lobfter, which, with the front of this animal, makes the whole fore-part of the head. See fig. 4, 5, 6. This claw confifts of two flattifh branched pieces, co- vered with a hard cruft or fhell, and fattened per- pendicularly to the lower part of the front by a foft fkin, which ferves them as a joint or hinge to open and fhut upon. Thefe pieces are befet with little hard eminences at the two edges that meet, and thus become fit to catch, and hold their prey near the mouth which is behind the claw, in order to draw their food therefrom.
At the lower end of each of the branched pieces, is a hooked nail, fomewhat like the nails of a cat 3 thefe nails are very large, hard, and jointed, fo that the animal can move them upwards and down-
* Adder-Bolts, wards,
32 The History and Memoirs of the
wards, without ftirring the branches themfelves: It is probable thefe nails ferve to fhut or clofe the ends of the claws, and gripe the prey to prevent its efcape; for by their means, the aperture of the claws forms a triangle clofed on all fides, which otherwife would be open at one end. See fig. 6. Thefe nails being jointed, may Itkewife ferve to raife or fail the prey, as the animal finds occafion.
All fpiders have 8 jointed legs, like the legs of Jobfters ; and at the extremity of each, are two large hooked jointed nails.
Between the two nails of each extremity, is a body not unlike a wet fpunge, aes like that found at the end of flies legs, and i in all likelihood. ferving for the fame purpofes; viz, to walk with the feet upwards upon {mooth polifhed bodies, where the hooks or nails would be of no ufe: thefe fpunges fupply a fort of vifcid liquor, which ferves to make them ftick or hang thereon: this vifcid liquor ftops with age, both in flies, and fpiders, fo that they become unable to walk long up a perpendicular glafs. And we even find, that an old fpider or fly, happening to fall into a deep China jar, is unable to get out again, and mutt die of hunger.
And the fame thing befalls fpiders with refpect to the matter, whereof they make their webb. An old fpider has no more of this matter left in its body, nor can fo much as refit its webb when broken, or difplaced ; all it can do is to expel fome weaker {pider of the fame fpecies, and pofiefs its neft, which I have frequently found it do. It is not unlikely, that the liquor at the extremities of the paws, is the fame with that which makes its webb, or at leaft near a-kin thereto, fince both of them ceafe about the fame time ; but of this we fhall fpeak more at large hereafter.
Befides
Royat ACADEMY of SCIENCES. 33
Befides the eight legs above-mentioned, where- with the fpider walks, it has two others nearer the head, which are of no ufe in walking, but ferve it in lieu of arms and hands, to place and take back the prey which they hold in their claws, in order to fhift and prefent different parts of it to their mouth, This fifth pair of legs, or thefe arms, are not formed a like in all the kinds of fpiders; in fome, they are perfectly like the other legs ; and in others quite different. Their difference will be noted when we come to the different characters of each fpecies of {piders.
Around the anus of all fpiders are four little mufcular papille, or nipples, pretty broad about their bafes, and pointed at their extremities*, hav- ing, a pretty free motion; every way from the middle of thefe papi/lz, as through a mould, or wier-drawer’s iron, iffues the vivid liquor, which produces the thread whereof their nefts and webs are formed. This mould has a {phincter to open and fhut it, by which means they can {pin bigger or fmaller at pleafure; and the fpider, being fufpended in the air by this thread, either ftops
~ when this mould clofes, or continues to defcend
by its own weight when it opens.
The manner wherein they make their webs, is as follows: when a fpider is to hang her work in a corner of a room, where fhe can eafily go to all the places the threads are to be faftened on, fhe opens and detaches the four nipples above- mentioned immediately, upon which a little drop of vifcid liquor appears upon the tip of each, This drop. being forcibly preffed againft the wall, fticks thereto by its natural gluten, and the {pider removing from the place, new matter continues drawing thro’ the hole ; and thusis the
* Plate I. Fig. 10.
Vou. Il]. N°. 24. D firft
34 The Htstory and Memorrs of the
firft thread form’d. Being arrived at the place of the wall, where fhe would have her web ter- tminate, fhe prefles the end of her azus againft the fame, and thus faftens the other end of the thread, after the fame manner as the firft. This done, fhe withdraws about half a line from the firft, and here faftens the end of a fecond thread, which fhe fpins forth parallel to the former, till arriving at the other end of the firft thread, fhe faftens the fecond to the wall, and thus proceeds till the whole breadth of her intended web be finifhed. Thefe parallel and longitudinal threads, which may be called the warp of the web being finifhed, fhe proceeds to crofs or traverfe them with other threads, and to this purpofe faftens one of their ends againft the wall, and the other upon the firft thread that. had been drawn; thus leaving one fide of the web quite open for the flies toJcome in at. Thefe latter crofs threads may be called the woof of the web; and being all of them but new fpun, they eafily ftick to every thing they touch, and confequently to the warp they pafs over, wherein all the ftrength and firm- nefs of this web confifts; whereas the firmnefs of our cloths depends on the interweaving of the threads of the woof between thofe of the warp.
To make the crofs-threads ftick the firmer, the {pider works with its four papil/e, and fqueezes clofe all the parts where the interfections happen, as foon as one thread is laid upon another, remem- bering to triple, or quadruple the threads at the borders; to ftrengthen them the more, and pre- vent an erupture being made in the web.
‘A fpider may furnifh twice or thrice as much miatter as is neceflary to make a web, provided fhe have not fpent too much in the firft; but if — anew web be wanting after this, fhe mut either
dif-
Roya ACADEMY of SCIENCES. 35
difpoffefs fome other fpider by force, or find a va- cant web, which is no unufual thing, by reafon the young fpiders always relinquifh their firft webs to make new ones. If the old {fpicler be not fupplied with any of thefe ways, it muit pe- rifh, for there being no living without a web, at leaft for the domeftick fpiders, tho’ fome of the reft need none. Thus much for the webs made in corners of rooms.
As to the webs made a-loft in gardens, &c. where the fpider cannot eafily come, the method of proceedure is thus: the animal places itfelf in a calm feafon on the end of fome branch of a tree, or any other body that projects far into the air, here ftanding firm on its 6 fore-feet, with the 2 hind ones, it draws a thread from its anus two or three yards long, which it lets float in the air till fuch time as the wind driving it againft fome folid body. It quickly fticks thereto by its natural gluten ; the animal from time to time pulls this thread towardsit, to learn whether the loofe end ‘have yet faftened to any thing, which it learns by the refiftance it meets withal in pulling. Find- ing it fixed, it ftrains the thread a little, and fixes it with its papil/e to the place where it ftands, This thread now ferves it as a bridge, or ladder, to go tothe place where chance has caift it, by which means fhe doubles this firft thread, which fhe afterwards tripls, or quadruples, according as its greater or lefs length requires more or leis ftrengthening. This done, the fpider places it- felf about the middle of this thread, and with i’s two hind paws draws from its anus a new thread, which it lets float like the former, till finding it fixed to fome body, fhe ftrains it a little, and then with a papilla faftens the end as perpendi- cularly as fhe can, on the middle of the firlt
D2 thread ;
36 The History and Memoirs of the
thread ; proceeding afterwards to ftrengthen its by doubling, or tripling, as in the former cafe- The like procefs fhe repeats fo often till the mid- dle of the firft thread become a centre; from whence proceed feveral radii, the work being continued till fuch time as fhe can go upon the crofs threads from the end of one of the radii, to the ends of all the reft This done, fhe fixes a new thread in the centre, and draws it along one of the radii, and from thence to the middle of one of the crofs threads, where fhe faftens it with her papillae, and by this means makes as many radii as fhe finds proper. The radii all made, fhe returns to the centre, and there faftens a new thread, which fhe draws and faftens down in a fpiral direction upon the radii, from the centre to the magnitude fhe would have the web. ‘This done, fhe takes up her lodging in the centre of the web, with her head always downwards, to avoid, as fhould feem, the too great brightnefs of the heavens, as having no eye-lids to reflrain and modify it, or rather, to fuftain and reft her big belly on a large bafe of her thorax ; whereas if fhe remained with her head upwards, the belly would only hang by a flender thredd, wherewith it is faftened
to the thorax, whican might be incommodious. The {pider only keeps in the centre of her web during the day-time; in. the night, or when it rains, or blows hard, fhe retires into a Hitele cell, built at the extremity of her web, under the leaf of a tree, or plant, or fome other place ftronger, and more ftable than her web, and which may afford her fhelter from the rain. ‘This place fhe ufually choofcs towards the higheft part of the web, that fhe may have immediate refuge there on occafion; for moft fpiders af-
cend with more eafe and difpatch than defcend. The
i it
Royal: ACADEMY of SCIENCES. 37
The fpider ‘lies in wait for flies, or other in- feéts, which entangle themfelves in her web, and which are to ferve it for food. When the fly is fmall, the fpider takes it in its claws, and bears it into her neft to fuck its juice ; but when the fly is too big, in proportion to the fpider, and with its wings and claws might be liable to in- commode her, the fpider in this cafe wraps her round and round, with a number of threads, which fhe draws from her anus, to fetter the fly, till fhe can no longer ftir either wing or feet; upon which the fpider carries it peaceably into her den, ‘and feeds of it. Sometimes the fly hap- pens to be fo big and ftrong, that the fpider can- - not compafs it, in which cafe, inftead of entang- ling it more, the fpider loofens it, or even, if that cannot well be, breaks the part of the web where the fly hangs; and, lets it go, applying herfelf in the next place, ‘either to mend her da- maged web, or make a new one,
All male {piders are fmaller than the female ones of the fame kind ; and this to fuch degree, that I have found five or fix male garden fpiders hardly balancing one female one. This is no un- common thing in moft infects, tho” quite contrary to what we find in quadrupeds, where the males are always bigger and ftronger than the females.
The fpiders of all kinds are oviparous, with this difference, that fomeé of them, as the garden fpider and {pinner, procuce-a reat number of eges ; and others, as the houfe {pid ler, very few 3 they lay their eggs orra piece of the web, which they bind together in aielufter, and breod on them in their neft. If they:be driven out of the neft, in the time when they are hatching, they take this ‘clutter of eggs in their claws above defcribed, and carry it with them. Ass foon as the little ones
D3 are
38 The History and Memoirs of the
aré hatched, they begin to fpin, and enlarge at fuch tate, that one may almoft fee them grow ; yet, without taking any food that I have been able to difcover ; if a very {mall gnat happen to fall in their way, they fly upon and make fhew, as if they fed on it; but if none come in a day or - two, or even more, they {till continue growing as faft as if they had fed, augmenting every day to more than double their bulk. :
The peculiar characters of each fpecies of fpi- ders, ate taken from the different difpofitions of their eyes; not but there are other confiderable differences between them, but thefe not uni- verfal.
The domeftick, or houfe fpider, which makes the firft {pecies, has 8 little eyes nearly equal in its forehead, in an oval fituation*. This fpider makes a large web ; its arms are perfectly like its legs, excepting that they are fomewhat fhorter, and that it never puts them tothe ground. . This fpe- cies changes its fkin yearly, even to the very legs, as lobfters do, which I have not obferved of any other kind. It is very long-lived, I hav- ing known one of them above four years, which had not grown any thing confiderable in body, but a great deal in legs. This fpider is liable to a difeate, which renders it frightful, being fome- times covered with {cales ftanding out an end, and the intervals thereof {warming with vermin, much like the lice upon flies ; but a deal fmaller. When the diftempered fpider runs faft, it throws off fome of its fcales, with the littl vermin. The difeafe is very rare in our cold countries, nor have T ever obferved it out’ of Naples. The fpider, when feized therewith, never ftays long in a place 5 and if it be fhut up, foon dies.
* Fig. 4
a
I The
Royat AcapDEmMy of SCIENCES. 39
The fecond is the garden fpider, which makes a large round web in the air, and ufually poffefles the middle thereof. It has 4 large eyes, placed fquare in the middle of the forehead, and 2 {mal- ler on either fide ofthe head*. The females of this fpecies have the largeft bellies I have known in {piders ; the males are very {mall ; they are of dif- ferent colours, but ufuaily feud/e mort {potted with white and brown ; tho’ fometimes they are all white, as thofe I obferved at Toulon, among the tuberofe flowers; and fome I have known all green; nor are they all of the fame fize, but the green ones are fmalleft, and the brown ones bigeeft of all. Pouring fpirit of wine on thefe fpiders, they did not feem at all difturbed there- by, no more than with aqua fortis, or oil of vi- triol; butoil of turpentine killed them in a mo- ment; which accordingly I have frequently ap- wh to deftroy broods of young {piders of this
ind; fome of them containing no lefs than. a hundred a-piece, which, in:a few days, will over- run a whole garden, and fpoil a great number of plants.
The third fpecies is that of fpidets in vaults and old walls. Thefe feem only to have fix eyes, all the other fpecies having eight. The eyes are placed two in the middle of the forehead, and two of each fide the head; all fix being nearly of the fame fize +. The fpiders of this fpecies are all of them black, and very hairy ; their legs are fhort, and they are ftronger and more mif- chievous, as well as longer lived, than moft other fpiders. If you take one, it will defend itfelf and bite the inftrument it is held withal, and though pierced in the belly, will fometimes live two or * three days5 whereas all the other fpiders die ee! + Fig. 6.
4 quickly
40 The History and Memorrs of the
quickly upon piercing theit belly ; nor do they ever defend themfelves, or bite any thing when taken. In lieu of a web to catch flies, thefe only fpin a few threads, 7 or 8 inches long, which iffue. from their nefts, like fo many radii, and — are faftened to the wall around the hole where they inhabit; any infect walking on the wall, and flicking againft any of thefe threads, adver- tifes the fpider, who lies perdue in her hole, and, upon this notice, inftantly rufhes out with prodi- eious. fwiftnefs, and feizes, the infect. I have teen a vigorous wafp carric’| off by one of thefe fpiders, which none of the other fpecies would have touched, both on account of the itings thofe infects are armed withal, and of the hard fcales wherewith their whole body is defended; but the fore part and legs of this {pider, being covered with a very hard fhell, and the hind part, or belly, with a thick clofe leather, % does not fear the wafp’s {ting ; and its gripes are fc ftrong and hard, that they are able to break the fcales of the wa{p.
The fourth fpecies of f{piders are thofe we call vagrants, by reafon they do not ftay at home in their refpective nefts, as all the other fpiders do, who wait quietly for their prey to come home to them ;. but, on the contrary, go out in queft of prey, and hunt ic down with infinite wiles and itratagems. They have two large eyes in the middle of their forehead, and two {mall ones at the extremities of the forehead, two of the fame fize on the back of the head, and two very fmall ones between that and the forehead *. The {pi- ders of this fpecies are of different fizes and co- lours, white, black, red, brown, and {potted, In one part of their body they are different from all
* Fig. 7
other
Rovat AcADEMY of SCIENCES, 41
other fpecies, viz, the extremity of their arms, and 5 pair of legs, which terminates in a clufter, or in?a plume of feathers; whereas in all the o- ther fpiders, it terminates in two hooks, like the . other legs. This plumage is ufually of the fame colour with the reft of the body, and fometimes equal in bulk to the whole head, The animal makes ufe of it, to throw upon the wings of flies it has caught, in order to prevent their motion and fluttering, which would greatly incommode it, in as much as this fpider wants the neceffary means, which others are furnifhed withal, ‘of ty-
ing and entangling its prey. | The fifth fpecies is, That of field-fpiders, vul- garly called, fpinners. This fpecies has its fore- part, or head, and thorax, flat horizontally, and almoft tranfparent, being covered with a very fine whitifh fleek fcale ; it has a large black fpot on its head, which I take for the brain, which appears through the tranfparent fhell it is co- vered withal. This fpider has 8 eyes ranged ina very extraordinary manner, two of them in the middle of the fore-head, fo extremely fmall and clofe to each other, that they appear like one little oval body: atthe right and left of the fore-head, are two little prominences ; and at the top of each of thele, are three eyes, placed very near each other *; thefe eyes are bigger than the two in the middle; their cornea is very prominent, white, and tranfparent, though the fund be black; whereas, the eyes in the middle, are quite black. ‘From each of thefe prominences, as well as from the two eyes in the middle, arife three very fen- fible canals, which terminate in the black fpot, ~ fuppofed above to bethe brain. As thefe canals recede from the eyes, they approach towards each
* Fig. 8,
other
42 The HisToRY and Memorrs of the
other, fo as to end almoft in the fame part. of the brain: in them are the optic nerves probably lodged. The legs of thefe fpiders are much flenderer and longer in proportion, than thofe of other kinds; but their arms are much fhorter, and more flefhy, bearing little or no refemblance ~ tothe legs, as they do m all ‘other fpiders : | their leas are fo full of hairs, that to the microfcope, they appear like writing quills.
The famous tarantula makes the fixth fpecies of fpiders; it has the figare and appearance of a common houfe fpider, but much {tronger, and more robutt in all its parts: the legs, and bottom of its belly, are fpotted with black and white ; but the top of its belly, with all the fore-part are quite black: its head and ¢horax are covered with one fingle black fhell, perfeétly like a little tortoife : it has eight eyes, which are alrogether different from thofe of other fpiders, both in co- Jour, and confiftence.. All the eyes of other fpi- ders, are cither black, or red, bordering on black; and are covered with a hard tranfparent feale, remaining fuch after their death; whereas, thefe are covered with a foft and moift cornea, which withers and finks when they are dead : their colour is white, bordering fomewhat on yellow, very bright, and fparkling like cats eyes, when wiewed in the dark ; they are fituate four ina fquare fieure, in the middle of the fore-head; and four in a: horizontal line, below the four firft: thefe laft border the bottom of the fore- head, and are placed immediately over the root of its gripe, or pinchers. Thefe eyes are of ciffe- year bulk; the four firft are nearly alike, being about a line in diameter, and fufficiently vilible without a microfcope ; but the latter-are not above half the diameter of the former, The tarantula
1S
Royat ACADEMY of SCIENCES. 43
is very mifchievous, and will bite on its own ac- cord, during the coupling feafon. I have feen them at Rome, but they are not minded, as having never been known to do any harm ; but in the kingdom of Naples they do adeal of mifchief, by reafon we fuppofe the country is much hotter there than at Rome. The fymptoms which be- fall thofe wounded thereby, are very whimfical as well as the cure. They have been defcribed by feveral Italian and French authors; and tho’ their hiftory appears fomewhat fabulous, it is real ne- verthelefs. An account of them has been given us by M. Geoffroy ; and an extract thereof in the hiftory of the academy for the year 1702, to which we refer the reader,
An explanation of the figures, tranflated by J. M,
Fig, 4. Reprefents_ the eyes and claws of the houfe {pider.
Fig. 5. The garden fpider, which keeps in the air, in the middle of its web.
Fie. 6. The black fpider, which inhabits in the holes of old walls.
Fig. 7. The wandering {pider, which does not keep in one neft like the others, and goes out to hunt flies and other infects.
Fig.8. The head and eyes of the field-fpider, commonly called the fpinner.
Fig. 9, 9. The tarantula.
Fig. 10. A fpider reverfed, which fhews the papille of its anus, which it makes ufe of for the thread,
Vor
44. The History and Memoirs of the
V. Of the effect of gunpowder, chiefly in mines, by M. Chevalier *.
Every one knows, that gunpowder is a compo- fition of faltpetre, fulphur, and charcoal, beat and mixed together; and that a certain propor- tion is to be obferved in the mixture of thefe in- gredients, and precautions taken in the choice of them, and in the manner of making the powder, which contribute to the goodnefs thereof. But this is not what we defign here to examine. It is of the effect of the powder, and chiefly in mines, which I propofe to treat.
The late marfhal de Vauban communicated to me a great number of experiments on this fubject. This great man who was always employed in pro- moting the king’s glory, and the grandeur of the ftate, having obferv’d on many occafions, that the fuccefs of mines did not always anfwer to ex- pectation, thought it neceflary by exact experi- ments to determine the different effects of mines in all the feveral circumftances wherein they may be employ’d ; and trom thence conclude on certain rules to be obferv’d on important occafions. The fuccefs has juftified thefe rules; but before | lay them down, I muft explain the reafon why gun- powder when it takes fire, is capable of making fuch great effurts.
Firft I confider, that air is neceffary to the ac- tion of the powder; for by experiments made in the air-pump, it will not take fire from a flint in the vacuum; and though it takes fire from the fun-beams, by means of a double convex-glafs, yei it is almoft withour any noife or effort.
Fapoy. ue, boy,
Secondly,
RoyAt AcADeimyof ScIENcEs. 45
Secondly, The bodies whereof gunpowder is compofed, do not with equal facility take fire. Sulphur takes it more readily than charcoal, and charcoal than faltpetre, which is the predominant ingredient in the powder ; there is commonly 3 parts of faltpetre, to one of both the other taken together. It is alfo to be fuppoled, that each: of thefe bodies is compoted of parts of unequal apt- nefs in taking fire.
Thirdly, The powder muft be very dry, that it may the fooner take fire; it mutt be granulated that the flame may very fubtilely communicate it- felf through the fpaces left between the grains, which mutt all perform their effort almoft at the fame time.
I. This being fuppofed, it may be conceived, that firlt the different bodies whereof powder is com- pofed, taking fire fucceffively, rhe fire directly im- preffes its action on the firft or moft fubtile, which - afterwards communicates a certain degree of velo- city to the fecond; and the fecond to the third, and fo. on till the whole matter being kindled, makes its effort.
2. Moft of thofe bodies againft which the powder acts, have alfo parts of unequal folidity capable of communicating to one another fuccei- fively the motion of the parts.of the powder; and the effort of the parts of the powder will be fo much the more confiderable, the greater number there are of parts of unequal folidity, either in the ingredients of the powder, or in the bodies againft which it acts; (all things elfe being equal) and that thefe parts have with one another, and nearer relation to a geometrical progreffion, beginning at the moft fubnle, and preceeding to the moft grofs, as has been fhown by the learned M. Hay- gens, in his Laws of Motien, and after him by
M. Carré.
-
powed
46 The History and Memoirs of the
It may therefore be concluded, that the bodies alone whereof powder is compofed, being put in motion by fire, become capable by ftriking againft one another to contribute to the #reat effeét which it produces : but I think it not poffible to reduce to calculation what fhare they have in it, becaufe the proportion of feveral parts of the bodies whereof powder is compofed, are not known, nor that of the bodies on which it acts. :
II. Let us now examine what effort the air contained in the grains of powder, and that which fills all chofe little {paces between the grains, is ca- pable of producing by its {pring when it is dilated by the action of fire. Experiments have fhewn, that the {pring of the air becomes capable by the heat of boiling water, to fuftain a weight three times greater than what it will fuftain in a tempe- rate degree of heat.
I fuppofe a certain bulk of powder, contains in all its pores, and between the {paces of the grains, as much air, as it contains proper ingredients of the powder; thus 2 cubic feet of powder, which weigh about 140 /%. contain 1 cubic foot of air. If a mine is conceived to be charged with 140 /d, of powder, and that the aperture of this mine Is a foot {quare, the air contained in the mine, will by the preffure of the external air, with which it is im equilibrio, fuftain a weight of more than 2,200 /b, which is the weight of a prifm of quickfilver, whofe bafis is a foot fquare, and 28 inches high. If to this air contained in the mine, a degree of heat is communicated equal to that of boiling water, it will become capable by its fpring, to fuftain a weight of about 2,900 /é. that is a third more than before; thus if the weight which refifts the effort of this air, is lefs than zoo /b. it will be lifted up. And if it is aig 3
that
Royat Acapemy of ScIENCES. 47
that the action of the fire, imprefies on the air a degree of heat 100 times greater than that which it receives from boiling water, it will become ca- pable of fuftaining a weight i00 times? greater. In this cafe, one cubic foot of air will fultain a weight of near 290,000 /d.
lt has been fuppofed, that the action of fire augments the force of the {pring of air only 100 times more than the heat of boiling water: but there isa probability, that it augments it confide- rably more; for it is certain that the force of the fpring of the air when loaded, augments in the fame proportion as its bulk would augment, if it was not loaded: thus by the heat of boiling wa- ter, the air would only augment its bulk one third; but, by M. Amonton’s experiments, pow- der, which has taken fire, augments its bulk 4000 times; and it muft be imagined, that the air contained in the. powder hath a great fhare in this increafe, which neverthelefs I ‘do not think it poflible to determine exactly.
However, without having any regard to the motion, which may be produced from the diffe- rent bodies, whereof the powder is compofed, ftriking againft one another, for this cannot be brought to a calculation; and only fuppofing, that the action of fire augments the force of the fpring of air 100 times more.than the heat of boil- ing water, it has been juft now fhown, that one cubic foot of air, contained in two cubic feet 0 powder, is capable of fuitaining a weight of near 290,000 /b. but this effort being made from all parts againft the furface of all the bodies whicir furround the powder, as from a centre to the cir- cumference, it is divided among all thefe bodies ; fo that if a cubic mine is fuppofed, whofe fix faces " equally give way, each-face of the mine will fuf-
' tain
48 The History and MemotrrRs of the
tain the fixth part of the whole effort of the powder which it contains; thus in the pre- ceding fuppofition each face will fuftain a weight of about 48,000 /b. but if there were five faces of this mine immoveable, the ef- fort would fall eutirely on the fixth, which would then fuftain the whole weight of 290,000 /d. This effort is much greater than what is found by experiments; for 140/b. of powder raifes only about 30,000 /. weight of earth, as refults from the experiments which fhali afterwards be given.
The reafon of this difference proceeded from many caufes; 1. From the powder not taking fire all at once, the action of the firft fire is fi- nifhed, or at Jeaft confiderably diminifhed at the time of the effort of the fecond.
2. A part of this effort is loft by the paflage which conveys the fire into the mine, and by the pores of thofe bodies which encompafs the mine. Experience fhows, that in counter-mines 15 or 20 feet diftance from mines which have been played, there is an infupportable fmell of burnt powder ; nay, that even the fmoak conveys itfelf through the earth.
3. The tenacity of the parts from being feparated is another obitacle; fo that a greater force is ne- ceffary, for example, to raife 1,000 /d. of old mafonry well bound, than the fame quantity of new, or fuch as is not well bound ; for, befides the weight of raifing them, this cohefion muft be alfo broken.
4. To fuftain the weight of the earth alone is not fufficient ; but a great part of the effort of pow- der is alfo employed in carrying it upwards with a certain velocity.
5. The refiftance of the furrounding air is ano- ther obftacle to be furmounted, to which no re-
i gard
Rovat AcADEMy of SciENcEs, 49
gard is had in practice, though it is very con- fiderable, and perhaps the moft confiderable of all.
III. To form a clear idea of the manner by which powder acts on bodies, let us fuppofe an immoveable gun fixed vertically with the mouth upwards, of an indefinite Jength, or at leaft long enough for a ball to make all the range which the powder can fend it; and having no regard to the friétion of the ball in the barrel of the gun, let us fuppofe that it is applied imme- diately to the powder, and that it is fo perfect a Caliber, as exactly to fit the barrel of the gun, fo that no air can pafs between; in order that we may only confider what can happen from the re- fiftance of the air, and the effort of the powder.
In this hypothefis, if fire is put to gunpowder, it will catch it fucceffively, and the ball will not go out till there is a fufficient quantity thereof, not only to get the better of the weight of the ball, but alfo of the column of air which refts up- it. So that if the ball be fix inches in diameter, it will weigh near 33/2. and the column of air will weigh about 440. Thus the ball will not be perceived to move, till that quar tity of powder takes fire, which is able to move a weight of 473 /6. The powder continuing 10 take fire, it will fucceffively augment the fwif.- nefs of the ball, till it has acquired its greateft ve- locity, which would be the fame with the in- flamed parts of the powder, did not the air refift it; but asthe refiftance of the air, which the ball expels, augments in the proportion of the {quare of the velocities of the ball, there is a fixed time when this refiftance becomes equal to the new effort, which the ball receives from the powder. Thus when there is too great a quan-
Woz. ill N°. 24 E tity
so. The History and Memoirs of the
tity of powder in the gun, it will not augment the velocity of the ball. Suppofing therefore that there is in this gun only a infficient quantity of powder, to give it the greateft velocity it Is ca- pable of acquiring, the effort of the powder will after that diminifh fucceffively, till it entirely ceafes 5 and then did not the air refift. the motion of the ball, it would continue to move with a uni- form fwiftnefs, equal to its greateft acquired ve- locity : but the air continually refitting, the iwift- nefs of the ball diminifhes each inftant, fo that there is a fixed time, wherein the remaining im- preffion, which the powder has given to the ball, is equal to the refiftance of the air, and then the ball can no longer move. But the weight of thé air and of the ball ating againft it, with an ef-
fore of 473 /b. as has been faid, will repel the
ball to the bottom of the gun, by accelerating its velocity, like all heavy bodies.
From what has been faid, it may be con- eluded,
1. That the beft powder (every thing elfe be- ing equal) is that which fooneft take fire.
2. That the barrel of the gun, near the breech ought to be fuch, that a greater quantity of pow- der may take fire therein before the ball goes out. This is the reafon why guns, with chambers, carry farther with an equal quantity of powder, or as far with a lefs quantity than thofe whofe bar- rel is entirely cylindrical.
3. That ina gun, whofe barrel is cylindrical, of a given length, there is a determined quantity of gunpowder which drives the ball as far as pof- fible; and this quantity is fuch, as may have time to take fire while the ball is inthe gun. But the more powder there is on fire in the gun, the more danger there is of its burfting, becaufe its
3 effort
| |
Roya ACADEMY of SCIENCES, " sT
effort is greater, and it remains longer againft the fide of the gun.
4. That the longer that part of the gun is, through which the ball is to run, fuppofing it does not attain its greatef{t velocity, the more powder may be put into it; becaufe the ball taking up more time in paffing, a greater quan- tity of powder has time to take fire, of which it receives the impreffion. This is probably the reafon, that fome very long guns, fuch as the Culverin of Nancy, carry much farther than com- mon guns of the fame caliber.
5. That the quantity of powder with which a gun is charged, and the fhape of its barrel being determined, there is alfo a length in the gun which has all poffible advantages; fo that a greater length would leffen the range of the ball. This length is fuch, that the ball may go out of the mouth of the gun, when all the powder has made its effort; and if the quantity of powder is undetermined, this length is fuch, that the ball
will go out of its mouth when it has acquired its
greateft velocity. Therefore guns of the new in- vention, whofe barrel near the breech is fpheri- cal or fpheroidal, in which the powder being more clofe together, takes fire more readily, are not fo longas thofe whofe barrel is cylindrical. 6. That the effort of the powder, towards one certain fide, is greater in proportion to the re- fiftance it meets with from the others; and thus the more difficult it is for a gun to recoil, whe- ther ‘becaufe of its weight, or any other impedi- ment, the farther will it fend the bal]. The dif- ficulty of conveying very heavy guns by land, and-the expence requifite for this, caufe them to be made as light as poffibie, provided they can refift the effort of the powder; bur guns made
t\r 4 Pe ior
52 The History and Memoirs of the
for fhips, are commonly much heavier than thofe defigned for land fervice.
Let us now apply what has been faid of the action of powder in general, to its particular ef- fort in mines. I fuppofe it is known what a mine is, and the different kinds thereof, as Four- neaux, Fougades, &c. The precautions which ought to be taken in digging and charging them, propping up the galleries and branches which lead to them, {topping them up, the way of dif- pofing the fauciffe, which conveys the fire to its all which things are well defcribed by thofe who have treated on mines. It is chiefly to determine the moft advantageous difpofition of them, and the quantity of powder with which they ought to be charged, that they may perform the effect propofed, that we were obliged to make thefe experiments,
Mines are either made in the body of the earth, fuch as are made by the befieged to blow up the batteries and works of the befiegers, be- fore they make a lodgment on the covered way ; or on rifing ground, where nothing joins to it either on the right or left, as to make a breach in ramparts made of earth; or to blow up walls, which may be dry or thrown down ; to conclude, fometimes they are made ule of to tear up rocks.
All the experiments have difcovered;
I. That the effet of the mine is always made on the weakeft fide; thus the difpofition of the chamber of a mine does not contribute to deter- mine this effect, either to one fide or another, as the miners had falfly imagined.
II. Vhat a greater or lefs quantity of powder is requifite, according to the inequality of the weight of thofe bodies which the mine is to raife, and accordi: g to the inequality of their cohefion,
and
Roya ACADEMY of SCINCEES. 53
and the refult of all the experiments which have been made, to know what quantity of powder mutt be ufed according to the different bodies, 1s to each cubic toife.
Lb. of powder.
Of loofe earth g or 10 Of firm earth, and ftrong fand Ii or 12 Of fat clayey earth 15 or 16 Of new mafonry, but flightly bound 15 or 20 Of old mafonry, well bound 25 Or 30
Ill. The aperture ofa mine, which has played in the body of the earth, being properly charged, is made in a cone, the diameter of whofe bafe is double the height taken from the centre of the mine.
IV. That when a mine is over-charged, it makes only a hole or well, whofe fuperior aperture is not greater than the chamber wherein the pow- der was lodged.
V. That befides the effort of the powder againft the bodies which it raifes, it alfo preffes and crufhes all the earth near it, both underneath and on the fides of it, and this preffure or crufh ex- tends fo much the farther, as the furrounding bodies make lefs refiftance.
To account for all the effects refulting from thefe experiments, and afterwards determine the quantity of powder with which mines ought to be charged, and the moft advantageous difpofi- fion to produce the effects propofed by them,
Let us, 1. conceive a mine, whereof all the parts furrounding it are incapable of compreffion, and make equal refiftance, fuch as a bomb of equal thicknefs every where would make, fuf- pended in the air; it is evident that in this cafe, befides the refiftance of the body, the effort of
Ba the
54. The History and Memorrs of the
the powder muft furmount the weight of the fur- rounding air; and then the body muft be re- duced to duft, or at leaft into very {mall pieces.
By the way, it muft be obferved, that the bomb differs from this fuppofed mine, only in its being a little thicker at the bottom, oppofite to the fufee than elfe where.
The bottom of the bomb, is made moft folid for two reafons. 1. That this part being heavieft, — may turn towards the ground when. the bomb " falls, left it fhould be broken by its fhock againft thofe bodies which it meets with. 2, that-it may not fall on the fufee, which might extinguifh it ; either of which cafes happening, the bomb would not execute the principal effect defigned, which 4; to convey the fire into the enemy’s magazine, after having by its fall, made way through the vaults or boards of the places, which contain them. Bombs are alfo on many occafions made ufe of in mines, as to blow up a butterefs in the walls of a rampart, when a breach:is-to be made in an invefted rampart, and in the fougades made for the defence of the outfide af a place.
Let us in the fecond place conceive a mine, wherein all the bodies which encompafs it, are equally capable of compreffion, and, make a refiftance with equal force on all fides, In this cafe, the firft effect of the fired powder, would be to crufh and comprefs equally all thefe bodies; and they will not be divided or feparated, till. by their compreffion, they become capable of refift- ing its effort; fo the powder therein may be in fuch a {mall quantity, that its whole effect may only terminate in the compreffion of the adjacent bodies. This is the reafon, why in mines made in the earth, the chamber is ftopped up with ttrong beams-well fupporied ; fometimes sup
wit
RovAb ACADEMY of SCIENCES. 55
with; ftones that the adjacent parts may have more refiftance. It is eafy to conceive, that if the ad- jacent parts to the chamber of fuch a mine, as has been fuppofed, were unequally capable of com- preffion, inftead of the compreffion extending equally, in;a.iphere, as in the firft cafe, it would in this-fecond.cafe extend unequally.
To. conelude,; if is fuppofed that ina mine, all the encompafiing. bodies are equally capable of compreffion, but that there is lefs refiftance on one fide than the other, as it happens to all mines which are made in the body of the earth, a {phere of compreftion will immediately be made e, whole diameter, wil! be fo much the greater, in propor- tion to the refiftance of the weakeft part on its being, raifed ;, on which three things may be obferved.
1. If the effort of the powder is very great in proportion to the refiftance on the weak fide, .the comprefting will not extend far; and this part will be raifed fo fuddenly, that the neighbouring parts having not time to fhake, there will only be made a hole or well, whofe diameter will be very, near equal to that of the chamber of the mine, the earth of which will be thrown at a ereat diftance. This is what happened when Verue was befieged by M. deVendéme, the befieged fprang two mines, which being overloaded, did not blow up the batteries which annoyed them ; thefe mines made holes or wells wherein the be- fiegers made lodgements under fhelter.
‘Secondly, if the mine is under charged, it makes only a finple compreffion, or at moft a little rifing near the weakeft part, as it happened at the fieges of Ciudad Rodrigo.
In fhort, if the mine is charged with a quan- tity of powder, between thefe two extremes, it
sae will
56 The Aistory andMemorrs of the
will raife a cone of earth, the diameter of whofe bafe, will have a greater or lefs proportion to its height, from the centre of the mine, according as the effort of the powder ts greater or lefs. And the moft advantageous effect, is when the diameter of the bafe of this cone is double its height ; for then almoft all the earth which was raifed, falling back into the aperture of the mine, the enemy cannot make ufe of it for a lodgment. In order to produce this effect, the quantity of powder ne- ceflary in proportion to the different bodies to be railed by mines, has been determined by experi- ments.
To charge a mine therefore, that it may per- form its effect with all poffible advantage, the weight of the bodies which are to be raifed muft be known 3 that is the folidity of the right cone muft be found, whofe bafe is double the height of the earth,over the centre of the mine, which ts eafy to be found by the rules of geometry; the little cone contained in the chamber of the mine, may be fubtracted ; but fuch minuteneffes are of no’ confequence, and the cube of its height may even be taken for the folidity of this cone; thefe folidities are not fo much unlike, as to caufe any fenfible difference in the effect of the mine. Having found the folidity of this cone in cubic coifes, multiply the number of thefe toifes, by the number of pounds of powder neceffary to raife the bodies which it contains, as direéted in the experiments ; and if the cone to be raifed, contains bodies of different weights, a mean weight muft be taken between them all, having alfo re- gard to thofe which have moft cohefion. It is in general beft to put rather a little too much powder than too Jittle. As tothe difpofition of mines, it muft be obferved for a general rule, that the part
towards
ee —s a oo
Royat ACADEMY 0f SCIENCES. 57
towards which we would determine its effect, fhould be the weakeft. We will not here enter into the particulars of this difpofition, it varies according to the variety of circumftances,in which they are em- ployed, and the effeéts we would have them pro- duce; and may eafily be concluded from the prin- ciples already laid down.
VI. A new confiruéction of fluices, by M.
de la Hire *.
Sluices are commonly made on fmall rivers, which have no great fall, and but little water, the river is therefore ftopped at fome convenient place, that a fufficient quantity of water may be collected above it, to carry a boat; and when the boats are come to the fluice, they expeditioufly open it, and the boats pafs through it, being fupported by the collected water.
The common way of fhutting fluices is very fimple, and of fmall expence, it is placing fe- veral pieces of fquare boards againft a groundfel fixed crofs the bortom of the river, and on the top againft another piece of wood, which alfo goes crofs the width of the river, and 1s parallel _to the groundfel, but is eafily moved on a great pin at one end thereof; and the other end faftened to fome folid and firm body, when it is in a fi- tuation parallel tothe fell. All the boards which ftop the fluice, and are placed againft the fell, and the tranfverfe beam at the top, are called aiguilles, and are retained or held only by the water, which rifes by degrees in the canal, or river, above the fluice: but all thefe azguz/les are never placed fo exactly clofe to each other, as to prevent the
® Dec. 3; 1707. ; waters
The History and Memo rrs-of the
waters running between them; which is a great fault in thefe fort of-fluices.
When the fluice is to, be opened, they haften to take out thefe azgui//es, and turn the tran{verfe beam atthe top, to give free paffage to the boat; but this cannot be done fo foon as not to endanger its running aground, or being faft on thegroundfel. in the middle of the fluice. Therefore it is the practice in many places to faften ropes to the top of all the azguilles, the more eafily to draw them on fhore, and more expeditioufly than by fland- ing on the beam,
But here is a way. of opening and fhutting fluicesatonce, and without trouble. They may be fhut. or ftopped with two doors, fuch as are commonly, made ufe of at. the entrance and going out of great fluices. They are folding doors which bear againft one another, and make a ia- lient angle to the fide up the river : but the whole art confifts in the conftruction of the door.
Each folding door* AB 1s only a frame of wood, of fufficient ftrength, for the ufe.and place. Theie framesare hung upon hinges-at C, which are on the pofts on each fide of the fluice, in the com- mon manner of doors, and open upwards of the river: but the real doors, which fhut.the open part of the frames, are hung on, hinges at D, on the upright battens of the frames, which.are to join er meet when the doors fhut, and thefe doors” open downward of the river contrary to the frames. Near E, they have eachya little latch, or rather a hafp,. with a hole, which, admits. a. ftaple,. thro’ which a pin may be put F, with.a long handle like a bolt, that it may be placed.in the hole or eye ofi the ftaple, when they are ftanding, on) the top of the door.
* Plate I, Fig. ri:
Ic
Rovar Acapamy of Scrences, 59
It.is) feen: by this conftruction, that the doors E, D,. being:faftened' to the frames: A B 5. and-the frames: being one againft’ another, the canal of the river willibe fhut or ftopped, and 'the water will rife againft thefé doors: on the fide up- the ri- ver; and)when the fhiice is-to be opened} they need only:draw out both the pins‘or bolts: at the fame time;: and immediately the two-doors going with the-ftream, the frames’may be-eafily) placed: on the: fides\of the canal, by drawing them with a chain or a rope GB; as-they ftyrd on the fhore ; for the water can have no great power over that part of the frame which is in it.
By this conftruction, it is alfo feen, that by drawing the frames to the fides of the canal, the doors ED will ftill continue with the ftream, but ar laft when the frames are quite open, the doors ED will be fhut and return to their place of themfelves, where they need only be faftened with the bolt.
In fhort, there will be no difficulty in fhutting up the fluice, for the water being then almoft on a level on both fides, has not more power againtt the door on one fide than on the other.
The parts of thefe frames may be ftrenothened by two binders placed at the top, higher than the level of the water when it is retained, that it may take lefs hold of the parts of the frame, when that is to be opened.
It will be obferved, that it is not neceffary that the door fhould be always as high as the opening of the frame, it is fufficient if it keeps up the water in the canal high enough to carry the boats. Let it alfo be obferved, that two great latches may be put inftead of the two hafps, which are in the figure, to faften the door the ftronger, and better to the upright of the
frame.
60 The History and Memorrs of the
frame. Thefe latches will faften into the catches which are to be fixed into the door poft, and there muft be to each of them a button faftened into the fame rod, which muft reach to the top of the door, and gothrough two ftaples, or rings, which are there to be fixed; fo that by pulling this rod, both the latches will lift up at once, and the fame rod will ferve to fhut them when the door is put again in its place, if the latches do not of themfelves fall into the catches by their own weight, and that of the rod.
eA DL E
OF TA E
PAPERS contained in the ABRIDGMENT
of
the History and Memoirs of the
RoyvyaL ACADEMY of SCIENCES at Paris, for the Year Mpccvii1.
I i
Inthe HISTORY.
: PON thunder.
5 Of fome fhells inclofed in ftone.
Ill. Of the force of rays of the fun in preffing
IV
and pufbing.
. Why in fummer ice melts fafter in vacuo,
than in the air.
. Why the tendereft glaffes are leaft fubjec to
break by fire.
. Of the effect of the fun’s beat on a pafte laid
upon a piece of polifoed glafs.
. Of an extraordinary cure performed by
mufick,
. Of the new ifland formed near Santerini. . Of the method of meafuring the beights of
places by the barometer.
. Of alittle fhell-fifh that feeds upon mufcles. . An account of Dr. John Scheuchzer’s dz/-
fertation on the origin of mountains.
. An account of Dr. John James Scheuchzer’s
- differtation on cryftal,
. An account of the fame author's differtation
intitled, Pifcium Querelz & Vindicie.
. On the generation of fiails.
XV.
62 A TABLE, Se,
XV. Of the eggs of the cutile-fifp. XVI. On the burning glaffes of the ancients,
XVII. 4 method of fiopping borfes fuddenly.
In the MEMOIRS.
I. Obfervations on the quantity of rain which fell at the royal obfervatory at Paris, during thé year 1707 3 and on the heights of the thermometer and barometer, by M. de la Hire.
I. 4 defcription of a new barometer, to know the weight of the air exalily,; with fome remarks on the common barometers, by M. de la Hire.
III. Refleéiions on the variation of the needle, chferved by the Sicur Houflaye, captain commandant of the foip PAurore, during the-expedition to the Katt Indies, made by the fquadron commanded by the Baron de Pallieres, 22 1704 and 1705, by M. Caf- fini the fon.
IV. Experiments and obfervations on the dilata- tion of the air by boiling water, dy M. de la Hire.
V. Reflections on the obfervations of the vari= tion of the needle, made on board the Mau-
repas, im the voyage to the South-fea;.
with fome remarks of M. de la Verune, commander of that veffel, on the navigation of the coafts of America ; and of the Terra del Fuego, éy MZ. Caffini the fon. VI. Conjefiures on the pofition of the ifland of Meroe, dy M. Delifle. VII. Reflections on the obfervations made by F. Laval, at the S, Baume; and other neigh-
ee, ae
A Taste; &ec. 63
neighbouring mountains, by M. Caffini the . fon.
VII. 41 obfervation of a luminous circle about the fun, by M. de la Hire.
IX. An extratt-of the obfervations made in the Weit Indies 7x 1704, 1705, and 1706, » by F. Feuillée, a minim, mathematicicn to the king 5 compared with thofe which were made at ihe fame time, by M. Caffin: the meee
AN
AiN.
ABRIDGMENT
O-B 5 FARE
PHILosoPHICAL DiIscovERIEs and Op- SERVATIONS in-the History of the RovyaL ACADEMY of SCIENCES at Paris, for the Year 1708.
1. Upon thunder ; tranflated by Mr. Chambers.
E have chymical operations in the air, as
well as in the laboratories, and fometimes the very fame: thus thunder is only an inflamma- tion occafioned by the mixture of a fulphurous matter, withan acid {pirit.
But a difficulty feems to arife hence, that thofe two matters when mixed together by a chymift, after they are once fet on fire, fpend themfelves intirely, fo that no new inflammation can be made without new materials; whereas, from one and the fame cloud, we frequently find a multitude of flafhes burit one after another, which indicate as many different inflammations. Now the inflam- mable matter in the cloud being diffipated in the firft lath, how fhould any new ones be formed?
M. Homberg is of opinion, that the fame mat- ters which take fire by their union, and by their firing become feparated again, may rejoyn each other anew, be kindled again; and thus for feve- ral times fucceffively. On earth this is impoffible, by reafon after they are once kindled, and by this means rendered extremely rare and light, the Jower air being heavier thanthey, preffes them on all fides; and thus raifes them to a region where
they
Rovait ACADEMY of SciENCcEs. 65 they are found in eguilzbrio to a thinner air; and thus are loft to us: but if the fame matters be taifed in exhalations from the bofom of rhe earth, they are already arrived at this sae of egui- librium and ’tis here they are kindled, where of confequence they find no heavier air to raife them after the explofion, fo that they cannot be difi- pated, but will remain where they were, and may rejoyn each other till fuch time as a fhower cait them down on the earth, and thus purge the air of them.
This explication is the more probable as it is founded on the operation itfelf, which repr refe nts thunder ; if in licu of pouring {pirit of nitre ha sad ly on an effential oy], which will produce a fudden inflammation, it be poured on drop by crop, we fhall only find an effervefcence raifed without any inflammation, and the mixture of the two esas becomes a refin ; which if put in a retort, and di- ftilled by degrees, will return the acid, andthe oy! whereof it was formed : now this acid and cy] are {till capable either of being kindled by mixing them again, or of producing a new refin, which will in- dure the fame operation it had undergone before, a3 long as you pleate. Here the fire of the diftilla- tion makes the fame feparation of the matters, as the explofion would have done, if they had been fuffered to kindle; whence it appears, that if they were not to fly from us, they would be as fic by their re-union to form a new flame, as a new refia.
As in each moment that a flafh of lightening ftrikes the eye; there is a large quantity of matier fet on fire, M. Homberg imagines, that fo many repeated inflammations may give a certain deter- mination to the air, and caufe = fome of thofe vai
5 able winds which blow indifferently. from all points Vox, lil. N”*. 24. F of
66 The History and Memorrs of the
of the horizon, and which are the only ones which we experience in thefe temperate climates. Hence perhaps it is, that we have more fouthern than northern winds, fince there are always violent thunders betwixt the tropicks, which are fouth- wards, in refpect tous; at leaft it is certain, that this notion will very well account why our winds blow in puffs, or blafts, fince the flafhes follow each other at fome diftance, and each gives its feveral blow ; and if it were certain, that the regular or trade-winds blow more continuoufly, it would be a confirmation hereof.
Il. Of fome fhells inclofed in ftone.
M. Tournefort has fhewed fome fhells inclofed in a bit of a rock, pierced by a great many cavi- ties, which were as their habitation. The entrance of thefe cavities was often narrower than their bottom, fo that thefe animals after being entered therein when fmall, muft have grown there, and preffed the ftone being yet tender, in proportion as they grew.
III. Of the force of the rays of the fun in prefing and pufbing.
We fhould not have fufpected, that the rays of the fun had the force of preffing and pufhing, even when they are re-united by the burning mirrour. M. Homberg has obferved, that if he expofed to ita very light matter, fuch as Amiantbus, and in a pretty large quantity, it was reverfed by the rays
of the focus above the coal which bore it, un- lefs it was prefented very flowly, and one part after the other, fo that it was not flruck too roughly by the /acws, nor all at once in the whole
fur
Royat Acapemy of ScIENcEs. 67
furface. Befides, M. Homberg having ftraitened a fpring of a,watch, and engaged one end of it in a block of wood, he drove by repeated ftrokes againft the free end of the fpring, the focus of a Jens of 12 or 13 inches diameter, and he faw that the fpring made very fenfible vibrations, as if it had been thruft with a ftick. This force of the matter of light agrees with the weight, that has been found in it by other experiments.
IV. Why in fummer ice melts fafter in vacuo,
than in air.
M. Homberg has found, that in fummer, ice melts much fooner in vacuo, than in the air. The reafon of it is very plain; ice only melts by the action of the fubtile matter or ether, and in vacua the whole fpace is filled only with this matter.
V. Why the tendereft glaffes are leaft fubject to break by fire.
M. Homberg has obferved, that tender glaffes, that is, fuch as have more falt in their compofition and lefs fand, or thofe which having more fand are very thin, are lefs futjeét to break at the fire and burning mirrour. It is eafy to fee that glafs is only brittle by the extreme heterogeneity of the particles of falt and fand, of which it is compofed, that-it breaks by the difficulty that the fubtile matter, when it is ftrongly agitated, finds to move freely in the interftices of its parts, and that it finds lefs refiftance in the particles of
falt, than in thofe of fand, which are more folid,
68 The History and Memorrs of the
VI. Of the effect of the fun’s heat on a pafte ; laid upon a piece of polifhed glafs.
A perfon having applied to a piece of polifhed glafs about half a foot fquare, a pafte of Spani/h white, and fize, put it altogether in the fun during the great heats of the fummer. The pafte which was towards the fun, having been ftrongly heated, bent toward the fun, and rolled upward, in fuch a manner, that inthis motion the lower furface, placed upon the glafs, raifed itfelf. But the fin- gularity of it was, that this furface raifed with it a flake of the glafs. This fake made a fort of var-
nifh upon the pafte like De/ft ware ; its thicknefs
was unequal, but it did not exceed half a line. Jc is very furprifing that the adherence of the pafte upon the glafs fhould be fo ftrong; and allo that it fhould be able to pull off from the glafs fo conft- derable a flake. It had been blown, and pro- bably the cane,- through which they blowed, had been plunged in the crucible at ditferent times which had made it divide into feveral flakes, which however did not appear, becaufe they were very exactly applied to each other. We owe this obfervation to M. Geoffroy.
VII. Of an extraordinary cure performed by | | mufick. |
Uhe extraordinary cure which we have fpoken of in the hiftory of 1707, is not fo much fo, or -at.Jeaft it is not any longer fingle. Here is an- other example which we had from M. de Manda- jor, mayor of Alais, in Languedoc, a man of fenfe and merit! A dancing mafter of Alais,
during
Royat ACADEMY of SCIENCES. 69
during the carnival of 1708, having been fo much the more fatigued in the exercifes of his profeffion, as they are the moft agreeable, fell fick with it the beginning of lent. He was at- tacked by a violent fever, and the fourth or fifth day he fell into a lethargy, which he was a great while a coming out of. He came out of it only to enter into a furious and filent delirium, in which he made continual attempts of getting out of his bed, threatning with his head and looks thofe who hindered him, and even all who were prefent ; and obftinately refufed, conftantly with~- out fpéaking, all the remedies that were offered to him. M, de Mandajor faw him in this condi- tion ; itcame into his head, that perhaps mufick might recover a little this fo difordered an imagi- nation, and he propofed it tothe phyfician. He did not difapprove the thought, but he juftly feared the ridicule of the execution, which would have been yet infinitely greater, if the patient had died in the operation of fuch a remedy. A friend of the dancing-mafter, who was fubjeét to none of thefe difficulties, and who could play on the violin, took that of the fick perfon’s, and began to play the airs that were moft familiar to him. They took. him’ to be more mad than the patient confined to his bed, and began toe reproach him ; ‘but prefently the fick perfon raifed himfelf upon his feat, asa man agreeably furprifed; his arms would beat time’ to the tunes; bat becaufe they held him by force, he could oily thew by his head the pleafure he felt. .By degrees, even thofe who held his arms, finding the effect of the violin, flackened the violeace wich which they had held them, and gave way to his motion in proportion as they found he was no loa: ger raving. At laft, at the end of aquarter of an hou; he fle -pt foundly, BY and
40 «The History and Memoirs of the
and had during this fleep a crifis, which brought him out of danger,
VIII. Of the new tfland formed near Santerini.
We are now better informed of the new ifland which has raifed itfelf near that of Santerini, or Santorin, which has been ‘mentioned in the hiftory of 1707*. AA letter, that F. Bourgnon, a miffi- onary jefuite at Saatorin, an eye witnefs of all this phoenomenon, has writ to M. de Feriol, the French ambaffador at the port, and that this minifter has {ent into France, has been communicated to the academy.
May 23, 1707, at fun-rifing there was feen from Santorin, 2 or 3 miles at fea, fomething like ‘a floating rock which had not been feen be- fore. Some believed it to be a veffel which was going to break againft fome little iflands or rocks which are there, and went to pillage it. They were furprifed to find it a new fhelf, and they were bold enough to get upon it, altho’ it was yet moving, and encreafed almoft fenfibly under their feet. They brought back, as a teftimony of their courageous landing, fome pumice-ftones of an ex- traordinary finenefs and delicacy ; and fome very Jarge and exquifite oyfters, that the rock where they were fixed, had raifed with it, from the bottom of the fea. They had a little earthquake ‘in Santorin two days before the birth of this fhelfs it increafed very fenfibly as well in breadth as height, till the 13th or 14th of Fume, without being accompanied with any accident. It was then almoit half a mile in circumference, and 20 or 26 feet high. It was round and white; the earth was light, and had a little clay in it,
* Pag. 13 of this volume.
They
Royat AcApDEMy of SCIENCES. 71
They began to believe, that this new labour of nature was finifhed, but the water of the fea be- came fenfibly thick every day, and had the colour of various mineral fubftances ; among which, ful- phur was predominant, the waves had an agitation, and boiling, which came from the bottom. Thofe, who would approach the new ifland, felt an im- moderate heat, which hindered their accefs to it: at laft there {pread in the air a ftink which infected the whole ifland of Saztorin, and ex- tremely incommoded the inhabitants ; all this foretold fome terrible change to this part of the world, and fear reigned in every mind. In effect there was feen on the 16th of Fw/y, at fun-fet, a great chain of 17 or 18 obfcure black 10cks, a little from one another, which went our of the bottom of the fea, towards the new ifland, and feemed to be going to join foon together, and with it, which actually happened fome days afterwards. ’ On the 18th there came out of it for the firft time, avery thick fmoke; and there were noifes heard which came out of the bottom of the new earth, 4o much the more threatening, as they were alfo more hollow. The rgth the fire began to appear very weak at firft, but it increafed continually. ‘Every night the new ifland feemed to be only made of a great number of furnaces, which vo- mited flames.And as if the heavens hada mind to contribute to this frightful illumination, there was {een one night toward the end of Fuly, only forafew moments, a ftream of fire which went from eaft to welt.
During this time, the ifland juft forming in- creafed very much, even in height. The waters of the fea boiled more violently, they were more Joaded with fulphur and vitrio!, and the infection was fo great at Sentorin, that they could noc
Fo 4 breathe,
“2 Tae HisTory and MEEMOIRS of ihe
breathe, efpecially when the wind drove the fmoak that way. Toward the end of Aug. the fubterra- neous noifes became more frequent, and fo terrible, that they equalled that of 6 or 7 great cannons dif-
charged all at once, the fire made new openings every day, and it threw into the air fometimes a prodigious quantity of fine afhes, which did much damage to the harveft of Sextorin, fometimes a like quantity of little ftones inflamed, which eawled a littl ifland, whereon they fometimes fell, to appear all on fire ; ; fometimes great burned rocks, which raifed themfelves like bombs and carcafies, and afterwards plnnged into the i at above 7 miles diftance.
Thefe terrible difcharges were become corti- nually more frequent fince the end of Auguft; and in fine, to the month of November, where my Bourgnon’s relation ends, It is very remarkable, that then it did not any more throw out fuch great ftones, nor'in fo great a quantity, that the fea was not troubled any more, that its boiling was calmed, that the ftink was hardly fmele any more at Saxtorin; and, onthe other fide the fmoak was every day blacker, thicker, and in greater abundance, the fire was greater, the fhowers of afhes were daily, and the fubterraneous noifes con- tinua! and fo violently, that it was hard to diftin- cuilh them from thunder. The account goes no farther than the 20th of November; and it is likely, that the prodigies of the new ifland are not yet difpofed to ceafe.
That cf Santorin itfelf, which was formerly called Therz, has pafied among the ancients for a new ‘production. [tis certain, that in 726, 1427, and 1573, it has received’ adcitions by fubterra- neous fires, or that the little neighbouring iflancs were formed as the Jat, which we have juft men-
tioned,
Royat AcADEMY of SCIENCES. 73
tioned. There was alfo in 1650 a furious ravage in Santorin and thereabouts, but without any other new production than that of a great bank, which perhaps will be the foundation of another iland. The fubterraneous furnace, which is in this part of the globe, muft be one of the mott ardent
IX. Of the method of meafuring the heights of places by the barometer.
M. Fobn Fames Scheuchzer, Doétor of Phy- fick, at Zurick, and member of the royal focie- ties of England and Prufia, having fent to the academy a great number of obfervations of the height of the barometer, which he has made in different towns of Switzerland, and upon fome mountains of that country, during the years 1705, 1706, 1707, M. Maraldi made ufe of them to find, according to the method explained in the memoirs of 1703 *, how much the places where they have been made, are elevated above the level of the fea. This method requires, that we know in what proportion the air 1s always dilated up- wards ; that we have correfpondent obfervations of the barometer, made in fome place, whofe elevation above the level of the fea is known, as M. Maraldi had hismade at Paris, and that we fup- pofe in a great extent of country, fuch as is that of France ‘and Switzerland, that the barometer
varies in the fame manner and in the fame time By this M. Maraldi found, for example, that mount och is elevated above the iea 1340 toifes, and as there is another pretty near it called Zitelif~ berg, always covered with ice and fnow, which thofe of the country fay, is the higheft mountain
* Vol. II. Page {5 of this abridgment. ;
0
74. The History andMemorrs of the
of Switzerland, and which M. Scheuchzer believes to be elevated 2000 feet more than Foch ; it fol- lows from hence, that the higheft mountains of Switzerland would be elevated 1660 toifes. They would be more fo than the Canigou, which is one of the Pyrenean mountains,
But it muft be owned, that this method for meafuring heights would be much more fure ; if ‘we were not obliged to fuppofe that the baro- meter varied in the fame manner and time in di- ftant places,which is not always true; and if in the Jame country, where we wouldtakea height, we had an obfervation of a barometer made at the fame time on the fea fhore, or in fome other phlice, whofe elevation above the fea was known, then there would not remain any more uncer- tainty than in the hypothefis of the proportion, according to which the air that furrounds the earth dilates itfelf upwards.
And even this uncertainty begins to diffipate 2 little ; and the progreffion, that M. Caffni has eftablifhed for the dilatation of the air in the place above quoted, in 1703, is fufficiently proved.
F.. Laval having meafured geometrically fe- veral heights-at Sains te Baume, and thereabouts, he Aicrgnede carried a barometer thither, and has obferved how much Jower it was there than at his obfervatory at Mar/eilles, of which he knew the elevation above the level of the fea. He hasfent his meafures and obfervations to Meff. Caffini, who have found what ought to be ; accerding to their progreffion, the height of the mountains, which gave the falling obferved in the barometer ; and they have found the fame heiehts that F. Laval found elfewhere by geo- metrical meafures. There was only two or three
toifes
RoyaAL ACADEMY of SCIENCES. 75
toifes difference, which is inconfiderable in pro- portion to great heights, and is befides almoft abfolutely unavoidable, becaufe in the leaft di- latation of the air a line of quickfilver anfwers to 6 toifes of air, and confequently, if in the ob- fervation of the height of the barometer made in the loweft place, we miftake half a line, which is very eafy, we miftake three toifes in the cal- culation, of the height, and much more, if the fame error is in the obfervation made at the higheft place. This isa general inconvenience of all the operations, where very {mall magni- tudes give great ones, to which they anfwer.
To meafure the height by the barometer with the greateft certainty poffible, the two places where we obferve the greateft elevation and de- preffion of the quickfilver muft be, as in F. La- val’s operation, fo little diftant that we may not fufpect the weight of the atmofphere to be dif- ferent.
Of a little fhell-fifh, that feeds upon mufeles.
M. de Reaumur has obferved the way taken by a little fhell-fifh to feed upon mufcles, which is very fingular and difficult to explain. This fhell-fith is of the fame fpecies with thofe which are called in Latin Trochus, or Turbo, that is, its fhell is one piece, and turned fpirally. The fifh comes half out of it when it pleafes, as the {nails do out of theirs, The mufcle being ine clofed in its two fhells would not feem likely to be the prey of this animal; and yet it is. It fattens itfelf to the fhell of a mutcle, pierces it with a round hole very exact, about a line in diameter, and paffes into it a fort of trunk or little hollow cylindrical pipe, 5 or 6 lines long,
which
76 The History and Memoirs of the
which it turns fpirally, and fucks the mufcle with it.
The difficulty is to know how it makes the hole. It is not with the trunk which fucks, for that is too foft and too blunt to pierce a very hard fhell. M. de Reaumur, by the diffection of this animal, has not been able to find any part of it proper. for this effect, though if it had any it muft be as fenfible as the hole; he has even met with many of thefe little fhell-fithes faftened to muicles, which they have not yet pierced quite through, he has feparated them, and feen nothing. He has alfo ncaa that thefe tra perfect holes were almoft as large in the botto as at their opening, which does not agree ith the figure of an inftrument, which proba bly would be more pointed at its extremity. Latftly, he has
aifo feen oval holes, and it is difficult either for an inftrument to make them, or for the fame that makes round to make oval,
He believes therefore that the animal may throw mpon the mufcle fome drops of liquor ca- ‘pable of piercing the fhell. This drop will na- turally be round, and fometimes it becomes oval, becaufe it does not fall perpendiculary upon the mufcle, or becaufe the mufcle gives it fome little motion. To render this conjecture {till more probable, it is to be wifhed, that in the imper- fe€t holes, and where the animal feems ftill to be working. M. de Reaumur had found there this fort of aqua fortis.
- He bas obferved, that there is never any hole in all the circumference where the two fhells of the muicle join, and he attributes this to a very ingenious precaution in the animal that attacks it. Which is, that if the mufcle thould open Its fixells, the trunk of the little fifh would not be ‘inthe hole thar it fhould make, it would eafily
turn
Royat ACADEMY of SCIENCES. 97
turn it away, and then the mufcle in fhutting its fhells, would fqueeze it, and perhaps cut it, or at leaft would keep its enemy prifoner.
M. de Reaumur has fometimes feen feveral holes upon the fame mufcle, and when he has found empty mufcle-fhells, he has almoft always feen of thefe holes, which makes him believe, that thefe fheli-fifh do not a little contribute to the deftruction of the mutcles.
XI. An account of Dr. John Scheuchzer’s differtation on the origin of mountains.
M. Fobu Scheuchzer, dottor of phyfick at Zurick, has done the academy the honour to de- dicate to it a Latin differtation upon the origi# of mountains, or upon the formation of ibe earth, which is not yet printed.
Defcartes, for it often happens that the hiftory of fome inquiries, or of fome difcoveries begin ‘by him, is the firft who has thought of explain- ing mechanically the formation of the earth : af- terward Steno, Burnet, Wocdweard, and at lak Scheuchzer have undertaken either to extend or rectify his ideas, and-have added them together.
If the globe of the earth was perfectly {phe- rical, that is, without mountains, and if the dif- ferent beds of fand, clay and ftones, of which it is compofed, were every where, as they are in an infinite number of places, pretty exactly pa- rallel between themfelves, and concentrical to the furface of this globe, we fhould eafily imagine that the whole had been formed of a troubdied fluid, if I may fo fay, and heterogeneous, of which the different parts, unequally heavy, wouki naturally feparate from one another by the laws of gravity, and be ranked in different circular beds, which would all have had the centre of the
] I hse
68 The History and Memoirs of the
globe for a common centre. Even this fepa- ration would have made the fluidity ceafe. This fyftem would not only be poffible, but almoft neceffary, for we could hardly attribute to another caufe the parallelifm and concentricity of the firata, That the the earth was at firft a fluid, and that by the laws of motion it is become folid by time, and is difpofed as it is, or that God created it all at once in the ftate to which the laws of motion would have brought it, is the fame thing according to the ingenious reflection of M. Defcartes. It is indifferent whether God created the egg, or the fowl firft.
The parts of land and water animals, branches and leaves, €@c. found in beds of ftone, and that pretty deep, confirm this fyftem of the fluidity of the earth. By what other means than this, could they be inclofed where they are? but it is alfo true, that we muft fuppofe a fecond formation of the beds or j/frata, much lefs ancient than the former, at the time of which the earth had nei- ther plants nor animals. Svexo eftablifhes feveral fecond formations, caufed in different times by extraordinary innundations, by earthquakes, and by the matter that the Vulcano’s vomit. Burnet, Woodward, and M. Scheuchzer, chufe rather to attribute to the univerfal deluge a fecond general formation, which however does not exclude the particular ones of Steno.
But the mountains feem to fubvert the fyftem of the fluidity, they could never have riien, fince all that is fluid becomes level. Neverthelefs this fyftem is fo probable in its felf, and fo well fup- ported in the greateft part of the terreftrial globe, that it deferves fome endeavours to preferve it. It is for this,that M. Scheuchzer adopts the opinion of thofe, who have believed that after the uni-
verfal
Royar Acapemy of SCIENCES. 79
verfal deluge, God being pleafed to make the waters enter again, into the fubterranecous refer- voirs, had broken and difplaced with his ail powerful hand, a great number of /irata, which -were before horizontal, and hed raifed them above the furface of the globe. The whole differtation was made to fupport this opinion.
'. As thefe heights or eminencies muft have been of a very folid confiftance, M. Scheuchzer ob- ferves, that God raifed them only in places where there were a great many beds of ftone. Frora thence it comes, that the countries where there is a great quantity, as Swifzerland, are very moun- tainous, and that on the contrary, thofe which like Flanders, Germany, Hungary, and Poland, have only fand or clay, and that to a very great depth, are almoft intirely without mountains.
It was impoffible that the broken, difplaced, and elevated /irata fhould remain horizontal ; and we never find any in the mountains with this direction, but what remains of it, is that they are ftill parallel between themfclves, and this, fup- pofing the difplacing, is in reality all that they could poffible preferve of it.
M. Scheuchzer has obferved their different di- rections, in a whole chain of mountains of three leagues, upon the borders of the lake Uri, and has fent to the academy a very curious map of them. There is no horizontal bed there, tho? they are all fo in’ the plains, and hardly any that makes a right angle with the horizon ; we find indifferently all the other angles. It is vifible that this is underftood of the turface or flopes of the beds. As to their direétion, which we fhould fee, if one fide cf the mountain was cut accord- ing to its inclination to the horizon, they are very different in different mountains, and fome:=
ties
80 The History and Memoirs of the
times in the fame. Some are in arches or vaulted; others are in a fort of triangle, and have fome very acute angles, but all the directions what- ever of one bed, are always exaétly parallel to thofe of many other neighbouring beds. What is here the moft fingular in M. Scheuchzer’s map, is the extreme direction of 2 different feries of beds, which meet at their convex parts,and form the figure of two branches of a curve that turns back.
M. Scheuchzer has made in the celebrated quarry of Glaris, from whence there has been drawn a great number of tables of ftone, an obfer- vation not very favourable to the fyftem of the - fluidity, which however he does not diffemble. The beds of this quarry, which are but an inch thick, are of two different natures, and alternately hard and foft; and to make tables of it that may be ufed, they muft cut a hard frratum with a foft one, without feparating them. The hard fuftains the foft which muft be at thetop, when they work it, as it is in the quarry. One would think that in a fluid, all the heavieft part muft have precipitated to the bottom, and that there could not have been beds alternately lighter and heavier. Neverthelefs a fingle bed, where the lighteft is always at the top, proves alfo the flu- idity, the whole difficulty remains in the alternate fituation of the beds. To give a folid fatisfaction of this diffculry, we had better wait for new ob- fervations which M. Scheuchzer feems to promife, than to imagine any folution, how ingenious fo- ever, Befides we have already launched too far upon a work which belongs to this able philofo- pher, and which the academy has no right to af- fume
XH.
Rowe AcADEMY of Sciences, 83
XII. n account gp Dr. John James Scheuchzer’s differtation on eryftal,
M. Fohn Fames Scheuchzer, brother to the former, and alfo doctor of phyfick at Zurick, a great natural philofopher, has fent alfo to the aca- demya Latin differtation upon cryftal, which he has not yet publifhed.
There is a'great deal of cryftal in the moun- tains of Switzerland, and it isa journey which the author made thither in 1705, which occafioned this differtation. We have but too few of thele fort’ of phyfical inquiries made by skilful perfons, who have feen them with their own eyes. M. Scheuchzer collected with great erudition all the different cryftals, perfect, or imperfect, coloured, mixed, and differently figured, which the ancient as well as modern authors have fpoken of; he ranges them under certain fpecies, and relates the different names that have been given them, or their /ynonyma, which is known to be very ufefal in fuch fubjeéts, and was wanting in this,
He afterwards enters into the philofophy of the formation of cryftal, and even undertakes to prove geometrically the neceffity of the hexagonal figure; which is common to it. M. Scheuchzer believes, according to the common fyftem, that the eryftal, as well as the precious ftones, has been liquid, and formed in ftones which were fo likewife. He feems perfuaded by experience, that thereiare no more new cryftals produced. Upon this foundation he conjectures, that when the exte- fiour crujt of the earth had been extremely foftened by the waters of the univerfal deluge, the fluid matter of cryftal had penetrated it, and gathered together in the cavities and fiffures of the ftones;
Vou. Ill. N°. 26. G where
82 The History and Memoirsof the
where it congealed by time. We muft not be furprized, that fo great a confufion as that which was caufed by the deluge upon the furface of the earth, is an epoch or an origin which frequently recurs in phyfical inquiries.
XV. Ax account of the fame author's dif- fertation, intitled, Pilcium querele & vindicie.
In a differtation of the fame author, printed under the title of Pif/cium querele & vindicia, and fent to the academy, the univerfal deluge is more fenfibly pointed out.
M. Scheuchzer has made a fort of catalogue, of all the ftones that he knows, like thofe which we have fpoken of in the hift. of 1703*, and 1706+, that is, which inclofe fifhes, or rather reprefen- tations, and at moft the fkeletons of fifhes. We have already faid how far thefe forts of ftones were from being, as has been commonly enough imagined, {ports of nature, or fortnuitous paintings ; and thus M. Scheuchzer introduces the fifhes com- plaining that thefe ftones, which are really their tombs, are taken for meer ftones, wherein their figures are found engraven by chance; and that thefe curiofities are referred to the mineral kingdom, by taking them away from the animal kingdom to which they belong. The author is perfuaded that thefe fifhes buried in ftones, have been there ever fince the univerfal deluge, and this feems true, efpecially with regard to thofe which are found in places, where no other accident could have brought them, and where we cannot believe that there has ever been any water fince that time. Such is the quarry of Oxingen in the diocefe of
* Waol...bl. bape 23. t+ Page 356 of the fame.
Conftance.
Roya AcapEmy of SCINCEEs, 83
Conftance. Several of M. Scheuchzer’s ftones have been taken out of it. The moft remarkable both for fize, and the perfection of the figure, is that which contains a great pike, of which there even remains in fome places petrified flefh. This proves alfo the reality of the animals if not more furely, at leaft more palpably than thofe delineations fo fine and delicate, which have no fubftance.
It is not only fifhes, that M. Scheuchzer fhews in the cabinet of curiofities, which he expofes to the publick view ; there are alfo two bones of the vertebrae of the back of a man, and alfo a feather of a bird found in ftone, but becaufe there is al- ways found more of fifh, than any thing elfe, it is they that are the fpeakers in the common fubject of complaint. It is vifible, that there is nothing but fifhes, that have been able to remain wrapped up in this deep mud or flime, which the deluge left upon the furface of the earth, and which af- terwards hardning formed different beds. All that was not naturally able to penetrate at leaft to a certain depth, remained expofed to the air, or was uncovered foon after, and confequently was deftroyed. This is the reafon that there is found a much greater quantity of fhells than of fifhes in- clofed in ftones, and almoft always the heavieft fhells. Their weight rnakes them fall lower in this general flime, and that which is found the loweit, is the beft preferved.
XIV. On the generation of fnails. Tran- flated by Mr, Chambers. |
The philofopher that fhould be reproached with too much application, to the ftudy of fuch contemptible things as infects, might clear him-
G 2 felf
84. The History andMemorrs of the
felf by only afking, whether the fmalleft pieces of God's handy- -work are below our concern ; but it ‘likewife happens, that thefe fame works which “the generality of men have been pleafed to con- fider as the fmalleft, are really thofe where the moft contrivance, uid the greateft miracles of ‘mechanifm appear, and if we henceforth prefer inquiries into the ftructure of the human body, ‘nothing but our intereft can juftify us therein.
If a common garden-fnail be examined out of the coupling-feafon, and its body diffected with all the care poffible, nothing will be found therein that feems to have relation to generation, and yet as has already been obferved, in the memoir of M. Poupart, this animal is an hermaphrodite, and confequently muft have a greater apparatus of genital parts, than moft others, Every thing too that paffes in it, muft be of a very fingular nature ; the chief of thefe fingularities we thall here deliver, but without explaining the, mechanifm, whereby they are executed, which we referve for M. du Vernev’s memoir on that fubje@, we thall there fee with amazement how much a {fnail ftands nature in.
This animal on the right. fide of its neck, has a little almoft infenfible cleft, which leads into the cavity of the body, where the inteftines are found, very winding, and fluctuating, in its belly ; but at the time of copulation, all this changes form and the animal is metamorphofed, almoft throughout. The little kind of gut being now driven from the bottom of the belly towards the neck fwells, . turns backwards, and difpofes itfelf in fuch man- ner, asto prefent itfelf to the cleft of the neck, which is now much dilated after the manner of a male and a female part, each ready to do its office 3 but this does not proceed till after the
I {nail
Royat Acapemy of Sciences, 8¢
fnail has met with another, and by feveral preliminary motions more vigorous, and as it were paffioned than one would expect from fo cold an animal, they have raifed each other into a proper difpofition, and are affured of a perfect underftanding.
The better to affure themfelves of this, they have another very fingular expedient which they never fail to put in practice together. With the male and female part there iffues at the aperture of the neck, a kind of fpear fhaped like the head ofa lance, and terminating in a very acute point; now the two fnails turning the cleft in their neck towards each other, upon their coming to touch in that place, the fpear iffuing from one, pricks the other, and the mechanifm which plays it, is fuch, that it immediately hereupon leaves the part it belonged to, and either drops on the ground, or is carried off by the fnail it has pricked. This fnail inftantly withdraws, but foon after rejoyns the other, which it pricks in its turn, and after fuch mutual puncture, the copulation never fails of being confummated ; whereas all the other preludes might have failed. The fpear emitted | on either fide, feems intended to advertife the two {nails, that they are in equal readinefs, for in this hermaphrodite kind, there is not as in our’s one principal and active fex, whofe difpofition alone might fuffice.
Snails ufe to couple three times at the diftance of about 15 days from each other, each time of copulation we find a new fpear, nature being at the expence of producing it, tho’ for a ufe feem- ingly of little importance. M. du Verney com- pares this re-generation to that of a deer’s head, and in effect there feems fome analogy between the fu ftance of the one and the other.
After
~
86 The History and Memorrs of the
After emitting, the fpear follows the recipro- cal penetration of the male part of each {nail into the female one, and as they have each of them the two organs of generation difpofed alike, at the orifice of their neck, to make each organ correfpond to its refpective one, ’tis neceffary that one of the fnails have its head upwards, and the other downwards, which they practice accord- ingly.
Their copulation lafts 10 or 2 hours,and produces efpecially towards the beginning, either a ftu- por or a tranfport, which hinders their giving any fign of fenfe. During all this time they ne- ver feparate, nor can be brought to it, do what you will; indeed they have a very cogent rea- fom for this firm embrace, which is, that the glans of the male part growing tumid, cannot get out at the paflage by which ic entered. Ie may be about an hour arriving at this extenfion and till then no feminar matter is emitted.
What is more, the /femen is not yet formed, nor is it till after the copulation is begun that na- ture fo much as goes about it, or employs any of the ftructure neceffary to provide it. There isa fingularity likewife in the matter of the femen, which isnot fluid, but of a confiftence like wax, and affumes the figure of the canals it paffes thro’. ft ts expelled by a motion like that of the intef- tines, when they evacuate their contents; and during all the time of copulation, except the firft hour, creeps gently forwards from each {nail into the other.
The canal it iffues from is longer than that of the female, which firft receives it; but from hence it paffes into other veffels belonging to the female fex, where at length it occafions the fecundi- fication, tho’ not immediately after their firft co-
pulation,
ee
Roya AcapDemy of Sciences, 87
pulation, nor even the fecond, but only after the third.
At the end of about 18 days they bring forth their eggs, by the aperture of their neck, and hide them in the ground with the utmoft care and induftry ; and what is further remarkable is, that upon opening a fnail prefently before it lays, no eggs are found therein, but only a kind of little ligaments, or embryos, which fwim in a very limpid liguor; and make brisk motions therein, Thefe embryos beome eggs in the road ere they get forth ; that is, are invefted with membranes, which has furnifhed them by certain liquors, and afterwards hardened.
All this is only the natural hiftory of the gene- ration of fnails; *tis only what is done, and not the manner of doing it. If this manner were lefe to the ableft naturalift to divine, it would doubt- lefs prove a very intricate enigma , accordingly it is thus far proved almoft impenetrable, not- withftanding we have all the pieces of the mech:- nifm in our hand, and fee them played under our eyes.
XV.. Of the eggs of the cuttle-fih.
M. Saulmon having procured from the fea fome eggs of the cuttle-fifh in bunches, there was found inall of them a little cuttle-fifh, very well formed; they were each held by a pretry long ligament to a thick trunk or common cord, out of which all thefe ligaments came, very much twifted toge- ther. Wedo nottake them to be the fame thing with that which is called vefcaria marina, and is believed by the failors to be this bunch of cuttle- fithes eggs, which the little fifhes are gone out of, and have left it dried, There is not any remain-
der
88° The History and Memorrs of the der of thefe ligaments of the eggs feen in the ve. ficaria, at leaft we cannot be affured of thems andthe irregular veficles, or grains, which com- pofe them, feem glued together.
XVI.. On the burning-glaffes of the ancients. |
Altho’ the academy does not propofe to make _ |
inquiries into antiquity, and is more employed in difcovering what is, than what was formerly thought, or what we may yet add to arts, than what has been practifed, it has however given a great deal of attention to an obfervation of M, de la Hires, on the burning-glaffes being known to the ancients. The burning mirrours certainly were; for fome hiftorians have pretended that Archimedes made ufe of one to burn a_ fleet, . and altho’ they attribute to it an impoffible ef- feét, this proves that they were known. But it is certain, that thefe mirrours, which they inven- ted, muft have been of metal, and concave, and had a focus by refiection, and we are commonly perfuaded, that the ancients did not at all know the focus by refraction of convex-glaffes. Never- thelefs M. dela Hire has found them in the firft fcene of the fecond aét of the Clouds of Arifto- phanes. Strepfiades is a dull, ftupid old fellow, who fays to Socrates, that he has thought of a fine invention not to pay his debts. ,
Strep. Haft thou feen at the druggifi’s this fine tranfparent fione, with which they kindle fire ?
Socra. Is zt not glafs that you mean? —
Strep. True.
Socra. Well, what is it thou will do with tt ?
Strep. When they foall give me a fummens, I will take ibis fouc, and putting it to the fun, I
| awill
Royat Acapemy of Sciencrs. 89
will make the whole writing of the fummons melt at a diftance. |
We fee plainly, that this writing was drawn upon wax, with which fome other more folid matter was covered. ‘This glais, which kindled fire, and melted the wax at the fun, was not con- cave ; for altho’ it had by virtue. of this figure a focus by reflection, this reflection which is necef- farily made upward, would have rendered the ufe of it very inconvenient, and very little popular ; the fummons muft have been held raifed in the air, that Strepfades might have been able to have melted the writing, and it is not at all natural that he fhould make this fuppofition ; whereas, with a convex glafs that burns downward, we might ftrike what we pleafe.
The {choliaft on Arifiopbanes fays upon this place, that it muft be meant of a round, thick glafs, made on purpofe for this ufe, which was rubbed with oil, and heated, to which a match was adjufed, or broaght near; for the Greek expreffion is equivocal, avd that in this manner the fire was kindled. We do not very well underftand what he means by his oil, unlefs it was made ufe of to give a greater polifh to the glafs; but in fhort, which is enough in this place, he imagined this glats to be convex, and it is a proof that in his time, which was much later than that of 4ritophanes, it was known that thefe glaffes burned.
We have nodefign of making here a learned differtation, in which it would be thameful to have any ftroke of erudition efcape. We fhall only obferve, that Pliny lib. 36 and 37, {peaks of balls of glafs, and balls of cryftal, which being expofed to the fun, burned either the cloaths or the flofo of ihe fick perfons, whom they intended
Vor, Ill. N°. 26, H to
go | The History and Memorrs of the
to cauterize. Laéfantius, in his book of the wrath of god, fays allo, that a glafs ball held to the fun, kindled fire even in the greateft cold. Here is the effect of convex glaffes inconteftably proved.
But if they knew that they burned, how were they ignorant of their magnifying the objects’? For it is difficult to imagine, that an invention fo agreeable, fo neceffary, and fo fimple was loft, even in the greateft barbarifm, and all the hifto- rical monuments concur in fixing the origin of it toward the end of the 13th century, when they began to difcover the ufe of fpectacles. If the Greek or Latin philofophers had known this aug- mentation of objects, would they not have made ufe of them in their inquiries, and would they not have mentioned them in their works an infi- nite number of times? ‘There would have been even fpread into their language, as in ours, me- | taphors, and phrafes taken from them. It is true, that there are two or three paflages in Plau- tus, which feem to prove optick glaffes; but when we look upon them more nearly, they do not prove them any longer.
Why therefore were they ignorant of the moft neceffary ufe of the burning “elafs? In the firft place, the falfe ideas of philofophers upon vifion, may have contributed to it. They believed that it was made, either by the flowing of I know not what fubftance, which came out of our eyes, and went to fearch for the objects, or by little re- prefentatrons of objeéts in miniatute which came out of them, and fought our eyes; all their diffi- culty was only to choofe one of thefe two fyftems, both equally falfe; they had no fufpicion of our pencils,-and foc?, and confequently they did not
fee any relation between a bugning-glafs and the manner —
Roya Acapemy of SCIENCES, gI
manner in which vifion js made, and one of thefe things was not like to conduct them to the other. Befides, it feems that their burning-glafles were balls of glafs, either folid or filled with water ; and it is demonftrated by dioptricks, that the focus of a glafs {phere is diftant from it 4 of its diameter. If thefe balls were but 4 a foot in dia- meter, which is the greateft they can have, we muft then bring an object within 1 inch + to per- ceive that it was magnified ; and it is very natural, and even almoft neceffary, that when we have looked through thefe balls, we muft only have feen very diftant objects, which have not appeared greater, but only disfigured and confufed; the clear augmentation of diftant objects requires either very large {pheres, which is impracticable, and does not fall into ule, or very {mall portions of very large fpheres, which are in ufe at prefent with great fuccefs, and cannot hardly ever be found by chance, nor eafy to imagine by reafoning. Be- fides, to know this, the glafs muft be worked as we do, and according to all appearance, the an- cients only knew how to blow it, and make vef fels of it. It is not therefore furprizing, that the knowledge of burning-glaffes did not carry them farther; it is much more fo, that there was not 300 years between the fpectacles and telefcopes. Every thing is flow enough among us, and perhaps we are juft upon the border of fome important difcovery, which we fhall one day be furprized that we were not arrived at.
XVIL. A method of flopping hor fes fuddend). “Tt is faid to be a known fact, that horfes which
run away, ftopall at once, if there is any thing | thrown
92 The History and Memoirs of the thrown upon their head which hinders their feeing. This being fuppofed, M. Dalefme has fhewn a very © eafy manner of difpofing two lines, which let fall at once upon the eyes of two coach horfes, two pieces of leather which are on the fide, in fuch a manner as immediately to hinder their fee- ing, Thefe cords may be pulled from within the coach, and this would be a very eafy way of preventing a very fatal accident, and even the fear of it.
lO —————
AN
AN ABRIDGMENT
PurLosoPHICAL Memorrs of the Roya ACADEMY of SCIENCES at Paris, for the Year 1708.
I. Obfervations on the quantity of rain, which fell at the royal objervatory at Paris, dur- ing theyear 1707, and on the heights of the
thermometer and barometer, by M. de la Hire *.
Obferved exactly each day of the year 1707, I in the eaft tower -of the obfervatory on a level with the great hall, the heights of the thermometer and barometer, with the quantity of rain which fell, and in the fame manner as in the preceding years, and as I have there explained them. But it would be troublefome to relate thefe obfervations day by day, therefore I fhall only give the refult of each month: the height of the rain which fell was in
Lines. Lines Jan 45 July 38 Feb, io Aug 343 March Ii Sept. 94 April 4; Octob 41 May 113 = Nov. 6 June 46%. Dee. a7t
The fum of the water of the whole year 215 Jines or 17 inches, 11 lines,
* fan. 7, 1708. ete Y LUC
94 The History and Memorrs of the
Which varies very little from 19 inches, to which we have determined the mean height of the rain water of each year. Neverthelefs we may fay, that this year has been dry, at leaft the {pring, fince it has hardly rained at all in April, or % of the beginning of May; how- ever, the year has been fruitful in corn, as it ge- nerally happens in this country, becaufe jthe greatelt part of the ground is cool and moift. The 12th of Augu/t, there fell 21 lines 4 of water; and during the 4, 5, 6 and 7th of Oéfober, it rained 34 lines in height with a weft wind with- out ftorms. There fell fnow on the 5th of March only ; but it melted very foon, and gave # a line of water.
The cold has not been confiderable during the whole year ; for my thermometer fell at the loweft but to 27 parts ; the firft of Fd. and in the greateft cold it falls to 31, but very feldom, and it was at 48 at the bottom of the caves of the obfervatory ; which we look upon to be the mean {tate of the air. It begins to freeze, when it is at 32; fo that it hardly froze this year, for the thermometer rofe again pretty foon; it was at the loweit at 31 inches only, the rft and 3oth of December.
If the cold has not been great, the heat on the contrary has been exceffive ; for the thermometer rofe to 6g } the 21ft of dug. the preceding day it was almoft the fame, and towards 3 in the after- noon, when the air is the hotteft, the thermome- ter marked 82; thus the heat has exceeded the nean ftate 34 parts or degrees, and the cold only ®02, From whence we fee, that if the cold had been as great as the heat was in proportion to the mean ftate, the thermometer fhould have fallen to14, as ic fometimes happens; for we sii oR
that
RoyaL ACADEMY of SCIENCES. 95
that the fpirit. of wine may dilate itfelf above the mean ftate, with the fame eafe that it contracts itfelf below it.
The reigning wind of the whole year has been between the S. and W. as it is always if this country ; and it is that which commonly gives us rain, and in a greater quantity, for it comes from the fea with regard tous. But in 4pri/ and May, the wind was often to the N. and thereabouts.
The barometer, upon which I make the ob- fervations, is always placed at the top of the great ‘hall of the obfervatory, which is about 22 toifes above the mean height of the river, and this ba- rometer marked 3 lines + lefs height, than another which is at the fide, altho’ they both make light ‘in the vacuum by fhaking the quickfilver. This barometer was at 28 inches, 3 lines } the 21ft of November, the higheft that it was the whole year, -altho’ the wind was then toward the W. and the sky very ferene; but the days before and after it tended tothe N. This is pretty near the greateft height that it rifes to here. It fell at the loweit the 4th of December, only to 27 inches, 1 line, which ‘is much lefs than it falls fometimes, and the wind was then towards the S. W. and with very little rain. I fhall give in another memoir particular obfervations upon the barometer.
The declination of the magnetical needle was 10° 10! towards the W. December 28, 1707, in the fame place, and with the fame needle, of 8 inches, which J always ufe.
II.
96 The History endMemorrs of the
Wl. A defcription of a new barometer, to know the weight of the air exactly; with fome remarks on the common barometer,
by M. de la Hire *.
In philofophical inquiries, we have very .often occafion to know exactly the weight of the air, what it is at a certain time and place, and it can- not be certainly known, but by the means of barometers. But in the fimple barometers, which are commonly made ufe of, and-which appear to be the moft juft, we cannot know exactly this weight, :becaufe of the little height of quickfilver which anfwers to a great height of air.
For as to the jheat which, dilates the air, .or the cold which contracts it, they are only parti- ‘cular accidents in fome particular {pace upon the durface of the earth, which do not increafe or di- minith the effect of the: gravity of the whole mafs of air, as may be demonftrated by what follows.
Let + there be the phial A, with the:bent tube BD, whichis fixed to it at the bottom inB; and let there be alfo the little capillary tube EF, which is fixed to it atthe top. If quickfilver is ‘poured into the tube BD, through the aperture D, it will enter into the phial, and raife itfelf to athe fame height as in.the tube BD, the air being able to.go out by the tube EF, and when there is.a little in the phial, we may feal the extremity of the {mall tube.
Now, if the phial A is immerged in water, luke-warm or a little hot, the air which is in- clofed will dilate, and the quickfilver wil] rife in BD, as to G, by the force of the fpring of the dilated air, and ic will defcend a little, as to the
* March 21, 1708. + Plate 1k. Fig. 1.
3 height
RoyAt AcApeEmy of Scitncrs. 67 height HH, in the phial, fo that this dilatation will make it fuftain a height of quickfilver H G 3 and if any body was inclofed in the air of the phial, it would then be ina much thinner air than it was before, and yet this body would be more compreffed than it was; for it will be be- yond that which it was in the open air, by the weight of a column of quickfilver equal to H G, fince this dilated air makes the fame effort on all fides, that it made to fupport the column of quickfilver FiG, and this according to the laws of liquid bodies, and it borrows this effort from the fides of the phial; but if this thinner air was only in fome open fpace about the earth, it muft be confidered as being inclofed in a thinner ait which furrounds it, of which it would borrow its effort, which could only be equal to that of thé air, which is on the fides and above it, and in this cafe, the bodiés inclofed in this thinner ait would be no more compreffed, than if they were at the fame height in the thinner air.
But to know exaétly the weight of the air in a éertain place, and ina certain time by the means of the barometer, there have been many invented; which give the difference much more fenfibly than the ‘fimple barometer; but it does not feem to me that it has more convenienciés, or 1s more gott than that of M. Huayzeas, which is com- monly called the double barometer ; perhaps, be- caufe of two tubes, and two boxes, or phials, which compofe it. M. Huygens has given a de- fcription of it in the Journal de Scavens of 1672, which is as follows.
This * barometer is compofed of two cylindri-
eal glafs boxes A and B, of equal thicknefs or
diameter, of 14 or 15 lines, and an inch in height. -* Plate II. Fig. 2 ;
Vor. III. N°. 26. I Thefs
98 The HisTory and MEmoIRs of the
Thefe boxes are joined by a tube ER of the fame material, and two lines diameter on the in- fide. This tube is bent at the bottom in R, where it joins to the box B. Above this box, there rifes another tube C D, whofe infide dia- meter muft be but a little more than a line.
There muft be between the middle of the box A, and the box B, about 27 inches 4.
They fill firft the box A, and the tube ER with quickfilver, holding it inclined, and having voided all che air that was inclofed with the quick-
-filver, they raife it up to put it in its vertical fituation, where it muft remain, the box A be- — ing upward, and the box B downward. ‘Then the quickfilver muft remain toward the middle of the ,box A, as aifo in the box B; and between the two furfaces of the quickfilver in both boxes there will be the fame difference of height as in the fimple barometers, which fhews the gravity of the air with relation to the quickfilver fufpended in the box A, above that of the box B.
Afterwards there is common water poured through the tube D, in which there is mixed % of aqua fortis to prevent its freezing in the win- ter, or fome other liquor which is coloured; and there is as much poured in, as quite fills the lower box B, and raifes the water in the tube to pretty near its middle in G, fuppofing the gravity of the air in its mean ftate.
After this conftruction, M. Huygens adds, that to find how much the differences marked by this barometer, are greater than thofe that the common barometer can make, there is a general rule, which is, that the proportion of the diffe- rences of this new barometer, to thofe of the com- - mon barometer, is as 14 times the fquare of the diameter of the bcxes, to once the fame plus 28
times
RovaL ACADEMY OfSCIENCES. 99
times the {quare of the diameter of the tube which contains the water.
This double barometer is very convenient for ufe, in its fhewing the change of the weight of the atmofphere much more fenfibly than the fimple ones; and if they are conftructed according to the dimenfions and manner which M. Huygens propofes, they will be about twelve times more fenfible than the imple. Neverthelefs it muft be obferved that the exactnefs, which we ought to hope from them, may be a little altered by the difficulty that the air may have to act upon the water of the little tube, and by the height where it may remain fufpended above the tube, either in rifing or falling, and this height may even change without the air changing its gravity.
For if the water is defcended in its tube by the increafe of weight of the atmofphere, the little tube being moiftened in the fpace which the wa- ter has quitted, the water will at firft fupport it- felf higher than it ought, becaufe its parts are as _ it were hooked together, and to the inner fides of the tube ; but it afterwards finks a little withour there happening any change to the atmofphere. On the contrary, when the atmofphere becomes lighter, the water does not rife faft enough, nor with the fame eafe that it ought, by reafon that it does not act freely. But thefe caufes of irregula- rity in this barometer might not be fo confiderable as thofe of the dilatation or condenfation of the liquor, with relation to the quickfilver in the heat and-in the cold, of which I have made very ex- act obfervations upon thefe very barometers, for two years, as I fhall relate in another memoir, which muft increafe or diminifh the charge upon the quickfilver of the lower box,
I 2 It
100 The History and Memo1rs of the
It was to avoid thefe accidents that I formerly propofed to Vi. Huygens, who was then retired into Holland, and with whom I had a corre- fpondence, to make fome alterations in his baro- meter, that I might not undertake any thing up- on this fubject, which might make him unealy, and alfo to have his approbation of it, if he thought that the thing deferved it ; and this is the anfwer he made to my propofal. Your tbought for the double barometer appears to me very good and ingenious, and I fee that it may be made to mark fiill greater differences then in mine, by prolonging at the top the tube of water above the tube of quickfilver, Hague, Aug. 24, 1690.
After that time, I had ineeleéted this invention ;~ but at laft I have perfected it, and put it in fuch
-a ftate, that it will have pretty confiderable ad-
vantages over the double barometers, as M. Huy- gens has judged ; and that they may be made as fenfible.as we pleafe, and if it is not more fen- fible than his own, it only wants $ of the quick- filver.
The figure * fhews the conftruction of this ba- rometer, wahidl h is almoft like the double barome- ter; but the boxes A and Bare only about 4 lines and half*in diameter; the thicknefs of the tube CD on the infide is but’a line in diameter, and the box K, which is joined to the top of the tube CD, is every way like and equal to both the
- others, but it muft have a little opening at the top. The three boxes are each 2 inches high, and the diftance between the middle of the wo boxes A and B, ought to be pretty near 28 inch, 4. As for the thickneis of the tube, which joins the two boxes A and B, it is not at all determined, for this tube ferves only for communication, me
* Plate It. Fig, 3. -_
1
RovaL ACADEMY of SCIENCES, I01
it is fufficient, that it be 1 or 2 lines infide dia- meter.
The quickfilver is put into the boxes A and B, as in the double barometer, and from the quick- filver of the box B, to about the middle of the box K, there are two different liquors, which cannot mix together, and are diftinguifhed in G, in the little tube C D, towards the middle, when the atmofphere is of mean weight.
By the conftruction the three boxes being of equal diameter, they will always have the fame height of liquor, or the fame weight upon the quickfilver of the box B, in all its different heights, which will be ,*, of BK, which is the height of the liquors above the quickfilver of the box B, in fupp ofing the liquors fenfibly of the fame weight between themfelves, and of the fame weight as the water, which is 14 times lighter than the quickfilver, according toM. Huygens 3 for the liquor will rife or fall as much in the box K, as the quickfilver in the boxes B and A, but it will rife in A, when it falls in B, and on the contrary.
In the alterations of the height of quickfilver or weight of air, it is evident, that the lower li- quor G Bewill act as in the double barometer.
My barometer may be ufed as the fimple baro- | meter, by fticking a little flip of paper divided into + lines upon the upper and lower boxes, which marks the entire lines of the height of the quickfilver, which anfwers to the weight of the atmofphere ; fo that we may always compare the true alteration of the atmofphere, with that which fhall be marked by the lower liquor, and inftead of dividing the height of the tube C D into parts at pleafure, which have no proportion to the height of the atmofphere, as is commonly done,
| I divide
3o2 The History and Memorrs of the
divide it into two parts, which fhall reprefent the heights of the atmofphere, in lines of quickfilver,. which may eafily be done.
For example, having found that the difference of the height of the quickfilver in the boxes A and B, when the atmofphere is light, and the air at 2 mean ftate of heat, is 29 inches, 2 lines; and ‘knowing the proportion of the weight of quick- filver to that of each of thefe liquors, and alfo their proportion of weight to the quickfilve: ac- cording to their heights, which is 2 inches, 2 Jines, take away 29 inches, 2 lines, and the re- mainder will be 27 inches for the true height of the quickfilver, which fhews the weight of the atmoiphere in this ftate, and in the time of ob- fervation.
This is the reafon that there muft be writ over- againft the point M, where the lower liquor is, in its tube, this height of 27 inches; and place alfo upon the boxes A and B, the two little flips of paper divided into 2 lines, fo that their divi- fion which fhall be marked at the height of the guickfilver be marked 27 inches.
If you have no regard to the alterations of the bulk of the liquors and quickfilver in cold and heat, with regard to the mean ftate, nor to the different heights of the lower liquor, which is a ttle heavier than the other, it is evident that the quickfilver will fall or rife in its boxes, in the manner that I have before faid ; for the liquors which we fuppofe very near of equal weight, will always charge equally the quickfilver of the lower box. We need therefore only know the motion of the lower Jiquor in its tube, in propor- tion to the motion of the quickfilver in its boxes. This may be found by experiment, if, after the &r{t obfervation when the atmofphere was Iight,
there,
eee ee
Rovat ACADEMY of ScreNcEs. 103
there be another made when it fhall be heavy, the air being pretty near the fame ftate of hear: for we fhall have upon the divifion of the boxes the height of the quickfilver, which anfwerts to the weight of the atmofphere ; and fuppofing it to be an inch, that isto fay 2 an inch upon each box, mark the height of the liquor, as in Z, 28 inches ; and divide the fpace M Z into the number of lines, which have been obferved for thefe two points M and Z, which is here 12, and continue thefe divifions above M and below Z, which is eafy to underftand. We fuppofe, that the tube and the boxes are of equal thicknefs. all the way ; if not, for greater juftnefs we mutt find by experiment other points of height of the liquor in different weights of the atmofphere.
We fee by what has been juft explained for the divifion, that if the true height of the quickfilver be known that anfwers at one time, as that which is here above marked, to the weight of the at- mofphere, there need only be at firtt put the little flips of paper upon the boxes A and B, which mark this height over-againft the furface of the quickfilver, and alfo the fame height at the fide of the tube CD, over-againft the furface of the lower liquor, and we have only to know the pro- portion of the weight of the liquors to that of the quickfilver, and the reft is done of itfelf.
Obferve that the agua fecunda made with £ of aqua fortis, is to the quickfilver in weight, according to the obfervations of M. Homberg, as pretty nigh 1 to 12, which is alfo the proportion of oil of tartar, that is put into the double baro- meter, as I have found by the examinations that I have made.
There only remains for me to examine what muft happen to my barometer, by the dilatation
and
to4 The History and Memorrs of the
and condenfation of the liquors, and of the quick- filver in the great cold and heat. By the experi- ment which I propofed before, where I took the mean ftate of the heat of the air, we found di- vifions with which we might be contented, if a great exactnefs was not required; and fo much the more, as there being but little quickfilver and liquor in the boxes of this barometer, the altera- tion of heat and cold, beyond the mean ftate, can caufe no great difference; yet we may draw two lines parallel to M Z on each fide of it, and very near to it, and there mark alfo by experiment, in the great heat and cold, the divifions which fhall anfwer to the heights of the quickfilver of the boxes, and do alfo the fame thing for the di- vifions of the boxes ; for as to the different con- ftitutions of the air between the extremes and the
mean, it will not be difficult to judge of them. Laftly, oil of tartar may be put for the lower liquor, as in the double barometer 3 and {pirit of wine, or oil of petroleum, for the upper ; which T believe to be more proper than putting fpirit of wine at the bottom, and oil of petroleum at the top, becaufe the oil of tartar alters its bulk lefs than the fpirit of wine by heat and cold; never- thelefs the {pirit of wine approaches nearer to the weight of the oil of petroleum, than to that of the oil of tartar. But there muft be a mark made upon the box K N, where the upper liquor is in a certain difpofition of the air and of thé atmo- fphere, to know afterwards how much this liquor’ will be diminifhed by evaporation, and to put in again as much as there was at firft; but the aper- ture of this little box may be lightly ftopped, which will not hinder the air from acting upon the liquor ; and even a {mall flender tube may be applied
Roya Acabemy of SciENcES. io§
applied to the top of this aperture, which will
preferve the liquorlonger.
Ill. Reflections on the variation of the needle, obferved by the Sieur Houflaye, captazit commandant of the fhip L’ Aurore, during the expedition to the Eaft-Indies, made by the fquadron commanded by the baron de Pallieres, in 1704 and 1705, by M. Calf- fini the fon *; tranflated by Mr. Cham- bers.
A journal of the obfervations of the needle, made by M. Houjfaye, captain of the fhip dz- yora, in a voyage to the Eaft-Indies, in the fquadron commanded by the baron de Pallieress was fent by the commiffioner of the marine in the eaft to the count de Pontchartrane, according to the orders which he had received for that pur- pofe. This officer, who has acquired great ex- perience in eight feveral voyages to the Eajt-lu- dies, not only relates the obfervations which he made in his laft voyage, but alfo compares them with thofe he had made in feveral places in his former ones, with defign to fhew the increafe or diminution, to which the variation is fubject in Jength of time. He has alfo taken care to note the obfervations, which he made in the fight of the capes, iflands, and coafts in his paffage, and informs us, that he made ufe of the Mercator’s chart of Pieter Goos, where the firft meridian paffes thro’ the pike of Teneriff. Having therefore a copy of this author’s chart of the Eaft-Indies, we had an opportunity of compar- ing his obfervations with the variations laid down
* April 25, 1708. - Vor. II]. N”. 26. K in
106 The History and Memoirs of the
in Dr. Halley’s chart, allowing for the difference of longitudes between the two.
At their departure from Port Louis on the French coafts, the variation of the needle was found 5°—— north-weft ; in Dr. Halley’s chart it is laid down as 6 —+ north-wett.
At 357 —long. and 22° north lat. the variatjon was found o; where in Dr. Ha/lley’s it is noted as 1°—! north-wett. ; At 353°—45'! —long. and 16-——30'— fouth ‘lat. the variation was found 2°—— -north-eaft ; where in Dr. Hailley’s chart it is noted as 3° north-eait.
At 354°—— long. and 18°’— fouth lat. the variation was found 3° : north-eaft 5 where in Dr. Halley’s chart it is 3°——} north-eaft. — This fame variation of 3°—# north-eaft, continued as far as 23°— fouth lat. Under the fame lon- ‘gitude of 354°— where in Dr. Halley’s chart it is “made 4° = north-eaft.
In thefe places M. HoufJaye obferves the va- riation in 1682 was found 11° north-eaft, fince which time it has conftantly diminifhed, fo ‘as now only*to be 4 or 5°
The greateft variation north-eaft, which he found in this voyage was 6 the longitude being 367'— and the latitude 28 — fouthward, in which place it is reprefented in the chart as fomewhat under 5’— north-eaft. This variation diminifhes as you proceed eaftward, and at length ‘turns to the north-weft; fo that within fight of the Cape of Good Hope, and along all the coafts of Angola, as far as Bengal, it isg or 10°— north-
i 2
weitwards ; and is Jaid down accordingly in Dr..
Halley’s chart. On the wellern fide of the bank Des Aiguilles, the variation was found 12°—north-weft, and on
RoyaL ACADEMY of SCIENCES. 107
on. the eaftern fide of the fame bank 13°—} to
14°—— and is reprefented much the fame in Dr.
Halley's chart. In 1680, M. Houffaye obferves the iysiniazion: at the Cape of Good Hope was only from 7 to 7°—1 north-weft, fince which time it has been Lae nually increafing, as well as.at the. bank Des Aiguilles.
Through the whole channel of Mofambicque,
rom 25°— fouth Jat. as far as within fight of the bay of St. Auguftine, in the ifland of Madagascar, the variation is found from 22 to 23°—— north- weft ; and in the year 1682 was found from 18 to 19° Dr. Halley’s chart for the year 1700, reprefents it in the bay of St. dugu/tine, as21°— which is fomewhat lefs than it was obferved in
1704, as it ought to be, by reafon of the annual increafe of the variation in this place.
_ Within fight of the ifland of Juan de Nour, the variation was found 22°—north-weft, where in the chart it is 20°——* north-wetft.
- Within fight of the iflands Mayotte, Amzuam, and Moely, the variation was found 20°—30'— north-weft ; formerly it was only 18°—— and in Dr. Halley’s chart is 20°— north-wett.
Under the line at 70°——long. the variation was found 169— mars web ; where in, Dr, Hal- dey’s chart it is 17°—# north- weit.
At 87°— long. and 15°— north-lat. the va- riaiion was found 10°—30/ north-weft ; where in Dr. Halley’s chart it is 12°— north-wett.
Within fight of Canary at 16°——30! north lat. and all along the coafts of Malabar, the va- riation was found 6° 30! north-weit, where the chart makes it 8°— north-weft.
AtCapeComorin in the variation was found 7° 30 north-weft ; in the chart it is 7°——3 north- weft,
K 2 Within
108 The History and Memorrs of the
Within fight of Point Galle, in the ifland of Ceilon, the variation was found 5° 2 north- weft in the chart it is 6° z,
Near the coat of Coromandel, the variation was found 5°—— north-weft, exactly the fame as in the chart.
In the iflands Andaman and Nicobar, the va- riation was found 3°— north-weft, precifely as jn the chart.
Within fight of the ifland Diego Rodrigues, the variation was found 16°=~3o! north-weft, which in the chart is 19° north-weit.
Within fight of the iland Maurice, the varia- tion was found 21° north-weft, where the chart gives it 20°——2 north-weft.
Within fight of the ifland Bourbon, the varia- tion was found from 21°——4 to 22 —— north- weft, where the chart gives it 21?——— north- welt.
At74°——long. and 25°— fouth lat. the va- riation-was found 23°— north-weft, where the chart gives it 22°—# north-weft.
At 72°—45' long. and 27°—15! fouth lat. the variation was found 24°—30'— where the chart _ ives it 23°—north-welt.
The fame variation continued as far 65°—— 45'—— long. and 33°—1o! fouth lat. where the chart makes it 23?—# north-weft.
From this place the variation continually di- minifhed, as they proceeded towards the Cape des Aiguilles about the middle whereof at 35°—— 30! lat. the variation was found 13°—— north- weft, and within fight of the Cape of Good Hope, and all zlong the coafts of Angola, as already mentioned, from 9?—! to 30°— north-wett ; in Dr. Halley’s chart the variation at the middle of the bank Des Aiguilles is 12°— :
t
-
- RovaLt ACADEMY of SCIENCES, 109
At the Cape of Good Hope fomewhat above 10°— and along the coafts of Angola from g to ro? :
As you proceed hence towards the ifland of St. Helena, the variation gradually diminifhes ; fo that within fight of that ifland, on the eaftern fide, it was found 1° or 1° 2 north- weft, where the chart gives it fomewhat above ze - north-weft.
At the ifland of 4/cenfion, there is no variation, or at moft not a degree north-eaftwards ; the chart gives it } of a degree north-eaftwards.
Proceeding hence for France, as you pals the line at 357 or 358° of longitude, there is no va- riation. The chart gives it a variation of $a degree north-eaftwards.
As we approach the Azores, the needle begins to decline north-weftwards ; fo that within fight of the iflands Corva and Flora, we find a varia- tion of 4°———to 4° 30/————. north-welft- wards, where the chart gives it 5° 3 north-weftward.
As we approach Zerre-Neuve, the variation increafes to 7 or 8°—~ and at length on the coafts of Britany dwindles to 5°— north-weit, as was obferved at our departure from Port Louis,
Many of thefe obfervations agree exactly with thofe of Dr. Halley’schart, and the generality of them only differ about a degree, which muft beallow’d avery great pitch of accuracy, conficering the difficulty of making exact obfervations of the va- . Flation at fea. This difference may alfo im fome meafure arife from the annual change found in the variation of the needle, which increafes in fome places and diminifhes in others, as appears from thefe obfervations. ——~. For at 354° —~ longi- tude, and 29°— fouthern latitude, the variation, | which
tro The History and Memoirs of the
which: is north-eaft, has in 22 years dwindled from: 11°—-to 5. At the Cape of Good Hope; the variation, which is north-weft, has. in 24 yeats increafed 2 or 3°——and in the channel of Mofambicque, near the bay of St. Augaftine, it has in 22 years increafed 4 or 5°—.
IV. Experiments and obfervations on the di- latation of the air by boiling water, by M. de la Hire *; tranflated by Mr, Chambers.
M. Amontons had long difcovered by experi- ments, that the’ heat of boiling water can only di- Jate air'to a certain pitch, whatever degree of fire be employed to make it boil; when he propofed to the academy a new thermometer, whereby to difcover the relation between the heat of air over the whole earth.
His experiments: were chiefly made with a ma-- chine very ingenioufly contrived, tho’ fomewhat compound and difficult of application, by means whereof he compreffed the air, in a glafs phial, with 27’ inches of mercury, beyond its natural comprefiion from the weight of the atmofphere. This phial was joined to a crooked glafs tube, whereia was mercury 27 inches above that in the phial, the ufe of his machine was to bring the mercury to this height, then he plunged the phial with its crooked tube in cold water, which at laft he placed over the fire till it boiled vigorouflys and this experiment being performed before the academy, it was obferved, that after the water boiled, the mercury fuftained in the tube rofe no higher, tho’ the fire wds confiderably increafed, than it did when it firft began boiling.
* Joly 24, 1708. i} This
RovAt ACADEMY of SCIENCES. ITI
This experiment I thought ‘very curious, but did not conceive why he made it with air com- preffed with 27 inches of mercury beyond its na- tural lead. To conclude from thence, that the air, fuch as on the furface of our earth, without further compreffion than that of the weight of the atmofphere, dilates itfelf by boiling water about -4 of its former bulk, fince in thele conclufions feveral things muft neceffarily be fuppofed about the nature of air, whereof we have no fatisfactory knowledge.
The firft experiments made by M. Amentons, Jed him infenfibly on to execute what he had pro- jected, without giving him roomto think of another fimpler, and ‘confequently jufter method of at- taining it. This was what induced me to make the following experiments of the dilatation of air, and its force, when heated by boiling water, to fuftain a certain height of mercury without intro- ‘ducing any foreign preffure, more than what a- rifes from the weight of the atmofphere, at the time and place of experiment. I took a glafg tube * ABC, bent in B, and to the extre- mity thereof C, faftened a phial D 2 inches in diameter, the tube was open in A, and its dia- meter about ; of a line on the infide. Thus far agrees with the phial and tube ufed by M. Amon- tons ; but it being impoffible to pour mercury into the tube, without compreffing the air in the phial, I faftened another very flender tube E F over the phial, which opening into it, Jet the air efcape in proportion as the mercury entered the tube A, till having. poured the mercury into the tube ABC, about 2 lines higher than the aperture of the leffer tube in the phial, I fealed the extre- mity F of this leffer tube, the mercury being now
* Plate I. Fig. 4. "
I at
112 The History andMemorrs of the
at the fame height in the phial as in the tube AB, and confequently the air in the phial, no more compreffed than the external air, which M. Amon- tons had not been able to attain, in pouring his mercury into the tube, as he himfelf confeffes in the memoirs of 1699, which was doubtlefs what led him to comprefs it with 27 inches beyond its natural load, to make its compreffion about double _ of what it ufually is.
I obferved at the fame time the height of the barometer, which was 27 inches, 7 lines 4, and the thermometer ftood at 42 degrees, which is al- ways at 48 in the vaults of the obfervatory, and makes what I call the mean ftate of the air be- tween heat and cold, the weather being moift with a fouth wind, and the day the 11th of De- cember, 1705.—- Without more ado, I put the phial in water, and the water over the fire, till making it boil violently, the mercury rofe 8 inches, 5 lines in the tube A B above that in the phial; but the third of 27 inches, 7 lines 4, is 9 inches, 2 lines $, and confequently the air in the ftate it was in, before its being dilated by the heat of the water, did not fuftain a height of mercury equal to 4 of the weight of the atmo- fphere, but lefs by g lines #.
This operation I repeated on the 16th of Fed. 1706, With the fame phial as before, wherein the mercury had been left ever fince, the little tube ftill continuing fealed; but this time the thermo- meter only ftood at 38 degrees, and confequent- ly the air in the phial was more contracted than in the former experiment, when the weather was warmer, and befides the barometer now ftood at 28 inches, 5 lines, and confequently the at- mofphere was 9 lines + of mercury heavier than before. On both thefe accounts, the mercury
fhould
Rovat AcADEmy of SCINCEES, 113
fhould have fallen in the tube were it was left, and was found accordingly 1 inch; 6 lines lower
_ than that in the phial.
Opening therefore the end of the little tube, to give room for the external. air to prefs upon tne mercury in the tube, it prefently rofe to the fame height as that in the phial; then fealing the little tube anew, I put the phial in water, which I made boil; but found that the mercury now only rofe 8 inches above that inthe phial, which is 5 lines -lefs than before, and 14 lines 4 lets than $ 4 of the weight of the atmofphere.
And yet as the air was colder and heavier, and confequently a greater number of its fpringy par- ticles contained in the fame compa{s of the phial,
‘the heat of boiling water, which was the fame
in both experiments, fhould rather have increafed
its effect, and made ic futtain a greater height of
mercury; but the contrary being found, we - mutt of neceffity confefs, that the nature of the air is unknown to us, unlefs we fuppofe that the weight ef the atmofphere acting on the mercury in the
tube had more force to deprefs the air in the phial
than the boiling water had to make the mercury rife, by opening and unfolding the iprings of the air inclofed in the phial. *Tis true, that according to the fuppofition of M. Mariotte, which M. Amontons makes ufe of, to infer the dilatation of air by boiling water, to be 4 more than what it naturally is, viz. That the fprings of air are comprefied in the recipre- cal ratio of the weights, we fhould always find the fame ratio between the weight of the at- mofphere, andthe weight of mercury raifed in the tube, as between the compreffion of the air by the weight of the atmofphere, and the effort made by the fame mercury in the tube to comprefs the eyot. Il N°. 26. me quan-
#14 The History and Memoirs of the
quantity of air firft contained in the phial, which effort makes what we call the dilatation of the {prings of air by boiling water to fuftaina weight, tho” in reality thefe fprings be not dilated 5 for the heat of boiling water aéting on the air in- clofed in the phial, makes no fenfible alteration inits bulk, while it obliges the mercury to rife a certain height in the tube, to make an equilibrium therewith. ’Tis therefore this height of mercury in the tube, that always balances the effort of the boiling water on the air in the phial; fo that this air in the phial muft now be confidered as com- preffed by the weight of the atmofphere, and the height of the mercury in the tube likewife, tho’ before it was only comprefied by the weight of the armofphere ; and as the bulks of the air in the phial are to be in the reciprocal ratio of the incumbent weights, it will amount to the fame as introducing into the phtal, where the mercury undergoes no fenfible change of height, a quan- tity of air compreffed by the two caufes, the weight of the atmofphere, and of the mercury in the tube, which had the fame ratio to the quan- tity of natural air in the phial ; and this air like- wife compreffed by the two former caufes, as the weight of the mercury in the tube would have to the weight of the atmofphere over the fame bafe. For an inftance.
Suppofing the weight of the atmofphere equal to 27 inches of mercury, the height of the mer- cury in the tube g inches, and the capacity of the phial 4 inches, which laft we fuppofe full of air, compreffed by the weight of the atmofphere, be- fore the mercury rifes in the tube. When the mercury is rifen 9 inches in the tube, the phial ftill remaining full of air, this air muft be compreffed therein be yond what ic was before in the recipr6-
cal
Roya AcADEMY of SCIENCES, 115.
¢al ratio of the incumbent weights, which are as 27 to 36, or 3 to 43 fothat it amounts to the fame thing, as if an inch of this comprefied air had been introduced into the phial, which inch of compreffed air would be the meafure of the effort, with regard to the 3 inches, into which the air of the whole phial would be reduced, which would balance the g inches height of mercury in the tube ; whence it follows, that this fuppofed quan- tity of air introduced into the phial, which is the meafure of the effort of boiling water on the air in the phial (it being the boiling that makes this effort) will always bear the fame ratio to the quantity of air natural!y compreffed in the phial, as the height of mercury in the tube bears to the height of mercury, which balances the weight of the atmofphere.
Examining therefore our two experiments by this rule, we fhall have for the farft effort of the boiling water, with regard to the weight of the atmofphere, § inches, 5 lines, to 27 inches, 7 lines $, which is nearly as 10 to 33 5 but for the fecond, we fhall have it as 8 inches to 28 inches, 5 lines, which is nearly as 10 to 35 43 whence it appears, that this ratiois far from 4 of the weight of the atmofphere ; and farther in the fecond experiment than the firit. Accordingly M. Aman- tons does not call it } 3 for he only learned it by induction but nearly +.
All our reafonings hitherto upon the dilatation of air by boiling water, is founded on the two known properties of air, yiz. its being a Auid, and its parts being fpringy ; for as to tts weight, it need not be regarded in thefe experiments, where its height in the phial is fo inconfiderable , {q that all the properties of fluid and fpringy bo- . L.2 dies
42 [me ae [re
116 The History and Memoirs of the
dies may be attributed to the air in thefe experi- ments.
Hence the mercury fhould only rife in the tube toa certain height, where it has fufficient force to bend, or ftrain the fprings of the air, to render it a balance to itfelf, which height will be the fame upon the iurface of the mercury contiguous to the compreffed air, whether we fuppofe a creat deal of air, or a multitude of {prings, or only a few, for the {prings will fuftain each other,
and are all fuftained at Jaft by the parietes of the vefiel they are contained in.
This appears the more probable, as in taking one 0! thefe phials with its tube ABDE *, and pewing mercury into it by the tube ED, till it rife to Ein the tube D E,, which is open, and only to F in the tube DB, which 1s faftened to the phial AB underneath B. °Tis certain, that the air in the phial, and in the part BF of the tube BD, will be cgi fed more than the ex- ternal air, as being loaden with a height of mer- cury EF; and in this ca fe, if the whole phial be taken away, or only its communication with the tube BD in B be ftopped, tis eafy to infer, that the mercury will ftill remain in F, and neither rife nor fall in the tube B D, tho’ the compreffed air in BF have no longer any communication with that in the phial, which is compreffed Jike- wife by thefe PapOaUnens, therefore it appears in- different, whether the phial be finall or great compared to the thicknefs of the tube.
Neverthelefs as neither the contraction nor ex- tenfion of {prings is infinite, but both of them have their bounds, it follows, that ftriétly fpeak- ing, they mutt not obferve the ratios of the in- Ct wade ent weights, even for a little change of weight; hence we have rcom to fufpedct, that
* Fig. 6. this
RoyvaL ACADEMY of SCIENCES. li7
this caufe alone may make fome alterations in the experiments of the compreffion and dilatation of air, and as in fuch a fluid as air, compofed of {pringy particles, there may be fome particular property unknown to us, which may hinder its acting after the fame manner as other fluids. I have endeavoured to make iome difcovery here- of, and with this view contrived the following experiment, which tho’ it bears fome refemblance to the former, is very different in the proportion of the tube to the quantity of air to be dilated by the boiling water.
I took the glafs tube * ABC, bent like a fy- phon, one branch whereof AB was 15 inches long, and the other BC only 8, its extremity was drawn into a capillary tube CF, and the inner diameter of the fyphon was 4 of an inch.
The fyphon being inverted, I poured mercury into it, which rifing equally in both branches of the fyphon, I only left 3 inches height of air in the fhorter branch, 77z. from D to C, then feal- ing the extremity F of the capillary tube, I in- ftantly plunged the tube in water, which I made to boil. Upon this, I found that the mercury in the long branch AB, only rofe x inch, 8 lines 4 above the level of what was firft in the fhort branch BC; but the mercury now fell as faft in the fhort eich. as it rofe in the long one, which was open a-top, and confequently the mercury rofe 3 inches, 5 lines ; and the long branch above that in the fhort one: when the boiling water had - dilated the air contained in it, the barometer then ftood at 28 inches, 3 lines, and the thermometer at 36 degrees2.
Now this ppssimice where the 3 inches height of air contained i in the tube BC, repr efent a little 8 Figs. :
phial
riS The History and Memoirs of the
phial, with regard tothe large tube AB, wherein the mercury rofe, gives nothing like what we learned from the two former; but as the air di- lated by the boiling water, pofiefied a greater fpace than it did before, which was not found in the former experiments, it could not here fuftain fo great a height of mercury, as it did there; and if we enquire by the rule of the air’s being com- preffed in the reciprocal ratio of the weights, what quantity of mercury muft be added to the long tube AB; to reduce the air, heated or dilated by the boiling water, to its former bulk of 3 inches, we fhall find upwards of 21 inches required ; for
it will be as three inches of sir. contained in the,
tube are to 31 inches 8 lines, which is the weight of the atmofphere, with doyble the dilatation of the air in the clofe tube; fo are 4 inches 8 lines 1, which is the whole air dilated in the clofe tube to the height 49 inches 8 lines 4, from whence fubftratine the weight of the atmofphere 2$ inches, 3 lines, and likewife the fall of the mercury in the clofe tube, which is 1 inch, 8 lines 4, the remainder is 19 inches, g lines, the height of mercery in the open tube, above that in the other tube, required to reduce the air in the clofe tube, which is dilated by the boiling water to its firft bulk of 3 inches, and yet it fhould only be about 9 inches 4, which is 3 of the weight of the atmofphere. Hence therefore I Jearn, that the quantity of the inclofed air, upon which the boiling water acts, may occafion a great diverfity in the refult of thefe experiments, and it would even feern to follow, that a little quan- tity of air, dilated by boiling water, becomes
more forcible than a great one. Another experiment I made with regardto what M. Nugiei had publithed in the Memoirs de Tre- VOUR
—_-
Roya AcapEMyY of ScIENCES. 119
woux for Of. 1705, observing what M. Aimontons had advanced in the memoirs of the academy, that the air is dilated, by the heat of boiling water, + of its natural bulk, he made three feveral expe- riments to be fatisfied of it. ———— By the firit, he found that air naturally compreffed, as upon the furface of the earth, is dilated by boiling wa- ter in fuch manner, that the fpace it now poflefles is to its natural fpace, as 2 to 1, or 4 to 2, and not as 4 to 3, according to M. Amontons; and he obferves very judicioufly, that the air, in his experiment, was not dilated to its utmoft extent, by reafon part of this dilated air was encompafitd with cold water, but makes no mention of ano- ther caufe, which likewife prevented its dilating, viz. the weight of the cold water, which had role above a hole, made in the bottom of the phial immerged in the water.
M. Nuguei’s fecond experiment was fomewhat different from the former; and by this he found the dilated air to the natural air, as 16 to 1 ; but as he does not regard the height of the water in the boiler, whereby the air was dilated by means of a hole at the bottom of the phial, fo great a
dilatation muft neceffarily have enfued.
His third experiment likewife gives the ratio
y of dilated to natural air, as 16 to 1 5 but Ido not conceive how he could make it after the manner he relates; for the cold water no: fooner enters _the phial plunged in the boiling water, than the phial fhould break.
He obferves upon thefe three experiments, that the firft is very wide from the other two, which could never have rofe from the fingle caufe af- figned by him.
The laft-of them I repeated with all the-‘cir- cumftance he mentions, and found that the bulk
of
420 The History and Memorrs of the
of the air, dilated by the heat of boiling nie 5 was to that of natural air as 5 to 2, oras22to1 nearly, which is very far Hos 16 to I, as found by him.
The great difference among thefe experiments fhews, that there are fome circumftances not at- tended to, which may produce great effects in the nature of air, and that we muit be warned elfe, from drawing any general confequence from a few particular wbteryanons: and condemning others, drawn from obfervations in the fame cafe ; what then occurred to me, as to the reafon of the diffe- rence between M, Nugzei’s obfervation and mine is as follows. M. Nuguet ufed a little phial, which only held 2 ounces, 7 drachms 4 of water, whereas that I ufec, held 25 ounces, and as we can never judge fo well from an experiment in httle as in large, there might fome diverfity arife from this quarter. I alfo obferved from M. Nz- guei’s account of his obfervations, that he firft filled his phial with water, and then emptying it, put it in the boiling water to dilate its air; now the little water, which might be lefc there- in, being raifed into bubbles, which would be put into a violent motion by the heat, I fan- cied, might not only extend the {prings of the air, but that poffefling a large bulk, they might have carried off, as they igued from the phial, mot of the air contained therein; as we find in eolipiles, which blow fo vehemently for a con- fiderable time, till no more water is lefcin the bowl. By this means only a little air muft have been left in M. Nugwet’s phial ; whereas that which I ufed being firft well dried, the heat had nothing to act on, but the air contained in it; but as all air abounds more or Jefs with watry particles, if this eficé&t had any place in thefe experiments, we we fhould always find great differences in thofe
3 made
RoyAL ACADEMY of SCIENCEs. 121
made like the two former at different times, when the air was probably more replete with wa- ter at one time than another: from whence thofe of M. Amontons were exempted, by reafon they were made with three different phials at the fame time. This induced me to believe, that the moif- ture of the air, when heated by boiling water, might poffibly make confiderable differences as to the dilatation of the air, tho’ it could not get out of the phial, as being retained by the mer-
Jeary:
But being, aware how wide our reafonings fre- quently are from the truth in phyfical matters, I refolved to repeat the experiment I had madeupon the dilatation of air by boiling water ina phial, and immediately after to make another with the fame phial, with a little water in it, either to confirm or overthrow the notion I had conceived about the difference between our experiments. ————— Accordingly the 18th of Fuly, 1708, the baro- meter ftanding at 28 inches, and the thermome-
‘ter at 55 degrees, which in the vaults of the ob-
fervatory ftood at 48. The wind being wefterly and very moift with a little rain, I took a new glafs phial, as dry as the conftitution of the air would allow of, and weighing it, found it 6 drachms ; then ftopping it well with a cork, thro’ which I had put one of the lees of a {mall glafs fyphon, I cemented it well to the cork with fealing-wax, leaving the other leg of the fyphon on the out- fide. This phial I put in cold water, holding it down, fo as both the cork and the fyphon were immerged, taking care only to fink the rrouth of the phial a little below the furface of the water, for fear the water fhould make way by its weight into the phial.
Vor. IH. N°, 27. M This
122 The History and Memoirs of the
This water being placed over a good fire, I prefently perceived a multitude of little bubbles begin to arife from the end of the fyphon, which fhewed that the air in the phial was beginning to dilate, and iffue at the end of the fyphon, by the heat it had conceived from the fire ; but as the water heated more and more, the air bubbles rofe from the fyphon with more precipitation, which continued till fuch time as the water boiled out right, when there were bubbles {till feen to arife, tho’ much lefs than before.
After the water had boiled fome time, 1 took it off the fire, keeping the end of the phial and fyphon {till under water, that as the water in the copper, and the air inthe phial fhould come to cool, no particle of air might get into the phial, either by the fyphon, or any little pores, that might be found in the cork ; and to fhorten the operation, I Jaded fome of the hot water off, and fupplied its place with cold, which was conti- nued till the water was-entirely cooled; then taking the phial out, I founda good deal of wa- ter had entered it, while we were waiting for the cooling, and as a mark, that the air left in the phial, was of the fame denfity as the external air, alittle water was left in the part of the fyphon, - which traverfed the cork, and was fufpended and counterbalanced within the air in the phial and the external air.
Taking out the cork therefore and the fyphon, and wiping the phial well on the outfide, 1 found it weigh wich the water in it 4 ounces, 2drachms, then filling it with water to the height, whereat the bottom of the cork had been, which was e- qual to the tulk of air it contained when I putit in the water, I found it weigh 5 ounces, 2 drachms; fo that the air left in the phial, was
equal
RovaLt ACADEMY of SCIENCES. 123
equal to an ounce of water, and from 5 ounces, 2 drachms, the weight of the water in the whole phial, with the phial itfelf, fubftiacting the weight of the phial 6 drachms 4, as I found it at firft. The remainder is 35 drachms 7, which is equi- valent to the whole air in the phial, when I put it in water.
_ Hence | infer, that the whole air of the phial, naturally compreffed by the weight of the at- mofphere, was to that which remained after its dilatation by boiling water, as 35 4 to 8, which is fomewhat lefs than 44 toa. Yet is this di- Jatation much greater than what I had found be- fore, which was only as 2 } to 1: hence as the air was very moift in this laft experiment, 1 had reafon to imagine, that the particles of water diffufed thro’ the air, might be the occafion, as I had before fufpeéted of this extraordinary dila- tation; for further fatisfaction therefore I in- ftantly proceeded to my laft experiment, as I had before refolved.
I poured the water out of the phial, and con- tenting myfelf to fhake it well without drying, 1 weighed it as before, and found it 6 drachms 2, and 11 grains ; fo that there were 11 grains of water fticking to its infide, then fitting in the cork and fyphon, I repeated the experiment as before, without omitting the leaft circumftance, The refult was, that the phial was found quite full of water, and that the ratio of the capacity of the phial to the remaining part, not poffeffed by the “water, was as 35 ito 1, as I found by weighing as before. Hence I can no longer make any doubt, but that a littl more or lefs water in the air, may occafion great variations in thefe expe- riments, fince bare 11 grains of water in the pre-
M 2 fent
124 The History and Memoirs of the
fent one, produced an effect 8 times greater than in the former experiment.
But tho’ the phyfical account fhould be difal- lowed, yet the experiments will ftill ftand incon- teftable, whereby fuch different dilatations of air by boiling water are produced ; fo that we may at leaft infer hence, that no exact ftandard of heat over the whole earth can be had by this method,. not even with ufing phials and tubes, like that I firft ufed, and which differs but little from thofe of M. Aimontons, which are hardly portable.
Upon the whole, were it not better, in lieu of this contrivance, to fubftitute good fpirit of wine thermometers, all graduated alike by careful expe- riments, without minding thofe equal divifions commonly placed on them, which are of no fer- vice for making an exact comparifon ; — fince there is no knowing whether the infides of the tubes thro’ their whole length, nor the propor- tion of tne bow] tothe tube? All required to this end, is to make feveral fuch thermometers nearly alike, and plunge them all into frozen wa- ter, leaving them fome time therein, and then marking the height of the liquor in each tube, the other divifions may be made after the fame man- ner, by warming the water gradually, and im- merging all the thermometers in it, care muft be taken withal to mark a point, which -may be called the mean degree between heat and cold; as that where the {pirit of wine ftands in the tubes in the vaults of the obfervatory, where it continues alike all the feafons of the year. Hence we might alfo learn, whether the deep mines and caverns of other countries, where the tempera- ture of the external air cannot reach, afford the fame degree of heat as ours, and whether the differences of foil occafion any variation therein. 2 ¥.
2
Royal ACADEMY of SCIENCES. 125
V. Reflections on fome obfervations of the variation of the needle, made in a voyage to the South-fea, aboard the /hip Maure- pas, dy M. de la Verune, commander of the faid fhip, with fome remarks on the na- vigation of the coaftsof America and Terra del Fuego, dy M. Caflinijun*; tranflated by Mr. Chambers,
The abbot Bignon has lately given us the ob- fervations of the variation of the needle, made in the fhip Maurepas in its voyage to the South-fea, in the year 1706, 1707, and 1708, wherein care is taken to note that the longitudes are reckoned ‘from the meridian of the pike of Teneriff, which gave us. an opportunity of comparing them with the variations laid down in Dr. Halley’s chart.
Thefe obfervations being very numerous, we fhall content ourfelves to give the refult thereof, and only nore fuch as were made near, or in fight of any iflands, or coaft, and which will admit of an exact comparifon. i
On the 27th of December, 1706, at 345°— 44! longitude, and 20°—44’ fouth laticude, near the ifland of Afcenfion,.the variation was found a 30 north-eaft. In Dr. Ha/ley’s chart the variation at this place is fomewhat above 7° north-eaft,
In December, 1707, at 295° 12/longi- tude, and 56°—-6 — fouth latitude, near the -Yland of the Hermit, the variation was found
20° north-eaft ; where in Dr. Halley’s chart it is 20°——30’—— north-eaft. At 310°———30'—— ong. and 52° 9’ —
fouth lat. near the iflands of Seba/t, the variation
* July 21, 1708. was
126 The History andMeumoirs of the
was found 23° north-eaft. In the chart it 4s 21°—30’— north-eatt. |
In the other parts of his courfe, both going and returning from Cape Horn to the equinottial, the variations obferved, commonly agree with thofe in the chart within a degree.
As tothe variations in the South-fea, Dr. Hal- ley has not laid them down in his chart, for want of obfervations of them ; for which reafon I have endeavoured to fupply in fome meafure that de- fect, by drawing lines to fhew the degrees of variations, from the obfervations made along the weltern coaft of Americz. The obfervations I chiefly make ufe of, were made near the coafts, which I fhall here relate, according to the order of the latitudes.
In Augufi, 1707, at 300°—10’— longitude, and 13°——6'— fouth lIatirude, near the point Canette, and that of St. Galland, the variation was found 7?————— north-eatft.
At 297°——27’/—— long. and 14°—1! fouth Jatitude, near Pifco, the variation. was found 7° north-eaft.
Aft-299° 30'/— long. and 31°——49/—— fouth lat. near Va/parem, the variation was found 8?—— north-eaft.
“At 299°—25) long. and 36° 30'— fouth lat. near the Conception, the variation was found 10°? ———— north-eatft.
From thefe obfervations it appears, that the variation of the needle increafes along the wef- tern coaft of America, as the fouthern latitude in- creafes, which is further confirmed by feveral obfervations, made at a little diftance from this coaft.————. For at the latitude of 44°—49’— the variation was found 12° north-eatt.
At
Royai AcADEMY of SCIENCES. 127
At the latitude of 48°-——58'— the variation was found 13° north-eait.
At the latitude of 53°—37'— the variation was found 15°— north-eatt,
And at the latitude of 56°——42'— the varia- tion was found 17°— north-eatt.
In other parts of the fhip’s courfe, where it appears by the longitude expreffed, that it was feveral degrees diftant from the coafts, the varia- tion is laid down differently under the fame pa- rallels, which may ferve in fome meafure to des termine the direction of the lines of variation, which we hope to be enabled to rectify by the obfervations that fhall hereafter be communica. ted; for befide that there are feveral of thefe obfervations, which it is very difficult to recon- cile, we fhould have feveral made at different diftances from the coafts, ere we can pretend to determine the direction of thofe lines with any precifion,
I fhall here add fome obfervations of the varia- tion delivered by Dampier, in his voyage round the world.
At the iflands of Seba/t, which he calls Sible de Ward, and defcribes them as 3 iflands fituate at $1°—25'— fouth latitude, he found the variation in the year 1683, 23°—10/— north-eaft. I have already mentioned, that the variation was found near thefe iflands 23° o'— inthe year 1707, ‘whence it appears that there has been no fenfible difference in the variation during the fpace of 24 “years, which feems to confirm what we have elfewhere obferved, that at Cape Horn the varia- tion has not altered in the {pace of 100 years.
At 47°—10'— latitude in the Sourh-fea, Dam- pier found the variation 15°—+ north-eatt.
And
128 The History and Memorrs of the
And at the latitude of 36°—— he found the va- riation 8° —— north-eatt. \
By which laft obfervations it appears, that in the South-fea near the weftern coafts of America, the variation continually increafes, as you recede from the equino¢tial, agreeably to what we have already infered from other obfervations.
To thefe obfervations of the needle, M. Clai- rambaut, who fent them to the count de Pont-. chartrane, has joined fome remarks on the navi- gation of the eaftern coafts of South America and Terra del Fuego, made by M.de la Verune ; which, together with a particular map of thofe countries, which he has promifed to fend, may ferve to rec- tify feveral fea-charts, wherein he finds the iflands about Cape Horn prepofteroufly placed.
His firft remark 1s, that the coafts from Cape St. Anthony, at the mouth of the river de /a Pla- ta to the ftraits of Magellan are laid down, a point of the compafs more eafterly than they really are.
Healfo obferves, that the diftance between the ftraits of Magellan to the ftraits of /e Maire, as well as the fituation, are very ill expreffed in the common charts; for by his account, thofe two ftraits are 55 or 56 leagues diftant, and that of /e Maire is fituate,to the north-weft 5°— north of the ftraits of Magellan. ———— But it may be here obferved, that in Dr. Ha/ley’s chart, printed in 1700, and M. Delifle’s chart of the {traits of Magellan, printed in 1703, thofe two ftraits are laid down very agrecably to his obfervations.
He alfo obferves, that the Terra del Fuego is not near fo large, nor fo much fouthern as was imagined ; and adds, that Cape Horn, which the common charts place 57°—40/— fouthern lati- tude, is only 55°——4o! fouthern latitude.
He
‘RovaL ACADEMY of SCIENCES. 129
He adds, that the ilands of Barzevelt, which the charts place in the fame latitude with Cape Horn, are fituate weft-north-weft of that Cape in 56°—35! —— latitude. —— In which he likewife agrees pretty nearly with M. Dedi/ic’s chart above- mentioned.
He farther obferves, that the iflands of Barie- velt are the moft fouthern lands ; and that there is no danger in paffing between thofe iflands and CapeHorn. Thediltance from the ftraits of /e Maire to Cape Horn, which is eaft-north-eaftwards of that ftrait, he obferves is 80 leagues, which a- grees very well with the diftance exprefied in Dr. Hiailey’s chart; but much exceeds that in M. Delifle’s.
After doubling Cape Horn, there is no far- ther difficulty, the charts being all good, as well as the coafts found, and the weather. moderate a- long Chili and Peru.
M. de la Verune makes. feveral other curious and ufeful obfervations on the navigation of theie feas; he points out the favourable icafon for pal- fing Cape Horn, and how to behave part in gO- ing and returning. The ifland Hermit he places 24 or 25 leagues from this Cape A rd, in the fame latitude, and makes it 18 or 20 leagues - in compafs. He alfo determines the fituation of the ifland Sebalt, whofe eaftern point is fituate N.N.E. of the ftraits of Je Maire, at about 55 leagues diftance ; and he takes them to form a kind of archipelago. At his return he faw them very di- fiinétly, and found their fituation very different from what is commonly fuppofed. He gives them an extent of 55 or 60 leagues, and notes that to avoidthem, they are obliged to range the Terra del Fyego, or to make a large circuit, when the wind does riot allow it. Laftly, he ab-
wont NN”, 27. N ferves,
130 The History and Memoirs of the
ferves, that the lands of Brazi/ are laid down more eafterly than they really are, by which means all the fhips, which go from the ftraits of Magellan or le Maire, find on their arrival at Brazil an error of dormie 200 leagues.
VI. Conjectures on the pofition of the ifland of Meroé, by M. Delifle *.
In tall Ethiopia, which is a country of very great extent, there is nothing more celebrated a- mong the ancients than the ifland of Mercé, nor any thing fo difficult to find among the moderns, or that they lefs agree in. If what the ancients have faid of it be true, this ifland could arm 250,000 men, and maintain 400,000 artificers. It contained a great number of cities; the chief of which was that of Meroé, which has commu- nicated its name to the ifland, and ferved for a refidence to the queens, regia & metropolis E- thiopum. Ifay tothe queens, becaufe it feems the women reigned in this country to the exclu- fion of the men. In the time of Auguffus, it was a princefs with one eye indeed, but of a maf- culine courage, virilis fane multer, fed altero o- culo capta. She made an irruption into Egypf, which at that time belonged to the Romans, but was obliged to fend ambaffadors to dugu/ftus. At the death of our faviour, there reigned another, one of whofe eunuchs was baptized by St. Philip, as may be feen inthe Ais of the apojiles. When Nero {ent fome of his guards into this country, to fearch for the fources of the Ni/e, it was alfo a princefs\ that reigned there, and all thefe three were called Candace; but we fee by a paflage of
* Nov. 14, 708. t Plate II. Fig. 7. i Pliny,
-
Royvar AcapDeEmMy of SCIENCES. 131
Pliny, that this name was for a long time be- come common to the queens.
If hiftorical differtations were fuffered here, in- ftead of reciting only philofophical and mathema- tical difcuffions, we fhould relate what Diodorus and ‘other authors have written to the advantage of this ifland ; but we muft pafs.to the difficulty that there is to difcover it in the modern geo- graphy.
This difficulty proceeds a little from the me- moirs, that we have upon Ethiopia ; for we mutt not’hope, that without a reafonable knowledge of the prefent ftate of the world, we can make the relation of the ancient geography to the new. When they firft began in Europe to have com- merce with the kings of Ethiopia, there were fome writers of no veracity, who, upon fligit informations, faid many things far from the truth, which threw the world into numberlefs errors; from which we have hardly yet been able to recover ; and it is upon the credit of thefe writers, that fuch wretched maps have been made, and that thefe places have been fo many ways dif- figured, that an ambaffador of the king of Erhi- opia faid, in Egypt, to young Thevenot, that our geographers had filled their country with mon- fters and chimeras.
Ic is true, that the jefuits, who have been pretty Jong in this country, have given us better infor- mations of it, and have made a map upon the fpot'very different from thofe made in Europe, Befides F. Balthazar Tellez, F. Nicolas Godinho, M. Ludolf, and others have given us defcriptions of the country upon much furer memoirs ; but they have only deferibed that part of Evhiepia, which we call dévjizia, and not that which we
N 2 call
132 The History and Memorrs of the
call Nubia; and yet this was neceffary to enable us to decide the queftion with any perfpectuity.
I fhal] not therefore undertake here to decide it; but the memoirs that I have received from that country under the protection of M. le Comte de Pontchartrain, enabled me to propofe at leaft fome conjectures. M. da Roule, the king’s en- voy into Ethiopia, as well to obey the orders of the minifter, as to acquit himfelf with more ho- nour of the g olorious employment, with which his majelty had -honoured him, had taken in Egypt all the, information neceffary for the road he'was to go, which was none of the leaft dificult parts of his commiffion. He had’ made'a deicription of Nubia, and of the courfe of the Wile, upon the depofition of many Scheicks, or chieis of fa- miles, who had travelled 15 or 20 times into’ Ethiopia, as welt by the Né/e, as through the de- ferts, He did me the favour to communicate to me what he had learned; and it is upon his me-. moirs that I fhall propofe’ my conjectures.
The ifland of Mercé was indubitably upon the Nile. The fource of the Nile, which was fo lone fought fer in vain by the ancients, is in 12° of north-latitude. Its cataracts, a little lefs cele- brated, but much better known than its fource, are 23° 4, and it is certainly between thefe two points, that the ifland of Mercé mutt be.
'. The ancients have faid, that this ifland was formed by the concourfe of the Afaberas and the Nile, and by another river named 4fape, which falls in hke manner into the Nile. That this ifland was terminated on the weft by the Nile, and was bounded on two other fides by the Afape and Affaboras ; which fhews that it was but im- properly called an ifland, fince it was not inclofed
on
Royvat ACADEMY of SCIENCES. 133
on all fides, and it muft be like that which we call here ?’ [fle de Pranee.
Notwithftanding fo formal a defcription, Mer- cator and Ortelius have reprefented the ifland of Meroe, as formed by two arms of the Nile, and called it Gueguere; and almoft every body have fuffered themfelves to be carried away by the au- thority of thefe two geographers, upon whofe credit they boldly pronounce, that the ifland of Meroé is now known under the name of Gueguere. Neverthelefs the iflands that are formed by the Nile alone above the cataracts are all fmall, which cannot agree with what we have faid of the largenefs of that of Meroé, nor with the number of its cities and inhabitants, and befides there is not one that approaches to that of Gueguere.
. The jefuits, who have been in Ethiopia, are perfuaded that the ifland of Mercé is nothing efe but the kingdom of Gojame, which is almott en- tirely inclofed by the river Nile, in the manner of a peninfula, as may be feen in the map; but this peninfula, which makes the kingdom of Go- jame, is formed only by the Nile, not by the Aftape, nor by the Ajiaboras, I mean not by any river that could be fuppofed to be the 4fape and the 4fabores, which is contrary to the defcrip- tion which the ancients have given of it. Befides the city of Merz, the capital of this ifland, muft ~ have been placed between the 16 and 17th de- gree of north latitude, as fhall be hereafter ihewn ; and the kingdom of Gajame does not go beyond the 13th degree. In fhort, if that which we now call the kingdom of Gajame, had been the ifland of Meroé, fo known by the ancients, would they not alfo have known the fources of the Ni/e, which are without difpute in the middle of this kingdom?
Tfaac
134 The History and Memorrs of the
Ifaac Voffius, of the royal fociety of England, is one of thofe who Jately has laboured the moft ufefully at geography ; and altho’ his pretended reformation. of the longitudes has done him no honour, he has neverthelefs made excellent in- quiries in thefe geographical works. He pre- tends that the pexinfula, made by the river Ma- reb on the fide of its fource, by a circuit almoft equal to that which the Ni/e makes ‘about the kingdom of Gojame, is the ifland that we fearch for; but befides, that this ifland is formed only by one fingle river, and not even by the Ni/e, contrary to what the ancients have faid of it, this penintula, formed by the Mared, has neither the extent nor the fituation that the ancients have given to the ifland of Mersé. And what abfo- lutely deftroys this opinion is, that the city of Mercé, the capital of the ifland, was upon the Nile; and that the ifland, or peninfula of Ma- reb, is very diftant from it.
Cellarius, whofe geographical works are now famous among the learned, has collected in his ufual manner all that the ancients have faid of the ifland of Mercé , but he does not give any intel- ligence of the prefent ftate of that country, with- out which we cannot conclude any thing ; he only feems to approve the opinion, which confounds the kingdom of Gojame with Mercé, which! have jult refuted.
F, Tellez, a yefuit, after having well confidered all that the miffionaries of his fociety have writ- ten upon Ethiopia, is perfuaded, that this is an imaginary ifland. If I had believed, that fuch an opinion could make any impreffion upon one’s mind, I would begin by refuting it; for it is ufelefs to reafon upon a thing that isnot, or at feaft whofe exiftence is doubtful: but it is ftrange
that
Royal ACADEMY of SCIENCES. 135
that any one can doubt of the exiftence of the ifland of Mercé, after what has been noted by the ancients with relation to it. Pliay affirms, that Simonides ftayed there 5 years; and that af- ter him Ariffocreon. Bion and. Bajfilis have de- fcribed. its length, breadth and diftance from the city of Syewe and the Red-/ea, its fruitfulneds, capital city, and have even related the number of its queens. |
Ludolf, who has not been able to find this land, any more-than F. Ze//ez, has not how- ever doubted but that in fome meafure it exifted ; but he pretends, that it muft be fought for more to the weft than has yet been done, and that it is among the countries to which we do not travel. That if after all the inquiries that fhall be made, it is not found, we may fay that fome arm of the Nile is dried-up, and that this is the reafon that we cannot difcover it: but this author is not aware, that thofe who have lately travelled over Ethiopia, have long coafted the Nile, and that they muft,. on the contrary, have left the ifland of Mercé to the eaft, fince the Ni/e bounded it onthe weft; and that thus it muft be looked for to the eaft and not to the weft, as he fays. And as to the rivers drying up, I own that there are many of them in Africa, which having flowed fome time through fands or fpongy grounds, weaken infenfibly, and at laft difappear ; but we do not put the N7/e nor the Zaboras in the num- ber of thefe rivers; and the power, or rather the licence of geographers, altho’ great, does not go fo far as to dry up rivers of this confequence.
Since therefore we muft find the ifland of Me- roé, and as it is the duty of a geographer to make the parallel of the ancient geography with the new, we may conjeciure, that it is this fpace
of
136 The History and Memorrs 6f the
of ground which is between the Nile and the ri- vers Tacaze and Dender , and | am going to en- deavour to eftablifh this conjecture by the fitua~ tion of this country, which appears to me con- formable to that which the ancients have given to the ifland of Merce, by. the rivers of which it is formed, by its extent, by its figure, and by fome other fingularities commen to the ifland of Mercé, and to the country I have juft pointed our,
The fituation of a place, ‘or country, is :pro- ved by the degree under which it 1s fituateds and by the diftance of this place, or country,’ from other places that are known to us. The city which isthe moft known of all thefe countries’ is the city of Syene: the latitude of it is not at all doubtful; and this is a fixed point, from which we may without fear, meafure the places about it. Pliny * affirms, that on the day of the fummer fol{tice at noon, bodies do not make any fhadow 5 and fora proof of it, they have caufed a well to be digged, which at that time is quite light. Jn Syene oppido, folftitii die medio, nullam umbram faci, puteumque ejus experiments gratia failum, totum illuminari. Strabo has {aid the fame'things in other terms, which fhews, that the city of Syene ts juttunder thetropick-of Cancer, at 239 of north latitude. Now fromSyene, tothe city of Meroe, according to the fame author, were rec- koned 5,000 fradia, in going toward the fouths and thete’ 5,c00 fradia reckoned in aftronomical meafures, make 7 degrees of a great circle, and give the pofition of the city of Meroe, at 159 4 from the equator.
This pofition of the city of Aderoe, which ~ agrees pretty juftly with that which Péolemy gives it in the ath book of his geography, is alfo con-
* Lib. II. cap. 73. firmed
__ Roya AcADEmy of SCIENCES. 137
firm’d by another paflage in Pliny, who fays, that the city of Mereé has no fhadow at all, any more than that of Syeze; and that this happens twice in the year, when the fun is in 18° of Zau- rus, and 14° of Leo. In Meroe, qua eft caput gentis FEthiopum, bis in anno abjumi umbres, fole duodevicefimam Tauri partem, (5 quartam de- cimam Leonis obtinente. Now it is certain, that when the fun is in thefe degrees, juft mentioned, it has about 16 degrees ! of declination, which is the latitude that the ancients have given to the city of Merez, and which refults from its diftance from that of Syene.
I could alfo prove by the climates the pofition of the city of Mercé: ‘The antients have placed it in the middle of the firft climate, of which the longeft day is 13 hours, which gives by calcula- tion 16 degrees +, which is the iame latitude that we have given to Mercé upon obfervations, and upon its diftance from the city of Syene. 1 have neglected in this calculation the refraction, becaufe it does not make any confiderable difference.
The ifland of Mercé was formed by the river Nile, and two other rivers, which came from the eaft, as, we have faid. Lujluant in Nilum, fays Strabo, duo flumina ad oriente delata, & Meroem iugentem infulam complectuntur. I can- not tell whether the antients knew any other ri- vers than thefe two, that flow into the N/e on the eaft fide; but we fee by the memoirs of M. dz Roule, that there are but two confiderable ones, the rivers Tacaze, and Dender. The river Tacaze being as big as half the Nz/e, has very much the appearance of being the Afadoras of the antients : this is the opinion of Juan de Barros, the Livy of the Portugueze; and two things will not permit me to doubrit. The firft is, that according to
wer Il.N°’.27. .O the
138 The History and Memorrs of the
the jefuits, who have been in E¢hiopia, it enters into the Nile at 17° 4 of latitude, which is within fome minutes near the fame height that Ptolemy gives to the outlet of the Afaboras, 700 Stadia below the city of Mercé, as we fee by Strabo, Diodorus, and others.
The fecond thing that makes me believe the Tacaze to be the fame with the 4fadoras is, that this river is otherwife called Atdara, as we fee by the relation of the fcheiks of Nubia, and by that of a Kecollet who has paffed this river in going into Ethiopia. Now the names Atdara and Afa- boras are not very different. I fuppofe that the Atbara is its true name, and that the Greeks have altered it as they have done many others, fince that ftill happens pretty often to thofe who are obliged to ufe foreign names in their writings.
As for the river Afape, it will probably be that of Dender ; for there are only the two rivers, Atbara, and Dender, at leaft that are of any con- fideration, which enter immediately into the Nile on the eaft fide.
‘The extent of the country that I have pointed out, is pretty near the fame as that which the an- cients have allowed to the ifland of Mercé, Diodo- rus, and Strabo have made the length of it 3,000 ftadia, and the breadth 1,000 ; that is to fay they have allowed it 120 leagues of length, and 40 of breadth, which agrees here pretty well; whereas, neither the kingdom of Gojame, nor the Peninfula, formed by the river Mared, approach to this extent.
And not only the extent is the fame, but alfo the figure of a buckler, which Diodorus and Stradvo give to the ifland of Meroz, fufficiently agrees with the country thatI fpeak of. Perhaps a fkilful painter might not think it exaét; but we muft nor look for all the regularity of defigning in the figures that
3 the
Roya ACADEMY of SCIENCES. 139
antients have given to countries, no more than to thofe that they have given to the conftellations.
_ There would be but one thing to apprehend, that the plan, which I here reprefent, was not very certain; and that to prove what I have ad- vanced, I had only accommodated it to the opi- nion of the ancients, like the Le/bian architects, who finding it difficult to fuit the ftones to their model, made their model conform to the ftone. But to that I anfwer, that it is the rivers which make the figure, and the greateft part of this plan, and that thefe rivers with their {prings, their courfes, and their outlets; are drawn from the map that F. Hieronymo Lobo, Francifco d’ Almeyda, and other Portugueze jefuits, have made upon the fpor; that they are taken from the verbal depofi- tions of the {cheiks of Nuéia, examined feparately by M. dz Roule from the itineraries of our French jeluits, and of the Szeur Poncet, whofe travels F, Je Gobiens caufed to be printed, and from fome other manufcript travels of Italian Recollets, fent into that country by the congregation de propa- ganda fide, of which I had collated copies.
Befides the affinity that I have related between the ifland of Mers#, and the country that I pro- pole to reprefent it, there are alfo fome others, as the rains, the fruitfulnefs of the country, and the hunting of elephants.
Strado fays, that the regular. rains begin only at Mero , and Pliny, that thofe._ who were fent by (Vero to fearch for the fources of the Nile, be- gan to find in thefe places trees, and plants, berbas demum circa Meroem fylvarumque aliquid appa- ruiffe, cetera folitudines. And it is exactly the obfervation, that F. Brevedent has made in thefe very places, We quitted, fays, he, the city of Corti, andthe river Nile, to enter into the defert
CF 2 of
140 The History and Memoirs of the
of Bihouda, We began to fee trees and plants, the rains being firft met with in thefe quarters, whereas all the reft to that place was only wa- tered by the overflowing of the Nile, or by the means of machines Which raifed up the water to fpread it upon the grounds, and this Poncet de- clares likewile in his itinerary. They might well May like Pliny, cetera folitudines, they who had walked many days in fand, or parched grounds, where they neither feund water, nor grafs, nor any thing but frightful folitudes. And without doubt it was in thefe defert places, that Camby/es, - king of Perfia, having loft part of his army, was obliged to return into Egyp#, without arriving at that part of Erhiopia which begins to be culti- vated and inhabited ; whereupon we cannot enough admire the vanity of thofe Greek authors, who would not willingly be ignorant of any thing, and who to find the origin of the name of Merce, have written, that Cambyfes had taken this city, and had changed the name, which it formerly bore, into that of his fifter, who was called Mercé, and that this princefs was buried there.
They have very much praifed the fertility of the ifland of Mercé, and the great number of its inhabitants 3 and this agrees perfectly well with the country of which I fpeak. F. Paulet, a je- fuit, fays, that beyond the Nile, over-againft Senna, the country {warms with people ; and that there may be feen thoufands of little villages'fpread over the whole country. J havea journey from _ the fame city of Sennar to Souaquem, an Mand and port of the Red-/ea, wherein it is faid, thatthe _ country which I defcribe, is well cultivated, and peopled. And in the detcription of Nubia, made by M. du Roule, upon the relation of the people of the country, it appears, that in thefe places =
eart
-Royat AcApemy of Sciences. I4f
earth is fo fruitful, that they have three harvefts in a year.
In fine, it is a little above Mercé, that they be- gan to fee elephants according to Pliny. The Piolomys, kings of Egypt, and among others the famous Philadelphus, who was {fo attached to the knowledge of nature and of the fciences, fent hi- ther to hunt thefe great animals, and had built fome places for the convenience of thofe that were jent thither ; and it has been obferved in the journeys from Seazar toSouaquem, which J have juft mentioned, that beyond the river 4/dara, toward the fame height tnat is pointed out by Pliny, they found in the mountains great quantities of elephants, and many other forts of animals,
It feems- to me that to complete the probability of my conjecture, there needs no more than to find the. city of Mercé itfelf in the ifland that I have juft {fpoken of, or at leaft to difcover the ruins or remains of it. If Zofephus and Heliodorus were to be credited, who place it at the uniting of the Nile and Afaboras, it would not be difficult ; we need only look for the conflux of thefe two rivers which would not be doubtful; but itis well Known, that LHeliodorus’s hiftory of Ethiopia 1s only a.romance, and there is great likelihood, that the little ftory which fo/ephus makes concern- ing Mofes's expedition into Ethiopia, when he was, fays he, at the court of Pharaoh and general of his troops, does not merit any more credit, fince it is not found in the fcripture, nor in Philos ‘thus it will be better to have recourfe to Strabo, who fays, that the city of Meret was 700 fadia above the union of the 4fadoras and the Nile, or to Pliny who makes it 70,000 paces. There is found toward thefe places the city of Guerre, that our travellers fay is one of the moft confiderable
of
142 The History and Memorrs of the '
of the cquntry. Might it not be what others call Meroét, or Guegueré, by a fort of reduplication ? But there is perhaps a rafhnefs in carrying meer conjectures fo far, and the academy profeffes a fe- vere exactnefs in the inquiries into truth.
VII. Refiections on the obfervations made by F, Laval, at St. Baum, and other neigh- bouring mountains, by M. Caflini, jun*. tranflated by Mr, Chambers.
Among a number of aftronomical and geogra- phical obfervations fent by F. Laval, to the count de Pontchartrain, there are feveral of the height of the barometer made at S+. Baum, and St. Pilon, on different days, and at different times of the day, which he has compared with thofe made at the fame time at his obfervatory at Marfeilles.
The better to perceive the relation between thofe obfervations he has made a table, in the 1ft column whereof are expreffed the days of the month, and times of the day, when fuch obfervations were made. The 2d expreffes the heights of the mercury at the obfervatory at Mar- feilles.The 3d and 4th the heighth of the mercury at the fame time at St. Baum, and St. Pilon. And the 5th of the height of the thermometer at S¢. Pz- lon.—————Too thefe are added 3 other obferva- tions of the barometer.
The 1ft made at the foot of the rock S¢. Pilon, where it ceafes to be perpendicular, and joins with the flope of the mountain. The 2d on the mountain des Beguignes, eaftward of St. Pilon. And the 3d in the plain below S¢. Baum, called the plain @’Aups.
* Dec. 22, 1708.
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Roya AcADEMy of SCIENCES. 143
To determine the height of thofe places with regard to each other, he meafured a bafe line of 155 fathoms in the plain d’ups, and from the extreams of that bafe obferved the angles between St. Pilon and the mountain des Beguignes, then taking the angles of the apparent height of thofe mountains, he found the height of the mountain des Beguignes geometrically to be 264 fathom above the plain d’4ups, and that of St. Pilon 181 fathom above the fame plain, which fets the mountain des Beguignes 83 fathom above St. Pilon. For the height of the bottom of the rock where the 1f{t obfervation was made, the rock be- . ing perpendicular from St. Pilon to this place, he had the convenience of meafuring it with a cord, and found it 63 fathom.
Now to find the refult of thefe obfervations of the barometer made at Marfeilles, and the places around, compared with the feveral elevations which were taken geometrically, we are firlt to confider, that the height of the obfervatory at Marfeilles above the furface of the fea is 24 fa- thom, to which 2 lines and 3 of mercury cor- refpond, as appears from the table in the memoirs for 1705.
Having therefore taken the differences between the heights of the mercury found at the fame time at the obfervatory, and at St. Pilon, which are 15 in number, and whereof the f{malleft is 2 inches, g lines $, and the greateft 2 inches 11 lines 3, ~we took the mean between them all, which is 2 inches 10 lines $3, to which we added the 2 lines } correfponding to the height of the obferva- tory above the furface of the fea. The fum 3 inches o lines, are $$, isthe depreffure of the mercury correfponding to the elevation of St. Pile above the furface of the fea. To which, in the table
above
144. The History and Memoirs of the above quoted, anfwer 481 fathom, the height
of St. Pilon above the fea according to the baro-
mieter.
So by comparing the obfervations of the baro- meter made at the fame time at Mar/feilles, and at St. Baum, which are 16 in number, the {malleft difference in the height of the mercury is found 2 inches 5 lines 4, and the greateft 2 inches 6 lines 3; and taking a medium between them all, we have 2 inches 6 lines 2,, which added to 2 lines }, for the height of the obferva- tory gives 2 inches 8 lines 23, for the height of St. Baum above the fea, the number correfpond- ing to which inthe table is 415 fathom 2, which fubftracted from 481 fathom, the height of S¢. Pilon above the fea leaves 65 fathoms 4 for the height of S¢. Pilon above S#, Baum———Y et this height by Father Laval’s menfuration with a cord, was only 53 fathom; but the difference between the heights of St. Baum and S¢. Pilon is too {mal] for any rules to be eftablifhed thereon ; we fhall therefore proceed to examine what refults from the obfervations of heights, whofe difference is greater, as the plain d’dups, and the mountain des Beguignes, which is 284 fathom above the fame.
The height of the barometer on this mountain was found on the 2gth of Fue 24 inches 1 line, at which time the mercury at Mar/eilles was 27 inches 4 lines high, which gives us a fall of 3 inches 3 lines between the obfervatory at Méar- feilles and the top of the Beguignes, adding there- fore the two lines } for the height of the obferva-
tory above the fea, to thefe 3 inches 3 lines, we —
fhall have 3 inches 5 lines + of mercury for the height of the mountain des Beguignes above the rae ace
Te i
Royvaz AcAvEMy of ScieNcEs. 146 face of the fea, the number correfponding to which in the table is 559 fathom, 1 foot.
On the fame day the height or the mercury on the plain d’ 4ups was found 25 inches 6 lines, at which time at the obfervatory at Mar/eilles it was found 27 inches 4 lines 4, the difference is 1 inch 10 lines 4, which added to 2 lines 5 for the height of the obfervatory above the fea, gives 2 inche o lines. 7, for the height of the plain @’ 4vps above the fea, the number correfponding to which in the table is 298 fathom, 1 foot 4. This fubftracted from 559 fathoms, the height of the Beguigwes, above the fea, gives 261 fathoms for the height of the mountain Beguignes above the ple in a’ Aups, according to the different heights of the barometer, compared with the table ADAVGAEASE: tioned,———— which height FP. Leve/ determin geometrically to be 264 fathoms, the difference therefore is only 3 fathoms: which is a precifion greater than we could ever have expected, con- fidering that an error of 4 of'a line in the obfer- vations of the height of the barometer, fuffices to make this difference.
So, if from 48% fathoms, the height of 52, Pi- lon above the fea according to the barometer, we fubftract the height of the plain @’4ups above the fea, which we have found to be 298 fathoms, 1 foot 4, we fhall have the height of Sf. Baice a- bove -the plain d’Aups, 182 fathoms, 5 feet, which is only 1 fathom, 5 feet more, than F, La- val had determined it geometrically.
"From thefe obfervations therefore it appears, that the difference between the heights of two’ places may be found wich fufficieat exactne/s, by the rule above laid down, piovided.. the height of the barometer, at the RiGee of thefea, be ae at “a fame time. For want of an obfervation at
Vou. IH. N°. 27. Pp the
146 The History and MeEmoIRs of the
the furface of the fea, we may fuppofe the mean height of the mercury there to be 28 inches 5 but then we muft not expect to arrive at this preci- fion.
Reflettions on the apparent depreffion of the hori- zon of the fea.
The height of St. Pzlon above the furface of the fea, being found by obfervations of the ba- rometer, as we have elfewhere fhewn, to be 481. An enquiry may be made into the obfervations of the apparent depreffion of the horizon of the fea, made by the fame father on that mountain.
Thefe obfervations he has reprefented in a ta- ble, wherein are expreffed the ftate of the air and the wind, which blew at the time of obfer- vation, together with the correfpondent height of the barometer and thermometer.
The greateft apparent depreffion of the horizon of the fea was obferved on the 25th of Zune, at 3 inthe afternoon, to be 57 ——-45’— the wea- ther then being hazy, and the wind at north-weft ; the. fmalleft was found on the 26th of Zune in the morning, to be 56'—o! the {ky being very clear, and the wind fouth-wefterly : taking there- fore a medium between thefe two obfervations, which differ 1’—45”’— from each other, we fhall find the mean apparent depreffion to be 56’ —52°
Suppofing now the femi-diameter of the earth to be 3271600 fathoms, as we found it by our obfervations in prolonging the meridian, we fhall find, that at the height of St. Pilon above the fea, which is 481 fathoms, the real depreffion of
the horizon fhould be 58’——57" which is greater by 2! 5" than the mean apparent de- preffion 56’—-52/——_—— This excels muft be
ewing to the refraction, which raifes the appa- I reat
RoyAL ACADEMY of SCIENCES. 147
rent vifual ray above the true one, by about the 28th part of the angle of the mean apparent de- preffion.
F. Laval remarks on his obfervations, that there is a variation in the refraction, at heights greater than thofe of the obfervatory at Marfeilles 5 but that this variation is not fo confiderable as in lower places; for in all the obfervations which he has had opportunity to make on &¢. Pilon, this variation never rofe above 1 —45/— whereas at his obfervatory it has ee to 3/—20/——_____In- deed as F. Laval has made a much greater num- ber of fuch obfervations at Mar/eilles, than at Sé, Prlon, *tis poffible, that by further obfervation on that mountain, a greater difference might be found than he has yet met with.
The fame father alfo notes, that his obferva- tions confirm what he had mentioned in the me- moirs fent to the academy, that the refraction is greateft when there 1s a fog in the air occafioned by a north-weft wind; and that it is even greater or lefs, as the wind is more or lefs frefh. On the contrary, that the fea never appeared lefs de- prefied than on the 26th of ‘fuze, in the morning, when the wind blew weakly from the fouth-weft, and the horizon was very clear. On the evening of that fame day, there being a great fog the re- fraGtion, was increafed by 1/—30"—- The weight and the heat of the air, feemed not to contribute any thing to the refraction, fince the barometer and thermometer were pretty much at the fame height on the 25th and 26th of June, and yet the difference of ine refraction was as great as he had ever known it.
NJ NN
VHI.
148 The History and Mrmorrs of the
VHI. An obfervation of a luminous. circle about the fun, by M. dela Hire *; tranf lated by Mr. Chambers.
On the gth of 4prii, in the prefent year, 1708,
at one in the afternoon, I perceived a large lu- minous ring about the fun very compleat in all its parts. Ihe fun was in the centre of this ring, the diameter whereof was 36°—— and his breadth a degree and half; the inner edge of the ring was pretty well defined, and of a colour border- ing on red; but the outer was whitifh, and thus loft itfelfin the ky. So much of the fky as ap- peared within the circle was very dark, and ef- pecially in that part contiguous to the circle. On the outfide ic was much clearer and whiter, tho’ the whole air was full of a fort of light fog, which had rofe a great height, there. was no parbelion, or mock-fun, on this circle, as. is frequently found on fuch circles near the horizon at fun-rife, where there are commonly two diametrically op- pofite to each other, and of the fame height with the fun; but ’tis very rare to obferve fuch cir- cles in the meridian, and ftill rarer to fee parbelia on them, efpecially when the fun. 1s very high, and the air well heated ; as in effect the pheno-
menon can only be owing to particles of ice, - ?
which occafion this appearance by refracting the fun’s rays 5 and as thefe circles have always the fame diameter, it, follows, that thofe icy parti- cles muft always be of the fame figure; °tis not fo eafy to give a phyfical folution of this phanome- non as of the rain-bow, the caufe whereof is evidently in the little drops of rain, which are fpherical, and of which we can make a perfect 1 uitati on by means of a little phial full of water,
* April 25, 17006 nor
a ee
RoYAL ACADEMY of SCIENCES. 149
_nor need we wonder, if there occur fome diffe- rences in the obfervations of the diameters of thefe circles, as well/as thofe of the rain-bow, fince in the latter, experience teaches us, that .the diffe- rent degrees of the heat of water produce a con- fiderable alteration.
IX. An extratt of the obfervations made in _ the Weft-Indies 77 1704, 1705, and 1706, by F. Feuillée, a minim, mathematician to the king, compared <oith thofe which were made at the fame time, by M. Caf- fini the fon *.
He fet out from Martinico, Fuly the 4th, 1704, and arrived the rath at Golfo-irite, which the
Spaniards cali Porto-cabeillo.
Obfervations for the height of the pole at Golfo Trifte, or Porto-cabeillo, July 12 Wetaton AtPorto-cabeilio,the meridian height > a of the upper edge of the fun i 7
Refra€tion minus the parallax + 9
Therefore the true. height of the ee upper edge- ' Rage HO Semi-diameter of the fun 15 50 Therefore the true height of the centre 78 32 56 a a of the fun : 21 57 52 herefore the fupplement of the height of the ae 5 eR pondae And the height of the «pole 19 30 48
"We fhall content ourfelves in the following obfervations, to sive the heichtof the pole, which refults from the oBfervations of the meridian height of the fun, having regard to the refraction, parallax, femi- ame. eae of eehnad ion ef the fun.
* December 20, 1707.
\
so The History and Memoirs of the Fuly 13, the meridian height of the? .4 4% upper edge of the fun x 578 *5 5 From whence we take the height of k ¥ the pole 198 Thefe obfervations concur in deter- termining the height of the pole ef 10 30 50 Porto-cabeillo to be
Obfervations for the variations of the needle.
_F. Feuillée fer out from this port the 14th of of Fuly to go to Santa Marthe, where he arrived the 21ft.- He obferved, as he went along, the mountains of Saata Marthe, which are of a prodi- gious height, and had their tops ftill covered with fnow, altho’ the fun was near the zenith.
The 18th he obferved, between Porto-cabeillo and Curacoa the variation of the needle, by the means of the amplitude, to be 6° 40’ N. E.
It is marked in Dr. Ha/lley’s map of variations in this place for the year 1700, about 7° N. E,
The 20 near Cape des Eguilles, a little diftant from Sakta Marthe, he obferved the variation of the needle to be 7° 6/,
Tr is marked in Dr. Halley’s map in this place above 8°
Obfervations for the height of the pole at Santa Marthe. Fuly 24,1704, at Santa Marthe, the meridian height of the upper edge (81 46 5 of the fun was Aug. the third 84>. 8g5 Aug. the fourth 84 24 10 In taking a mean between the height of the ole, which refults from thefe obiervations, we shall have the height of the pole At St. Marthe II 19 55
Thele
Roya ACADEMY of ScIENCES. 161
Thefe obfervations were made 100 paces from the fea.
Obfervations for the height of the pole at Porto- Bello.
Sept. 7, 1704, at Porto-Bello, they , meridian height of the upper edge 8 38 V7 of the fun
The 12th 84 44 49
The 13th 84 22 0
O. the 3d 70.3326
The 4th FO. 2G), FO
The 22d 69 27 50
Taking a mean between the height of the pole which refults from thefe obfervations, we fhall have the height of the pole, ~ At Porto-Bello. rears
Observations a the fatellites of Jupiter, for the longitude of Porto-Bello.
Ofober 47, At 2® 4! 25" in the morning at Porto-Bello, the benniter our of the firft f stellite i in- to the fhadow of Fupiter, the sky ferene and clear. ns FONAE " 33 5" at Paris, by the cor- rected calculation.
5" 28! 40” difference of the me- ridians between Paris aid Porto-Bello, by which Porto- Bello is more eafterly.
- Obfervations of the length of the pendulums at. Porto-Bello.
F. Feusllée applied himfelf during his ftay at Porto-Bello, which was above 2 months, in find- ing the length of the pendulum. He had for this purpofe. fufpended a musket-ball to a thread
of
362 The History and Memorrs of the
of fillk grafs, and having fpent the greateft pare of the day, whilft he ftayed in this port, in comparing the vibrations of this pendulum with that which he had brought from France, he found that the length taken from the centre of the ball,
being 3 fect, 5 lines: 4, agreed perfectly well
with the mean motion,
According to this obfervation, the length of the pendulum at Porto-Bello is about 3 lines lefs than that which we obferved at Paris. It is alfo 1 line 2 Jefs than what was obferved at Caienne in 1672, by M,. Richer, tho’ this ifland is 4 or 5 degrees nearer to the equator than Poro- Bello.
The length of the pendulum at Por/o-Bello only differs about a line from that which was obferved in 1682 at Goree of 3 [Sits 6 lines 5, and ae Guadaloupe of 3 feet, 6 lines 3
Obfervations of the variation of ihe Beedle at Porto-Bello.
F, Feuillée having with great care. drawn 2 meridian line upon a horizontal plane, placed there 3 compafies of different fizes, the biggeft of which was 9g inches, 7 lines, and found the declination of the needle 7° 25! N. E.
This declination is marked in Dr. Halley’s te above 9° N.E.
Obfervations for the height of ibe pole at the fort |
of Bocachica.
This fort is 3 leagues, or thereabouts, to the fouth of Carthagena, built at the entrance of the © ulph. Dec. 14,1704. meridian height ofthey ¢ ,¢ 56 8 10 lower edge of the fun
The
aie. a
Rovat AcApemy of SCIENCES, 153 The 2oth, meridian height of the up- b 6 eT per edge By the mean of thefe obfervations, we
have the height of the pole at the t 10 20 25 fort of Bocachica
Obfervations for tbe beight of the pole at Cartha- gena, 1705. Jan. %, 1705, at Carthagena, meri- dian height of the upper edge of (56 46 20 the fun Fan, 2 50 5t 47 Jan. 3 57 3 2 Taking a mean between the height of the pole, which refults from thefe obfervations, we fhall have the height of the pole, At Carthagena cf 10 30 25
Obfervation of the eclipse of ihe moon, Dec. 11, 1704, @¢ Carthagena.
h At o 51 47 in the morning, the beginning of the eclipfe. 3 36 32 endof the eclipfe. 2 44 45 total duration.
F. Feuillée made this obfervation with M. Cou- plet the fon. They had a more favourable time than we had at Paris, where the fhadow of the earth did not appear well terminated ; fo that we could only obferve the beginning of the eclipfe, * and the immerfion of fome fpots. This is the refult of the comparifon of this obfervation, with thofe which were made at the royal obfervatory.
AEC 5% 47 in the morning at Carthagena, the beginning of the eclipfe. esVOL. dl N°. 27. Q At
154. The History and Memoirs of the
h
At 6
6)
AA HARA DH
/
yn 40 at Paris, the beginning with a te- lefcope of 3 feet.
12 53 difference of the meridians between Paris and Carthagena.
59 21 at Carthagena, mare humorum enters
12 © at Paris, the fhadow at the edge of mare humorum
12 39 difference
3 29 at Carthagena, the beginning of
Grimaldi
14 30 at Paris, by Mefff. de la Hire
11 1 difference
6 45 at Carthagena, end of Grimaldi 17 30 at Paris, by Meff. de la Hire 10 45 difference
9 9 at Carthagena 21 o atParis, by Meff. de /a Hire 11 51 difference of the meridians between
Paris and Carthagena
Taking a mean between the difference of the meridians which refults from thefe obfervations, we fhall have the difference of ,the meridians be- tween Paris and Carthagena 5 11! 50".
Odbfervations of the fatellites of Jupiter at Car-
thagena, Jan. 8, 1705.
At 11 28 46 in the evening at Carthagena, the
emerfion of the firft fatellite out of the fhadow of Fupiter through
fome fogs.
16 39 54 at Paris by the corrected caicula-
r
od
tion. 11 8 Difference of the meridians be- tween Paris andCarthagena.
3 Fan.
Royat ACADEMY of SCINCEES. 155 | Fan, 16.
h At 1 20 15 in the morning at Carthagena, the
emerfion of the firft fatellite out of the fhadow of Fupiter, the heavens being clear and ferene.
6 31 15 at Paris by the corrected calcu- lation
5 11 20 difference of the meridians between Paris and Carthagena.
The laft obfervation having been made in fe- rene weather it feems beft to fix here, and deter- mine the difference of the meridians between Pa- ris, and Carthagena of 5° 11! 20!
Odbfervations for the variation of the needle at Carthagena.
F, Feuillée has found by feveral obfervations
the variation pf the needle at Carthagena to be
2° wh. Ee
It is marked in that place in Dr. Halley’s map
of variations §? oa: No EE,
Objfervations for the height of the pole at fort St. Louis. This fort is fituated to the fouth of the ifland of St. Domingo. Feb. 21, 1705, meridian height of the upper
edge of the fun 61° 32/ 25! Which gives for the height of the pole at fort St. Louis nite biabt
Ovfervations for the height of the pole at the ifland of St. Thomas,
March 17, 1705, meridian height of the up-
per edge of the fun ZO aN oO Which gives the polar height for the ifland of St. Thomas 13.2854
Q 2 Ob-
156 The Wistory and Memoirs of the
Obfervations made at Martinico.
F. Feuillce went at the return from his voyage to Martinico, where he made new obfervations during his ftay.
He gives notice that his obfervations were made to the eaft of the ifland at 7 or 8 leagues diftance from the place where Meff. des Hayes and du. Glofs made theirs, fo that the difference of the meridians between Paris and the place where he has made his obfervations, muft be lefs than that which refults from Meff. des Hayes and du Glos’s obfervations.
Fune 28, 1705, meridian height of the upper edge of the
° Ul lj Sun — —— 81 39 10
The 19th of Aug. ee 88 18 37°
The 2d of Sept. eed 83 26 37 The 14th —_ — 78 54 28 The 16th —— 78 8 55 The 20th no —— 4G) 1542 The 22d ne ns 75 48 20 The goth wes 72 40 47 The 1ft of O27. oa 2 a7 ag The 4th ae —— 71 8 16 The 6th weet 70 21 18 The gth os oe The 20th wee 65 6 43 The 3d of Nov. ee 60 23 30 "The 14th —$ 57... 93 19 The 18th oe 56 11 48 The 20th os a 55 32 25 Phewoth)? eee 53.59 45 The 26th of Dec. eee G2 Meh Bal The 31ft — - 52. 2a 8
Thefe obfervations give the height of the pole in the place where FP. Feuii/ée made his obferva- tions
Royat AcADEMY of SCIENCES. 157
tions at Martinico between 14° 42’ 5” and 14° 43/55", almoft the fame as that which refults from the obfervations, which he had made at the beginning of his voyage; therefore we may de- termine the height of the pole at this place to be 14° 43/0".
Odbfervations of the fateilites of Jupiter at Mar- tinico, ¢he 18th of Oktober 1705, at h / 4 > . - . . 3 10 41 inthe morning at Martinico, the im- merfion of the fecond fatellite into the fhadow of Fupiter.
The 19th of Oktober, at
56 47 in the morning at Martinico, the im- merfion of the firft fatellite into the fhadow of Fupiter, the heaven being ferene.
9 39 at’Paris, by the corrected calculation.
12 42 difference of the meridians between
Paris and Martintico.
The 25th of October, at
2 © 54 in the morningat Martinico, the im- merfion of the third fatellite into the fhadow of Jupiter.
5 18 46 inthe morning at Martinico, the e- merfion of the third from the fhadow of Fupiter. ‘
2.17 52 total duration in the fhadow of Fu-
piter.
The 26th of October, at 4 51 6 in the morning at Martinico, the immerfion of the firft fatellite into the fhadow of Fupiter near the ze- nith. g 4 24 at Paris, by the corrected calculation. 4
ty
pw
158 Ihe History and Memorrs of the
h
4
19
/ AS
13 26
12 19
32 13
' fe)
Wis. =a it 18 difference of the meridians between Paris and Mariinico.
The 4th of November, at
57 in the morning at Martinico, the im- merfion of the firft fatellite into the fhadow of Fupiter.
51 at Paris, by the corrected calculation by an obfervation of the following day.
54 difference of the meridians between Paris and Martinico.
The 27th of November,
36 inthe morning at Maréinico, theim- merfion of the firft fatellite into rhe fhadow of Fupiter. The wind thook the telefcope.
38 immerfion obferved at Paris.
2 difference of the meridians between Paris and Martinico.
The 27th of December, at 14. in the morning at Martinico, the im- merfion of the firft fatellite into the fhadow cf fupiter near the zenith. 16 at Paris, by the corrected calculation. 2 difference of the meridians between Paris and Martinico.
The 28th of December, ai 42 in the morning at Martinico, the im- merfion of the fecond fatellite into the fhadew of Fupiter.
The 28th of February, 1706, at 34 at night at Martinico, emerfion of the firit fatellite our of the fhadow of Jupiter near.the zenith, 14
RoyvyaL ACADEMY of SCIENCES, 159
14 39 18 at Paris, by the corrected calculation. 4 312 44 difference of the meridians between Paris and Martinico.
The 23d of March, at
10 47 33 at night at Martinico, emerfion of the firft fatellite out of the fhadow of Fupiter.
14 59 28 at Paris, by the corrected calculation.
4 11 55 difference of the meridians between Paris and Martinico.
The 15th of April, at
Ir 7 44 at night at Martinico, emerfion of the firft fateilite out of the fhadow of Fupiter.
15 20 44 at Paris, by the corrected calculation.
413 0 difference. of the meridians between , Paris and Martinico.
Almoft all thefe obfervations concur in giving the difference of the meridians between Paris and Martinico 4° 13! o!.
We had determined it by the comparifon of two obfervations, made at the fame timeat Paris and at Martinico to be 4°13 28".
Therefore we may for greater exactnefs deter- mine the difference of the meridians between Paris and Martinice to be 4° 13/15".
Obfervations of the eclipfe of the moon, April 27, 1706, @¢ Martinico at 8 12 58 atnight, beginning of the eclipfe 10 49 ‘0 end of the eclipfe. - 2 36 2 total duration
F. Feuillée obferved during the time of this eclipfe, the immerfion and emerfion of feverai
fpots, of which we were not able to obferve the cor-
z60 The HisTory and Memoirs of the
correfponding ones at Paris, becaufe the fky was not very ferene. This is the refult of his
obfervation with ours, At, h / u Diy k 9 42 2.at Martinico promontorium acutum,
y quite in the fhadow. 17 55 © at Paris the thadow was at promon- torium acutum 4.12 58 difference of the meridians. between Paris and Martinico. 10 49 © theendof the eclipfe at Martinico. 15° 2 Bo\at Peres: 4 13 30 difference of the meridians,
Taking a mean between the differences which refult from thefe two obfervations, we fhall have the difference of the meridians between Paris and Martinico 4° 13! 15".
The fame that we determined by the fatellites of Fupiter.
This eclipfe was obferved at the fame time at the port de Paix, in the ifland of St. Domingo, where the end was feen at 9" 40’.
We fhall therefore have the difference of the meridians between Martinico and the port de Paix of 1° 9! 0”; which being added to the dif- ference of the meridians between Paris and Mar- tinico of 4° 13'15%, gives the difference of the meridians between Paris and the port de Paix, in the ifland of St. Domingo, of 5 22! 15",
Obfervations of the length of the pendulums at Martinico.
F, Feuiliée having fufpended a musket:ball to a thread of filk-grafs, found by feveral obfervations, the length of the pendulum to be 3 feet, 5 lines +%> greater by 4 of a line than what he found at Porto-Bello of 3 feet, 5 lines ,4.
Ob-
Roya ACADEMY of SCIENCES. 161
Obfervations of the variation of the needle.
F. Feuillée at his return to Martinico, found the variation of the needle to be 6° 10’ N.E. pretty near the fame, that he had obferved in 1704 in the fame place.
All the obfervations juft related, added to thofe which are inferted in the travels of the academy, will ferve to determine pretty exactly the coaft of South America from Caienne to the I/fthmus of Panama, and the fituation of many of its iflands.
Vou. Ill. N°. 28. R A
5 ee We” a ae ~
PAPERS contained in the’ ABRIDGMENT of the History and Memorrs of the Roya AcapeMy of, ScrENcES at Paris, for the Year Mpccix.
In thee HISTORY.
1. F the foagreen, which comes from Turkey.
Il. Of great cold coming with a fouth wind.
Ill. Of the Seine mot being entirely frozen in the bard winter of 1709.
IV. Of a pullet with two bearts.
V. Of the legs of fea-urchins.
Inthe MEMOIRS.
I. Odfervations on the quantity of rain which fell at the obfervatory during the year 1708, with the alterations which happened to the thermometer and barometer, with re- gard to the beat and feafons, by M. dela Hire. |
Il. Obfervations on the quantity of rain water, and on the winds, by M.\e Comte du Pontbriand, at bis cafile two leagues weft from St. Malo; communicated to the aca- demy by M.du Torar, of the academy, and compared with thofe which we have made at Paris at the royal oblervatory, during the years 1707, and 1708, by M. dela oe
Il
A TABLE, &e. 163
Ii. Ob/ervations on the water which fell at Ly- ons, during the year 1708, by M. de la Hire. my est
IV. A comparifon of the barometrical obferva- tions made at Paris and at Zurich, in the
~ year 1708, by M. Maraldi.
V. Obfervations on the motions of the tongue of the wood-pecker, by M. Mery.:
VI. An explanation of fome facts in opticks, and of the manner in which vifion is per- formed, by M. dela Hire.
VII. 4” examination of a confiderable difficulty propofed by M. Huygens, againft the Car- tefian /yftem of the caufe of gravity, by M. Saurin.
VIII. Obfervations on the weight of the atmo- [phere, made at the caftle of Meudon with M1. Huygens’s double barometer, by M. de la Hire.
IX. 4 comparifon of the barometrical obferva- tions made in different places, by M. Ma- raldi.
X. Obfervations on cray-ffo, by M. Geoffroy,
un,
Xf. of the formation and growth of the foells of land and water animals, either of the fea or of rivers, by M. de Reaumur.
XII. Conjectures and refleétions on the matter of Jive or of light, by M. Lemery the fon.
XIII. Od/ervations on the evaporation which hap- pens to fiuids during a great cold: with
. remarks on fome effects of the froft, by M. Gauteron, of the royal faciety of {ciences at Montpellier.
- XIV, The variation of the needle at Nuremberg,
by M, Wurt-Z_ baur.
R 2 XV.
sod Go A TaBLe, &ec.
XV. A comparifon of the obfervation of the e- clipfe of the moon, Sépt.29, 1708, made at Nuremberg, Genoa, aud Marfeilles, by M. Caffini the fon.
XVI. Reflections on the obfervations of the eclipfe of the Jun, March 11, 1709, made in different countries, by M. Caffini the fon.
AN
AN
ABRIDGMENT
CO ee aed ae: Wee
PHILOSOPHICAL DiscovERIES and Os- SERVATIONS in the HisTrory of the RoyAL ACADEMY of SCIENCES at Paris, for the Year 1709.
I. Of the fhagreen which comes from Turkey.
M. Faugeon having been curious to know what the fhagreen is, which comes from Turkey, in- quired of M. Feriol, ambaffador at Conftantinople, from whom he received. all the information that he defired. There is no animal of this name, as fome have imagined. They make the fhagreen of the fkin of the buttocks of horfes and mules, which is well tanned, and rendered as thin as poffible ; it is prefied for a certain time, after being ftrewed with the fineft muftard-feed. When the feed takes well, the fkins are beautiful; if not, there remain fome fmooth places called mirrours, which are a great blemifh. The fineft fhagreens
are made at Conftantinople, and in fome parts of Syria.
Il. Of great cold coming with a fouth-wind.
It has been thought furprifing, that the cold of the winter 1709, which was fo extraordinary, and rigorous, lafted feveral days at Paris, with the wind at fouth. To affign the reafon of it, M. de la Hire las faid, that the mountains of
Au-
The History and Memorrs of the
Auvergne, which are to’ the fouth of Paris, were then. all covered with fnow ; and M. Homberg, that a very cold north-wind, which came a great way, and extended very far, having preceeded, the fouth wind was but a reftux of the fame air, which the north had driven, and had not been heated. in any country. Thefe two caufes may eafily be joyned together.
Ill. Of the Seine not being entirely frozen in the bard winter of 1709.
There were another wonder in that winter. Notwithftanding the extremé violence of the cold, the Sei#e was not entirely frozen at Paris, and the middle of its current was always free, only there floated fome great flakes of ice in it. And yet, in lets feveré winters, the Seize has been fo frozen, that carts might go upen tt. M. Hom- berg is: of opinion, that in our climate at leaft fich great rivers would not freeze of themfelves, except toward the edges, becaufe their current 1s always too firong tov Wards the middle ; and there- fore if they did not break the ice 4t the fhoar, which they never fail to do for different reafons, the middle would flow as ufual, and would not éarfy flakes of ice with. it; fuppofing alfo that there fell no fmali rivers into the great one; but as they do fall into it, the ice carried by it in the middle comes for the moft part from the fmall rivers, which are eafily frozen, and where people break the ice; that thefe quakes being ftopped either by a bridge, or bend of the river, or by any obftacle whatfoever, hold and ftick together by the cold, and afterwards form a fort of cruft, which covers the whole furface of the rivers and
laitly,
Royat ACADEMY of SciENcEs, 167 laftly, that as the cold of 1709 was very fudden and fharp from its very beginning, the fmall ri- vers which fall into the Seine above Paris, froze all at once, and entirely; fo that their flakes which would have faftened on the furface of the Seine, could not be carried into it; at leaft inva fufficient quantity. It is pretty remarkable, that the very violence of the cold was partly the caufe that the Sezwe did not freeze.
In the fame winter, the ice of the port of Co- penhagen was 27 inches thick, even in the places where it was not accumulated. This fact is the more worthy of attention, becaufe in she great froft of 1683, the royal fociety having caufed the thicknefs of the ice of the Thames to be meafur’d, when they went upon it. in coaches, found it to be but 11 inches.
i. Of a pullet with two hearts.
M. Pilaniade, of the royal fociety of Montpel- ier, being at Paris, met with two pullets within a fhort fpace of time, each of which had twe hearts. He gave thofe of the laft to M. Cafini the fon, who brought them to the academy. M. Litire foaked them in warm water, in order to examine them. ‘They were oi-equal fize; and each of them very little lefs than the heart of a pullet of the fame age. They were placed even with each other, at the diftance of half an inch 5 each of them had its ventricles, its auricles, and ‘all the blood-veifels, like common hearts; and had nothing fingular, except their being both faftened by their lower vena cava to one of the lobes, of the liver. MesLittre conjectures, that ‘the blood of the right ventricle of the right heaxt
. 5 went
168 The History and Memorrs of the
went into the right lobe of the lungs; and the
blood of the right ventricle of the left heart into the
left lobe. . As forthe other circulation, either the
oorte of both hearts might be united, and form
but one, or the aorta of the right heart furnifhed
blood to the parts of the right fide, and that of ‘ the left heart to the left fide; or both diftributed
themfelves equally through the whole body, fo, that there was always a double artery. Befides,
as each of the hearts had almoft as much force as
one fingle heart, this pullet had twice as much
life as another, and if one heart failed it, it
would have another to fupply the place. This
confirmation, which, according to what has been
feen, is probably not very rare in this fpecies,
cannot be impoffible in men, and perhaps it has
already produced fome phenomena, which have
confounded the naturalits.
~ —— V. Of the legs of the fea-urchins.
Naturalifts think that the fpines, with which the fea urchins are furrounded, ferve them to walk upon inftead of legs. But M. Gandolphe having obferved at Mar/eilles that thefe animals walked pretty quick at the bottom of the fea, has difcovered, that this motion is not executed by their fpines, but by legs difpofed about their mouth, which is always turned againft the bot- tom of the fea; thefe legs immediately difap- peared as foon as the urchins are taken from the bottom of the water, and thence came the com- mon error. It was known that they walked, and they were not feen to have legs, becaufe they had not been feen walking in the fea. They are like thofe of a flat infeét, called the peonrew
whic.
Royat Acapemy of ScIENCEs. 169
which M. Gandolphe has ftudied at Dunkirk, and has promifed a defcription of it, which pro- bably we fhall never fee; for the academy have been informed of his death this year, and are afraid of lofing, with fo good a correfpondent, a. great many fine obfervations.
Voir olf. NT. 28; S AWN
AWN
ABRIDGMENT
Or otis
PH1LosopHicAL Memorrs of the Royar AcADEMY of ScIENcEs at Pars, fgg the Year 1709.
I. Obfervations on the quantity of rain which fell at the obfervatory during the year.1708, with the alterations which happened to the thermometer and barometer, with regard
to the heat and feafons, by M. de la Hire.
HE quantity of rain, which fell during the year 1708, wasin
Lines. Lines. Jan. 283 July 29 Feb. 15 Aug. iehe March B53. Sept. 12 April 17% . QOctob. 15 May 30%. Nov. 64 June 23s Dec. 92
Yotal 219 lines 4, or 18 inches }.
This quantity of water is not very far from 19 inches, to which we have fixed the mean years; and as M. Mariotte had formerly determined By. like obfervations, which he had caufed to be made at Dijon by one of his friends.
The greateft quantity of rain that fell in one day, was but ro. lines about May 24, and O@. 20; and with an almoft north wind, which is obfer- vable ; for this wind feldom brings us the greateft rain.
The prevailing wind of this whole year, was the foucu, and ic feldom turned towards the north, 3 and
/
~ Royar Acapemy of ScIENCEs, 971
and often to the eaft and weft. There were great fogs both at the beginning and end of this year.
“There fell three inches of fhow, Feb. 14, and about as much Nov. 14, anda little Dec. 5.
During the whole year there were ayotel moet but not very violent.
~ My thermometer, which is at 48 parts of its divifion, in the mean ftate of the air, and at the bottom of the caves of the obfervatory, where it always remains in the fame ftate, being expofed in an open place, but theltered from the wind and fan, was at the loweft at the beginning of the year, Feb 13. at 27 parts $3 and it begins only to freeze in the country when it i8 at 392 parts, which fhews, that it was no very_great. cold at that time ; for before that day, and afterwards, it was always towards 35 or 40 parts. At the end of the year, on O47, 29, it froze, the ther- mometer being, at 29 parts, but without continu- ing; and the whole month of November was pretty mild in proportion to the feafon. The thermometer fell alfo to 25 parts Dec. 12; and on this day was the hardeft froft of the whole year, which was not very confiderable, for the ~ thermometer fometimes falls to 13 parts.
The greateft heats of this year were Aug. 15 and 16, asufual; the {pirit of the thermometer rifing to 66 parts 4 towards fun-rifing, and to 76 “parts about 3 in the afternoon. Thus the heat and cold of this year were nearly at the fame de- gree with regard to the mean ftate.
My barometer was at the loweft at 26 inches g lines Fan. 10, with a moderate fouth eat wind, as it was on the days before and after; and it was at the higheft Nov. 17, at 28 inches 1 Tine $ with alow north north-eaft wind, and on the days before and after towards the fouth;
2 {g,
172 The History and Memoirs of the
fo that the difference between the loweft and the higheft was 1 inch 4 lines 4 nearly. I have alfo another barometer, in which the quickfilver keeps up at three lines higher than in that which I make ‘ufe of to mark my common obfervations every day, though thefe 2 barometers make light in the vacuum by agitating the quickfilver, which fhews there is no air in them, or very little in propor- tion to what is commonly thought. Thus this difference of heighth muft come only from the different weight of the quickfilvers.
I obferved the declination of the magnetital needle Dec. 27, and found it to be 10° 15/ to the weft. This needle is 8 inches long, and is that which I always ufe.
I]. O6-
~ RoyvaL ACADEMY vicsbieé 473
0. Obfervations on the nail ty of rain water and on the winds; by M. \e Comte du Pontbriand, at bis caftle 2 leagues weft from St. Malo; communicated to the academy by
MM. du Torar of the academy, and com-
_ pared with thofe which we have made at Pa- ris, at the royal obfervatory, during the years 1707 and 1708, by M, de la Hire*.
Quantity of rain-water.
In 1707. At Pontbriand. At Paris. Lines. Lin. 9 204 10
2 maT
Jan. Feb.
March April —— 7$—— 4 May -—— 6!——11} June ——314——17 July 40 38 Aug. ——38 344 Sept. 203-——~ 9} Oct. ——32 ——,1 Narie—s1035—— 6 Dec, ——57+ 27%
Inch. Lin.
Total at Pontibrand 24 10% Paris 17 112
In 1708.
At Ponthriand. At Paris. Lines. Lines. 35 —28 1§84—————-—15 224 16 30% ERE 26}-———-—-30$ 24 -————23§ 10 —32
67 —I5 437 12 357 15 II 6! 247 aot 9g
Inch. Lin.
Total at Poathriand 24 6 Paris
18}
Some like obfervations, which M. Ze Comte du Pontbriand had communicated to we before, fhewed that it rained a little more towards St. Malo than at Paris, which is confirmed by the 2 years which we have juft compared,
#'Fe 9. 1709.
0%
174 The History and Memoirs of the
On the winds in 1707,
In Fan. the winds were generally more to. the S. at Paris than at Pontbriand, by a quarter of the compafs.
In Feb. almoft the fame.
In March the quite contrary to the preceding months.
In April much the fame as in Fan.
In May the winds were different in thefe two places.
In Fune pretty much alike; but fometimes more to the S. at Paris than at Pontbriend, bya quarter of the compafs. ae
in Fuly the ie almoft the fame, with very great heats, the 21ft at Paris, as.atPontbricnd,the wind being S.E. S. and:S. W.
In Aug. pretty often more to the S. at Paris than at-Ponibriand,
In Sept. the winds a little different in thefe two places.
In O@. fometimes the fame, and femetimes oppofite,
In Nov. often the fame, but at Paris fome- times more to the S. than at Pontbriand.
In Dec. often the fame, fometimes oppofite, but often at Paris more to the S. than at Powt- briand,
At Poutbriand the greateft rain on the fame day was 10 lines Fuly 3, with a N. E. wind: that day the wind at Paris was S. W, with thun- der, but without rain. In all the reft of the year, the.greateft rains on the fame day rofe bat to 6 lines at Powtbriand. But at Paris the rain was_ 16 lines Fuly 15, with a {trong wind to- wards the S; but at Pontbriend there fe bat 6 lines and half, with the fame wind that, cay
‘
AL
Rovart ACADEMY of SCIENCES, 175
At Paris the greateft rain was 21 lines + Aug, 12, with a low wind towards the W. and at Pouthriand 5 lines, witha N. wind. In Of. at Paris, the 4th and 5th together gave 24 lines, with a wind toward the W. and at Pontoriand 6 limes 4, witha N. W. wind.
On the winds in 1708.
In Fan. the wind more to the S. at Paris than at Pontbriand, and fometimes the farne.
In, 72d. often the fame.
In March generally the fame.
In April the fame, but on fome days a little different.
In May at Pontbriand, the night between the 6th and 7th a fharp froft, which blafted all the trees ; but at Paris fine weather: the winds dif- ferent. ~ Tn Fune the winds different, and at Paris u- fually more to the S. | .
In uly very few obfervations at Ponthriand, fo that nothing is difcovered of the difference.
In 4ug. more to the S. at Paris than at Pont- briand,
In Sept. as in Aag.
fn Of. the winds different in thefe two places.
In Nov. alittle different.
Tn Dec. the fame.
We cannot make a very juft comparifon of all thefe winds; for M. du Pontbriand marks the rhumb only on thofe days when it rained.
At Pontbriand the greateft rain on one day was but 9 lines; the 20 and 27 of Ofober, the wind being S. E. and S$: W. and 8 lines 4- pril 22, witha S. EB. wind. O&.20, at Parts, it rained ro fines, with a ftrong N, wind. On the
27th,
176 The History and Memorrs of the
27th, at Paris no rain; wind N. April 22, at Paris no rain, foggy. .
At Paris the greateft rain on one day was 11 lines 2, May 24, with a N. N. W. wind, and at Pontbriand 4 \ines 3, witha N. W. wind. At Paris g lines, July 2, wind S. W. at Pont- briand no rain. At Paris again, 10 lines OZ. 20, as was marked above.
IIE. Odjervations on the water which fell at Lyons, during the year 1708, by M. de la Hire *,
F. Fulchiron has obferved exactly the quantity of rain water, and melted fnow, which fell at Lyons at the obfervatory of the jefuits, and in the fame manner that I obferve here; of which © this is the refult of each month which he has com- municated to me.
In, Lin, In. Lin. Jan. 2 0. July 1.6% Feb. 3° 720 Aug 3 9Bu: March. 2. o2)\- Sepe. pes a April 3 gb 1 OR. 1 It May 2 2+ Novem. Oo 10 June 4 102 Dec. 2\ 7s
Sum of the whole year 35 inches, 9 lines.
We fee by this, that the quantity of rain water at Lyons was double what it was at Paris; and it is not probable, that this comes from the two great rivers which flow by it, and at mott could only form a great many fogs; but rather from the great mountains, which are but little diftant
* Apri 13, Frog: from
Roya AcADEMY of SCIENECS. 177
from it, where there always falls much more water and fnow than in the plains.
IV. A comparifon of the barometrical obfer- vations made at Paris and at Zurick, dur- ing the firft fix months of the year 1708, “by M. Maraldi.
M. Scheuchzer has fent to the academy a me- moir, wherein are feveral obfervations, which he has made at Zarick during the firft fix months of the year 1708, on the barometer, thermometer, winds, conftitution of the air, quantity of rain which has fallen, and on the augmentation and diminution of the Limat, a river which paffes by Zurick. They were made every day of the month, and often twice on the fame day. Toall thefe ob- fervations he adds others at the end of each month, upon the difeafes, which prevailed during that month.
For the barometrical obfervations, he made ufe of two tubes, one upright, the other inclined, in which the motion of the quickfilver is twice as fenfible as inthe upright one. Thefe heights are divided into inches and lines of the Paris foot. Thete two barometers often agree together, but fometimes there is a difference of 4 lines. In the comparifon which we have made of thefe obfer- vations with our own, we have made ufe of the upright barometer. To meafure the rain, he fays, he made ufe of the method of the academy and of the Paris meafure. He allo ufed the fame meafure, to know the augmentation and diminu- tion of the Limat. Md Warns 15% !
Fan. 1, the barometer was at the obfervatory at 27 inches, 5 lines, the wind being S. At Zu- yick, with the fame wind, the barometer was at Vor. WI. N°. 28. T a" 3G
178 The HisTory and Mrmo1rs of tke
26 inches, 3 lines; fo that the difference between the obfervatory and Zurick was 1 inch, 2 lines, by which the quickfilver was higheft at the ob- fervatory. The moft common and mean diffe- rence is 1 inch, 4lines. After Fan.1, the ba- rometer rofe in both places till the 34, and then fell rill the roth, when it was at Paris at 26 in- ches, 10 lines 4, at Zurick, at 25 inches, 11 lines, which are almoft the loweft to which it falls at either place ; thus it had fallen about 6 lines; in this interval the wind was at Paris S. or S. W. at Zurick it was at the fame time almoft quite op- pofite; that is, N.or N. W. The barometer rofe the reft of the month. At Paris the 19th and 20th, there were very violent S. W. winds. M. Scheuchzer obferves alfo, that on the 19th there was a ftrongS. W. wind; and adds, that on the 25th at 10 p.m. there was a very vio- Jent wind, which threw down a great many chimneys. His thermometer was Fan. 29, at 10 degrees, which is the loweft to which it fell. During the month of Fan. it rained at Zurick 18 lines? ; at Paris it rained above 34 lines. The diminution of the Limat was g inches, the augmentation two.
At the beginning of Feb. the barometer being very low at both places, it rofe from the 6th to the gth, in 3 days, a little more than 10 lines at Paris, and 8 lines at Zurizek; it then fell till the 16th, and afterwards rofe till the 22d, being as it had been Feb.g, at Paris at 28 inches, 1 line, at Zurick at 26 inches, 8 lines, which are almoft the greateft heights to which it ufually rifes. Dur- ing the month ‘of Feb. there generally prevailed the farne N. and N. W. wind at Paris and at Zurick, and in both thefe cities there fell the fame quantity of rain, that is, 19 lines. The di-
| ; minution
RoYAL ACADEMY of SCIENCES. 179
iminution of the water of the Limaz in height was g inches 3, and the augmentation 1 inch #.
There happened feveral variations in the height of the barometer in the month of March, and thefe variations happened on the fame days, and were almoft the fame at Paris and at Zurick. It continued elevated the two firft days, and funk the third : it rofe the three following days, and funk again till the eleventh. After having rifen till the fixteenth, it funk a third time till the twenty-fecond. The wind was N. at Parzs, and N.W. at Zurick. It rained at both places 17 lines. ‘The augmentation of the Limat was 5 in- ches, equal to the diminution.
April 10, at Paris, the barometer was at 27 inches 2 lines $, with a weft-wind; at Zurick, it was 25 inches 11 lines, witha north- wind, he barometer rofe a little the following day in both cities, and it funk again the 12th at Zurick and at Paris, where it continued to fall again the 13th with a violent fouth-wind. It rained in Apri] 26 lines.at Paris; and 52 lines 2 at Zuri ck.The Li- gat increafed 24 inches, and fell but 4 an inch.
The days that the barometer continued higheft in May at both places were, the 7, 8, 9, and 28th, and the days that it fell moft were the 16th and x7th. The fame at both places. It rained in May, at Paris, 27 lines}; at Zurick, 21 lines 2, The diminution of the Limat was 4 inches, and the augmentation 18.
During the month of Fuze, the barometer ge- -nerally continued at a great height, except the 4, 27, and 3oth, when it was at Paris at 27 inches 5 lines, at Zurick 26 inches i line. The days that it continued at the higheft were the 14th and 15th, being at Paris at 28 inches, and at Zurick at 26 inches 5 lines. It rained at Paris
ae 25
180 The History and Memoirsof the
25 lines , at Zurick 66 lines . The augmen- tation of the Limat 21 inches, the diminution 7.
The greateft height to which the barometer rofe in the 6 firft months of this year was at Paris, on the 9th and 22d of Fed. to 28 inches 1 line; and the leaft height to which it fell, was Feb. 1, when it was at 26 inches ro lines. So that the variation from the greateft to the leaft heighth was 1 inch 3 linesat Paris. At Zurick the greateft height was 26 inches 8 lines, Feb. 9, and.22. The leaft was 25 inches 11 lines, Fed. 1. ‘The difference is g lines, being lefs by 6 lines than what happened at Parzs.
A comparifon of the barometrical obfervations made at Paris, and at Zurick, the 6 laft months of the year 1708.
In Fuly the barometer generally continued at a ereatheight at both places ; it was at a mean height only on the 6th and 7th, being at Paris at 27 inches 7 lines; at Zurick at 26 inches 2 lines 4 and 3 lines; fo that the difference was 1 inch 4 lines, as we have already concluded by other com- parifons. The wind, which prevailed at the fame time in thefe two cities, has generally been dif- ferent, and often oppofite. It was the fame only for 4 days, the rith, the 18th, and the 22d, being in both places north-eaft, and the 16th fouth- welt. The thermometer was the higheft at Zu- rick the 28th, at Paris the 20th. In Fuly it rained at Paris 28 lines, at Zurick 48. The wa- ters of the Limat augmented 1o inches, and di- “minifhed 16; thus M. Scheuchzer fays, that the augmentation of the rivers does not anfwer tothe quantity of rain, fince the Limat diminifhed more than it increafed, tho’ there fell a great quantity of rain during the month of uly,
In
Roya Acabemy of SciENncEs, 181
In Aug. the variation which happened to the height of the barometer was 4 lines at Paris, and 3 at Zurick. The winds were moft. part, of the time very different in thefe 2 cities, The day that the thermometer rofe the higheft, was the _.a5th at Paris, the fame as at Zurick. It rained at Paris 22 lines $, at Zurick 35 lines ?. The waters of the Limat increafed 3 inches in height, and diminifhed 22 inches.
In Sept. the day that the barometer was the higheft, was the firft, both at Paris, and at Zu- rick 3 and the day that it fell the loweft, was the 26th at both places. The roth, a fouth-eatt wind prevailed in both places ; the 2oth, a fouth- weft wind ; the 21{t, a fouth wind: on the other days the winds were different. Itrained at Paris 12 lines, at Zurick 34. The Limat diminifhed 12 inches without having increafed.
In Of. the barometer continued higheft the 6th and 7th, the 18th and the rgth, both at Paris, and at Zurick. During almoft the whole month there were north, north-eaft, or north-weft winds. It rained at Paris 14 lines 3, at Zurick 27 lines 4. The perpendicular height of the waters of the Zimat diminifhed 10 inches without having increafed.
In. Nov. the days that the barometer was the higheft, were the 1ft, and the 19th, the fame at Paris and at Zurick ; and the day that it fell the loweft at both places was the 23d. The fame wind prevailed the 24th and 26th. The coldeft ' day was the 25th at both places, It rained at Paris 5 lines $, at Zurick 7. The diminution of the Limat was 6 inches without having increafed.
In Dec. the 14th was the day chat the barome- ter was the loweft in both places. The days that 5 nape was the loweft, were at Pai
the
182 The History and Memorrs of the
the aith and 14th, at Zurick the 12th and the 29th. There was no day when the wind was the fame in both places. It rained at Paris 9 lines 2; at Zurick it rained 21 lines 2. The diminution of the Limat was 4 inches without augmentation.
The total fum of the raia which fell at Paris; according to our obfervations, was 20 inches one Jine; that which fell at Zurick is 30 inches; fo that there fell almoft 3 of rain more at Zurick, than at Paris. M. Scheuchzer thinks it rains more in Swifferland, than in France, becaufe of the great quantity of mountains, where the clouds being driven by the winds, commonly pour down in rain and fnow. ‘The great quantity of rivers which proceed from thefe mountains, give room alfo to imagine that the rain falls there in greater abundance. He thinks alfo, that there falls more rain in the countries near the fea, than in thofe which are inland. He fays, that at Upminfter; in England, according to Dr. Der/am’s obferva- tions, it rains 1g inches of water, when at Townley in Lavcafhire, there fall 39 inches.
In the 6 firft months of the year 1708, the augmentation of the waters of the Limat was 71 inches 4; the 6 laft it was 13; and the total aug- mentation 84 inches 4. The diminution during the 6 firft months was 35 inches, and 67 in the 6 laft. The total diminution 102 inches, greater by 16 inches than the augmentation.
M. Scheuchzer fays, that the augmentation of the waters in the rivers of Swij/er/end comes chiefly from the melting of the {nows upon the mountains,which appears by feveral torrents of that country, and in particular, by thofe which he calls Taminna, the waters of which increafe every evening, in fummer, often to a foot in height,
tho’ it has not rained all the day. From the di- minution
‘Roya Acapemy of Sciences. 183
minution of the waters of the Limat being greater than the augmentation, M. Scheuchzer infers, that his country is colder than that which is farther from the A/ps, where it is winter the greateft pare of the year, there being in Swifferland but two months of fummer, which ought rather to be called a {pring.
VY. Obfervations on the motions of the tongue of the wood-pecker, by M. Mery *.
In order to give a more juft explanation of the motions of the tongue of the wood-pecker, than that which appears in the works of M. Bore/li and M. Perrault, I fhall defcribe more exactly than they have done all the parts on which its motions depend.
- Notwithftanding the tongue of this bird feems to be very long, yet its proper length is certainly but 3 or 4 lines ; for that of the body and branches of the os hyoides, which thefe authors have afcrib- ed to it, do not belong to it in anatomical ftrict- nefs. :
The tongue of the wood pecker is made of a very fhort little bone, covered with a horn of a fcaly iubftance: its figure is pyramidal; it is articulated by its bafe, with the anterior extre= mity of the os byoides. 4
The os byoides is about 2 inches long, and 2 a line thick ; it is articulated by its pofterior extre- mity, with 2 bony branches more flender than its body. Each branch is compofed of 2 bony threads of unequal Jength, joined together, and clofed at the end. The foremoft thread is but 1 inch £ long ; ‘the hinder, which was unknown to M. Borelli, is 5, or thereabouts, being united to a
* March 13. 1709. F e . ' ede Ittle
184 The History and Memorrs of the
little cartilage which terminates it; fo that, each branch is 3 times as long.as the body of thé os. Syoides and that of the tongue together. Thefe.. branches which belong to the os hyozdes, are bent » in form of an arch; the middle of which occu-.. pies the fides of the neck, the anterior extremities pafs under the beak, Bae are terminated in the: . body of the os hyoides; their pofterior extremities pafs over the head, and enter the nofe on the right fide; but it 1s obfervable, that they are not arti- culated to it; which contribures very much to the egrefs of the tongue, as J shall thew hereafter.
The os hyotdes and the anterior thread of its branches, are inclofed in a fheath, formed-of the membrane which lines the infide of the lower beak. ‘Fhe extremity of this fheath is united to the open- ing of the fcaly horn of the tongue. This fheath is prolonged, when the tongue comes out of the . beak, and contracts when it returns.
The fcaly horn, which covers the little bone of the tongue, is convex above, plane underneath, and hollow on the infide: it isarmed on each fide with 6 very fine, tranfparent, and inflexible points: their extremity is a little turned towards the throat. It is probable that this horn, armed with thefe little points, is the inffrument with which the | wood-pecker catches its prey; which he does with fo much the more eafe, as this inftrument is always lubricated with a glutinous matter, which is poured into the extremity of the lower beak by 2 excretory ducts, which go from 2 py- ramidal glands fituated at the inner fides of this
art. . 3 To make ufe of this inftrument, nature has gi- _ ven the wood-pecker feveral mufcles, of. which. fome belong to the branches of the os Ayoides: thefe draw the tongue out of the beak; others ~ ‘belong
7
Rovav AcaveEmy of ScitEncEs, 185
belong to the fheath, which inclofes the body of the os byoides, with the anterior threads of its branches ; thofe draw the tongue into the beak. Laftly, the tongue has its ‘proper mufcles, which draw it up and down, and to each fide.
Each branch of the os byoides has but 1 mufcle, which alone is as long as the tongue, the os hy- oides, and one of its branches together ; thefe 2 mufcles derive their origin from the internal, late- ral, anterior part of the lower beak, and in re- treating they involve the pofterior threads of the branches of the os byoides, and paffing above the head, they are at laft inferted at their extremities, whence proceed 2 elaftic ligaments, which uniting together form a third, which faftens them to the membrane of the nofe. Thefe ligaments are very fhort; but are eafily prolonged by being drawn. Now as the refiftance of thefe ligaments may eafily be furmounted by the contraction of thefe mufcles, it is eafy to conceive, that when they contract, they draw the pofterior extremities of the branches of the os hyoides out of the nofe, and carrying them away on the fide of their origin, they drive the body of the os Ayoides, the anterior threads of its branches, and the tongue out of the keak ; which they could not have done, notwithftanding the great flexibility of the os byoides, if its branches. had been ftrictly faftened, or articulated with the bones of the nofe; for tho’ the arches, which they defcribe, may be extended, they could not have been fuficiently prolonged to drive the tongue 4 inches out of the beak ; which they do with fo much more eafe, as they have their mo- tion free in thefe muicles, where they are inclofed as in a canal, and alfo are not articulated with the bones of the nofe.
Vou. IH. N°. 28. U To
186 The History and Memoirs of the
‘To draw the tongue into the beak, nature has given to the fheath which inclofes the os hyoides, and the anterior threads of its branches, two mufcles to pull it back ; and becaufe their pro- longation and contraétion muft be equal to thofe of their antagonifts ; fince the tongue makes the fame way in retreating into the beak, as it does in going out of it, nature has taken care to place thefe mufcles in the little fpace which is between the under part of the /avynx and the end of the beak, to caufe each of them to make two circum- volutions a contrary way, about the upper part of the trachea, whence thefe two mufcles draw their origin ; after which they crofs one another behind the /erynx, and at laft line the infide of the fheath to which they are united; now as its ex- tremity is joined to the opening of the fcaly horn of the tongue, it happens that when thefe two mufcles contract, they pull and draw this fhedth backward, and thus drawing the tongue into the beak, they drive back the pofterior ex- tremities of the branches of the os byoides into the nofe. The 3 elaftic ligaments, which I have mentioned, ferve alfo to draw them back ; for after having been prolonged by the mufcles, which draw the tongue out of the beak, they contract as foon as thefe mufcles are relaxed, and draw into the nofe the branches of the os hyoides, to which they are faftened.
There is above the skull a groove, which with the skin forms a canal, which inclofes the hinder part of the branches of the os hyordes, with their mulcles, in which thefe parts have their motion free. ‘This canal hinders the branches of the os hyoides from receding either way when they are drawn forwards, and makes them: eafily refume their place, when they are drawn backwards. ;
3 ; I
Royar, Acapemy of Sciences, 187
_If we do but refleét on the length of the tongue, the os Ayoides, and its branches joined together, and on the origin and determinate infertion of the mufcles, which make the tongue of the wood- pecker go in and out of the beak, it will be eafy to judge that M, Borel//i was miftaken; for if we confider, that the tongue of this bird, the os dy- oides, and the branches joined together, are 8 in- ches in length, and that of this length there comes 4 inches out of the beak when it is drawn, we fhall eafily conceive, that the tongue making the fame Way in fetreating, as it did in going out, the mufcles, which pull it backwards and forwards, muft each of them have prolongations and con; tractions of 4 inches, and that confequently they muft be above 4 inches long, not being able to contract their entire length. Thus, of the 4 firft mufcles, which M. Borelli allows the tongue for its motions, two taking their origin from the ex- _ tremity of their lower beak, and the two from the fore part of the skul], and all the four being inferted into the middle of this length of 8 inches, it 3s vifible, that thefe mufcles could never have fuch an effect, fince at moft they would be each of them ao more than 4 inches.
'M. Borellz would not have fallen into this opi- nion, if he had obferved that the two mufcles; which rife from the beak, run through the whole extent of the body and branches of the os byoides, His miftake therefore comes from having divided . each of thefe mufcles into two, and from having ‘known that the anterior threads of the branches of the os #yoides, at the end of which he places the in- fertion of the four fir mufcles of the congue; which he hasdeicribed. As forthofe, which turn about the trachea, he knew the true ule of them. »
Le As
3188 TheHistory and Memoirs of the
-- As for M. Perrault, he was much more mif- taken than M. Borelli, For firft he makes no mention of the mufcles which incompafs the ¢ra- chea, and yet it is by their ation alone, that it is withdrawn into the beak. Secondly, he makes M. Borelli’s 4 firft mufcles rife from the larynx, and fends two of them to the pofterior extremi+ ties of the branches of the os fyaides, and the other two to their anterior extremities, to draw the tongue in and out, and thereby he falls into the fame inconvenience with M. S8ore//i;. but this miftake is the greater, as there goes no mufcle from the larynx, to be faftened to the branches of the os byoides,
In fhort, the whole inquiry which thefe gen- tlemen have made to explain the motions of the tongue of the wood-pecker, is terminated in the mutcles, which make it come in and out of the beak. It does not appear, that their anatomifts gave themfelves the trouble to penetrate farther into its ftruéture: thence it comes that thefe gen- tlemen have told us nothing of the 4 mufcles’ pro- per to the tongue of this bird, by which it is moved up and down, and to each fide, whether it is placed within or without the beak,
Allthefe mafcles derive their origin from the anterior part of the branches of the os Ayoides, two from one, and two from the other, and are ter- sninated each of them in a long flender tendon ; thefe four tendons embrace ithe body of the as byoides, and are infertéd intothe bate of the little bone of the tongue. When all thefe mutcles act together, they hold the tongue ftraits when the mufcles of the. upper part--contract at the fame time, they draw the tongue upwards ; when thoie of the under! part “are -in adtion, they draw it downwards. But when two mufeles- placed -oa the
-Rovat AcADEemy of ScrEnces. 189
the. fame: fide act, fogether, they pull it- to that fide.
Now, as of all the- naufcles els ferve ion the diGatens motions of the tongue, only thefe four Jat. are inferted into it it is vilible, that the mufcles, which pull it in and. out, do not pro- perly . belong to it,- but to the fheath and branches of the os 4 hanes where thefe mufcles are inferted as I have fhewn; whence it follows, that the motions, which the tongue makes going in and out of the beak, belong alfo to thefe parts, and not to the tongue, fince in thefe two motions it may remain unmoveable,
An explanation of the figures in Plate III. Fig. 1, 2, and 3.
A. The tongue of the wood-pecker, .
B.. The proper bone of its tongue,
_ ©. The dcaly-horn armed with points, in which this bone is received.
D.D.D.D. The four proper mufcles of the fongue,
» E. The body of the os hyoides.
F. F. Its two branches.
G. G. The anterior threads of thefe branches.
H.H. Their pofterior threads.
LI. The two glands, which nis the platineas matter to lubricate the tongue.
_ °K. K. The apertures of the excretory veffels of thefe glands,
LL. Vhe membranous fheath, which ictal ‘the os hyoides, the anterior bhteags of its branches, the four mufcles of the tongue, and the anterior part of the two mufcles, which draw it back inte the beak.
M. M. The two mulcles, which puil the tonzue out of the beak,
N..D
igo The Hisrory end Memoirs of the
N.N. The two mufcles, which pull it into the beak.
VI. An explanation of feme fatts in opticks; and of the manner in which vifion ts per-
formed, by M, dé \a Hire +.
We know that the pupil of the eye in moft ani- mals contracts with a {trong light, and opens con- fiderably in the dark. It is eafy to fee in the diffection of the eye, that the zrzs, which is per- forated in the middle, where it is called the aper- ture of the pupil, is a circular mulcle, which cam contract by retreating towards its circumference, which then increafes the aperture of the pupil ; but in relaxing, its parts return from the centre of the pupil by an elaftic power; and this is what diminifhes the pupil.
To underftand rightly how this change can be made in the pupil by the action of the mufcle, we muft confider that the body of this mufcle is toward its circumfevence, where it is faftened within the eye, and that all its fibres feem to tend from the circumference toward the centre, which they do not reach; for they are terminated at the little circle, which forms the pupil. Bur this mufcle having a pretty confiderable thicknefs to- wards its head, if its fibres recede from each other according to the thicknefs of the mufcle, where there ought to be a great quantity of them, their extremity which forms the pupil, muft draw nearer to the head, and confequently dilate the pupil; but when the action of the mutcle ceafes, the fpring of the*fame fibres may replace them in their firft ftate, and clofe the pupil; or there
‘+ March 30, 1709. Ne might
Royvat ACADEMY of SCIENCES. I91
might be fome elaftick fibres in this mufcle, which would ferve only for this purpofe ; or laftly, we might imagine another mufcle of but little thicknefs, couched upon the firft, the fibres of which would be circular, and ferve it for an an- tagonift ; forthe circular fibres of this mutfcle, receding from each other according to their plane, would clofe the pupil, the action of the other mufcle having ceafed ; and this opinion feems to me the moft natural, or I am moft inclined to follow it.
_ But of two antagonift mufcles the ftrongeft will always prevail, when there is no particular de- termination for either: whence it follows, that if _that which dilates the pupil is the ftrongeft, as it appears to be, we fhall judge that the natural ftate of the pupil is to be dilated.
The action of opening and fhutting the pupil is not of that kind’ which we call voluntary, but of that which is neceffarily performed by a foreign caufe, as it happens to feveral parts of the bodies of animals.
It feems probable, that a very. great light making too ftrong an impreffion upon the bottom of theeye, hurting, and in a manner burning it, as when we look at the fire, or at a white body expofed to the fun, obliges us immediately to clofe the pupil as much as poffible, to receive fewer of thefe too luminous rays, and to remove the danger which threatens the eye. On the con- trary, when we look attentively at any object in the dark, we do all we can to fee diftinétly, and perfeétly to difcern al] the parts of it, which we cannot do without the help of a pretty vivid light ; wherefore we dilate the pupil, that there may enter into the eye a greater quantity of thefe feeble rays, which altogether will make a ftronger
im-
192° The History and Memorrs of the
impreflion by reuniting themfelves in the prin- cipal organs of vifion.
But tho’ we are expofed toa pretty ftrong light, we do not always clofe the pupil, when we are attentive to look upon any object, the image of which isto be ftrongly painted on the bottom of the eye, which is obfervable in thofe animals, which can clofe and dilate the pupil in an extraor- dinary manner, fuch as cats 5 for when they are”in a ftrong light and quiet, their pupil is almoft quite fhut ; and if any extraordinary object, which roufes their attention, prefents itfelf, we fee them Open it at once as much as they can.
Nature feems to have given a particular ftruc- ture to the iris of this fort of animals, that it fhould not clofe circularly, but fidewife, that it may open readily and confiderably in the dark, where they moft often feek their nourifhment.
What attention foever we give to fee the {mall parts of an object, the pupil will always be lefs open ina ftrong light, than in the dark, efpecially if this attention lafts any time; for a ftrong light naturally obliges it to fhut, to hinder the principal organ of vifion from being hurt, Thus, in the dark, or in a faint light, we cannot queftion but that the pupil puts itfelf in its natu- ral ftate of dilatation, and that it does not open fo much as the equilibrium of the mutcles, which compofe the iris, permits, as it happens to all the parts of the bodies of animals, which are moved by antagonift mufcles.
The following obfervation is pretty common, and thofe who have made it have always obferved the fame thing. If you plunge the head of a living cat into water, the pupil immediately quite opens itfelf, tho’ the animal is expofed to very
brighs
Royat AcapEemy of SCIENCES. 193
bright objeéts; and then you may fee diftinétly the leaft parts that are at the bottom of the eye.
I undertake therefore to explain here by the laws of opticks:
ift.. Why luminous objects do not by their prefence oblige the eye of this cat to fhut.
2d,. Why we fee the bottom of the eye di- ftinétly,.
Let.O.* bea luminous or very bright object,
of which the rays OB come as parallel to each other.as far.as the cornea BB, the object O being at a moderate diftance from the eye. It is known that the eye being expofed to the air, the greateft refraction of the rays OB. is made at firft upon the cornea, and that. afterwards, after two other refractions, much lefs than the firft, upon the furfaces of the cryftalline, thefe rays meet in D, upon the bottom of the eye, which we call a good conformation. — But if the eye BB D is plunged in the water A A, fo that the furface A A is perpendicular to the rays OB, which come from the object O to the eye, then thefe rays OB meeting the fur- face.of the water A A perpendicularly, will fut- fer..no refraction therein, and will enter the eye a-crofs. its humours, which are but little different from the water, fuffering a little refraction there- in ; whence it follows, «hat. they will have adi- rection, to affemble towards E, very, far beyond the eye, and confequently that they will meet the bottom of the eye in points FF, diftant from each, other, .inftead of meeting in the fame. point D,
But. the rays of the! luminous. point Q,..which,. are entered into. the eye, occupying at that time a very confiderable fpace F Fen the bottom of the eye,..will make but a yery faint impreffion.on it,»
> * Plate III. Fig. 4. "AiR
fon. 1k N°. 28. x whereas,
194 The History and Memorrs of the
whereas they would have touched it very briskly, | if they had met in D; wherefore this luminous object in this cafe muit not oblige the pupil to contract. Befides this animal being in a violent flate, gives attention to all that furrounds it, which muft alfo oblige it to keep its pupil very open, as I have obferved already. | |
For this reafon nature has given fifhes, which live in the water, a very convex, and almoft fpherical cryftalline, that the rays of objects, which are in the water, and fuffer but little re- fraction in paffing thro’ the cormea, may turn fufficiently upon the furfaces of the cryftalline, to be colleéted onthe bottom of the eye. And if we find, that fome divers perceive objets in the wa- ter at a greater diftance than they would in the air, it can be nothing but a particular cafe of the conformation of the eye of thefe divers, who hay- ing the fight very fhorr, becaufe of the very con- vex figure of their cryftalline, can fee very di- ftinétly in the water, like fifhes, diftant objeéts of which the rays in the air would meet between the cryftalline and the bottom of the eye, and meeting the bottom of the eye in a confiderable {pace would be there confounded, and confequent- ty would make a confufed vifion.
We muft now explain why, when the eye of the cat is immerged in water, we perceive di- ftinctly all the parts of the bottom of the eye, as if it was not filled with humours.
It is certain, that the larger the windows of any room are, the brighter the objects will be there- in, and the more diftinétly feens wherefore we have a better view of the parts of the bottom of the eye of the cat immerged in water, when the pupil is very much dilated, than if it was con- tracted. But it is not only the great aperture of a ca bt An the
RoyaArt ACADEMY of SCIENCES. 195 the pupil, which makes us fee objects dutinetly, fince . ia men, who. have the gutta [erena, and whofe pupil is very open, we can perceive nothing at the bottom of the eye, which is expofed to the air... It. is therefore the water, which touches the eye, that makes us fee thefe objects, and this is what we muft explain by the fame principles of opticks, which we ufed at firft.
When an eye well formed isin the-air, the rays which diverge from a point D * of its bo:tom, having paffed thro’ the three furfaces of its hu- mours, turn from them in fuch a manner, as to come out almoft parallel to each other; wherefore we can fee this objeét D diftinctly ; fince rays that are parallel, or almoft parallel, always make a diftinét vifion in our eye, and yet we do not fee this obje& D,
Let us now examine what muft happen to the fame rays, which diverge from. the poin: D. of the bottom of the eye of the animal, when it is immerged in water.
Let BBD, as before, be the eye of the ani- mal immerged in water, of which the furface is A A. It follows, that the rays DB, which di- verge from the point D of the bottom of the eye, being a little turned or refracted upon the two furfaces of the cryftalline, muft meet the cornea, while they are yet diverging : but.as in coming out of the cornea in BB, they meetthe water AA, the refraction of which is not-fenfibly . different from that of the aqueous humour, where they paffed in touching the corwea, they mutt. continue their courfe in the fame right line, and continue ftill diverging quite to the furface of the water in A, whence at laft they muft go out to enter into the air, being yet more diverging than they were
* Fig. 5. fis2 | | x 2 in
£
196 Lhe History and Memoirs of the
in the water by the laws of dioptricks ; and con- fequently wherefoever we place our eye to receive thefe diverging rays, which are then dire¢ted as if they came from the point F, nearer to the cornea than the point D, we may very diftin@ly perceive the point D, as placed at EK and in the air.
This is what the plain furface of the water pro- duces upon thefe rays; but there is alfo another obfervation to be made, which fhews us why we do not fee the obje€ D of the bottom of the eye; when it is out of the water; and why we fee it when it is immerged.
The furface of all well polifhed bodies fends back the light, and fends it back or reflects it fo much the more. ftrongly as it is more polifhed ; and if thefe polifhed bodies are alfo tranfparent, a part of the light will pafs thro’ the body, and-an- other part will be reflected ; and this will always be in proportion to the tranfpirence and polifh. But as we have no bodies, whofe furface 1s more polifhed than that of liquids, we might fay there would enter into the eye expofed to the air, much’ fewer rays of light, than in the water, if the cor- mea was not always covered with a clear and unctuous liquor. This, therefore is not the rea- fon that we do not fee the bottom of the eye, when the cornea is expofed to the air; and that we do fee it, when the eye is in the water; for if the rays of light are reflected upon the cornea in the air, they will be reflected alfo upon the furface of the water, and almoft in equal quan- tity; which is contrary to the opinion of fome, who-have pretended that a great many were loft upon the cornea in the air, and have not ob- ferved, that no fewer were loft upon the furface
of the water. But
Rovat ACADEMY of ScIENCEs. 197
But it isnot fo much the quantity of the rays that are reflected upon the corwea, or upon the water, that muft be confidered, in what may bring fome interruption to a very clear vifion, tho’ the rays are rightly difpofed to make it, as the direétion of the fame rays reflected. For if thefe reflected rays are parallel, or nearly fo, to the axis of theeye, which meets the principal organ of vifion, where we fee the objects moft diftinétly, and where the object, which we confider atten- tively, is painted, we muft fee a pretty ftrong light in this place, and this by its brightnefs will hinder the diftinguifhing of thefe objects, which otherwife are of a dark colour; and this will hap- pen to the cornea of an eye, tho’ the light illu- luminates it only aflant. For the cornea being of a convex figure, fome rays may {trike upon it obliquely, which will be direéted almoft accord- ing to the axis-of the eye of him who looks; which does not happen to a plain furface, which would be perpendicular to this axis, where thefe rays would be reflected according to the fame in- clination to the furface, with which they had met it. Wherefore we can fee much more diftinly, and without the mixture of this foreign light, the parts of the bottom of the cat’s eye immerged in water, than if it was expofed to the air. It is for this reafon alfo, that when we are in the air out of a room, and look thro’ glafs, tho’ ever fo clean, upon the objects therein, we cannot fee them without difficulty, becaufe of the inequality of the furface of the glafs, which reflects the light every way.
We may make the experiment of what I here advance, by looking at an objet thro’ a round. glafs bottle, and afterwards thro’ a piece of plain glafs, the light playing in the fame manner upon the fpherica! and plain furfaces of thefe two glafies :
for
198 The History and Memorrs of the
for the head of him that looks near would hinder the rays which fhould fall upon the plain glafs, and nsight be reflected in the eye towards the: axis of vifion; but it will not be the fame thing upon the furface of the glafs bottle, where fome will always enter the eye almolt parallel to the axis, becaufe of the convex figure of the bottle.
In.what I have hitherto faid, I did not think it
neceflary to exprefs what part of the eye I took fur the principal organ of fight. But one of the moft famous anatomilts of this company having — examined the fact, which is the fubjeCt) of this memoir, and. having accounted for it very learn- edly by the motion of the animal fpirits in the eye of the cat, is for the choroides in oppofition to the retina, following, as he fays, the opinion of M. Mariotte. -_.M. Mariotte’s difcovery is one of the moft cu- rious that has been made in philofophy, and as the experiment is very eafy to make, we could not doubtof it. Yet [here repeat, that the defeét of vifion at the place where the reti#a is perforated by the choroides, provesnothing againft the retina, and that the cheroides can only “be confidered as an intermediate, organ, which communicates to the re- tinaithe vibration or motion, whichit receives from the light with its different modifications. And can we look forthe principal organ of a fenfe any where but in the nerves, which communicate with the brain, and can inform-the foul under different appearances of what. paffes out of. the body, and that by the interpofition of a certain medium pro- per to move them ; for the nerves are too delicate parts to be laid open.
It will be the fame with regard to. the other fenfes,.as to the fight, and we cannot fay, that the skin, which covers the whole body, is the
pro-
\
Royat AcApEmy of ScIENCEs. 199 principal organ of feeling, nor that the mem-
brane of the drum of the ear is that of hearing s
any more than that the skin of the tongue is thar of tafting, becaufe, when this skin is erate we have no fenfation of taftes.
The black colour of the choroides is very pro- per to be fenfibly fhaken by all the different and Jeaft motions of light, as we fee in the experiment of the white paper expofed to a burning mirror, which cannot be inflamed unlefs it is blackened 3 for the motion of the particles of the body which tranfrnits the light, or the light irfelf, acts ftrongly among, the points fet with black bodies wherein it is engaged ; whereas it is only reflected upon white bodies, which are compofed only of very {mooth parts Jike little mirrors. The retzna there- fore will not be fhaken by a reflection of the lu- minous rays upon the choroides, which is black, as our anatomift pretends. In fhort, the conclu- fion of his memoir fhews me, that he is not of M. Mariotte’s opinion, as he fays he is, but that he has followed mine, changing only the defini- tion of the principal organ of vifion, which he afcribes to the choroides, and Ito the retina. Thus the whole difference between him and me will be in the name of the principal ergan, for he makes vifion confift in a reflection of the Jumi- nous rays upon the choroides, and Tin a fhaking of the parts of the choroides, to be tran{mitted to the optic nerve or to the retina.
As for M. Mariotte’sopinion, be thinks, thatthe
' choroides is the principal and only organ of vifion,
and that this membrane alone carries to the brain the fenfations of colours, fince being a production of the ~7a mater itaccompanies the opticnerve all the way to the eye, where being arrived, it forms the choroides ; and laftly, that the optic nerve ferves
only
200 Fhe History aud Memoirs of the
only to contain the fpirits, and that it has no fibres.
But it feems to me not eafy to conceive, how the foul can have a fenfation of a very great quan- tity of objects, which are perceived all at once, and in the orderin which they are ranged, without imagining an infinite number of very flender f- bres, which compofe the optic nerve, and are dif- pofed in order on the whole furface of the retina, which the membrane alone of the pia mater, or of the choroides, could not do without a great confufion, even tho’ it had fibres like thofe of the optic nerve. But we fee that the functions, which I have afcribed to the choroides and to the retina, are both together. neceffary for vifion, and that one cannot be done without the other.
I could add alfo in this place, that we perceive colours only by a fenfation of heat; for no body imagines there is light without heat, whether this light comes directly from the luminous body, or by refleCtion. But as this heat is ufually fo faint, efpecially if the luminous body is very diftant from the body which it illuminates, there muft enter into the eye a pretty large quantity of thefe rays, and at the fame time they muft meet ina point upon the black body of the choreides, to make a ftronger impreffion upon it, and to make no confufion with thofe which come from other luminous points, and quite near, and modified in different manners, which the fenfe of feeling can- not perceive. This is a thought, which | think might be luppoyees, by Way ftrong, reafons.
vie
Royrat ACADEMY of SCIENCES. 201
VII. An examination of a confiderable diff- culty propofed by M. Huygens, againft the Cartelian /yffem of the cauje of gravity, by M. Saurin *.
The moft ordinary effe€ts of nature, which are the leaft ftriking to the vulgar, are not always fuch as give the leaft degree of exercife to philofo- phers. Such is the phenomenon of gravity. A ftone thrown up in the air falls down directly up- on the furface of the earth ; people do not-ufe to be furprifed at it; and yet to find the caule of this fall, is one of the moft difficult problems to be refolved in phyficks ; and we are not yet ar- rived toa folution‘{ufficiently demonftrated, which throws a full light upon all the difficulties.
I have undertaken a little treatife upon this fub- jet, which I have begun to read in our parti- cular affemblies. The academy may fee, that | place the caufe of gravity in the centrifugal effort of the celeftial matter which fareupdad us; and that I make this effort rife én it, from its circular motion about the axis of the earth, according to the notion of the Cartefian vortices. One of the principal objects thar I have propofed in this little treatife, is to defend this opinion againft the dif- ficulties, which have made two of the greateft geometricians of our age, M. Huygens, and Sir I, Newton who rejeét the hypothefis of the vortices.
M. Huygens makes three objections againtt this bypothefis, in his difcourfe on the caufe of gravity ; but only two of them appear to me worthy of confideration. It is of one of thefe two, which has often been repeated after him by a great many authors of all fizes, that we find a folution im the
* April 10, 1709. Mon. LL. IN. 29: ¥ fecond
202 The History and Memoirs of the
fecond Fournal des Scavans for the year 1703. I was willing to expofe this folution before-hand to the criticifm of the learned, that I might be fure not to deceive myfelf in thinking it fupported by a true demonftration, and to take advantage of the new lights, which their reflections might give me. -It has merited the attention of two authors, who pretend, not without reafon, to be profound in thefe matters, and are not much difpofed to favour me; but tho’ they have combated it with a good deal of fpirit, one in his Recherches de Pkyfique & de Mathematique, and the other in the Memoires de Trevoux ; 1 will venture to fay, that they have not weakened the confidence that I had inthe fecurity of this folution.
The other objection of M. Huygens is to be the fubject of this memoir, and I muft own I am not yet perfeétly fatisfied about it. Therefore I fhall not give this inquiry, as I did the former, the title of a folution, but of an examination.
In heavy bodies we perceive but two things clearly ; one, that being let go in the air they move according, to a direction which tends nearly to the centre of the earth; the other, that they endeavour to move according to the fame line when they are retained: and it is exa¢tly this ef- fort with which they prefs, or pufh what retains them. that is called gravity.
It is evident, that thefe two things are the effect of one and the fame caufe. The force, of what nature foever, which makes the heavy bodies move according to the conftant direction obferved by them, is the very fame that makes thefe bodies prefs according to the fame direction, the plane oppofed to retain them.
The queftion therefore about gravity is, only to give the reafon of a certain motion, namely,
3 | of
RoYAL ACADEMY Of SCIENCES, 203
of that\ particular motion, which carries bodies towards the centre of the earth, which on that account are called heavy.
If we confult our notions of the phyfical caufe of motion, they will prefent us with nothing clear, nothing diftinét but the fhock or impulfe: thus it is by this principle that we muft give a reafon for the motion of which we are feeking for the -caufe, or abandon this inquiry, and give up the hope of ever being able to explain in an intelli- gible and reafonable manner the phenomenon of gravity; and if we fhould not fucceed in explain- ing it by this principle, it will certainly fhew the infufficience of our knowledge, but not that of the principle,
See therefore according to this notion, in what manner we philofophife upon gravity with M. Huygens. Heavy bodies move toward the centre of the earth; therefore they are driven thither. Bodies cannot be driven but by other bodies in motion which fhock them; there are therefore other bodies in motion, which ftrike thofe which we Call heavy, and by this fhock drive them whi- ther we fee them tend. Thefe other bodies are not perceived; it is therefore a fubtile matter, which the delicacy of its parts hinders us from feeing ; and as we know befides, by a thoufand other effects, that the earth fwims in a fluid of an inconceivabie fubtilty, which furrounds it on all fides, there is no room to queftion its being to this fubulle matter, that we are to afcribe the im- pulfe, which produces the motion of the heavy bodies.
But how does it produce it? To explain: this in order, { fhould make long deduétions; but I omit them, and come directly to the point. Ic is its circulating about the earth with an extreme
+2 rapidity ;
204 The History and Memoirs of the rapidity : in this circulating it makes an effort to recede from the earth; and the grofs bodies not having, the fame motion, and not making the fame effort, muft be neceffarily driven towards the earth. Thus far M. Haygens and 1 have gone hand in hand, and philofophifed in con- cert: but now we are going to part; and this is the point of our feparation. M. Huygens makes the celeftial matter move circularly every way about the centre of the earth 5 that is, in his fyftem the centre of the earth is the common centre of all the circles defcribed by the celeftial matter: whereas, according to Defcartes, it is all moved the fame way about the axis from W. to FE. and defcribes circles, of which the planes are parallel to that of the equator. It is this bypothe- fis that I defend againft the two objections of M. Huygens.
The firft is drawn from the direction which heavy bodies obferve in their fall. M. Huygens pretends, that in the fuppofition of parallel cir- cles, defcribed by the celeftial matter, the bodies ought to fall according to lines perpendicular to the axis of the earth, and that they would be driven toward the centre only in the plane of the equator ; whereas we learn from the experiment, that they every where follow the fame direction which tends tothe centre. This is the objection, which I think I have fufficiently anfwered in the Fournal des Scavans.
I fhall now examine the fecond. M. Huygens obferves, that to produce the degree of gravity, which we find in the terreftrial bodies, the ve- locity of the celeftial matter, which moves circu- larly, muft be much greater than the velocity of the daily: motion of the earth about its own axts, Whence he concludes, that if the celeftial matter
moved
Rovat AcApemy of SCIENCES. 205 moved the fame way witha like velocity, it would be impoffible for it not to carry away with it all’ the bodies which are upon the furface of the earth, by the continual effort of fo rapid 4 mo- tion, which does not happen. * |
I fhall propofe this objection in its full force. The bodies, which-are upon the eafth, being car- ried away with ic about its own ex7s in 24 hours, neceflarily make an effort themfelves to recéde from the centre, and their effort is proportioned to the velocity, which carries them along. If the celeftial matter moved circularly, only with the fame velocity that the earth turns, it would make no more effort to recede from the centre of the earth, than the bodies do, which are upon the earth; and confequently there would be no gra- vity ; thefe bodies being thrown into the air would not fall back again. To whatfoever place of the furrounding fluid they fhould be carried, and afterwards let go, they would remain fufpen- ded and at reft, as they would be in equilibrio with an equal bulk of the celeftial matter.
The bodies therefore which are upon the earth, are heavy, and being thrown into the air, fall down again, only becaufe the celeftial matter makes more effort to recede from the common centre than they do: and if we retrench theif effort from that of the celeftial matter, the quan- tity of effort which fhall remain, and is the de- gree of force with which they aré driven toward _ the centre, will be exactly equal to their degreé of gravity. Thus the celeftia] matter mutt circulate fafter than the earth turns; and the excefs of its velocity above that of the earth muft be fach, that there may refult from it this quantity of effort equal to the degree of gravity of the ter- reftrial bodies.
M.
206. The History and Memoirs of the
M. Huygens has found by an exact inquiry, that it required the circular motion of the celeftial matter to be about 17 times as quick as that of the earth. This calculation is founded upon a curious propofition ; but it isa little embarraffed. It may be made in an eafier manner by fuppofing the truth of another theorem, which jis very eafily demonftrated. This theorem is, that in equal time the fpace run over by a body which falls perpendicularly, is to the {pace or arch run thro” by the celeftial matter, which moves circularly, and produces gravity, as the fame arch is to the diameter of the circle which it defcribes. And confequently if the number of feet, which this
_ diameter contains, is multiplied by the number of feet, which a body that falls perpendicularly runs over in a fecond, this product will be equal to the {fquare of the arch, run over alfo in a fecond by the celeftial matter.. We know by experiments made with a great deal of exactnefs, that a body, which falls perpendicularly, runs over about 15 feet in a fecond: the diameter of the circle de- fcribed by the celeftial matter near the earth, not being fenfibly different from that of the earth it- felf, is 39,231,600 feet. Therefore by the theo- rem, thefe 2 numbers multiplied together, will give a product equal to the {quare of the arch run over by the celeftial matter; and the fquare root of this product, which is 24258, will be the number of feet equal to the arch run over. There- fore, to produce the degree of gravity, which we find upon the earth, the celeftial matter runs over 24,258 feet in a fecond.
The earth making a revolution in 23, 56, or in 86,160", and the circle which it defcribes, be- ing 123,249,600 feet, what it runs over in a fe- cond muft be 1430 feet. Thus the velocity of
the
Royat ACADEMY of SCIENCES. 207
the ccleftial matter, which makes it run over 24,258 feet in a fecond, is to that of the earth, which runs over only 1430 in the fame time, as the firft of thefe numbers is to the fecond. Now if we divided thefe two numbers one by the other, we fhall find they are nearly as 17 tor. In mea- furing therefore the degree of gravity by the fole centrifugal effort of the celeftial matter, which comes from its circular motion, it is demon- ftrated that the velocity of this motion muft be 17 times as great as that of the daily motion of the earth, or furpafs it 16 times.
But to know ftill more exactly how far the difficulty goes, let us examine what impreffion this prodigious velocity, which we are obliged to afcribe to the celeftial matter, can make upon the terreftrial bodies, and we fhall fee if any means will offer to render it infenfible.
The late M: Mariotte made a great number of experiments on the force of the fhock of fluids, and in particular of water and air, He has found*, that water going with a velocity, which makes it run thro’ 3 feet $ ina fecond, and with this velocity ftriking perpendicularly a furface of + a foot fquare, fuftains a weight of 3 Ib, 2. He has alfo determined, that the air going 24 times as faft, made exactly the fame effort. Thus the air running thro” 78 feet in a fecond, and with this velocity fhocking a furface of 4 a foot fquare, oppofed perpendicularly to its courfe, would fuftain a weight of 31b.2: but if we allow it the
velocity by which the celeftial matter furpaffes that
of the earth, what weight will it fuftain? Ic is eafy to calculate it. The efforts of the fame fluid, which goes with different velocities, are to each other as the fquares of the velocities. The velocity
* Mouvement des eaux, p. 187, and 195.
of
208 The History and Memoirsof the
ef the gir, which makes it {uftain glb, 2, is 78 feet in a fecond; that of the celeftial matter, the velocity of the earth being fubftraéted from it, is 22,827 4: fay, asthe fquare of 78 is to the fquare of 22,8274, fo is the weight of 31b. 4, to a 4th term: this 4th term will give the effort of. the air, or the weight fought. In performing, this operation, we find, that if the air went with the velocity of the. celeftial matter, it would fuftain a weight.of above 320,000 !b;*
In this calculation, we have followed the de- termination of M. Marioite, who .allows to ait a velocity only 24 times as great as that of water, to make it fupport the fame weight that
ater does 3 but other experiments prove, that it rauft go 30 times as faft; and if we follow thefe experiments, the weight which the air will fuftain with the velocity of the celeftial matter, will be diminifhed, but yet it will be. more than 200,000]b+}.
Such would be the force of the air carried along with the velocity, which agrees with the celeitial matter toproduce gravity. Whence we fee, that tho’ the effort of the celeftial matter moved with this rapidity fhould be but ,30009 part of that of the air, it would however fuftain the weight of one pound, by acting againft a furface of 2 a foot {quare, and that if it was near 2,500,000 times weaker, it would {till fuftain the weight of anounce; fo that if a body that weighed but an ounce was fufpended in the air at the end ofa thread, and oppofed'a furface of half a foot fquare
* It is exadtly 321,187 Ib, + Exaly 205,560 and 14,508 Ib. and 2,340
*
245336 38,025
to
~Royat AcAvEmy of SCIENCES. 209
to the courfe of the celeftial matter, it would drive it from weft to eaft, with:an effort which would caufe itto make that way an angle of 45 degrees, abftracting all other refiftance but that of the fufpended body.
Tt would be impoffible, becaufe of the. dante and continual agitation of the air, and of feveral other confiderations, to determine exactly how much the effort of the celeftial matter with equal velocity muft be weaker than that of the air to become infenfible, but it appears to me, that it muft be 3 or 4 millions of times. It remains to know, whether it can be fuppofed without abfur- dity, or whether we can give any probable reafon of the weaknefs of this effort.
We know that fome fluids are more or lefs fluid than others, and that they make more or lefs refiftance to.the motion of bodies; and con- fequently more or lefs effort againft bodies at reft, when the fluids themfelves are in motion. Thus we have juft feen, that the air muft go 30 times fafter than water, to have an equal zmpetus: whence it follows, that going with the fame ve- locity as water, it muft make goo times lefs effort than water, goo being the fquare of 30. The rule which is given upon this point, is, that the efforts of different fluids which go with the fame velocity, are as their denfities; it is upon this principle alfo, that we make the air goo times thinner than water. This confequence however might be falfe; for the rule upon which it is founded, is not exactly true, but when the fluids compared differ only in denfity. In that cafe it 1s eafy to comprehend, that if, of 2 fluids car- ried along with the fame velocity, one is for in- ftance twice lefs denfe than the other, ic muft make twice lefs effort; for at each time the body,
Pon. UloN”. 29. Z againtt
210 The History and Memorrs of the
againft which it acts, is ftruck by twice fewer varticles, and confequently is twice Jefs ftruck.
he rule therefore is certain and evident, but it is defective, becaufe there are in fluids a great many other differences to be regarded. The force of the thock in thofe, which go equally faft, does not only depend on this, that in equal time they {trike with the fum of the efforts a greater or lefs quantity of particles; but in this alfo, that they make more or lefs refiftance to the divifion; that is, the particles have more or lefs eale to be feparated or difplaced. Now a greater or lefs facility of being difplaced may have feveral caufes, and by the concourfe of all thefe caufes be- come as confiderable as we pleafe.
The firft caufe that prefents irfelf,-is the diffe- rent degree even of denfity. I have made ufe of denfity already : it is a double ufe that I make of it, but not a bad one; and it comes here under another confideration. It is plain, that a fluid muft be fo much the more eafy to divide, as its particles are Jefs clofe, and lefs near to each o- ther; that is, fo much the more as it is the leis denfe. The more or lefs afperity, or inequality in the furfaces of the particles, and their figures more or Jefs irregular and embarrafling, are two other caulfes worthy of attention, which may pro- duce great differences, with regard to the facility. of fluids to divide, and confequently in the force of their fhock.
I thoughe at firft, that I might add to thefe ar- ticles the different degree of fubtuilty. And indeed it was natural-enough to think, that, fuppofing all other things equal, the fluid, which had its particles the leaft grofs, fhould be divided with moft facility, and make leaft effort againit the obftacles oppofed to, its courfe. This thought
3 quite
2
Rovat Acapbemy of Sciences, 211
quite pleafed me: it furnifhed me with the eafivft way in the world to reduce to nothing the force of the fhock of the celeftial matter, which we may make as fubtile as we will: but in feeking to demonftrate a propofition, which appeared to me fo probable, I have found, contrary to my expectation, tho’ after Sir J. Newton, that it was falfe, and that two fluids of the fame nature, and denfity, which differ only in the fmallnefs of their particles, make an equal refiftance to the motion of bodies; or, if the fluids themfelves move, have an equal impetus. 1 confefs I have been much grieved upon this head, and it was not till after thoroughly difputing againft my own de-
monitration, that I confented to throw it afide. However, let the notion be ever fo falfe, from which I thought I might draw fo great an advan- tage ; yet the more or lefs fubtilty is ftill a mate- tial confideration in another part; for a fluid, which fhould be fo fubtile, that all bodies would give it a free paffage thro’ their pores, would without doubt ftrike thefe bodies with much lefS force than another fluid of the fame nature would, of which the particles would be too grofs to be able to pafs thro’ the pores of the bodies. It is evident, that tho’ thefe two fluids were of the fame denfity, they would fail in proportion tothe effect of the fhock in the cafe of two fluids un- equally denfe 5 all that in the fubtile Auid con- tinues its courfe thro’ the pores of the bodies, _freely and without fhocking them, not being to
be reckoned. Now how far may nor that go? The texture of the moft folid bodies is perhaps infinitely more rare than we think, What is very certain, is, that the fenfes and imagination deceive ys therein. Jf we confule them, who would fay £4 that
212 The History and Memorrs of the
that what a bit of oak contains of its own proper matter makes but the 2oth part of the bulk under which it appears? Perhaps it may not make the thoufandth part, or the hundred thoufandth ; but at leaft it is eafy to demonftrate that it does not make the 20th. The wood of oak weighs lefs than water, and water weighs near 1g times lefs than gold. <A bit of oak therefore weighs more than 20 times lefs than a bit of gold of the fame bulk: but it is a principle demonftrated by M. Huygens himfelf, that the fpecifick weight of bodies exactly follows the proportion of the quan- tity of proper matter which they contain under an equal bulk. Upon this principle, a bit of oak contains 20 times lefs proper matter than a bit of gold of equal bulk; and confequently, by fup- pofing the gold perfectly folid, and without pores, which is very far from being true, the quantity of proper matter, which a piece of oak contains, 1s not the 2oth part of its bulk; certainly our eyes do not tellus fo. By the fame reafoning, a body, which fhall weigh 20 times lefs than an equal bulk of oak, and 400 times lefs than an equal bulk of gold, will alfo contain 20 times lefs of its proper matter than the oak, and 400 times lefs than the gold: do the eyes judge thus of it ?
I have no light into the abfolute folidity of bo- dies: I know by the weight the different propor- tions of denfity or rarenefs between them; but if we confider a body in itfelf, and without compar- ing it to.others, it is impoffible to know what its abfolute degree of folidity is; that is, to deter- mine what proportion there is between the quan- tity of proper matter that it contains, and its bulk: thus I know that a piece of oak is 20 times lefs folid than -an equal piece of gold; but then to what degree is this piece of gold folid?,. How
many
. Royvat AcADEMY of SCIENCES. 213
many pores has it? How much proper matter? This I am abfolutely ignorant of; or rather I know with the utmoft evidence, that it cannot be known ; andI dare advance this propofition,which may feem a paradox, thatif we would maintain, that in a piece of gold, there is not of proper matter the hundred millionth part of its bulk, we might indeed maintain it without a pofitive proof, but we might boldly defy the natural philofophers to demonftrate the contrary.
I do not doubt but the imagination of thofe, who judge of every thing by their fenfes, is fhock- ed at it. Gold is the moft heavy of all the bodies that we know: it has always feemed very pon- derous to them, and therefore very maffy; this confufed notion will always pafs among them for an experiment as evident as a demonitration: but when we fupport a weight, the fenfe of gravity that we have is relative to the degree of itrength that we have to fuftain ic: what a man finds light is an enormous weight for a child, and we might have fuch a ftrength, that the moft heavy mafs would feem as light as a feather. ‘Thus in judging by the fenfe, men a thoufand times ftronger than we, finding gold rooo times lefs heavy than we find it, would alfo judge it to be 1000 times lefs folid than we judge it to be, To conclude, as neither the fenfes nor the imagination are to be heard upon this point, and as reafon does not fix any bounds for us, we may give to the texture of bodies all the rarenefs, as well as to the celeftial matter all the fubtlenefs of which we have need; provided only that the fuppofition which we fhall make for the effect that we would explain, is not oppofed by other effects.
Here is another article, upon which we cannot build too much, which is referred to that of the
figutes
214 The History and Memoirs of the figures more or lefs embarraffing; that the parti- cles of the celeftial matter have neither a determi- nate figure nor bignefs each particle being able to divide, and dividing infinitely, according as there is occafion, and with the utmoft facility, they accommodate themfelves without difficulty to all forts of places; which diminifhes infinitely in the fluid its refiftance againft being difplaced, and fo much weakens its effort.
To all that we have faid upon the caufes which may contribute to render the effort of the celeftial matter infenfibie, we may add thofe experiments of Sir I. Newton, which are in our favour. He made them to determine whether the celeftial matter, which penetrates all bodies, and fills their pores, had any fhare in the refiftance, which thefe bodies fuffer when they are moved in a fluid; and he has not found more refiftance on that fide, than if this matter did not exift, and the pores were entirely void. We fhall not take advantage however of his difcovery :_ what confequence could we draw from an infenfible refiftance in fuch weak motions as thofe of the experiments which we can make? But it is a matter of great furprize, that fo able a man as Sir J. Newton fhould conclude the vacuum from it, or be near concluding it, in- viting us alfo to repeat the experiments, to con~ vince ourfelves more and more of the pretended folidity of this concluficn.
If after all the confiderations that have juft been made, we fhould be ftruck as with an abfurdity, with this prodigious rapidity, which we afcribe to the celeftial matter near the earth, tho’ it does not make itfelf fele there, there feems to be no other way to take, than to digeft this abfurdity, as we are obliged to digeft fo many others in moft phy- fical fubjeéts, and generally in moft of the objects
. at
RoyvazL ACADEMY of SCIENCES. 215
of our knowledge: for, in fhort, this abfurdity, whether pretended or true, to which the opinion, that I defend, leads, is found to be a neceflary confequence of the mo‘t certain obfervations of the aftronomers, as I am going to demonitrate. ~The planets, which turn about the fun at diffe- rent diftances; go fome of them fafter than the others: the famous Kepler was the firft, who ob- ferved, that their velocities keep an inverted ratio of the fquare roots of their diftances. Suppofe for example, that the diftance of Venus from the fun is-to that of Mercury, as 9, to 43; I take thefe numbers, becaufe they are convenient, and not very different from the exact proportion that thefe two diftances have between them ; the {quare root of 9 is 3, thatof 4 is 2: the fquare root of the diftance of Venus. being, therefore to the fquare root of the diftance of Mercury, as 3 to2, we find, according to Kep/er’s rule, that in an in- verted ratio, the velocity of Venus is to that of Mercury, as2 to 3. _ All the obfervations confirm this rule ; it is not only followed by the principal planets, which turn about the fun ; but alfo exactly by the little planets, which make their revolutions about a principal one; this M. Caffmi has fully verified in the fatellites of Zupiter, and given us a theory of them, and by his learned and ufeful difcoveries has a very great fhare in the glory of the pro- grefs, which aftronomy has made in our days, and a great one in the glory even of that which it fhall make. after. It is the fame with the 5 fa- tellires of Saturn, as with the 4 of Fupiter. I is therefore a law inviolably obferved by the ce- leftial bodies, in the {mall particular vortices, as well as in the great one: and as the moft reafon- able hypothefis of the motion of the planets, or rather
216 The History and Memoirs of the
rather the only reafonable one is, that they follow the courfe of the celeftial matter, which carries them along, it is to the different velocities of the celeftial matter taken at different diftances from the centre of the vortex, that Kepler’s rule muft be applied.
To come now to the demonftration, which I have promifed ; if by this rule we find the velo- city, which agrees with the celeftial matter near the earth, we fhall find that it muft be to that of the earth almoft as 17 to 1, fuch exaétly as we have already feen that the degree of gravity of the terreftrial bodies required : the calculation of it is neither long nor difficult.
The moon being diftant from us, or from the centre of our particular vortex about 60 femi-dia- meters of the earth, the circle, which it runs thro” about this centre, is 60 times as great as that de- fcribed by a point of the furface of the earth under the equator; and confequently it has 60 times more way to go to finifh its revolution, than this point Kas. Thus, if the moon fhould finifh its revolution only in 60 days, it would go as faft as the earth which turns in a day: if the revolu- tion of the moon was finifhed in 30 days, its ve- locity would be double that of the earth under the equator: the moon employing but a little more than 27 days and half in its courfe, it follows that its velocity is a little more than double that of the earth. This being fuppofed, the diftance of the celeftial matter, which circulates here below, and is diftant from the centre of the vortex only one femidiameter of the earth, and the diftance of the moon, which we have made 60 of thefe femi- diameters, are to each other, as 1 to 60, and their {quare roots nearly as 1to 8, or as 2 to 16, oras a little more than 2 to17; therefore in an
in-
RovaLt ACADEMY of SCIENCES. 217
inverted ratio, corformably to Kepler’s rule, the velocity of the celeftial matter near us is to the ve- locity of that, which carries on the moon, as 17 to a little more than 2 ; but we have found that the velocity of the moon, or of the celeftia] mat- ter, of which it follows the courle, was really to the velocity of the earth, as a little more than 2 to 1; therefore the velocity of the celeftial matter here below, is to the velocity of the earth nearly, as17to1. 9. E. D.
Such is the perfect agreement, between what velocity the phenomenon of gravity requires in the celeftial matter, and what we find elfewhere, that it muft have in virtue of a law eftablifhed by the -obfervations, aud demonftrated as the fundamen-
tal law of the whole fyftem of the univerfe, by the ingenious author of The New Explanation of the Motion of the. Planets. If fo wonderful an agreement does not entirely deliver the mind from the trouble, which this rapid motion of the ce- Jeftial matter near the earth gives it, of which however we do not perceive any fenfible effect ; it muft at leaft difpofe it to recéive more favour- ably the confiderations, which we have propofed to refolve, or weaken the objection of M. Huy- gens. It is true, that a great many difficulties prefent themfelves ; and I fhall not diffemble,that this very law, which the velocities of the planets follow, when confidered in the celeftial matter, is fur- rounded with difficulties ; there are feveral which a littke attention diffipates ; it would be tedious and ufelefs to dwell upon them: there are others more confiderable, and among thefe two principal ones, which I fhall touch upon in a few words.
The firft offers itfelf immediately, and it is impoffible not to be ftruck with it. According
Vor III. N°. 29. Aa to
218 The History andMemorrsof the
to Kepler’s rule added to the bypothefis of our vor - tices, the celeftial matter makes 17 revolutions about the earth in a day, whence comes it, that the earth makes but one? Why does not it fol- low the rule? This difficulry is common to the other vortices; Jupiter and Saturn turn each about his own centre ; and both of them infinitely lefs quick than they ought to do according to the rule. The fun, which occupies the centre of the great vortex, turns in like manner about his own axis, and takes about 27 days and half in turning ; whereas, according to the rule, it ought to em- ploy but a little more than 3 hours. I confefs I am not fatisfied with the lights that I have into this difficulty, and that I have not any more folid anfwer to give, than that which may be feen in the new explanation of the motion of the planets, a work which it would be more eafy to criticize, than to make a better.
The other difficulty is Sir J/aac Newton’s.. In the midft of an uniform fluid, and at reft, that is, which has no other motion than the mere agita- tion of its parts every way, which renders it fluid, he conceives a folid fphere, which turns about an axis, almoft like the earth. This fphere, as it turns, makes a continual impreffion on a firft fur- face of the fluid, and this upon another, and this Jaft upon another, and foon. On this arbitrary fuppofition, he inquires geometrically in. what proportion the motion is communicated from each furface to the next, or what fhould be the propor- tion of the velocities at different diftances from the common centre ;_ and his avaly/s giving hima different proportion from that which is obferved in the planets, he concludes that they are not car-
ried along by the fluid, and that the Carfejian V0re
“Roya ACADEMY Of SCIENECs. 219
vortices are incompatible with the law eftablifhed by Kepler. t
I pafs over a great number of reflections that might be made on Sir [/aac Newton’s demon- ftration: I am willing to admit it, but when I do admit it, I rejeét however the conclufion that he draws from it againft our vortices. It has no force but in virtue of the fuppofition, which Sir I. Newton takes for granted, of a fluid perfectly uniform, and every where of equal fluidity, and of a refiftance on the fide of the furfaces, in the ratio of the velocity. But if we fuppofe the fluidity to augment in proportion as it recedes from the centre, or a refiftance greater than in the ratio of the velocity, we fhall find without difficulty the fame proportion that is given by the rule.
What we fay here has not efcaped Sir J/aac Newton’s exactnefs; he has exprefly obferved it ; but he contents himfelf with faying thefe fuppo- fitions would not be reafonable ; and tho’ the Jaft isinconteftable, he choofes rather to confider gra- vity as a quality inherent in bodies, and to renew the exploded notions of occult qualities and at- traction. We muft not flatrer ourfelves, that in all our phyfical inquiries, we can ever furmount all difficulties: but however let us always philo- fophize upon clear, mechanical principles ; if we quit them, all the light that we can have is ex- tinguifhed, and we are plunged anew into the old darknefs of peripateticifm, from which heaven
-preferve us.
A a +2 VII.
220 The History and Memoirs of the
VIII. Odjeruations of the weight of the at- mofpbere, made at the caftle of Meudon, with M. Huygen’s double barometer, by M. de la Hire*; tranflated by Mr. Chambers. |
» Thebbé de Louvois having a curiofity to fee the
practice of levelling, and how the weight of the atmofphere is found by cbfervations of the baro- meter, I made the following ones in his prefence, with all the accuracy poffible. We had the ufe of a very good telefcope level, and one of M. Hluygens’s double barometers, which we found in the caftle.
One morning at the bottom of the caftle, the li- quor in the tube of the barometer ftood at 33 divi- fions 4; upon which defcending by the iron grate in the great road leading to Ver/ailles, we found the liquor in the tube fallen to 28 divifions 4, the {pace defcended being 159 feet, 3 inches, and the fall of the liquor 5 divifions from the firft ftation.
Continuing then to defcend in the great road leading to Paris, as far as the opening of a litrle path, which goes to the river, we found the li- quor in the tube at 24 divifions $, where the fpace we had defcended was 106 feet, 3 inches, and the fall of the liquor from the former ftation was 4 divifions.
From this ftation to the river near the mills, we defcended 134 feet, 3 inches, when the liquor was found in the tube at 21 divifions, and con- fequently had fallen 3 divifions .
After noon the barometer was carried to the wall of the mill-pond, at the top of the park,
* June 5, 1709.
where
Roya AcADEMY of SCIENCES. 221
where the liquor in the tube ftood at 38 divifions 2, and by the levelling it appeared, that we had afcended above the level oF the caftle 112 feet, 4 inches. _ But returning in the evening to the caftle, I found the liquor in the tube at 36 divifions, and confequently for thefe 112 feet, 4 inches, the liquor had altered 2 divifions }; but having found it in the morning at 33 divifions $, we learned that between morning and evening a change of 2 divifions 4 had happened in the weight of the atmofphere.
The whole height from the river to the mill- pond was exactly level at feveral ftations, and found agreeably to the preceding obfervations 512 feet, 1 inch, or 85 fathoms, 2 feet, 1 inch, being the greateft elevation about Paris,
Towards the evening | found the difference be- tween the furface of the mercury in the two cifterns of the barometer at the bottom of the caftle was exactly 29 inches, and the liquor in the tube was 12 inches 4 above the mercury in the lower cif- tern, The divifions of the tube for meafuring the height of the liquor, were equal to 4 lines and , which I take for 4 lines 4, on account of the {mall- nefs of the difference, and for the eafe of calcula- tion.
Now to deduce the exact weight of the atmo- fphere from thefe obfervations, they muft be re- duced according to the ftructure of this barometer, as already explained in our memoir of barome- ters, But firft, in order to compare the heights of the liquor between the fide of the river, and the top of the mill-pond, the obfervations muft be reduced to the fame hour, by reafon of the change which happened in the weight of the at- mofphere between morning and evening ; and as
the
222 The History and Memorrs of the
the obfervation at the river-fide was made about noon, I fhall reduce it to that made at the mill- pond in the evening, when the liquor was at 38 divifions $, on a fuppofition that the diminution of the atmofphere proceeded uniformly from morning to evening. Hence initead of 21 di- vifions obferved by the river-fide, I take 22 £ by adding 3 the difference between morning and evening, and fubtracting thefe 22 divifions + “from
4 38, the remainder 45 divifions 2 gives the al-
oD teration of the height of the [ieerca an afcent of 512 feet under a conftitution of air, fuch as that in the evening of the fame day..
The reduction of the divifions of the tube to che eal height of mercury, correfponding to the weight of the atmofphere, will be eafily made by the rules I have already given, and the objer- vation I made in the evening of 29 inches diffe- rence between the heights of mercury in the cif- tern, when the liquor was 12 inches 4 above the mercury in the lower ; for fuppofing what I have actually found, that the weight of mercury is to the weight of the liquor in the tube, as 12 to 1, dividing 150 lines (to 12 inches $) by 12, we fhall have 12 lines 4 for the height of mercury, equivalent to 150 lines of liquor. We muit fub- ftract therefore 12 lines $ from the 29 inches dif- ference between the heights of mercury in the cifterns, and the remaining 27 inches, 11 lines 4 will be the height of mercury, which weighs as much as the atmofphere on the day of obfervation towards the evening at the height of the plain of the caftle at Meudon, which is Be fathoms, 4 feet above the river Seine, againft the mills in the month of September, when it is ulually very
low. h
Roya Acapemy of SCIENCES, 223
It remains to find the value of the divifions of the tube, with regard to the heights of mercury, which reprefent the weight of correfpondent divi- fions of the atmofphere. In thefe barometers, which are formed according to the proportions given by M. Huygens, where the diameter of the cifterns is 14 lines, and that of the tube 1 line, we fhall have it by a rule found in my former memoir, as 12 times the fquare of the diameters of the cifterns to the fquare of the fame diameter -+- 23 times the fquare of the tube ; fo are the divifions of the tube, or the heights of the liquor to the heights of mercury reprefented by them, which is here as 2352 to2193 wherefore the 16 divifions 7, found between the higheft and loweft, which anfwer nearly to 73 lines, has about 6 lines 3 for the true height of mercury, correfponding to the change of weight of the atmofphere, between the rivet-fide and the wall of the mill-pond in the park ; fo that dividing 512 feet, which is that height by 6.2, we fhall have 75 and $4 or 12 fathoms, and nearly 4 feet height of atmofphere for a line of mercury, at a time when the weight of the whole atmofphere was 27 inches, 11 lines 2, at the furface of the ground in the caftle of Meudon ; and above the river, when it is low againit the mills, at the foot of the mountain, 66 fathoms, 4 feet. ————- We here make no account of the different weights of the atmofphere, in the different parts of this height, nor of the dif- ferent afcents of the liquor, which might have arofe from the different heat at different times of the day, which dilates all liquors more or lefs, and even mercury itfelf; for that the heat was pretty much the fame at the beginning and endin of the obfervations. *
But as in the making thefe barometers they
3 might
o o
224 The History and Memorrsof the
might have deviated a little from the proportion above-mentioned, between the diameters of the cifterns and the tube, J have made a calculus of what would enfue upon other proportions, and find that the difference would be very inconfide- — rable, tho”? the diameters of the cifterns were 1 or 2 lines either bigger or lefs.
Tho’ it cannot be doubted, that to find the weight of the atmofphere, it is much furer to go upon ¢reat heights than upon {mall ones, pro- vided fuch heights be exactly known by reafon of the difficulty of making an exact eftimate of the heights of the mercury in the tube, yet I have not thought it amifs to make obfervations of leffer heights in order to find how they would agree with thofe of Meudon.
Accordingly I have feveral times obferved the height of the mercury in different feafons, and different years, at the top of the terrafs of the ob- fervatory, and the bottom of the vaults and cel- Jars thereof, in the fingle barometer ; and taking . a medium between all thefe heights which agreed with an obfervation I had made in Sept. 1705, the time when the air is nearly of the fame heat in the vaults,*as at the top of the mercury of the barometer then ftanding at 28 inches in the large hall; and confequently the atmofphere being very heavy, as it was when the obfervations were made at Meudon; and the feafon being likewife the fame, I found a change of 2 lines } in the heighth of the mercury, for 28 fathoms or 168 feet height of the atmofphere ; and confe- quently for 1 line of mercury we have 74 feet 3, or 12 fathom 2 feet 2 ; and by the obiervations made at Meudon I found, for the fame line of mercury 12 fathoms 4 feet, the difference between which, viz. 1 foot + -is very inconfiderable in fuch obfervations, Another
~ Rovar Acapemy of ScIENCEs. 226 ~ Another obfervation which I made at Toulcx in 1682, upon the mountain Claret, which is 257 fathoms above the furface of the fea, gave me in that feafon, and under thofe circumftances of air, fuppofing the air equally denfe in this whole height, 12 fathoms for 1 line of mer- cury.
But it being certain that heat and cold. may oc- cafion fome alterations in barometers wherein the weight of the atmofphere has no concern, as I have fhewn in the memoir already cited; by rea- fon fome part of the air next the earth being heated more or lefs than the reft, will make a change in the bulk both of the mercury and the liquor; befides, that a moift air when heated, di- Jates more forcibly than a drier, and confequently will fuftain the mercary to a height beyond what it would ‘have frem the bare weight of the atmo- fphere, &c. J have therefore made feveral ob- fervations and experiments: to bring all thefe effects to fome further rules.
--Placing a fingle barometer afide of one of M. Huygens’s double ones, and of M. Amontons ther- mometers- by them, I obferved their feveral heights every day for 3 years together, without over-looking, the leaft circumftance that might have any concern therein, but there having hap- pened no confiderable cold in all that time, but only violent heats in the fummer, I compared the ftate of thefe barometers in the great heat, with -that they were in at the mean heat of the air, as it is found in the vaults of the obfervatory, or at moft when it begins to freeze; and I found that the mercury in the fingle barometer does not un- dergo any fenfible change of height, whether it be expofed to the open funin the heat of fummer, or be in the fhade in a place moderately cold.
Bee.4N°.29. | Bb In
226 The History. and Memoirs of the
In the following obfervations [I expreffed the eight of the mercury in the fingle barometer, b inches, lines, and points, which are 6th parts o lines, the heights of the liquor in the double ba- rometer being exprefled by the divifions on that barometer which are each equivalent to. 4 lines, but are reduced afterwards into lines.
inch. . lin. _ pol.
I. The fingle barometer et 3 att
ing at
The double barometer in the great : div. 2 heats ftood at 1 $9456 SV. And in a moderate degree of heat at 41 4
The difference is 4 $ Or 16 2 II. The fingle barometer ftand- ing at -_ it A S94 The double barometer in the great y dj heats ftood at a2 We And in a moderate degree of heatat 37 +
oe
The difference is 4 Or
bh
19 0
Ill. The fingle barometer ftand- i 2 : ite Siw ce: ing at _ The double barometer in the great di heats ftood at i Bde Andina moderate degree of heat at 28 The difference is, 4 2 Or 19
VI.
Roya ACADEMY of SCIENCES, ni inch, lin. IV. The li barometer oe ing at aX: De “The double barometer i in the great i 3 heats ftood at oe 3 Andina moderate degtee of heatat 34
The differenceis 4 = 3 Lg Migs 6 sealife 8.
Vv. finele barometer ftand- ; ing ti ngle_barom ai - bay 10 66
“Phe double barometer at a mode- t fate degtee of heat ftoéd at —— 33 And the barometer being “began 0} : 30
Wl
to the open air when it began to a freeze ftood at
- patteree,
The difference is 2 ;
Or IO =
>
Being defirous likewife to find what would be- fall the double barometer, when expofed to the fun about noon, in’ the greateft heats of Fly, in the year 1708, and the better to difcover the ef- fects thereof, I placed M. Ammontans’s little fpirit of wine thermometer afide of it. ;
I obftrved the liquor in the barometer at firft rife very flowly in comparifon of the fpirit of wine in the barometer, bat after they had ftood upwards of an hour in the fun, carrying them back to their former place, which is in the fhade, I ob- ferved the liquor in the barometer fill continued rifing, while the fpiric of wine, on the contrary, kept defcending apace, to recover its former ftate. Now tho’ fpirit of wine be very fenfible of heat,and water very little in comparifon there- of; yet one would expect the fame thing to be-
Bb2 fa]
228 The History and Memoirs of the
fal the water in the barometer, and the fpirit in the thermometer, and that the caufe ceafing, the effect muft ceafe likewife. We find, however, that the mercury having received a much greater degree of heat than the liquor, and preferving it Jonger withal, by reafon of its greater denfity, continues ftill to heat the liquor, even when re- moved from the fun, and thus raifes it confide- rably higher, than it was therein; and the rather, as the bulk of the mercury undergoes no fenfible change by heat and cold, as I found by expofing the fingle barometer toa hot fun.
As to the fpirit in the thermometer, the cafe is very diffetent ; for being a fluid very eafy to be dilated by the fimalleft heat, ic condenfes again with equal eafe upon the fmalleft cold.
*Tis beyond doubt, that the different heights above-mentioned, between the liquor in the dou- ble barometer, while the fingle barometer re- mained at the fame height, and confequently the atmofphere was equally heavy, arife chiefly from the dilatation of the liquor ; whereof there is fuf- ficient quantity in the phial, at the bottom of the barometer, and its tube flender: for upon the {malleft {welling of this liquor, by the heat, a very fenfible proof of it mult appear in the little tube, which however does not obtain fo much in my barometer; where, the liquor being but lit- tle, the elevation, occafioned by the heat, is in- confiderable, I have fhewn however how it may be applied, without falling into any error, by confounding the effect of the barometer with chat of the thermometer, which, in the double baro- meter, occafions great irregularities,
TX,
Rqwean a tena 229
IX. A bon faa! of the rbot Peal obfer vations, nade in different places, by M. - Maraldi *
To arrive-at Bike knowledge of the caufe of the phenomena, obferved by the means of the -baro- . meter, it is not fufficient to have obfervations made only in one place, it is neceflary to make them alfo in different countries, to compare thefe _ obfervations together, to obferve the et between them, and their differences.
Without a great number of thefe dbiarvatithis. we aré liable to miftakes in explaining by caufes, which would fuit only a particular country, phe- nomena which may have more general caufes ; and we might confider, as a property of the whole mafs of air, what agrees with it only in fome circumftances, or in a certain extent of country.
Several learned men, who have perceived the phyfical ufes that may be drawn from barometri- cal obfervations, have applied themfelves for fome time to make them in different countries. The marquis Salvago having communicated to me thofe which he had made at Genoa 3 years ago, I have compared them with our own, which were
made at the fame time at the obfervatory. In comparing thefe obfervations, we have found fome, which had particulars in them, waich I have thought worthy of being remarked. I hall
afterwards relate fome experiments on the dilata- tion of the air, made near the equinoctial, which I have had occafion to examine.
The marquis Sa/vago, in his obfervations made at Genoa, uled a fimple barometer, divided into
* July 20, 1709, inches
230 The History and Memoirs of the inches and lines of the Paris foot. This baro- meter. 18 fituated in an apartment, where the gechta ver remains a line lower than at the fea
ore, as has been found by obfervation; fo that ifwe would reduce the obfervations of Genoa to the level of the fea, we muft add a line te each height of quickfilver, which I fhall hereafter men- tion. rnd on aifsrnt |
In the relation. of thefe obfervations, we fhell not follow the order of time in which they were made; but I fhall begin with the moft remark- able. yey
In,1707, at Paris, from Nov. 15 to 18, the barometer continued for 4 days at the height of 28 inches within about 4 a line; the next day, Nov. 19; it, fell to 27 inches, 4 lines, having fallen 8 lines in. 24 hours ; the next day, it rofe again 10 lines, being on November 20, at 28 in- ches, 2 lines; during this variation the conftitution of the air didnot change the sky having been very calm and ferene; |
The fame year, at Genoa, from Nov. 15 to 18, the quickfilver continued at the height of a little more than 28 inches, as it had been the fame days at Paris.. The next day, Nov. 19, at Genoa, the wind being S. the barometer fell to 27 inches, 5 lines, having fallen.in one day 7 lines at Genoa, almoft as it did the fame day at Paris. ;Tt remained only that day in the fame fituation ;| but ic rofe again the next day to 2$ inches; and the 21ft, to 28 inches, 2 lines, as it happened at| Paris, the wind was turned to the N. 1
Fhe fame year, from Nov. 20 to. 28, the ba- rometer remained at Gevoa and at Paris generally. at 28 inches, 1 line. During thefe 8 days at Paris, the wind was fometimes?at W?* and fome-
2 times
er .
RovaAt ACADEMY) of SCIENCES. 231 times, at. Mi W. at, Genga, the wind was, always N..
Nev, 30). at Paris, the barometer fell to. 27 inches, o,jiness, the .wind being N. W.,.i Des. ts
it ‘role. again, to. 27 inches, 19, lines, the: wind being W, and the weather fair ; the next dayj,,.it rofe 2 lines) more, having, been.at' 28 inchess fo thar at Paris, jrom Nev. 28\§0-,30,. it fell, above an inch i in two, days ; 3, and; from Now. 30-t0 Dec. 3, it rofe 10 lines in 24 hours. _
The fame variations almoft happened alfo at t Ge- noa on the fame days. By the obfervations of the marquis Sa/vago, from Now.28, when the baro- meter was at 28 inches, 1 line, it fell che i¢ goth to 27 inches, 4 lines, having fallen g Tice in two days, the wind being N. a the next day, it rofe & or Glines, a little lefs than 4 it had the fame day at Rapes] <)
It appears from thefe obfervations, that great variations happen, in a littletime in the height of the barometer, both at Paris and Genoa; and that there is a great conformity in thefe variations, which happened at the fame time in fuch diftant countries. It appears alfo, chat they have no great relation to the changes of the winds ; for the varia- tions of the barometer, which happened from Nov, 19 to 20, happened at Paris: withoutany remark- able alteration of wind; and if on that day the ba- rometer fell at Gezoa witha S. E. wind, and rofe with a N. wind; in the variation which happened the 28th, the quick filver fell with a N.E. wind which “commonly makes it rife. So at Paris, the barometer fell with a N. W. wind, and rofe with a W. with which it ufed to fall. But what-rapi- dity muft we afcribe to the winds, to caufe fuch quick alterations in cities: fo-diftant ? |
It
232 The History and Memorrs of the
It is not only in thefe fudden variations, which happen very feldom, that we find this conformity ; there is the fame agreement alfo in the changes of the barometer, which are made more flowly, and happen in thefe. two cities during the whole
ear. ; As it would be tedious to relate all the obfer- vations made for the three laft years, in which this agreement is found, I have made choice of the moft remarkable.
At Paris. At Genoa. 1706. Barom. Winds. Barom. Winds.
Ui ee taped hr eas Sete 8 Ee 7. 28) “OS egim: 28 oF N.
Fromm Yan. 1 to 7, in the fpace of 6 days, the quickfilver rofe 12 lines at Paris, and g % at Genoa.
Febiiags) 6 27) gus. 9905" Gay 19. 28 1 calm 27 113 N.
From Feb. 13 to. 19, in 6 days, the barometer rofe 10 lines at Paris, and 6 at Gexoa.
Of. 31... 28 o calm 28 o calm. Nov, 4, 26 9 S.E.rain 27 1 S.W. BO. vacazodmw 22Gcnc INS
By the obfervations of Of. 31, and Nov. 4. in 4 days, the barometer fell at Paris 13 lines ; it fell at the fame time at Genoa 11 lines, tho’ the winds were different. Nov. 20, the barometer rofe to a great height, being the fame within about 2 lines in both thefe cities, tho’ the wind was S. at Paris, and N. at Genoa.
Dec. 10 28 1 calm 28 4 ON. carrey Fw 29) 55 Sie
By
Rovat AcApEmy of SCIENCES. 233
By thefe obfervations the barometer fell, in 5 days, about 1 inchat Paris and at Genoa.
At Paris. ero AE Genoa. 1707, Barom. Winds. Barom. Winds. Mar.t3. 27 11 W. 28 o N.
yi fp 09 NOE, anh StS: Be.
In 4 days, the barometer fell 6 lines at Paris, and 4 at Genoa, tho’ the wind was very different.
Fuly 20. 27 11 S.gentle 28 o N. gentle ees ae NW. 27 6° S/E.
Fuly zo, the winds being oppofite at Paris and
Genoa, the barometer rofe pretty equally; it fell
afterwards 6 lines in each place, in 4 days, the
winds having changed, and being {till oppofite, that, is N. W. at Paris, and S. E. at Genoa,
PreraeLeeeyt0:S. W. S80 Sake aagce ag ‘a calm. a 530 NH. In 5 days the barometer fell 8 lines at Paris, and 1o at Genoa.
1708, jam. 1-26.10 cal.andfair27 3° S.W.clo. am, 23-8 S.W. Sor. 18. - Star, The barometer rofe in 6 days at Paris 10 lines, at Genoa 8, the winds being very «lifferent in thefe two Cities. | PE, OCR! VER SEN. 9 papell ty FO. 24 rd calm ‘oo, ON: By thefe obfervations the barometer rofe 6 lines in thefe two cities, the wind having been variable at Paris ; at Genoa it was always N.
Vou. UI. N°. 20. Co March.
234 The History aud Memoirs of the
At Paris. At Genoa,
1708. Barom. Winds. Barom. Winds.
Mar.20. 27 84calmandfair27 7 calm Bsn. - 27 uae IN 27 gS UN
The barometer being at a mean height, funk in 2days 6 lines at Paris, 4 at Genoa, with aN. ‘wind at both cities.
Meaiiss Sis egy 34 28 o N. 17, 27 4S.W 27 5 SE, Nov.19. 28 24calm 28.2. calm
23, 27 3:6 Weel 27 os acm 24.) 29-112N.W.25tb.27 10) N.
The roth, the barometer being ata great height fell till the 23d, and from the 23d to the 24th rofe 6 lines in a day. But at Genoa this variation was a day after it happened at Paris.
Dec. 10... 27 113 calm Ye ¥ abe «18 Ben 29 OL. FAM 27 45 fain
By all thefe obfervations, and a great many others, which I do not relate, it is manifeft, that there 1s a great agreement in the variations, which happen at the fame time at Paris and at Gina, whether thefe alterations were quick and fudden,
like thofe which were firft related, or more flow like the laft.
This correfpondence of the alterations of the barometer, feems to have no great relation to the conftitution of the air, or to the winds, which prevail at the fame time in different countries ; for the quickfilver rifes at Genoa, when it rifes atParis, and falls in like manner, whether there is the fame conftitution of the air, or whether the fame wind prevails in both thefe cities, which is very
rare ;
RoyaL ACADEMY of SCIENCES. 235
rare ; or whether both of them are different. It would be a thing worth examining by obferva- tions made in very diftant places, to what dif- tance fuch a conformity in the variations of the barometer is found. .
This long feries of obfervations at Paris and Genva, compared together, fhews, that to find the height of mountains, by barometrical experi- ments made at the fame time in different places, after the manner propofed in the memoirs of the academy, thofe muft be made ufe of, where the quickfilver Keeps in the barometer ‘at a mean height, and preter thefe before others, where the quickfilver is found near to greater and {maller elevations, becaufe in the mean heights of the quickfilver the differences between different coun- tries are more uniform.
By the comparifon of the obfervations made with this choice, we find between Paris and Genoa a difference of 3 lines height of quickfilver, which it has at Genoa more than at Paris ; and as in the obfervations at Genoa, the barometer is a line Jower than it fhould be at the fea-fide, there re- fults a difference of 4 lines of quickfilver between the Paris obfervations, and thofe which fhould be made at Gezoa by the tea-fide. This difference between the level of the fea at Genoa and at Paris agrees with what had been concluded by the ob- fervations of Paris and Colioure, related in the memoirs of 1703.
It has been obferved in this memoir, that the differences which happen to the barometer in the fame place, between the greateft and fmalleft ele. vation, are greater in the northern than in the fouthern countries, where thefe differences leffen ; fo that towards the equinoctial they are reduced to a trifle,
@c2 Several
236 The History and Memorrs of the
Several obfervations received fince that time from feveral places, are conformable to. this ob- fervation, At Upminfter, in England, which is more N. than Paris, the variations of the baro- meter are alfo greater than at Paris; thofe at Pa- ris are greater than at Genoa ; and the variations obferved at Genoa, are allo greater than thofe which refult from ‘the obfervations of F. Laval made laft year at Mar/eilles, which is more fouthern then Genoa.
This remark, which is confirmed by a great number of obfervations made at the fame time in different places, does not agree with the obfer- vations made by M. Scheuchzer at Zurick thefe 3, laft, years ; for tho’ Lurick i is much more to the N. than Genoa, the variations have been obferved to be fomething fmaller at Zurick, far from hay- ing been greater than at Genoa. In 1706, the difference between the greateft and leaft elevation, of the barometer was at Zurick 10 lines. At Ge- noa, the fame year, this difference was 1 inch, 1 jine. In1707, at Zurick, it amounts to 11 lines ; at Gezoa, it wast inch. In 1708, by the obfervations made at Zurick with the upright ba- rometer, which I think preferable to the inclined one, the variation was 10 lines; at Genoa 1 inch; at Marfeilles 10 lines £, as at Zurick.
Ic muft be obferved, that the places of the ob- fervations, where this tule is found, are fituated. at heights very little different from each other, and are bu little elevated above the furface of the fea, as appears by the difference of the heights of the barometer, which is found between thefe obferva- tions, and with regard to thofe which have been made near the level of. the fea. But it is not fo with regard to the obfervations of Zurick, which are not conformable to this rule. For by the ob-
fervations
RoyaL ACADEMY of SCIENCES. 237
fervations made during the whole year 1708 at Genoa and Zurick compared together, there is a difference of 1 inch, 8 lines of quickfilver, found between the level &: the fea and Zurick; which Shews that the place of the Zurick Beletitiensi is very much elevated above the places of the ~ obfervations, and {till more above the level of th for ah..3 4
‘This variation of the barometer being lefs im the high places than in the low ones, is alfa: confirmed by the obferwations fent laft year by F. Laval to the academy : for having made barometrical ob- fervations for 10 days together on the mountain of St. Pilon, which is more northward. by 2’ of a degree than Mar/eilles; and is elevated above the level of the fea about 480 toifes; having com- pared them with thofe which were made at the fame, time at the obfervatory at Mar/feilles, he found that at Marfeilles the barometer. varied 2 lines 4, when it varied but 1 line 3 at St. Pilon.
F. Laval afcribes this difference partly to the heat, which is lefs in elevated than in low. places, partly to the nature of the air, which being more rarefied in the elevated. places, is lefs fubjeét to the alterations, which contribute either to its heavinefs or lightnefs.
We might fuppofe, that it is fome heteroge- neous matter difperfed in the air, which caules a part of thefe variations, and has a greater effec in the lower air than in the upper.
Having compared together. the barometricat experiments, which have been. hitherto made. in different parts of the earth during the. whole year, I have found that the variations of, the barometer obferved at Zurick approach much nearer to the variations obferved near the equinoétial, than the others made hitherto in Europe.
3 Mt ate
238 The History and Memorrs of the
I have examined on this occafion various expe riments made near the equinoétial on the dilata- tion of the air, to fee whether the air of this cli- mate by dilating followed the reciprocal ratio of the weights from which it is relieved, according to M. Mariotte’s tule.
Thefe experiments were made at Malaca by F. de Beze, during a ftay of 7 months which he made at that place, which, tho’ fituated in 2 de- grees of north latitude, enjoys, according to the report of the fame father, a pretty temperate air for the climate, the heat being temperate, and not very variable.
Thefe experiments are related among the Od- fervations Phyfiques {8 Mathematiques, printed in 1692, with #. Gouze’s notes in the following terms.
<¢ An able philofopher told me before my de- “¢ parture from France, that he had been affured “© chat there was no fenfible difference in the ba- ‘© rometer, found in all the places fituated be- ** tween the tropicks, provided the obfervation “* was made ina place on a level with the fea. ** T was willing to examine the truth of this when *¢ J arrived in the Jxdies; and as] had no baro- «© meter mounted, I made ufe of a elafs tube 29 “* inches long, fealed hermetically, and exaétly “¢ divided into inches and lines, with which I “‘ made the Toricellian experiment in different “¢ places between the tropicks; but I have found’ “* every where a pretty fenfible difference in the “ elevation of the quickfilver, not only with “© regard to the different places where F ob- “© ferved, but often alfo in the fame place, where’ “< the quickfilver was more or lefs elevated ac- “ cording, to thé different difpofitions of the air;
bd ae shew ee lee 4A hee Ano ae “¢ tho’, colay the truth, this difference does not - gy =
ao.
Royat ACADEMY of SCIENCES. 229
© equal that which is found out of the tropicks, ‘* fince, according to what I have been able to << obferve, it does not exceed 5 or 6 lines. << T have already fent to France the experiments which J had made on this fubject at Siam and Pondichery, Thefe are what we made at Ma- ‘© Jaca and Batavia. “© Having chofen at Majaca a day when the air appeared very pure, and the heaven was not covered with any clouds, to make the ex- periment: we found, that the quickfilver in the tube kept up conitantly to the height of 26 inches 6 lines above the furface of that “¢ which was in the bafon, “© The heat was at that time pretty great for the climate, and the thermometer was at 69 deg. “¢ As I have obferved by feveral experiments, that the quickfilver ufually kept up to a greater height when the heat was lefs, and that it fell when the heat increafed, tho’ the fky was equally ferene and clear, I thought it would be proper to mark the degrees of the thermometer at the fame time, tho’ there is not an exact proportion between them. _* Being afterwards willing to try the elaftic force of the air, we left three inches of air at the top of a tube, and having reverfed it in *¢ the quickfilver, where it immerged 7 lines, ‘* that of the tube remained at the height of 20 “inches 7 lines above the furface of the other ; _** and the air dilated occupied 7 inches ro lines.” Having afterwards left 7 inches, 6 lines of air, the quickfilver remaingd at the height of 16 in- ches, and the air dilated occupied 12 inch. 5 Jin. In confidering thefe obfervations, it is eafy to fee that they do not follow M. Mariotte’s rule; for in the firft experiment, 7 inches 10 lines of ait
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240 The HisTory dnd Memorrs of the
air dilated after the reverfing of the tube, to 3 in- ches of natural air before the reverfing, has not the fame proportion as 26 inches 6 lines in vacuo, 6 5 inches lines excef$ of 26 inches 6 lines, to 2orinches 7 lines, the height which the quick- ftiver had with the dilated air, as it ought to be according to the rule, | It is the fame with the fe- cond’ experiment 5 but in thefe 2 expériments, rhe proportion of the diated air to the natural air, is lef8 than the atmofphere, to the difference be- tween the heightof quickfilver in the vacuum, and the height of che quickfilver with the dilated air.
Having calculated thefe 2 experiments, to know what the dilatation of the air fhould be by the common rule; im the firft where the natural air was 3 inches, after the reverfing the dilated air ought to occupy according to the rule 9 in- ches 11 lines; but by the experiment it occupied no more than 7 inches ro lines; the difference betwWeen the experinent and the rule is, 2 intches ¥ line, by which the {pace occupied by the dilated air, was lefs. ;
In‘the fecond experiment, 7 inches 6 lines of natural air after the reverfing, ought according to the rule, to be dilated, and fill the fpace of 15 iaches r line; but by the obfervation it occupied no more than 12 inches 5 lines ; the difference _ between the obfervation and the rule is, 2 inches _ Sines, by which the obfervation is lefs; and con-_ fequently, according to thefeexperiments, the air of Malaca does not follow the rule, and is lefs di- Jated than that of Europe.
Befides thefé experiments made at a time when the air: was pure and férene, F. de Beze made others alfo, whilft the fky was lefs clear, and very cloudy, and that the height of the quickfilver in the vacuum was greater than in the preceding: obfervations. They
Roya ACADEMY of SCIENCEs, 241
They are related after the firft in the follow- ing manner,
«- At the end of the moon, the fky being ** very cloudy, and the air lefs clear than ordi- ‘“* nary, I repeated thefe experiments in the fame ‘“< place, the thermometer was at 63 degrees.
‘© Having filled the tube with quick-filver, << and reverfed it in that of the bafon, where it “¢ immerged one inch; it kept up at the height *< of 26 inches ro lines } above thie furface of the ** quickfilver.
«© flaving afterwards put fome quickfilver in ** the tube to the height of 26 inches, that there ** might remain 3 inches of air, and having “* pluaged ic in the quickfilver, the air dilating it- *« felf, occupied 7 inches 5 lines 4, and the *¢ quickfilver 20 inches 6 lines £. /
‘© Having left 6 inches of air, the quickfilver *¢ kept at the height of 17 inches 2 lines 3, and ** the dilated air filled the reft of the {pace 10 ‘© inches g lines 3. aa
«« Having left g inches of air, the quickfilver << occupied but 14 inches 6 lines, and the dilated ‘© air 13 Inches 6 lines. Thefe experiments ** were made in a place raifed 15 or 20 feet per- "© pendicular above the level of the fea.” |
By the comparifon which we have made of thefe obfervations with the rule, we find the fame difference between them as in the preceding ob- fervations; for the 3 inches of natural air after the reverfing, dilated in fuch a manner as to oc- eupy only 7 inches 5 lines 3, whereas, by the rule, it ought to contain a fpace of g inches 6 lines £. The difference between the obfervation and the rule is 2 inches 1 Jine 4, within about £ a line of what was found in the firft of the pre-
Vou. HILL N9, 30, Dd ceding
242 The History and Memorrs of the
ceding experiments, which fhews the exactnelS of both of them.
In the fecond experiment, 6 inches of natural air inclofed in the tube, after the reverfing fills the fpace of ro inches 9 lines 3; this fpace, by the calculation founded upon the rule, fhould be 13 inches 3 lines. "The difference is 2 inches 5 lines 2, by which the dilatation is found lefs by the obfervation than by the rule.
In the laft experiment, 9 inches of natural air inclofed in the tube being dilated by the reverfing, occupied 13 inches 6 lines, and by the calcula- tion founded upon the rule, it ought to fill 16 inches 1 line 4. The difference is 2 inches 7 lines ce by which the experiment gives lefs than the rule,
It is therefore manifeft by all the experiments of F. de Beze, that the dilatation of the air,
which refults from them, is much fmaller than that of our air, and that it does not follow the proportion found by the experiments of Europe.
It might be fuppofed that this phenomenon comes from the particular conftitution of the air of Malaca, which being very much rarified by the heat of the climate, is afterwards lefs fufcep- tible of fo greata dilatation as ours; but fo far as we may judge by expetiments made in Europe, this explanation alone is not fufficient to give the reafon of the great difference between the dilata- tion of our air, and that of Ma/aca, even though we fhould fuppofe the heat which caufed this rare- faction to be as great as that of boiling water. Thefe are the objervations which we made.
I took a tube 38 inches long, in which I] put quickfilver to the height of 35 inches, fo that there remained 3 inches of air; I immerged this whole tube in boiling water, to rarefy the air contained in it; J afterwards ftopped the aperture
wich
Roya AcADEMY of SCIENCES. 243:
with my finger, and having taken the tube out of the water, I reverfed it in the quickfilver; fo that above an inch was immerged. Immediately after the reverfing, the quickfilver kept within a few lines of where it keeps by the dilatation alone without having rarefied it. But the quickfilver was feen to rife in the tube, as faft as the air was condenfed in cooling ; and when it was entirely cooled, the quickfilver rofe an inch and 2 lines more than it did immediately after the reverfing, and more than M. Mariotie’s rule required ; and confequently the rarefied air was Jefs dilated than by the rule, by the fame quantity of 1 inch and 2 lines. We have found by the experiments of Malaca, that the 3 inches of air dilared 2 inches 1 line lefs, than by the rule ; the air of Mailaca therefore dilates lefs than our air rarefied by the heat of boiling water.
I made the fame experiment upon 6 inches, and afterwards upon 9g inches of air, and I always found that our air’rarefied by heat, dilated much lefs than the air of Me/aca, and that the diffe- rence found with regard to the rule is twice as great in the air of Malaca as in ours rarefied. Whence we may infer, that this lefs dilatation of the air of Aa/aca comes not only from the great heats of the climate, but from its own nature be- ing lefs apt to dilate than ours.
As the air dilates otherwife at Malaca than it does in France, at an almoft equal height with ‘tthe furface of the fea; and as in France the dila- tation is found at great heights different from that which happens to the lower air, as refults from the obfervations made on the mountains of Auvergne and Roufillon, we may infer, that the whole mals of the air has not the property of di- lating itfelf according to the ratio of the weights.
a2 We
244 The Wistory and Memotrrs of the
We may alfo infer from thefe different dilatations, that the air is heterogeneous in thefe different parts, and that we fhould therefore be cautious of founding a general fyftem upon particular experiments, let them be ever fo certain and nu- merous,
Jr muft be obferved, that at Cayenne, the pa- rallel of which differs from that of Malaca but 2 degrees + towards the N. the refractions of the {tars have been found fmaller than in Europe. It would be a thing worth examining, whether any relation is found between the manner, in which the air is dilated under feveral climates, and the different refractions of the celeftial objects obferved_ at equal heights above the furface of the fea.
X. Objervations on cray-fifh, by M. Geof- froy, suntor * ; tranflated by Mr. Cham- bers.
Among the multitude of obfervations on the feveral parts of natural hiftory, there are fome ftill obfcure, and as it were unknown, for want of being confirmed by new experiments : and yet the making new difcoveries is not enough to make philofopby flourifh, unlefs we prevent the old ones from being loft. Hence there is a neceffity for handling a-new fome fubjeéts which feem to have been negleéted for a certain {pace of time, and of which nothing is known, but upon the credit of fome writer, whom it may not always be fafe to truft.
In purfuing this method, one has the pleafure either of confirming the vulgar opinion, or of confuting it, or at leaft of clearing and explaining it; fer when only a few perfons have treated a
*=Aug. 23,°1709.
fubjec,
.s
RoyaLt ACADEMY @f SCIENCES. 245
fubjeét, it rarely proves, to be exhaufted. This was what induced me to make obfervations a-new on the cray-fifh, and particularly on the ftones found therein at the time when they change their covers, and which, by reafon of their figure, are called crabs-eyes.
The common opinion touching thefe {tones is,
that they are found in the brain of the animal, which is what Ge/ner, Agricola, and Bellonius af- firm ; and yet fo far are they from being in the brain, that they are rather found about its fto- mach, _ Van Helmont feems to have been the firft who apprehended this, but he having rendered him- felf fufpective on other occafions, his opinion could not make its way; but the vulgar one ftill pre- vailed, except in a few perfons who could fee that experience was fer him.
This author had obferved, that towards the © middle of Fwxe the. cray-fifhes begin to grow fick, as being the time when they are to change their coats, or covers. For nine days, and up- wards, they continue languifhing, and as it were dead ; in which compais of time, He/mont af- firms, that a new membrane is formed, which inclofes the ftomach, and that between this and the former ftomach, a milky liquor is difcharged, which, falling on either fide, hardens into ftone. This new membrane, according to him, arifes from the pellicle formed on the furface of the milky liquor, and growing into a new ftomach 3 the old one within it, and the remainder of the liquor with the ftones themfelves, refelve by little and little, and ferve the animal for food during 27 days that thefe {tones lait; for the animal eats nothing all this while, nor is there any thing elfe found in its ftomach,
3 I
246 The History and Memorrs of the
I have not been able to trace all thefe matters related by Van Helmont, but have made fome ob- fervations which agree with his.
I have found cray-fifhes very foft, and fo ready to quit their fhell, that it was quite raifed, fo as to let the new one appear under it, like a very thick membrane, which only wanted time to become as hard as that going off,
This outer fhell when it rofe, I found very thin, and the inner membrane, which ufes to line it, no longer adhering thereto, but forming a new fhell. And the like I have obferved in the tail, commonly called the neck of the cray-fifh, where the fhells readily arofe, and let the mem- brane that was to fucceed them appear.
The fame I have found upon breaking the claws; fo that upon the whole we may fay, that while the craw-fith is putting off its fhell, the in- ner membrane thereof feparates therefrom, and growing gradually thicker, at length forms a new fhell.
And I have fince obferved, that thofe which are beginning to quit their fhells, and whofe in- ner membrane is come to a competent thicknefs, have ftones in them perfectly formed, refembling in figure the heads of young mufhrooms.
To afcend to the origin of thefe ftones, I have opened cray-fifhes at other times of the year with- out finding any thing in them: but in my laft obfervations made this month of 4uguf, opening fome vigorous cray-fifhes, which were only be- ginning to moult, in lieu of each ftone, I found a film or /amina, fwimming in the middle of a flimy fubftance, and which was perfectly the em- bryo of the ftone. This ftone, with its flime, were inclofed in a little flender membranous
bag.
I
RoyAL ACADEMY of SCIENCES. 247
I have found others, where the ftones were quite formed, and the ftomach folid and full of a brownifh liquor, very mouldy and fetid.
Under the bag where the {tones are inclofed, I have found a fat membranous veficle, whofe ufe I do not underftand, only it has been obferved, that when the ftone difappears, this veficle be- comes full of a fweet limpid water, and _poffeffes the fame {pace as the ftone poffeffed. _ In others, I have found large fair ftones, and a new delicate membrane, inclofing the ftones and the ftomach. Upon raifing this membrane, there were 3 new teeth vifible thereon, fimilar in all refpeéts to thofe of the old ftomach; fo that no doubt can any longer remain, whether this membrane be- comes at length the real ftomach.
In cray - fifhes, which had caft their coats, I have found the ftomach full of a brown liquor, the membrane of the ftomach being here very tender, and no appearance of vifcid matter in if, nor any remains of the former ftomach. The ftones were much leffened, and appeared as if co- roded by fcme diffolvent ; they were covered with a very fine membrane, which was the only thing that parted them from the cavity of the {tomach.
In other cray-fifhes, which had moulted a lon- ger time, I did not find the ftones in their ufual -places, but quite in the ftcmach, where they were joined together by their concave parts. _. In others, where the new fhell was almoft ar- rived at its full hardnefs, I found nothing in the place where the ftones ufed to be lodged, buta white fpot, which was no more than the two membranes of the veficle, that had contained the {tone, fhrunk clofe together. Upon opening the ftomach, I found it full of a yellow liquor and food,
248 The History and MeMo1Rs of the
food, without any remains of a ftone; and Have fometimes even found pieces of fhells, and claws of other cray-fifhes half digefted therein. In thefe laft are likewife found the fpace formérly poffeffed by the ftones, taken up by another ve-. ficle, full of water, already mentioned. —— All which obfervations prove, ‘
ft, That the ftones taken from the heads of cray-fifhes, are not lodged in their brain, but clofed in the ftomach, which is placed below.
adly, That they are not the feed or origin of the new fhell, as fome have imagined, fince they fubfift after the fhell is formed.
gdly, That upon cafting their fhells, they likewife change their ftomach, without any appa- rent renovation in the other parts, excepting the inteftine, which feems to fhare the fate of the ftomach.
4thly, That the ftones are not found till their feafon of moulting, and that they are afterwards lodged in the new ftomach, where they continue leffening, and at length are totally confumed.
sthly, That thefe ftones, together with the old ftomach, ferves the animal as food during its ficknefs, occafioned by the moulcing.
Some authors imagine, that the blue colour of fome of thefe flones avifes from apeculiar malady, incident to fome of them at the time of their midulting. If this be not the real caule, *tis at leaft certain, that the ftones of this colour affume a flefh colour by boiling; and J have even known them turn red’ by the mere heat of the fun.
Hence it is, that among thofe ufed in the fhops, fome are blue, and others carnation ; for T can fcarce conceive that the greateft part of the ‘ftones, commonly fold, are’ counterfeit, as. fome have afferted, on account that the great quantity
thereof
Royal ACADEMY of SciENCES. 249
thereof in ufe, fince we find cray-fithes enough almoft every where; befide, that thefe ftones confift of layers, or /frata, like bezoar, which art would have much ado to imitate; not to mention that they turn black, exfoliate and yield a urinous {mell upon calcination ; a proof of their being really derived from the animal kingdom. ‘To which may be added, that in the analyfis, they yield an urinous {fpirit, with a little volatile falr. - Upon the whole, ’tis more than probable, that the crabs eyes ufed among us, are taken from the living animals; and that the blue or ruddy ones, mixed among them, come from the fick and dead ones.
The virtues of crabs eyes are commonly fup- pofed tobe no other than as meer abforbents ; but the following experiment will prove, that they have other properties, which carry them in- to the very mafs of blood.
A perfon having taken a potion, wherein crabs eyes were an ingredient for fome acrimo- nies which .incommoded him, found himfelf feized all at once with an eryfipelas in the face, which hereby became {trangely bloated, attended with violent prickings, the bloating reached his throat, and hindered his fwallowing. At firft, it was feared, that fomething had been mixed among the crabs eyes, or that they had been pounded in a brafs mortar, and had imbibed the pernicious quality thereof; upon which the fame ‘potion was ordered with other crabs eyes, which ftill produced the fame effedt, till at length the patient. being informed that there were crabs eyes in the draught, eafed the phyfician of his per- plexity, by telling him, that fhe had found the like every time fhe had taken crabs eyes ; upon which, the crabs eyes being difcontinued, the
Mow. EN? 30... aE e {ympom
250 The History and Memoirs of the
fymptom ceafed, and it has been fince obferved, that crab’s eyes had the fame effect on her fon 5 upon which it may not be amifs to obferve, how much the effect of remedies may be difturbed by conititutions. Tho’ we only fpeak of the ftones found in cray-fifhes: yet there is a {pecies of lob- fters, called aftacus marinus, where they are like- wife found. This fpecies is perfectly like our cray-fifhes, fetting its bulk afide.
To conclude ; if fome people have an averfion for cray-fifhes, Van Helmont obferves, that thofe animals, in their turn, have fo great a one for hogs, that if any come near them, they prefently die. Hence, fays he, it is that in Brandenburg, where © {tore of them are caught, the waggoners, who carry them, are obliged to keep watch all night, to prevent any hogs from paffing under their wag- gons; for that if only one paffed, there would not be a cray-fifh alive next morning.
XI. Of the formation and growth of the fhells of land and water animals, either of the fea or of rivers, by M. de Reaumur +f ; tranflated by Mr, Chambers.
The wifdom of nature would not have done enough for the prefervation of animals, if, con- tenting herfelf to have framed their internal parts with wonderful art, fhe had not employed the fame addrefs to defend them againft other bodies around them, the too rude touches of fuch bodies would have quickly deftroyed thofe fo flender canals, and thofe fibres fo very fubtle, whereon their whole mechanifm depends. Hence we fiad thofe delicate parts invefted with diverfe coats, or
+ Nov. 1709. covers
Roya ACADEMY of SCIENCES. 251
covers, not eafy to be altered by the bodies a- round, being not only in an under skin, clofer and "firmer than. the reft ; but this ufually covered with hairs, feathers, fcales, or fhells. Under thefe little ramparts, if I may ufe the term, the ani- mal machines are fheltered from all the attempts of bedies, which are continually rubbing and beating upon them; and the care of nature is even gone fo far, as to proportion a ftrength of thefe defences to the weaknefs of the parts within ; I mean, that thofe animals, which either by their figure, or their foftnefs of their fubftance, lay them moft open to the bodies around, have the ftrongeft coverings. Thus we find fhells on thofe whofe fubftance is very foft and moift, and figure almoft flat or fpiral, which would otherwife, by this double difadvantage, be liable to lacerations from the ground, fand, or ftones they creep upon. The number of different kinds of animals, both in land and water, preferved by means of fuch fhells isimmenfe ; as is alfo the art and ingenuity they are framed withal. Nature feems to have taken pleafure in varying their ftructure, colour, and fhape; infomuch that the admirers of the beauties of the creation have moft of them made it their bufinefs to collect all they could meet withal, every new fhell furnifhing fome new curiolity ; their cabinets, tho’ they only contain afmall parr of thofe which deck the univerfe, yet have enough to excite the admiration of all, who know how to admire. Hitherto indeed they feem to have confined themfelves to the bare contemplation of this beautiful piece of wo.kmanfhip, no body that I know of, having explained the manner wherein it is produced ; “fo that finding nothing to be learned on this | héad among authors, I con- fulted nature herfelf by feveral experiments ; and
Ee2 *tis
252 The History and Memoirs of the
tis on the refult thereof the following fyftern is formed.
Tho’ at firft fight, it may appear moft natural to explain the formation of fhells before their growth ; yet I fhall here obferve a contrary or- der, and begin with explaining the manner in which they grow, by reafon this was eafier to be difcovered by experiments, and that it afforded an eafy infight into their formation ;° which, as one may fay, is only the firft degree of growth.
A body may grow in two different manners, or to fpeak more precifely, the little parts of matter which unite themfelves to thofe a body before confifted of, and hereby augment its bulk, may be joined to it in two different manners. The former when they have firft paffed thro’ the body itfelf, and are’prepared therein, and hereby rendered fit to poffefs the place they are carried to, ere they become united thereto, which is commonly called, growing by vegetation, and in fchools, by intuffufception. Thus it is the’ fap mounts in plants, by little canals in the plants themfelves ; which, after preparing it, fuitably conveys it to diverfe parts of the plant, where it ftops and adheres, and confequently inlarges the body of fuch plant: and ’tis thus that the blood in an animal, being conveyed by the arteries to the extremes of the body, adheres to the flefh and augments its bulk.
The 2d fpecies of growth is, when the new parts are applied to the body, without paffing through, or undergoing any preparation in the body itfelf, which is called growing by appofition, and in the fchools, by juxtapofition, Thus it is all thofe artificial plants grow produced by the chymifts, as likewife all chryftallifations, falts, Fe.
Now
Roy ati AcADEMY of SCIENCES. 253 - Now the growth of fhells muft be performed after one of théfe two manners; they who make every thing vegetate, evento ftones, would hardly have fufpe@ted that fhells; which are wroaghe with fo much art, fhould be produced by a fimple juxtapofition, and the analogy, which feems to be between them and bones (for may they not be confideréd as external bones) feems to con- firm the opinion, fincé bones really vegetate ; but there is no great ftrength in bare conjectures, and ’tis experiments alone, made on the things. themfelves in queftion, that can fupport fuch reafonings ; *tis they alone mult fhow the way nature has been pleafed to take to arrive at her end; and by them we fhall hereafter fhew, that fhells are formed by a fimple appofition. My experiments indeed have only been made on fome fpecies of fhells, both of the fea, river, and land kinds; but this I apprehend fufficient to intitle me to an explanation of the growth and formation of fhells in general, for the fame rea- fon, as the explaining how one plant vegetates, crin what manner nutrition is performed in one animal, would be allowed fufficient for all. ence I fhal] content myfelf with relating the experiments, I have made on diverfe kinds of land fnails, to prevent the tedious repetitions I muft fall into, were I to give the like experiments up- on water-{nails, both fea and river kinds, upon feveral fpecies of two leaved fhells, as mutfcles, -pallourdes, pectongles, &@c. which it would not be ealy for many people to repeat after me whereas every body may make them on land fnails. AN I think neceffary to note is, that I inclofed the feveral kinds of fea and river fhell- fithes in little tubs, which I funk in the fea or ri- ver, after firft piercing them full of little holes,
big
254 The History and Memoirs of the
big enough to let in the water, but not to let out the fifhes; by which means I was enabled to make much the fame experiments, and with the fame fuccefs upon their fhells, as thofe I am go- ing to relate upon the fhells of land {nails, Thus much laid down, I pafs on to explain the growth of fhells.
When the animal, which before exactly filled its fhell, grows, the fhell can no longer cover it all over, but neceffarily leaves part of the body bare, which bare part is always that next the aperture of the fhell; for the animal can only grow on that fide. All animals, which, like the fnails, inhabit twifted or fpiral fhells, are only capable of augmenting on the fide of their head, which is that of the orifice of the fhell; whereas the fifhes of two leaved fhells,as mufcles, are capable of growing in their whole circumference. Now in all the fpecies of fhell-fifhes, ’tis this fame part of the body, thus uncovered by the growth of the animal, that makes the fhell grow, and the mechanifm whereby it is effected, is as follows.
Tis a neceffary effect of the laws of motion, that in liquids flowing in canals, when the the little part of fuch liquids, or any little foreign bodies mixed with them, which by reafon of their figure, or their likenefs, moves flower than the reft, muft recede from the centre of motion ; that is, range themfelves near the fides of thofe canals; and it frequently happens, that fuch par- ticles do likewife adhere to the inner furface of fuch canals, when they happen to be viicid e- nough for that end. Of this we have inftances in the common water-pipes, whofe parietes upon opening them, are frequently found covered over with a little cruft of vitcid fubftance ; and fome
wherein
Royat ACADEMY of SCIENCES. 25¢
wherein Certain waters are conveyed, with a ftony cruft ; it is certain withal, that the liquids, flow- ing in fuch canals, prefs, or impel their parietes on all fides, or which amounts to the fame, prefs the little vifcid or ftony particles of the crutfts above-mentioned againft the fides; fo that if thefe canals were pierced like fieves,with a multi- tude of little holes of a proper figure, to give paffage only to fuch little vifcid and ftony bo- dies, they would break out of the canals, and place themfelves on the external furface thereof, and there form the cruft, as is feen on the infide; with this only difference, that the former is ca- pable of becoming much thicker and ftronger, as being lefs expofed to the friction of the liquor, than that formed in the infide of the canal.
Now the growth of fhells is the work of a me- chanifm of this kind; the external furface of the new-formed part of the body left bare by the old fhell, is full of a multitude of canals, wherein the proper fluids are circulating, that are to fuf- tain the animal; and a great number of vifcid and ftony particles are intermixed therewith, which being lefs fluid than thofe which compofe the liquids they are among, are caft neareft the fides of the veffels, which being full of an infinite number of pores at the external furface of the body proper to give them paflage, they eafily efcape out of their containing veffels, as being continually driven again{t the fide by the circula- ting liquor, and place themfelves on the external furface of thefe canals, or rather over all the fur- - face of the body not covered by the fhell, where
they arrive with the more eafe, as all the pores give them a free exit ; whereas feveral of thefe “pores may be ftopped on the reft of the body by the fhell it is covered with.
3 Thefe
256 The History and Memoirs of the
Thefe particles of vifcid and ftony matter being arrived at the external furface of the body, eafily adhere to.each other, as well as to the extremity of the fhell ; and when the moft fubtle and fluid part of them is evaporated, they compofe a little folid body, which is the firft layer, or firatum, of the new piece of fhell, and other particles of a like matter to that of the firft firatum, whereof the circulating fluid contains enough, iffue from the fame veffels, by the fame mechanifm; here it being no danger, that the firfl fraium fhould have ftopped all the pores; and thus forma fe- cond fratum of fhell; and after the like manner arifes a third and a fourth, till the new fhell have arrived at a certain thicknefs, which is ufually much lefs than that of the old one, when the farther growth of the animal gives rife tc another new piece of fhell.
*Tis the experiments I am now going to deli- ver, that are to fhew whether this be the real manner of nature’s proceeding, or whether all I have advanced be only matter of imagination.
I began with fuppofing that the animal grows before its fhell, of which it is eafy to be fatisfied, by obferving a garden fnail at the time when its fhell is about to grow, or enlarge; for here it is vifibly too fmall to cover the body. On this oc- cafion, they faften themfelves to the wall, where “they remain at reft, and give opportunity for ob- ferving a part of their body come beyond the fhell all around and this like all the reft of their body, is full of a prodigious number of little ca- nals, as appears by the naked eye; but much more by the microfcope.
The pores I have fuppofed in thefe canals, are too {mall to be vifible ; but their exiftence may be evinced from their effects, with as much
certainty
Royan ACADEMY of SCIENECS, 257
certainty as-if one;faw them ever fo plainly. To do this, we need only break off a piece of the fell of a fnail, without wounding its body, which may always bé eafily done, by reafon it only {ticks to it in one place ; for in a little time after we fhould find the skin of the animal covered with a) liquid fubftance, which could not have come from the veffels it was contained in, unledfs there had been pores:in thofe veffels to let it pafs ; andif for further fatisfaction this liquor be wiped off the skin with a linnen cloth, in a few hours more, you'll have a dew liquor o° the like kind fucceeding it, which coming at once over the whole bare part, can only have pafied through its pores.
*Tis this liquid, or rather the lefs fiuid and moveable particles therein, that ferved to make the fhell grow; of this there will be no room to doubt, when it is confidered how it repairs the lofs of a piece of its fhell, which may ke clearly feen *, by putting a fnail, thus ftripped of a piece of fhell, in a place where it may be com- modioufly obferved. In a veffel, for inftance, where it does not remain long, ere it faftens a- gainft the fides of the veffel, as it does againft a garden wall, when its fhell grows in the ufual courfe. Upon this the liquor is feen to thicken and fix, that is, its more volatile parts evaporate, and leave the groffer behind, which form a thin kind of cruft over all the naked part of the ani- mal. ‘This cruft:may be perceived in four and twenty hours times, in which ftate it may be compared for its finenefs to a {pider’s web. ’Tis this cruft that forms the firft fratum of the new fhell, which ina few days more grows thicker by the appofition of new layers under the firft,
* Plate III. Fig..6. |
Mandi! N°. 30. Ff til!
258 The History and MEmorRs of the
till in 10 or 12 days that the new piece of fhell is arrived at much the fame thicknefs as the reft. When you would obferve the new piece of fhell arrive at this thicknefs, care muft be taken to put up a proper food with the animal, efpecially if the fracture were made near the aperture; for - otherwife the bulk of its body will diminifh con- fiderably : fo that what fhell is left them, being large enough to cover them over, there are only the firft leaves of a new fhell formed 5 and it may in fome cafes be likewife proper to pull them from the fides of the veffels, when they continue there for feveral days together, in order to induce them to ufe the food, and repair the expence made in producing the firft leaves of a new piece of fhell. For their food one may give them herbs, or even earth, and paper frequently fprinkled with water, for they will eat indifferently any of thofe things, which may fupply particles of matter firm enough to form a fhell ; and the earth, for inftance, muft needs abound with a multitude of little Jamine, whence the ftones are formed that grow in its bofom 3 if fuch ftony lamine circu- late with the liquors in the veffels of the {nail, they muft doubtlefs be very fit to form the feve- ral ftrata of thells. Now it may be fhewn, bya very eafy experiment, that fuch little {tony par- ticles do circulate with the liquors: in order to this, one need only put a certain quantity of the liquor in a, ‘veffel, and expofe it fome days to the openair. After the fubtlett part is evaporated, a folid matter will be found at the bottom, among which. a multitude of little white friable corpuf- cles, like grains of fand, only thinner, will be found. °*Tis known lilkew ite! that {nails at the beginning of winter make of this fame liquor a
little Jid, for the orifice of their fhell, to cover themfelves
Royat ACADEMY Of SCIENCES. 259
themfelves clofe up. This lid indeed is of a dif- ferent texture, from that of the fhell; but it is folid, which is enough to fhew that there is plenty of folid particles mixed among the liquor; all the difference of texture between the lid and the fhell, probably arifes from the difference of the pores
thro’ which it paffed, in order to form them, The fingle manner of forming a new piece of fhell, in the room of another broken off, might fuffice to prove, that thefe bodies do not vege- tate; for if they grew by vegetation, there are only two ways for it, neither of which is compa- tible with the preceding experiment: for either thefe liquids, which the animal furnifhes for the growth of its fhell, and which on this hypothefs, can only be conveyed to it, by the little part it is faftened by, which may here be confidered as the root of the fhell ; either, I fay, thefe liquids muft here meet with canals to carry them to all parts of the fhell, or canals to carry them only to the extremity, which is to be enlarged. Now in both thofe fuppofitions, it would come to pafs, - that when a piece of the fhell had been broke off, the liquid, flowing in fuch fhell, muft extrava- fate and pour forth at the rupture made in jt. In which cafe, it would be on the circumference of the hole made in the fhell, that this liquid would be found, which, in reality, we only find on the body of the animal ; and this liquor, after fixing, would make a kind of cal/us, which gradually enlarging, would at length clofe the hole. ’Tis thus the cal/us’s have broken; bones are formed by the extravafation of the juice, which before ferved to feed, and make them grow ; and ’tis thus that after cutting a piece of flefh from any part of the body, the adjacent flefh extends, and at length covers the part before left bare. Laftly, ! eo the
260 The History and Memoirs of the
the fame thing is found to befal trees; for upon ~ gutting off a part, the juice oozing from it, forms a callus, which, by degrees, covers over the whole wound; but the quite contrary paffes in the production of the new piece of fhell, nothing comes out. of the fhell, and the whole compafs of the hole clofes at the fame time, by the liquor oozing from the fubjacent body, and to prevent any fufpicion, that this liquor iffues from the fhell in fome infenfible manner, and falling by its Own weight, by the body of the animal, ga- thers in fufficient quantity, to compofe at Jeneth a new picce of fhell, always placed directly under the old one, I fhall fubjoin two experiments, which, at the fame time, will remove this fcru- ple, and demonftrate what has been already ad- vanced,
* I have broke feveral fnail-fhelis in two dif- ferent manners, the firft by miking a large hole between the two extremities of the fhell; that is between the fhell and its orifice, and thro’ the hole thrufting a piece of thin fkin between the ani- mal and its fhell and faftening this fkin to the inner furface of the latter, fo as to clofe very ac- curately the hole made therein: here it is evident, that if the hell were not formed of a liquid fpring- ing immediately from the body of the animal, but of another ozing from the fhell, a piece of new fhe'l muft have form’d itfelf on the external fur- face of the {kin ; and no fhell could poffibly be formed between the body of the fnail and this fkin: the contrary, however, came to pafs; the fide of the fkin which immediately touched the body, becoming lined with fhell, while nothing appeared on the other fide.
* Fig. 7- The
Roya AcADEMyY of SCIENCEs. 261
The fecond experiment is no lefs decifive than the former for breaking feveral fnail fhells, fo as to leffen the number of their circumvolutions : reducing for inftance a large garden-fhell *, which ufually confifts of 4, or 4 4, to 3 4, or 4; and thus rendering them too {mall to cover the animal, I putthem much in the fame condition as they were in, when the growth of the body left part of it bare; this done, I took, as in the former expe- riment, a piece of the thin fkin, as large as the aperture of the fhell; and thrufting part of it be- tween the body of the fnail and the fhell, and faftening it to the inner furface of the latter, I turned the reft of the {kin over the external fur- face of the fhell, and faftened it in like manner thereto, fo that the whole circumference of the aperture of the fhell was covered with the fkin, Now if the fhell grew by a principal vegetation, one of thefe two things muft happen, either that the piece of fkin thus clinging about it, would have hindered its growth; or the fhell growing and extending, would have carried the fkin with it. But the contrary happened, for the fhell crew, and the skin remained as I left it; the growth of the fhell being fo conducted, that the thicknefs of the skin remained between the new piece of fhell and the old; which latter therefore could contri- bute nothing to the formation of the former.
Nor is there any difficulty in conceiving how the little parts of -folid matter, mixed among the fluid, fhould faften themfelves to each other, in order to form a firft firatum of the new fhell; nor how a fecond firatum fhould unite itfelf to this firft ; a third to the fecond ; and fo of the reft. At leaft this difficulty is no other than what we meet withal, in explaining the mexus of the parts
+ Fig. 8. of
262 The History and Memorrsof the
of all folid bodies ; in effect, whatever fyftem we adopt, ’tis obvious, that fuch folid particles float- ing ina very vifcid liquor, are greatly difpofed to unite together, and form feveral firata, as above-mentioned, I proceed now to give an experiment, which may let fome light into the manner wherein this is effected.
I pounded fome {nail fhells in a mortar, and after reducing them into a very fine powder, pafled it thro’ a very clofe fieve, in order to feparate the coarfer parts. This powder being put in a veffel, and vinegar caft thereon, a fermentation arofe, and a kind of pafte was formed, which being left to dry in the air, attained a confiderable hardnefs, efpecially the firft layer, or that next the air; on the contrary, when I moiftened the fame pow- cer with water, a pafte indeed arofe; but upon its drying, the little particles of the powder crum- bled again, and ceafed any longer to adhere. Hence it appears, that the acids analogous to thofe of vinegar, are proper to bind the particles whereof the fhell confifts together; they who make ufe at every turn of the acids in the air, may here find room for them, by fuppofing that they contribute to the coagaulating of the li- quid, which fixes itfelf on the body of the fnail. But to make this conjecture carry a face of pro- bability, it feems neceffary, that there fhould be fome acids found mixed with fea-water, to help éoxculate the liquids whereof {ea-fhells are formed 5 whereas if this were true, the» powder of a fea- fhell, mixed up with fea-water, and then dried, muft come to a better confiftance, than what we obferved the fnail-fhell did, when mixed with ri- ver-water, which in fact it does not.
Nor need we apprehend, that the firft leaf of a
fhell fhoutd ftop all the paffages, by which the liquor
Roya AcaDEMy of ScIENCES. 263
liquor is to iffue to form a fecond leaf, or firatum 5 and foof others, till it have arrived at a thick- ~ nefs. °Tis -hardly poffible, that the new leaf fhould clofe fo exactly about the body- of the fnail, as intirely to ftop all the little pores thereof; - but the difficulty vanifhes at once, upon confi- dering that this firft leaf could not be formed without a diminution in the bulk of the {nail’s body, both on account of the folid particles, whereby the fhell is formed, and of a much larger quantity of fluid matters mixed among them, which had fince evaporated. Hence it follows, that there muft be room enough left between this new leaf and the body of the animal, for new liquor to place itfelf between them, and thus form a fecond ftratum by the fame mechani{m as the firft, and fo a third, and as many more as is ne- ceffary to give the fhell its due thicknels.
The feveral ffrata, which compole the thick- nefs of fhells, become very fenfible upon throwing a fhell in the fire, and taking it out again, after it is a little burnt ; for here its thicknefs fubdivides into a great number of different leaves, which are at a little diftance from each other, the fire having found an eafier paffage between thefe leaves than betweeen the leffer Jemine each of thefe confifts of ; and the like ufually happens in other bodies formed of frata. Waitnels all thofe kinds of paftries, formed of what we commonly call puff- pafte, the whole ftruclure whereof is to be formed of alternate layers of pafte and butter laid one over the other ; which, upon baking, divide in- to feveral leaves or fhivers, by reafon paflages are eafieft opened by the fire, or are even found al- ready open between the feveral layers, which can never be exactly applied one over the other thro” their whole extent.
I The
264 The History and Memoirs of the
The feveral leaves may be eafily faftened: to each other, without their faftening likewife to the body of the animal they are to cover, which the moifture of its skin muft neceffarily prevent ; and) if any flight adhefion fhould happen, the various motions of the anima! within its fhell, would be enough to break them again.
Vis a neceffary confequence of this fyftem of the growth of fhells, that their inlargement fhould only. proceed by increafing the number of their fpiral wreaths or circumvolutions ; and that the length of each circumyolution fhould'always remain the fame, which accordingly is a matter of fact, one may eafily be convinced of, by only; reducing the fhell of a fnail, arrived at its utmoft growth, to the fame number of circumvolutions as that of a young fnail of the fame fpecies, the two fhells: will be found of the fame fize. I have frequently compared the fhells. of {hails newly: hatched, or which I had even taken out of their eggs before hatching *, with other: fhells of the largeft fnails of the fame fpecies, from which Thad retrenched all but the like number of {piral circumvolutions, as were in the little ones, in which cafe they appeared both equal. Itmay be added, that the numberof thefe circumvolutions makes a confiderable addition to the fize of a {nail’s fhell a fingle circumvolution, more or lefs occafioning a very fenfible difference, for the diameter of each circumvolution is near double that of the preceding one, and but halfof the fol- lowing one; whence tt follows, that a half or evem a {of a circumvolution. more muft make a con- fiderable enlargement; and yet it frequently proves difficult enough to difcover, whether a fhell con- tain or a + of acircumvolution more or lefs
* Fig 9. than
"Roya AcApEMy of SctENncEs. 265
than another. The only fure way to compare the number of circumvolutions between two thells of the fame fpecies, is to compare large onés with very fmall ones, in which cafe the dif- ference eafily appears.
What has been hitherto faid of the growth of fhells, will exernpt us from the neceffity of enter- ing into the detail of their firft formation ; for ’tis eafy to conceive, that when the body of a little em- bryo, which is one day to fill a large fhell, is ar- rived at a certain ftate, wherein the feveral skins that inclofe it are of confiftence enough to let pafs thro’ their pores the only liguor fit to’ form a fhell, this liquor muit place itlelf on fuch skins, and thicken and fix there ; and in one word, be- gin the formation of a fhell in the fame manner as it afterwards continues its growth. Snails do not leave their eggs, till they have firft covered themfelves with fuch a fhell, which now confifts of one circumvolution, and fomewhat more.
It remains to iolve two difficulties, which feem pretty confiderable: the firft naturally arifes from the experiments above related, and ftands thus, _ the new piece of fhell, formed in lieu of the old one which had been pulled off, is of a whitifh colour, and confequently very different from the reft of the fhell, whence it fhould feem to be of a different texture, and may hence be inferred to have been formed after a different manner; ‘fo that the foregoing experiments will determine no- ‘thing as to the ordinary way of growth.
“To obviate this difficulty, it will be neceffary to account for the regular variety of the colours
in certain fhells, or the fame experiments, which fhew the caufe of fuch regularity, will effectually remove this objection.
Vor. III. N°. 30. Ge This
265 The History and Memoirs of the
This regular variety of colours is peculiarly obfervable in a little ipecies of garden {nails *; the ground of their fhell is white, citron coloured, yellow, or fome intermediate colour between thefe, and on this ground appear various ftripes, which twift fpirally like the fhell, and in fome fhells are black, in others brown and reddifh, in others the breadth cf each ftripe gradually increafes as it approaches towards the aperture of the fhell ; and it fometimes happens, that two of them fpread fo much as to meet, and form only one broad {tripe afterwards. In fome fhel!s there are 5 or 6 fuch ftripes ; others have but 3 or 4, and others only 2, or even a fingle one. A fort of white and brown ftripes may alfo be feen on the large garden-fnails,; but they are much lefs confpi- cuous, and muft be viewed with fome attention ; to diftinguifh one from another in each kind of fhells, the ftripes are not all of the fame breadth in the fame part of the fhell. There feems but one plaufible way of accounting for the variety of thefe colours on the principles we have here eftablifhed of the growth of fhells by juxtapofi- tion ; for having confidered the skin of the ani- mal as a kind of fieve, which gives paffage to the particles, which are to form the fhell, *tis ob- vious, that if we conceive the skin as differently pierced in ditterent parts, or which amounts to the fame, that it is compofed of different fieves, fome whereof pafs particles of different figures or natures, from thofe paffed by others, and deny entrance to thefe, it will follow, that fuch parti- cles of different nature or figure, muft form bodies, which will reflect the like differently, that is form picces of fhell of different colours.
* Dig. § +30
Tis
RovaL ACADEMY of SCIENCEs. 267
°Tis likewife a neceffary confequence of the manner of growing of a {fnail’s fhell, that the whole furface of this fhell (I do not fay its whole thicknefs) fhould be formed by the collar of a fail, as being the part next the head, and which therefore, upon the leaft growth of the animal, muft be lefc uncovered, ’tis this therefore that is to enlarge it ; and we may confider this as the manufacturer of the whole furface or circumfe- rence of the fhell: fo that it will fuffice, if this collar be compofed of different fieves, to forma fhell of different colours. For inftance, if it had two or three little fieves proper to tranfmit black or brown particles, and the fides of thofe fieves be parallel to each other, while the reft of its fur- face tranfmits other particles proper to exhibit yellow or citron colour ; for the fhell formed of particles paffed thro’ thefe feveral fieves, muft evi- dently have a yellow or citron colour’d ground, with black or brown ftripes thereon, almoft pa- rallel or approaching each other infenfibly, and which will become larger in proportion, as thefe fieves are enlarged.
Tho’ we were to difcern nothing like thefe different fieves juft mentioned on the collar of the fnail, they afford us fo probable a folution of the diverfity of colours in fhells, that one would be induced to admit them, but fortunately enough they difcover themfelves, efpecially in the little fpecies of fnails, fo remarkable for the diftinct- -nefs of its ftripes*. Upon the ftripping one of thefe fnails of a part of its fhell, all the reft of the body appears of one uniform white colour, excepting the collar, where the white has more of a yellowith caft ,; and befide this is befet witha number of black or brown ftripes, equal to that
= Fig." to. j Gg 2 o!
268 The History and Memorrs of the
of the ftripes of the fhell, and placed in the fame direction. Thofe inails which have only one black ftripe ontheir thell, having but one black {pot on their collar, andthofe which have 4 ftripes on their fhell, having 4 likewife on their collar: thefe ftripes are placed immediately under thofe of the fhell, and begin at about a line’s diftance from the extremity of the collar, which itfelf is ufually fpotted with black all around; but the length of thefe ftripes in the collar differs in different {nails of the fame fpecies; one cannot overlook the fieves I have above-mentioned, in obferving thefe {tripes, whofe different colour abundantly proves the difference of their textures.
To remove all doubt, whether thefe fpots do the office of fieves different from thofe of the reft of the collar, and that the reft of the collar, which likewife appears of a different colour from the reft of the skin of the body, does alfo tranf-_ mit particles of a different nature or figure, the bufinefs muft be to learn, whether experiments agree with this reafon; and all neceffary thereto, is to let a {nail repair the fhell, which has been torn from it; for if it appear, that fo much of their fhell as is formed over thefe black ftripes is black, and what is formed between them is of a different colour,both from thofe ftripes,and from the reft of the body,it muft be allowed incontefti- ble, that thefe different parts do the different of- fices above afligned them. Now experience a- grees perfectly with the reafon already laid down, * the fhell growing on the collar over the brown or black ftripes, is itfelf brown or black ; that formed between them is white or yellow ; and that on all the reft of the body white, but a different white from that of the collar when it happens to
* Fig, 11, be
Royvat AcapEmy of SciENcEs. 269
be white alfo. : the fame is obfervable in the large garden-{nails, where all the fhell formed over their collar is brown, or of a colour. like that of the old fhell, and the fhell on all the reft of their body white.
We come now to a fecond fcruple, which may arife upon repeating the experiments here re- lated. The new fhell formed over the collar, in the room of the old piece broken off, fometimes proves of a different colour therefrom, which feem a contradiction to the account here laid down,
But there will be.no great difficulty in reconcil- ing this kind of irregularity with the reafonings and experiments above, when *tis.confidered that the new fhell formed over the collar never differs in colour from the old, unlefs its external furface be extreamly rough, and as it were furrowed over, while the reft of the fheil is quite {mooth.
This inequality of furface of the new fhell is oc, caftoned by the motions the {nail puts iorth, when it would re-enter its houfe before this part be thick enough to fuftain itfelf, without bearing on at; for’tis evident upon thus fhrinking it, when there is only one or a few leaves formed of the
‘new piece of fhell, ic muft bring the extremity of fuch pliant leaves towards the old fhell, and thus reducing them into a lefs compafs, makes diverfe folds therein, which of itfelf were almoft fuficient to change the colour of the new fhell; but there
4s fomething more in it; for the firit new fra- tum formed upon breaking off a large piece of old fhell is ufually white, by reafon the particles of the liquid difpofed to form a fhell of this co- Jour, are tranfmitted more readily thro’ the pores than thofe which form a fhell of any other co- lor, as is evident enough, the reft of the body of 3 ; the
270 The History and Memoirs of the
the animal being palpably covered over with liquid ere any be perceived on the collar; whence it happens, that this liquid fpreading upon the collar, forms the firft leaf of the fhell white; but this leaf being extreamly thin, is tranfparent like- wife, and rarely hinders the fhell, which the collar itfelf produces afterwards, from appearing of its natural colour. Now, if the fnail happen to fhrink into its fhell when only this firft white layer is formed, it is clear, that it muft draw the extremities of fuch leaf towards each other, by reafon it adheres to it in forne places; and will occafion it to make pleats or folds, and increafe its thicknefs by diminifhing its breadth and tranfparence, which muft give the new fhell a kind of middle colour, between that ufually formed on the collar, and that on the reft of the body ; but the internal furface of the new piece of fhell being, always fmooth, muft always be of the- colour naturally produced by the pores corref- ponding to it, and accordingly we find its colour diverfified after the fame manner as that of the old fhell, even when the externa! furface is of a diffe- rent colour from what it fhould naturally have.
It would be wrong to conclude from what has been here fhewn of the formation of the ftripes which adorn certain fpecies of fhells; that the external furface of all fhells fhould either be ftriped, or have one uniform colour; and that there fhould be no fhells, whofe external furface exhibits {pots or {tains differently placed, irregu- larly figured, and feparated from each other by unequal diftances, fuch as the fhell, fig. 12. upon this ground, that fuch fpots cannot be produced on the furface of the fhell, without different fieves on the collar of the animals to tranfmit a diffe- rent liquid from what paffes thro’ the other
places,
~Royat AcaApEmy of SCIENCES. 271
places, and. confequently without the apparatus neceffary to produce a ftriped fhell ; for it is ob- vious, that the fieves muft have fubfifted during ’ the whole formation of the fhel!, in order to ren- der this fhell ftriped in its whole compafs 5 but if it happens on the contrary, that thefe fieves change fo as the pores which before tran{mitted a liquid matter proper to form a brown fhell, become ei- ther too wide, or too narrow, or alter their figure in any other manner after filterating a certain quantity of their firft liquor, and the like altera- tion befall the reft which tranfmitted a liquid pro- per to form a white fhell; the confequence mutt be, that the fhell now formed, will exhibit feve- ral black and white fpots, combined with the fame irregularity as the fieves had been altered.
This will not appear a fuppofition without all foundation, to fuch as confider, that certain alte- rations befall even the fieves of the collar of fnails, which produce ftriped fhells ; for fome of thefe fhells may be found wherein the ftripes are very {trong and vivid towards their aperture, while there is no appearance of any ftripes on the firft circumvolutions of the fpiral; that is, on thofe next the vertex of the fhell: now this change of colour can only proceed from a like change in the fieves of the collar; ’tis true, we are to con- ceive much more confiderable changes on the col- lar of the animals which inhabit fuch fhells as that of fig. 11.5 but thefe changes are equally poffible _with the other. .
The fluidity of the liquor whereof the fhell is formed, may alfo have fome fhare in the irregu- Jar diftribution of the colours on fome kinds; for it is eafy to conceive, that if the liquid which fome animals yield for the formation of their fhell, be fluid enough to run eafily from one
place
272 The History and Memorrs of the place to another, fhells may eafily come to be ir- regularly marked, provided there be fieves on their collar, which tranfmit different liquids; fince in that cafe it muft frequently happen, that the liquid will not remain in the place where it was firft lodged; but that what for inftance was deftined to form a white fhell, fhall remove itfelf to a place where a liquid iffues that is to form a black fhell; as on the other hand, that which forms the black fhell, they run into a place where another liquor iffues to make a white fhell: now, as this muft happen very irregularly, according to the different pofitions the animal is in, where the fhell is formed, the {pots muit likewife be difpofed very irregularly.
Recourfe however muft be had to the firft of the two caufes above affigned, viz. a change of the texture of the fieves of the collar, in order to account for the regular pofition of the red fpots, in a fquare or rectangular figure, which adorn the fhell reprefented in fig. 13, it being neceffary to form it fuch, that the fieves in this fquare, or rectangular figure, which tranfmit the liquid proper to give fuch colour to the fhell, ftop, and open again at a certain rate.
Tho’ the collar of the {nail trace out the whole circumference of the fhell, and tho’ this fuffice to diftribute colours regularly thereon, yet it does not give it all its thicknefs, which receives a con- fiderable augmentation from the particles of the li- quid iffuing from the pores of the reft of the fkin : this is‘eafily fhewn, for upon reducing the fhell of a large {nail to the fame number of circumvolu- tions, as that of a fmall one, tho” they appear equal- ly large, yet that of the large one will be found the thicker: this increafed thicknefs of the fhell is particularly obfervable in fome fpecies of fpiral
i{ea-
RovaL ACADEMY of SCIENCES. 273
fea-fhells, where it fometimes rifes to fuch a pitch, that the firft circumvolutions of the fhell grow ups fo that the animal is obliged to withdraw its tail into the circumvolutions. further off, as ap- pears very fenfibly in fome fhells difected by M. Merry; one whereof is reprefented by fig, 12, where the {paces 2 22, formerly poffefied by the body of the animal, are become quite folid.
.. The anima’s tail not adhering to the vertex of the fhell, as fome have imagined, it can eafily difplace it; efpecially while the part whereby the animal is faftened to the fhell, is chang- ing (for this part changes according as the body of the animal, makes more, or fewer, fpires: ) thusa little fnail, for inftance, fhall be faftened by a part of its firft circumvolution, and when its grown bigger, fhall only be faftened by the fecond. }
_ _ The laft frrata formed by the fkin which does rot cover the collar of the {nail ought to be white agreeably to all that has been hitherto advanced, and they are fo accordingly, as may eafily be perceived by rubbing off the firft ffrata of the external furface of thefe fhells, with a file; thofe which then remain appearing white, or the fame may be proved with lefs trouble by confidering, that the colours of the empty fhells found in gar- dens, are frequently almoft effaced, and fometimes appear quite white; the firft ftrata which are the only coloured ones, having been carried off by ‘too much attrition againft the ground.
The growth of fhells being proportionate to that ofthe animals inhabiting them, is. hardly fenfible; yet in the generality of fhells, we can eafily diftinguifh their feveral ftages, or degrees of growth: thefe are expreffed by feveral little parallel eminences, which one would be apt to
Wer. TN”. 30, Hh take
374 The History and Memorrs of the
take for the fibres of the fhell; they are fpread over the whole furface in fuch as are flat, or two leaved ; and over the whole breadth in thofe twifted fpiralwife. The leaft refie€tion on the manner above explained of the formation of fhells, will Jet us fee, that they cannot grow without pro- ducing the little eminences juft mentioned; for each new piece of fhell muft be faftened imme- diately under that preceeding it, which, of confe- quence, will be higher than this, by the whole thicknefs it had attained when the growth of the anima] gave rife to this laft,; ander which likewife muft be placed the piece produced next to this ; by fuch means the fhell muft be covered with a multitude of little eminences parallel to each other, which may be diftinétly 4een on the fhells of {nails}, where they are very near together. Fach fhell* has ufually fome of thefe eminences much more diftiné&t than others, and further afun- der, which exprefs the different times when thie fhell ceafed growing, and bears fone analogy to the different fhoots obfervable on each branch of a tree, the heat of fummer, or the cold of win- ter, putting a ftop to the growth of the animal ~ which inhabits the fhell, as is eafily obferved in {nails, its fhell is topped of courfe while thofe feafons Jaft; I mean the extent or compafs of it, not its thicknefs, which is continually increafing by the flux of fluid particles from the body of the animal: hence when it begins to grow again, in a more favourable feafon, the new piece of fhell it now produces, is faftened under a much thicker fhell, than when its growth proceeds gradually ; and confequently, that former term mutt be ex- preffed by a larger eminence. + Fig. 6. * Fig. 7, 18. ! There
Royat ACADEMY of SCIENCES. 276
There is one other thing which renders the {e- veral places where the fhell began growing, after having ceafed for fome time, fenfible, wiz. a change of colour on the ftripes above-mentioned 5 the black or brown ftripes are in thefe places, of a much brighter colour, and fometimes fcarce different from the reft of the fhel] ; nor will the caufe of fuch change be far to feek, if it be re- membered, that the + fieves of the collar which tranfmit the liquid proper to form thefe black or brown ftripes, have their origin at the extremity of the collar ; whence it is obvious, that the farft ftratum of fhell drawn by the extremity of this collar, muft be of a different colour from that of the ftripes ; but as the growth of the animal] oc- cafions the f{tripes of the collar to be fouad under this firft fhell, while it is yet very thin, but con- fequently tranfparent ; it does not hinder the fhell produced under it, from appearing black where itis fo; but when the animal has ceafed growing for fome time, it increafes the thicknefs of this fell produced by the extremity of the collar, fo that the fhell which the ftripes of the collar pro- duce under this laft, when the animal begins to grow again, being placed under a piece of fhell much thicker, and lefs tranfparent, the colour of thefe ftripes is the lefs difcernable: and thus ap- pears different here, from what it is in the reft of the ftripes.
The figure of certain fhells is what may now feem the moft difficult to reconcile with this theory of their growth, and accordingly make the fecond difficulty whichI propofe to folve ; the chief objections drawn from the figures of thells againft their growing by juxtapofition, may pe reduced to 4; iff, The change of the curvity
f Fig. 7. Hh in
276 The History and Memotrs of the
in certain parts of fome fhells; for how on this fyftem fhould the curvity of fome fhells be pro- duced, which, after extending for fome time out- wards, turns again upon itlelf,’ as in fig. 15, ° which reprefents t the tranfverfe fection ofa fhell of this kind, where it may be feen? But after the thell has twifted from A throush CCC to EER, it turns back again to DDD, a meer appolition of parts ought rather to continue the fame curvity. 2dly, How are the horns produced which we find on certain fhells? By horns, I mean a kind of eminences feea on fome fpecies of fhells, which by their figure refemble the horns of fome animals, fuch are the eminences in fig. 14 and 15, reprefented by the letters CCC, gdly, How can the furrows, or flutings, be formed, which inrich the external furface of certain fhells, while their internal furface is perfeétly fmooth ? For why fhould fuch fhells be thicker through their whole Jength in fome places, than in others, as are thofe of fig. 17, 18, 19? Laftly, How cana cavity be formed, wherewith the body of the ani- mal has no communication, and which runs all alona the acclivity of the fhell, as that repre- fented by E, fig. 7.
The fhells of land fnails will yet furnifh an an- fwer to the firft of thofe difficultiest. The Jaft {tage of growth of thefe fhells is a kind of rim or ledge, about a line broad, which turns outs wards ; whereas all the réft ip the fhell turns in- wards ; this ledge formed, the growth of the fhells is at an end ; they who may never have feen a inail’s fhell without: fuch a ledge, feem to have fome reafon to conclude, that thefe fhells can ne- ver be produced by a fimple juxtapofition; for in that cafe dfs fhould twift a contrary wey from
t Fig. 6 | what
- RoyaL ACADEMY of ScizNcEs. 277
what they do; but if it be confidered, that fnails’ of all ages. and degrees of growth below the high- eft, have no fuch ledge, the difficulty difappears,
for the fame thing doubtlefs ‘happen ‘to fuch fhells,-as that of jig. 15. This ledge is of the {fame colour with the ftripes in the little ftriped inails, reprefented 1 in fig. 1y, and accordingly the extremity of the collar is of the fame colour as the skin, which forms the ftripes, as may ee feen in fig. 10.
The curvity of the fhell is unchangeable, unlefs that of the body of the animal, which is its mould, happen to change, ’tis eafy to imagine probable caufes of fuch a change i in the growth of the fnail. For inftance, *tis not unlikely, that the internal fibres of the collar may grow fafter than the ex- ternal @mes ; the confequence whereof mutt be the latter’s pulling the collar of the fnail towards them, and obliging it to bend outwards.
As the different length of the fibres of the col- lar gives us an eafy conception, how it may come to be bent outwards ; {6, by attending to this different length of the'fame fibres, we may con- ceive how the bodies of feveral animals come to be twifted fpirally; for fuppofing that from the production of fuch animals, the fibres of a cer- tain part of their furface are ‘lotiger than thofe of the oppofite furface, *tis evident the body will erook itfelf fo as, the furface, whofe fibres are fhorteft, will form the coneave of the curvity ; ‘and the other furface, whofe fibres are longeft, the convex which is enough to make the body of the animal defcribe a fpiral, fince it cannot grow with- out always bending thus on. icfelf, provided its Jong and fhort fibres grow in the fame proportion. aris true, in the cafe above- mentioned, it would ved delcribe {pirals, whofe feveral circumvolu-
tions
278 The History and Memoirs of the
tions would be almoft in the fame plane ; whereas few animals have the fhell or the body, which ferves it as a mould, twifted inthis manner, but have the feveral fpires, both of their body and fhell, in different planes; but with one fuppo- fition more, we fhail eafily conceive how thofe laft fpirals are formed; for {uppofing, befide the two furfaces, whofe fibres have been Jaid down as Jonger one of them than the other, that there are two other directly oppofite furfaces, each of them comprehended between the preceding ones, but fmaller than them ; and that thefe two laft fur- faces are alfo formed in fuch manner, that the fibres of the one are longer than the correfpond- ing fibres of the other. This muft needs oblige the body of the animal to incline itfelf on one fide, and hereby form fpires fituate in different planes.
If land fnails happened to produce a ledge Ijke that found at their laft term of growth, after the formation of each quarter of a circumvolution, and that their external fibres relaxing hereupon, they produced another quarter of a circumvolu- tion, bent the fame way as the former; after which they produced a new ledge, and fo ina fucceffion their fhell would be divided from fpace to f{pace, by a number of fuch ledges, which would be a pretty ornament to it. *Tis + by @ - jike artifice, thatthe fhells of the feveral fpecies of fea fnails, which appear fo wonderfully wrought, are formed, the working being only fo many little ledges of fhell difpofed at certain dif- tances, which yet beautified in fuch manner, as if nature had been at the pains to carve it.
} Fig. 16, °17. The
Roya AcApemy of ScIENCES. 279
’ ‘The *horns found on fome fpecies of fhelk, are alfo produced by the fame mechanifm as the reft of the fhell, certain flefhy tubercles erowing on the body of the fifhes, which in- habit them, ferve them as moulds; and ac- cording as more or fewer of thefe tubercles are formed, while the animal grows one circumvolu- tion, there are more or fewer of fuch horns in the fame circumvolution. They are hollow when thefe tubercles have remained on the body of the animal all its life-time; partly hollow, and partly folid, when the fame tubercles had been partly diffipated, and quite folid, when the tubercles had been quite vanifhed during the animal's life. '~To the fame formation, and that of the ledges, we areto afcribe much fmaller eminences, which from their figure, may be called prickles, ufu- ally found at the end of the terms of the fenfi- ble growth of thefe fhells, as may be obferved in jig. 18. .
The flutings found on the external furface of fhells, while their internal furfaces are perfectly fmooth, will not be lefs eafy to explain. It wiil fuffice to obferve, that the whole extremity of the furface of the animal’s body is likewife fluted ; and hence we may find the fhell likewife fiuted in its internal furface to fome diftance from its extremity +; but in regard the reft of the fur- face of the animal’s body is f{mooth and foft, the animal growing, and the part of its body not fluted, coming to correfpond to that of the fhell, which is what this part furnifhes; for the fhell ferves to fill or ftop the internal flutings, whence the fhell is only found fluted on its external fur- face, excepting only the firft lines of the breadth of its internal one.
* Fig. 14, 15. + Fig. 17, 18, 109. here
280 The History and MEMorrRsof the There * is a flat fea “fhell, much like the kind called S?. ames, whote formation would have cappeared very difficult; but for-what we have fhewn of the formation of the futings in other fhells, this fhell is likewife fluted, but the two ‘fides of each flute are little canals inclofed on all fides with fhells, and perforated from the vortex of the fhell to its extremity. Tis eafy to fhew -how thefe httle canals may be forméd, all re- quired being to conceive, that the firft extremity of the body. of the fith is deeply fluted, and the reft of its body quite fmooth, and its fabftance too hard to enter the channel or fluting, formed by the extremity ; fo that the reft of the body only produces afew leaves or fhells, which are ap- . plied over this fluting, without clofing it intirely, but leaving a little canal fuch as above related.’
Before we come to explain the formation of the cavity running along, the flight of certain fpecies of fhells, between which and the body there is no communication, it may be necefiary to define what we mean by flight. To form a precife idea thereof, it muft be obferved, that when the col- lar of the animal draws the feveral {piral circum- volutions of the fhell, that part of the external furface neareft the axis it winds about, forms fpires, whofe diameter or width is Jefs than that of the fpires defcribed by the other points of ‘the collar. Now that part of the fea-fhell formed by thefe fmaller fpires, is called its Aight; a tolerable notion whereof may be conceived “from the flight _ Of a ftair-cafe.
To unfold the myftery of the formation of this cavity along the flight, it -muft be firft obferved, . that the upper fuifabe of the collar is convex, and the lower concave ; as is evident hence, that the
* Fig. 19. Pe) firft
RoyvaAt ACADEMY of SCIENCES, 28;
firft is placed under the concavity of the fhell, and the fecond over its convexity : * now the up- per furface of the collar being always left bare, by the growth of the animal, ’tis this that forms the new fhell, and that part of the upper furface of the collar, which traces the fmallet {pires, is likewife that which produces the flight of the fhell; imagine now the collar of the animal to {pread and extend, in order to produce a new piece of fhell, and confequently a new piece of the flight, as the animal is twifted within its whole fhell, we are to conceive at the fame time that a certain part of its body extends and winds a- bout a part of the flight it had not before reached to; this part thus applied to a new place of the flight is that where the lower furface of the col- Jar makes an angle with the upper. Now if we conceive this part of the animal to be neither crooked nor flexible enough, to mould itfelf per- feétly upon the part of the flight, it is new ap- plied on, ’tis evident a little void fpace will be left between the flight, a part of the body-of the animal, and a little piece of the old fhell found between this part of the body and the flight. The part of the body which contributes to inclofe this cavity, not being covered with fell, will yield a liquor proper to form one; and by the production of this new piece of fhell, the little hole will be furrounded on all fides ; and ’tis ap- parent this fame hole mutt run all along the flight by reafon the fhell cannot grow, but it muft be formed at the fame time.
_ If the little part, which helps to inclofe the hole, emits {tore of liquor, the hole by this means will become quite folid, being {topped up by the new fhell; this accordingly befalls feveral new
* Fig. 7.
&:7 Vor Ill. N°. 31, i fhells
282 The History and Memoirs of the
fhells, whofe flights are much thicker than it feems they fhould be. - Ifthe curvity of the flight diminifh enough to give the body of the animal room to mould it felf thereon, after the fhell has made a certain number of fpires, ’tis evident no more hole muft be formed, and that what is already formed muft be ftopped towards its upper furface. This ac- cordingly actually befalls fnails, which have at- tained their Jaft degree of growth, or to whofe fhell the ledge is formed, as may be feen in jig, 11. The little fhell there reprefented has a little ledge B BB, and the hole which fhould appear in E, were it not arrived at its period of growth, is {topped up, by reafon of its arrival thereat. The fame thing befalls large fnails, and the only reafon why we fee the holes E in fg. 7 and 8, upon the flight of their fhell is, that they had not attained their utmoft growth; otherwife thofe holes would have been covered over as in fig. 11. When the collar draws the feveral f{pires round a little cone, ’tis evident a little conical fpace mutt be left vacant in the middle of the fhell; that is, a little cavity will appear, round which all the {fpires are placed. Several fpecies of iea-fhells, as that of jig.12, and diverfe kinds of land {nails have fuch a conical aperture.
If the vertex of the cone, round which the collar of the animal winds, be at the origin of the fhell, ’tis evident this hole muft terminate in the point of the fhell, which will clofe it here. Such is the hole of the {nail fhells above-mentioned, and that of fig. 12, which terminates where the fhell corn- mences ; but ifthe vertex of the cone be beyond the origin of the fhell,; it muft be perforated throughout; and after this manner are feveral fea-fhells formed.
Laftly,
Roya ACADEMY of SCIENCEs. 283
Laftly, if we fuppofe the collar of the animal twift round a folid of fome crooked figure, in lieu of the cone above fuppofed, and the verter of this folid to be at the origin of the fhell, ’tis like- wife evident, that a hole will be formed in the fhell of the figure of fuch folid.
If the animal inhabiting fuch a fhell, form a cavity all along the flight thereo*, fuch as we have already reprefented on the fhells of large garden-{nails, this its fhell muft be perforated with two feveral holes through its whole length, and confequently will have two oblong apertures*, _ wherewith the body of the animal has nocommu- nication. | |
Thefe two holes may fometimes alfo be pro- duced after the fame manner as that running along the flight. To conceive this, we need only ima- gine, that the part which afterwards poflefles the place of that which has formed the hole, by reafon it could not mould itfelf upon the flight, that the part I fay of the animal’s body that fucceeds this, cannot adapt itfelf exactly to the fhell it has pro- duced,
A volume would hardly fuffice to relate ail the remarkables in the figures of fhells, I have pre- fcribed myfelf narrower bounds, and the more willingly I do it, as there is fcarce any thing ex- traordinary in them, whofe formation may not be reduced to fomething already laid down.
da explanation of the figures, tranflated by _M.
Fig. 6. reprefents a fhell of a great garden {nail, broken in two different places. The let- ters A A A mark the circumvolution of the holes that have been made in it. We fee thefe holes
‘Fig. 15. Li 2 {topped
284 The Wirstory and Memorrs of the
ftopped by new pieces of fhell, placed immedi- ately under the old one. It muft be obferved, that this new fhell is not coloured like the old one, that it has not alfo different little lines, which may be called fibres of the fhell, though impro- perly becaufe of their figure ; and thefe fibres are marked diftiné&ly upon the old one.
Fig. 7. The letters A A A mark the circum-
volution of an aperture made in the fhell. It is a ~ piece of thin skin, which ftops this aperture ; it is pafted to the inner furface of the fhell. B re- prefents the new fhell, which has formed itfelf upon the furface of the skin which touched the body of the fnail.
D D 1s the circumvolution of the aperture of the fhell, which is not turned back like that of of jig. 6.
E marks by a prick’d line the aperture of a hole, which runs along the whole flight of the fhell, quite to its fummit or point P.
C C is one of the notable bounds of the growth of the fhell. We there fee the rays almoft inter- rupted, or faintly traced.
Fig. 8, is the fhell of a great garden fnail, of which the circumvolution of the aperture went juft to A, but broken according to the turn of this aperture, which is bounded by the letters BCC. CCC isabit of thin skin, which here appears pafted upon the outer furface of the fhell, but we mult alfo imagine it pafted upon the in- ner furface of the fame fhell ; {fo that it covers the whole edge of the fhell, which is confequently contained between the two extremities of this piece of thin skin. EDDDQ mark the new fhell which has been produced, and feparated from the old one by the thicknefs of the skin upon which it is applied.
Fig.
Royat Acapemy of Sciences. 285
Fig. g. reprefents the fhell of a {mall fnail, newly come out of its egg.
Fig. 10. is a fmall garden fnail, with 5 black or brown rays painted upon its fhell; the inter- vals between thefe rays are of a lemon colour. This fnail appears divefted of a part of its fheil, which went before to A A A, and 1s at prefent terminated in BB, which was done on purpofe to fhew the collar of this fnail, which is alfo marked with 5 rays CC CCC of a brown colour, but not fo deep as that of the fhell ; the origin of thefe ~rays is at fome little diftance from the extremity of the collar ; and they ufually are but a line or two in length. The {pace between thefe rays, and that which is between the neareft extremity to the edge of the collar, and that edge of the collar A A is of a much brighter colour than that of the rays, and alfo more brown than that of the reft of the skin,’ which is from the extremity of the rays CC CCC the moft diftant from AAA, quite to the fummit P of the fhell.
The edge A A A of the collar of the animal is of a brownifh colour.
Fig. 11. is alfo a ftriped fhell, with only 3 rays. ‘There have two holes been made in this fhel], of which the fartheft from the collar is marked A, and the neareft DCC. The fhell which was formed to ftop the hole A, is of a different colour from the rays and their intervals. But that which ftopped the hole DCC is of the fame colour with the old one; fo that the black rays are continued in CC, and D is of a lemon colour. This Jaft hole however is here painted not quite fo near the edge of the fhell as it fhould
e. BBB mark the return of this fhell, which was arrived at its laft degree of growth. This 3 return
286 The History and Memoirs of the
return is of a brown colour; it has alfo been feen (in fig. 10.) that the extremity of the edge of the collar is brown. The origin of the rays of the fhell is not at this return, as the origin of the rays of the collar is not at the extremity of this collar.
E marks the fhell, which then ftops the cavity along the fight.
Fig. 12. reprefents a fhell, called Ja Veuve; it is marked with different black {pots, of irregular figures, and placed irregularly on a white ground.
At A there is a hole, which goes juft to the fummit of the fhell. This hole is formed very differently from that of fig. 7 and 12,
Fig. 13. is a {pecies of turbinites, upon which appear diferent little fquares, of a red colour, difpofed in a pretty regular proportion.
Fig. 14. 1s the fection of a fhell, where the tail of the animal has been obliged to abandon the firft turns, becaufe they are grown quite folid. The letters A AAA AA mark the fpaces, which at firft were occupied by the body of the animal, and afterwards filled up. It fhews alfo that part of the fpace EB is become folid, namely that which is marked E, the body of the animal oc- cupied only the fpaces BB, DD DD, Ge.
CCC C are thofe eminences of fhells, which TY have called horns, or fections of thofe emi- nences.
Fig. 15. is the tranfverfe fection of a fhell, which after having made a certain number of fpiral turns in CCCC one way, turns back again in DDD.
A A are two holes, which are in the whole length of the fhell, with which the body of the animal does not communicate, which occupies the fpaces BBB, &c.
CCC are eminences, or little horns. Fig.
aera Nat? : es 1 Poe ae
JSMynde/e)
Roya AcapeEmy of Sciences, 287
Fig. 16, is a fpecies of ¢urbinites, which feems very artificially wrought. This ornament comes from different returns, fuch as the laftt AAA difpofed from fpace to fpace.
Fig. 17. has alfo feveral returns like the pre- ceding. But we may alfo obferve, that each of thefe returns is fluted.
BB is the inner furface of the fhell, which is fmooth, tho’ the returns are fluted,
Fig. 18. is a fhell with the outer furface fluted, tho’ the inner furface is {mooth.
CC, CCC, DDD are 3 bounds of very fenfible growths, the laft of which DD DD is adorned with feveral little eminences, which I have called points, becaufe of their figure.
Fig.19. is alfoa fluted fhell, but it has this fingularity, that each of the ribs of the flutings are themfelves little canals; that ts, there remain void fpaces in theymiddle of thefe ribs through their whole length ; and thefe holes are furrounded with fhell in fuch a manner, that the body of the animal does not enter within. We have opened one of thefe canals marked B, DD, AA, CC. It appears, that the inner furface D D, which is applied to the body of the animal, is terminated in A A, that is, thefe long holes are not fhut up from A A to the extremity C C, into which the body of the animal enters.
XII. Comeciures and Reflections upon the . matter of light, or fire, by M. Lemery, jun. tranflated by Mr. Chambers,
The matter of fire is the 1ft, and moft pow- erful diffolvant of terreftial bodies, we having no other that penetrates fo deep, and disjoins the component principles fo compleatly ; it is to this matter the chymift is indebted for the fecrets he
Pelt. 13,, 1705. ex-
288 The History and Memoirs of the
extorts from nature which he would never reveal unlefs forced, and as it were tortured by fo active a diffolvant. Now a matter which con- tributes fo much to our knowledge of other bodies, does certainly deferve to be itfelf ftudied in its turn.
It is allowed to be the real principle of heat, light, and even of the fluidity or fufion of feveral terreftrial bodies, which, without the mixture and action of this matter would always remain in a folid form ; but as it is not always found in fufficient plenty, or meets with bodies which make too much refiftance, we fometimes find, that inftead of liquifying or keeping them in their former fluidity, it engages itfelf in them, and becomes inclofed in fuch a manner as to re- main imprifoned, and to need fome external caufe to come to its affiftance, and open the cells on the outfide, wherein it was retained.
There are 2 remarkable circumftances in this imprifoned matter; the firft, That it fometimes makes a fenfible increafe in the weight of the body it is contained in; and the 2d, That it re- tains all. its peculiar properties during the whole time of fuch captivity, whereof it gives evident proofs, when ever occafion is given it, of break- ing loofe from its confinement, and making an effeét upon fome other body. ,
Every body will not allow of what I here at- tribute to the matter of fire, it is even alledged, that fuch doétrine is repugnant to our idea of what conftitutes the proper nature of this matter, and yet it is fupported by fo many and folid ex- periments, that feveral chymifts of the firft clafs, have been obliged to adopt it————To fet it in a further light, and have the more pretence for applying it to certain phenomena, which I pro-
pote
RovaL ACADEMY of SCIENCES: 289.
pote to. account for in this memoir, and fome others, | T fhall relate the experiments it is ground- ed upon, and anfwer fuch objections as are brought againft it; objecti ions, which, notwith- ftanding all the verifimilitude given it by experi- ments, are of force fufficient to bring its truth in queftion. | /
Every body knows, that feveral metalline bo- dies when expofed to the fire, as reoulus of anti- mony, lead, tin, and even mercury; notwith- ftanding that they loofe a great deal of their own fubftance, which flies into the air during the opé- ration, are fo far from weighing lefs than the did before, which one would naturally expect, that they weigh a great deal more. Now, the quettion is, whence this augmentation of weight fhould arife ? And whether hie fire, which reduces thefe bodies into the calcined {tate we fee them do not likewife give them this additional weight ?
It may perhaps be anfwered, That this aug- mentation of weights arifes from the acids of the wood, or coals, which are introduced into thefe bodies, by means of the fire, and remain. in them, when the particles of fire ate gone off.-—— But ic is difficult to conceive, how a fufficient quantity of thefe acids fhould arrive at a calcined body to produce an augmentation, which, asM, Homberg obferves, fometimes amount to 7, th part of the whole, it is certain ere they reach the body expofed to the fire, they mutt pafs through the veffel wherein the matter is contained ; and yet the veflels ufed in thefe operations are fuch as will hold the moft violent acids, without letting them efcape thro’ their pores ; if therefore fome acids of wood find means to pafs along with the particles of the fire, thro” the pores above- men- tioned, yet the difficulty of paffing i is fuch, as to
Vor- Ill. NY. 3y. sy make
290 The History and Memorrs of the
make their number very fmall; fo that much the ereateft part of the acids muft be ftopped,; and re- tained by the particles of the vefiel itfelf, which. is ufually of a nature difpofed to abforb them; the matter of fire, on the contrary, paffing freely and plentifully through all kinds of veffels, mutt be allowed much fitter to make this aug- mentation, which being very confiderable, will fuppofe a copious caufe, fuch as fire alone can fur- nifh ; but what proves the point ftill more fully is, that upon expofing thefe bodies to the fun’s rays collected by a burning-glafs, their weight is no lefs increafed than if they had been expoted to 4 common fire: now in this cafe all acids of wood, and coals, are effectually precluded ; and whatever fuppofition we go upon, it will be equally difficult to exclude the fire from its fhare in this phenomenon.
But befides proving that the matter of fire in- finuates itfelf into certain bodies, and augments their weight, it muft likewife be fhewn, that this matter in being thus repofited in bodies, al- ters not its nature, but retains all the particular properties which conftitute it matter of fire. The proof of this fecond article will be a confir- mation of the firft; for if what is introduced into the bodies during their calcination, be the real matter of fire, when we conceive, that this mat- ter engages itfelf, and refides therein, with all its native properties, it will be eafily allowed, that the augmentation of weight arifes chiefly there- from. :
Now the matter of fire retained in metalline bodies, is kept too clofe to be able to manifeft it- felf by any of the fenfible figns, which fhould make it known, and diftinguifh it from other matters; the reafon is, that to become perceive-
ede SE able,
“Rovat Acapemy of ScIENCES. 293
able, it muft force its prifon doors, and make an attack upon fome other body 3 but the cells it is repofited in, are fo ftrong, and folid, that no- thing lefs than a fire of fafion will faffice to break them, and difengage the fiery particles contained in them.
It is otherwife with thofe which had infinuated into ftony or faline bodies, by means of calcina- tions for thefe bodies being of a laxer texture, water alone fuffices to make them a paffage out ; for that by impinging againft the particles of thofe bodies, it not only deftroys the union, but reduces them into a fine powder, capable of being fuftained in the fluid: thus the reafon why lime- water for initance is a drier, and abforbent, is owing to the {tony particles it is replete with, and if lime fteeped in water be unfit for the ufes of building, it is by reafon its particles having been much attenuated by the fluid, unite again fo inti- mately as to ‘form one compact and durable mafs.
As water therefore difunites the particles of faline and ftony bodies when calcined, and grinds them fo very fmall, if there be any matter of fire lock’d up between the particles thereof, it mutt efcape by means of this difunion; and this it does accordingly, throwing itfelf into the aqueous fluid which had delivered it, and which becomes more or lefs heated thereby, in proportion to the quantity of this matter.
Another remarkable effect is obferved in fome of thefe bodies ; viz. That making a very ample provifion of the matter of fire, and being lable to let it loofe again upon the flendereft occafion, when they are applied upon an animal body, the fiery particles which iffue from them, and infinuate into the texture of the part, burn, “and make an
i Kka2 efchar
02 ‘Lhe History and Memoirs of the
efchar differing only in degree from that prodae by a live coal, or a hot iron.
The bafinels for the accounting for the effects above-mentioned, on the fappofition of particles of fire latent in fuch bodies, is a violent pre- fumption ip favour of the hypothefis ; but what renders it inconteftable is, the manner wherein calcined bodies become difpofed for fuch effects, which is in confequence of their being expofed to the matter of firc————Add to this, that the Pp operties they acquire hereby, are the fame as thofe of natural fire; and that none of thefe ef- fects are unaccountable for, without any tolerable fatisfaétion upon any other footing.
For to take a particular inftance, when lime caft in water turns that liquid hot, and makes it boil as fire would do, fhall this effec be attri- buted to any fermentative particles contained in the lime, and’ brought into action by the fire? With what ground ‘can this be done, when we find nothing in lime but a pure earth, {tripped of all falts, the fire feeming to have expelled all other matters to m ake room for itfelf? And how fhould ‘a pure earth, when fteeped in water, be able to heat’'it? But the particles of fire, fay they, are only fuch, by reafon of the rapid motion they are agitated with. Now fuppofing them engaged in the texture of erofs bodies, they muft quickly ioofe their motion, and confequently ceafe to be fire, and thus become incapable of the effects at- tributed to them, fo that fome other caule muft be had recourfe to. ~ Tanfwer, that the matter ef fire muft be confi- dered as a fluid of a ¢ertain nature, and’ endued with properties peculiar to it, which diftinguifh it from all other fluids, Now I agree, that thefe pr aa depend on ttle rapid motion of the les
ticles
that when this matter is in a fufficient quantity to
Royat AcADEMY of SCIENCES. 293
ticles of this fluid; but conceive withal, that the figure of each of thefe particles mutt be taken into the account: be this at it will, when this Auid happens to be detained in the texture of any grofs bodies, its condition, I fuppofe, is no worle than that of other fluids, and confequently muft have the fame fate: now water is likewife a liquid, whoie fluidity, as fhall hereafter be fhewn, de- pends upon the matter of fire, and confequently whofe fluidity muft be much fhort of that of fire’; and yet we fee water daily inclofed in numerous bodies without Joofing its fluidity, or any of the properties which characterize it; fo that upon bringing it forth, we find it the fame matter as
“before: ; and much more muft the matter in que-
ftion, when in the fame circumftances, retain its nature, and be found upon its enlargement. with the fame properties as before.
But it will be replied, that the bufinefs here is not about a comparifon, but to fhew how the particles of fire detained in a grofs body can pre- ferve their motion, This we fhall confider accord- ingly, after firft difpatching the following diffi- culty, the anfwer to which will naturally lead to that folution.
Tis eafy to conceive how a grofs fluid, whofe particles are in a moderate agitation, fhould be retained in the texture of a folid body ; butit is
fcarce conceivable, but that a matter fo fubtil and
active as fire, fhould not find fome paffage out of
the bedies it has been introduced into, or fhould
not even make itfelf a paflage by the rapidity of its motion. —
' Tanfwer, that as to what regards the activity of the matter of fire, it is certainly very great; and
fuy-
294 The Hisrory and Memotrrs 6f the
furmount the refiftance of a folid body, it makes its way thro? by breaking the continuity of its parts; but it is not always that it is. in quantity fufficient for this purpofe; in which cafe its force being inferior, or only equal to the refiftance of the folid body it is inclofed in, all its activity and efforts remain ufelefs, unlefs they be affifted by fome foreign caufe acting on the outfide, ~~ As to the fubtilry of the particles of this mat- ter, it muft be allowed very confiderably ; but the queftion will be, Whether the pores of the cells they are inclofed in may not be ftill fmaller? As we have no mictofcope fine enough, nor any meafure exact enough to decide this point, and there being witha] no inconvenience in fuppofing the pores above-mentioned fmaller than the parti- cles of fire, I inclined to this fuppofition, by rea- fon of the ftrong arguments we have, that the matter of fire is a€tually retained in the texture of feveral bodies. — ay eek Nor do I pretend, that the pores thro’ which the particles of fire cannot pafs, fhould be im- penetrable to all other kinds of matter, for how {mall foever thefe particles be, I can conceive others 100 times {maller, which can eafily pervade all pores, and whofe office may perhaps be to fill ‘the vacuities of the univerfe; but notwithftanding that their fmallnefs furpaffes that of fire, I do not apprehend them fo proper to produce the effects here treated off, as the matter of fire My reafon is, that one of the chief properties of fire is to diffolve and liquify terreftrial bodies, ‘which it effects by dividing and difuniting the particles, and giving each the neceflary motion to conftitute it a uid ; but the fubtil matter above-mentioned, finds fo open a paffage thro’ all bodies, that it ef-
capes on every fide without making fo ftrong an ace ims
RoyAL ACADEMY of SCIENCES. 295 impreffion on thofe bodies as we fird from the matter of fire, which being lefs fubtil than the former, and ‘confequently unable to purfue the fame roads, is forced to break the obftacles in its way, and thus deftroy the natural texture of the bodies ; this reafoning might be confimed by feveral fenfible facts, of which, the following is one: if a net be fpread in the ftream of a river, the particlesof water finding an eafy paflage thro’ the holes or mafhes thereof, will do it no damages but ifa body come which is too bulky to pafs thro’ thofe mafhes, it muft either be ftopped thereby, or break the net; and the fame befalls the matter of light, which, according to its quantity and ftrength, is either detained in bodies, or diffolves them, |
Now to conceive without the help of any com- parifon, how the matter of fire inclofed in the cells of a folid body, fhould be able to preferve its motion, we need only obferve, that there is 4 more fubtil matter continually pervading the pores of thefe cells, and which of coniequence muft keep up the agitation of the particles refiding therein.
Mz. Saurin has fhewn, that we may fafely affirm, that the proper matter, even of the moit folid and heavy bodies, does hard!y make the 100,00oth part of their bulk. Now, though we fhould abate a good deal of this fuppofition, yet there would ftill be room enough in the moft folid bodies to give paflage, or even lodging, to a large quantity of foreign matter, in which cafe the fubtile matter abovementioned, paffing more copioufly than can well be imagined, the fiery particles, notwithftanding their imprifonment, will not want caufes fufficient to maintain their fluidity and motion,
In
296 The Hisroky and Memorrs of the
In effet, tho’ it fhould be granted, that the particles of fire engaged ina folid body, could not always preferve their motion therein, it would not follow hence, that they muft loofe their pro- per nature of fire; for it is not only to the rapi- dity of their motion, but alfo to their figure, and their {mallnefs, that their peculiar properties are owing: thus the particles of water are at reft when frozen ; and yet no body will fay, that they are effentially different now, from what they were before, finee we find the leaft agitation, or the f{malleft degree of heat; enables them again to produce effects which they had ftill remamed fit for by their peculiar figure, and whereof no other. body, though expofed to the fame heat, would ever be capable.
We likewife know, that fale is the matter of taftes, and has certain properties arifing from the peculiar figure of its parts, and yet it : only, atts when iielneds or which amounts to the famej when it floats ii a fluid, which keeps its particles in motion. Now will any one alledges that fale, when undiffolved, is not the matter of taftes, nor has the fpecial properties which characterize a falt? This can never be faid while its particles re- tain their effential figure, the chief fource of theie properties.
Hence, tho’ it were true, that the retention of particles of fire in a folid body, fometimes robbed them of their motion, they would only be in the cafe of frozen water, or folid falr; and might be reftored to their former effects by recovering their motion,
It may perhaps be demanded, why the matter of fire, which had penetrated into a folid body, fhould not be able to get out again without the help of a foreign caufe to facilitate its efcape, the
paflages’
Rovat ACADEMY Of SCIENCES. 297
paffages having been open enoughto let it in, can- not be too narrow for its exit. . Lanfwer, that while the body is expofed to the fire, its pores are opened, and dilated, and fe- vera] of the fiery particles which are continually entering it, go out again with the fame liberty fo long as the Tealsextion of the pores remains ; but when the fire ceafes to act, the caufe of this dila- tation ceafing likewife, ‘the particles of the body which before had been {welled, do now fhrink, and their pores return. to their farft {tate ; upon which the: particles of fire which had infinuated into the cells of fuch body, are now utterly fhut up, beyond a poffibility of efcaping, till fome new dilatation of the pores, or a fufion of the body fet them free.
*Tis no wonder, that bodies, which, by their calcination have ftored up a large quantity of fire, fhould not-afford any fenfe of heat upon touching ; for as the particles of fire inclofed with- in them, cannot reach the hand, which is only applied on their furface, the effet will be the fame, as if they had no fire at all; as we find that fale is only fenfible to the tafte, when it is dif- engaged enough from all other bodies, to make an immediate impreffion upon the organ of that fenfe: and hence if a body newly taken from the fire, give a vehement fenfe of heat, this is not owing to the particles of fire imprifoned in it, but to thofe which have found paffages open -enough to let them out: for we may fuppofe two kinds of pores, fome which are naturally big enough to give free paffage to the matter of fire at all times, and others which only afford it, when dilated by heat. Laftly, it may be further eked) why the mat- ter of fire inclofed in faline and ftoeny bodies, does
met. FN®. gi. not
298 The History and Memoirs of the
not break the texture of the parts, which oppofe: its efcape, fince we find water do it, which yet is incomparably lefs active than fire.
I anfwer, that if the quantity of matter in fire contained in lime, were as great as that of water poured on it, 1¢ would probably need no foreign affiftance to get forth; but notwithftanding all. its activity, its quantity may be found fo fmall, compared to that of water, that the particles of water fhall be more effectual than thofe of fire. Now ’tis evident, that the fire procured from the bodies above-mentioned, is much lefs in'quantity than the water ufed to procure them.
Further as co fixed alcali falts, which likewife contain particles of fire; water, tis known, dif- folves them with furprizing quicknefs, and fire itfelf would hardly be able to bring them fooner to fufion. If then water make {fo perfect a dif- union on the particles of thefe falts, it wall hereby afford a free paflage to the matter of fire re- tained among thofe particles ; and if nothing than a fire of fufion fuffice to prove the fame difunion in thefe falrs, the matter of fire contained therein, being in much lefs quantity, and confequently much lefs powerful than that of a fire of fufion, *tis evident on this occafion it muft act lefs effec- tually than water 5; nor muft we fuppofe, that the liquid thus poured upon lime and alcaly falts, does alone open a paflage for the matter of fire, but there being all the room imaginable to fuppofe, that this matter {till retains its motion within the bodies, we conclude, that ’tis continually at work in its prifon to force a way thro’ the fame 5 ancd.that if it prove unable, notwithitanding all its efforts, to make its efcape, without an extraneous aid, yet i¢contributes confiderably, and facilitates the effect of this aid.
Whe
Royar ACADEMY of SCIENCES. 499
The fun only feems a vaft fund of the matter of fire, or if you had rather, a huge flame of the fame effential nature as ours, fince we find, that both the one and the other produce the very fame effects ; but this luminary being at 2 great diftance from us, can only act on terreftrial bo- dies, in 2 manners, viz. either by emanations and effluxes of his fubftance, emitted from thence to us, an hypothefis liable to feveral difficulties, and inadequate to certain of the phenomena, or by trains of the matter of this fire diffufed thro’ all the intervals of the fluid mafs, between the fun and us, which trains come to act upon terre- {trial bodies, when preffed or impelled towards them by the prefence of the fun. Each train may be confidered as a little fun continued, but {till depending upon the large one, which is the fource of their motion or action, upon terre- Strial bodies.
Thefe trains which form the luminous rays, and are immediate agents of light, do not differ as to the matter from that of the fun itfe! f, as we find by certain experience: hence as the fun is a flame which produces the fame effeéts as a cull- nary flame, we may infer the manner of its acting upon terreftrial bodies, from that wherein our flame is found to act: now we know, that upon plunging one of the abovementioned bodies in a common flame, ’tis the proper matter thereof, without any foreign affiltance, that penetrates, heats, and modifies them according to their pecu- liar nature; and when the fame bodies are pre- fented to the fire without touching the flame, the impreffions they receive therefrom, are effentially the fame as thofe, which the flame, if immediately applied thereon, would have produced: the only difference is, as to more and lefs, fo that a body
iia acted
300 The History and Memarrs of the
*éed on immediately by a little flame, will be heated and altered after the fame manner, as if placed at a confiderable diftance from a large flame. oe
All this gives a fufficient indication, that the matter of fire or light, interpofed between the flame and us, is of the fame nature as the flame itfelf ; and why then fhould the luminous rays, which tranfmit the a¢tion of the fun to us, and feem only to be continuations therecf, be of a different matter from the fun’s body? In effect, when collected by means of a burning glafs, they aét with an equal or even more vigour, upon ter- reftrial bodies, than the moft violent flame could do, if immediately applied on the fame bodies ; a proof not only that the matter of thefe rays-is the fame as that of the fame; but alfo, that the flime confifts in a colle€tion of a vaft quantity of the matter of light, which aéts the more forcibl's as it is more copious, and collected clofer. On this footing, the fun only feems to differ from the rays of light, colleéted by a burning-glais ; in this, that the matter of light being there much more copious, and more colleéted than it is in the rays, would aét more readily and forcibly: upon bodies immediately applied thereto.
The vehement action of the rays united by a burning glafs, fhews, that the fluid, which in their natural ftate feparates and extends them, does likewife ferve to moderate this action, and ren- der it more fupportable; for without fuch me- dium, inftead of enlightening and exciting a gen- tle warmth, they would confume all bodies, and even deftroy the organ of fight. To explain this by a fenfible comparifon, the air is that to the reys of light, which water is to the particles of fire, in a Balneum Maria, the rays being tem- mee ai pered
Royat ACADEMY of SCIENCES. 30%
pered in their paffage thro’ the air, as the fire is in its paffage thro’ the water 5 or the rays of light might be compared to corofive {pirits, which tear and lacerate when they are pure, but produce an agreeable fharpnefs when diluted with:a fufficient quantity of fome other fluid. ALERT
~ The matter of fire driven by the fun upon ter- reftrial bodies, modifies them differently accord- ing to their refpective natures ; fome it eafily puts and preferves in a ftate of fufion, and fuch are the particles of water, which originally are folid, and owe all their fluidity tothe action of the matter of fire lodged amongft them : this we prove hence, that their fluidity remains while the fun deter- mines'a fufficient quantity of this matter, to con- vey his action upon terreftrial bodies; but in thofe feafons when he only fends a little, fuch little being infuffrcieat to maintain the fufion of thefe particles, they relapfe into their firft ftate of immobility, from whence they recover, prefent- ing them to the fire; or which amounts to the fame; and the fun begins to fhed a greater quan- tity of the matter of fire upon terreftrial bo- dies. | bgt se *
From what has been faid, we learn, 1f{t, that ice is only a reftoration of the particles of water into their natural ftate; 2dly, that the bare abfence of the matter of fire fuffices to effect this reftoration ; and 3dly, that the fluidity of water is a real fufion like that of metals expofed to the fire, only dif- _ fering from it in this, that metals require a large quantity of particles of fire to liquify and fupport them in a ftate of liquification, whereas the parti- cles of water feldom receive fo little fire, as co al- Jow them to refume their natural folidity.
Another effect of the matter of fire fhed upon terreftrial bodies is, to engage itfelf in certain
Bihaes? ah Ps com-
302 The HisTory ana Memoirs of the
compofitions of falr, earth, water, &c. together with them to form oils, fats, and in fine all inflam- able bodies, which only become fuch by the great quantity of particles of fire lodged in them. What leads me to this fentiment is, that upon de- compounding thefe bodies, they turn intirely into falt, earth, water, and a fine fubitance, which paffes thro’ the clofeft veffels, and maugre all the care of the beft artift, fpends itfelf in fufh- cient quantity to produce a confiderable diminu- tion in the weight of what remains. Tis certain, that falt, earth and water, whether united together, or feparated, never become in- flammable, but even ufually hinder, or retard the inflammability of bodies, which naturally hayethat property ; it may even be afferted, that the eficct of thefe principles in the compofition of inflam- mable bodies, is only to ftop and arreft the mat- ter of light or flame, which never rifes into the air under this form, except when the inflammable body having been firft expofed to the fire, that agent has broke the cells thereof, and given
room for the inclofed matter to fly off. °Tis the real matter therefore of fire or flame, which fteals from the artift in the exalyfis of in- flammable bodies, ali that remains of thofe bo- dies after the decompolition, being the materials whereof the cells were formed, 1n which. this matter was retained ; it will be eafily allowed, that this matter, when free and left to itfelf, muft pervade the clofeit veffels, when we confider that there is no yeffel but what the fire will readily pe- netrate, fo as to heat a fluid contgined in it; and as to the caufe of inflammability, experience fhewing us, that falt, earth, and water, in what- ever circumftance is found, never becomes inflam- mable ;
RovAt ACADEMY of SCIENCES. 303°
mable; to what can we more probably attribute the effet abovementioned, than to the matter of fire, which, as already proved, forms the flame, and gives it all its properties.
Nor need we be furprifed, that calcined me- tals, and all bodies in general, which have pro- cured a ftock of light by calcination, do not” kindle by the fire as oils do; for to make a body kindle fo as to be perceived, the luminous fub- ftance iffuing continually from it, muft be copi- ous enough, and form a mafs fufficiently firm to prefs the matter of light diffufed thro’ the air vi- goroufly, and on all fides, fo that the particles of this matter ftriking each other fucceffively, and according to the direé&t determination communi- cated to them, do hereby tranfmit the preffions of the flame, to a diftance greater or lefs; but when only little particles of luminous fubftance, are diffufed from folid bodies, they prefently become fo darkened by the air around them, as to be dif- abled from making preffions efficacious, and ex- tended enough, to become fenfible to the eye.
Upon the whole we conceive, that the matter of light lodged in inflammable bodies, expofed to the fires, iffues out every moment in much greater quantity, than the fame matter lodged in calcined metals; whether it be that fuch metals contain lefs of this matter than the oils, or whether having a clofer texture of parts, they do not allow it fo free egrefs ; but at each effort of the agent which obliges them to let go, they let only {mall parcels exhale, incable of fenfibly affecting the eye.
This reafoning perfectly agrees with a known fact, which is, that upon expofing very inflam- mable bodies,fas paper or ftraw, to a toofimall fire, they fometimes confume intirely without cafting any flame, by reafon the external agent teing
" too
304 The History and Memoirs of the
too weak to expel a great quantity of the matter lodged in fome bodies all at once, this whole inatter flies off fucceffive in little invifible portions, anfwerable to the force which procures them de- liverance.. ,
We might here take occafion to account for fe-
veral curious phenomena, wherein this fyftem of imprifoned fire perfectly quadrates, and which are even fo naturally deducible herefrom, that each phexuomenon feems a kind of proof of the truth thereof. How precifely, for inftance, does the matter of light feem to agree with the pho/phori, both natural and artificial ; and to thofe violent fermentations accompanied with flame, which the oyls ufed in fuch experiments, are obliged to ex- hale, when penetrated by nitrous, or vitriolic acids? But were I to enter into a precife detail of all the experiments of this kind, and the par- ticular circumftances which accompany each, I fhould go far beyond the bound prefcribed for this paper, and incroach on the fubject of future ones. - | fhall only here obferve, that all pho/phori in general may be confidered as a kind of {punges, filled with the matter of light, which is fo feebly. retained therein, as toneed but very little external help to become capable of exhaling under a lu- minous form, and even of burning and fetting on fire fuch bodies as come imits way.
It follows from the whole, that if the fun feem to be a kind of large receptacle, or fund of the matter of fire, we have an infinite number of petty receptacles in inflammable bodies, which feem to have been formed to fupply the want of the fun ; in effect the prefence of fire being indifpen- fibly neceffary to light and heat, and the great
lumt
i
RoYAL ACADEMY of SCIENCES. jog
laminary not being. always in our hemifphere,: but rétiring to a-great diftance from us in certain feafons, or which amounts to the fame, only de- termining a little quantity of the matter of light upon terreftrial bodies, we find a happy fubiti- tute inthe bofom-of the earth, whereby to remove all the evils, into which the abfence or diftance of the fun would unavoidably throw us; I mean, a fufficient quantity of the matter of light, to form a fort of little funs, which warm and illuminate as mel! as the great one.
XI. On the voleporatiene of ‘fluids in cold weather, with remarks on fome effects of the ‘frofts, by M. Gauteron, of the royal academy of Montpellier ; tran/lated by Mr. Chambers.
We ufually esngdée the evaporation of fluids
as an effect of the heat, or motion of the am- bient. air, and it will appear furprizing, that a aye opbone caufe fhould produce the fame ef- eft; .and that a fluid fhould lofe more of its parts in the fevereft froft, than while the air is in a temperate ftate, ———— Yet this is what I found in the great froft of this winter.
I have even obferved, that the greater the cold is, the greater has the evapor ration been, and that ice itfelf lott confiderably, as much in propor. tion as the fluids which withftood the froft.
- Tt began to freeze at Montpellier, on the 12th of December, 1708, the wind being at north, ; from north-eaft, and the common _thermome- ters ftanding at 10°, and that of M- Amontons?s at the 53°: At6 o'clock this evening, I expofed an ounce of common water, in a china cup, to be froze, which was done accordingly before or. Ml; N°. 71. M m morning,
306 The History and Memoirs of the
morning, and weighing it at 8 a-clock the next. day, I found that the water in freezing had left 24 grains of its weight. This diminution was very real, fince, upon melting the ice, the wa- ter was found to have loft 12 grains more, not- with{tanding al] our precaution to prevent any fe- cond evaporation. The fame experiment re- peated feveral days running, gave me much the fame thing; with this difference, that the evapo- ration was much greater in a ftormy night, or when the wind was {trong.
The thaw enfuing thereon, prevented the fur- ther profecuting of my experiments ; but it tak- ing certainly again to froft on the night between the 6th and 7th of Fanuary, 1 took occafion to make the following ones.
For on the night between the 7th and 8th, I expofed common water, brandy, oil of olives, oil of wallnuts, oil of turpentine, and mercury, an ounce of each, to the open air, the common thermometer ftanding at the fecond degree, and that of M. Amontons’s at 51°—6 lin.— The wa- ter was prefently froze, and in an hour loft 6 erains; the oil of wallnuts loft 8 ; and the brandy and oil of turpentine each of them 12, in the fame {pace of an hour, while the oil of olives and the mercury feemed rather to have gained than have loft their weight. Next day the dimi- nution of the frozen water was found 36 grains ; that of the oi! of wallnuts, which did not freeze, 40 grains; and thofe of the brandy and oil of turpentine, which alfo withftood the froft, 64 each ; the mercury and oil of olives remaining much in the fame ftate.
Tis needlefs to note the evaporation produced day by day during the great cold; fince, under equal circumftances, the evaporation was AeeY
the
Royat AcaApemy of SCIENECs. 307
the fame ; but a vehement cold and {trong winds, always made it greater than a lefs cold and calm weather.
*Tis obfervable, that the firmeft ice is not ex- empt from evaporation in a fevere cold; for we find it loofe 36 grains from 8 in the morning to 1 in the afternoon, and 36 grains more from that time to 8 in the evening; and the evapora- tion in the night was much az the fame rate; fo that the ice loft 100 grains in 24 hours, notwith- ftanding its feeming firmnefs and folidity, and this ata time, which feemed more proper to bind, than to loofen the fmalleft of its parts.
The night between the 1oth and rith of Fan, proved the coldeft that has-been felt in this coun- try, the liquor in the conimon thermometer funk intirely intothe bow] ; and that of M. Amontons’s ftood at 51°—1 lin. which is almoft the extreme cold of the 8th climate; in effect, the cold was felt very pinching inthe warmeft houfes, and few people could fleep foundly how well foever they were covered. This night the evaporation was very great, the common water Joft 48 grains, the oil of wallnuts 54, and the oil of turpentine and brandy 72.
This is a fhort ftate of what I obferved on the evaporation of fluids in the great cold: my re- marks upon froft are,
Firft, That the furface of freezing water ap- pears wrinkled over, and that thefe wrinkles fometimes form parallel lines, and fometimes radii, which feem to go from the centre to the circumference, and upon freezing it in a cylin- drical phial, I have found hollow tubes, formed around the cylinder from top to bottom, and
feeming to go from the circumference to the centre,
Mm 2 Secondly,
‘308 The History and Memoirs of the
Secondly, That water covered a-top and at the. fides with oil, froze about half an hour Jater than. the water expofed naked to the air, and in fréez- ing fermed.a banch ‘of ice about an. inch enpee the furface of the oil. Aa
Thirdly, That oil of wallnquts preferved water from a moderate froft, which oil of olives had not been able to do.
Fourthly, That hot water, ready to boil, frees about half aa hour Jater than cold.
Fifth! Yo That brandy, oil of wallnuts, ae ae of turpentine did not freeze at all. is
Sixthly, That tho’ the sky was very olan dur- ing the froft, yet the {un appeared.a little pale.:
Seventhly, That the orange and olive trees loft their leaves and branches, and moft of them died to the. very roots and what is more, the laurels, yews, grannate trees, fig-trees, jcflimines, and fome oaks themfelves . underwent, the fame. fate. The Rhone was froze 12 feet deep, and the pond: de Tkau, notwithftanding its natural ftorminefs, and. its communicating with the fea, ‘by a -very, fhort and broad canal, was fixed from end to end, and feveral perfons went from the baths of Ba- laruck to Sette over the ice, a road unknown to our forefathers, and which Pealiaps le be fo to our pofterity.
Eighthly, That the thaw on the 2 aa of oa as alfo that on the 26th of Fed.. were followed with an epidemical. catarrh, which ages any body efcaped.
All thefe effects muft have arofe Aas the fame caufe, viz. from the change in the air dur- ing the frolt — My fentiment of this change is as follows.
The fun’s rays. emitted in the winter, ‘Sallnoes
all eaalayuely on the furface of the earth, take up LW ihenk a. Mi _ more
Ro¥AaL ACADEMY ¢ iaeunveah 309
more room. thereon, and, are. Jefs. reflected. upon ithemfelves ; whence it follows,” that the earth ‘mutt be lefs heated, in the winter time, and that, the wtherial matter, moft fulceptible of motion, ‘will recede to that part where the fun is moft perpendicular to the earth, leaving fuch etherial matter as-is leaft dilpofed for motion, on that Balt of the earth where it,is winter. |
Now the zetherial matter is commonly: Blocod, cha? caufe of the motion. of fluids, and ¢hat the air of itfelf owes its motion and fluidity to the fame: hence al] fluids muft remain in a ftate of ftiffaefs or condenfation, when this matter loofes) part of its force ; and hence the air itfelf mutt, be denfer: in winter, than in,any other feafon,
But we likewife find by feveral experiments, that the air contains a falt, which is fuppofed to be of a nature approaching that of nitres; now this, and the condenfation of the air being fup- pofed, I fay, thar the molecyles of this. nitrous fale muft be brought nearer, and confequently their bulks enlarged upon a condenfation of the’ air; as on the contrary, they muft be divided and further attenuated by the motion of that fluid, if the fame thing befal all fluids, which have dif-. folved any falc; that is, if the heat of the fluid keep the falt exactly divided, and the coolnefs of ice, or-of a fubterraneous place, give room for the particles of the diffolved falt to gather toge- ther and cryftallize, why muft the air, which is capable of rarefaction and condenfation, be ex- empted from, this general law ?
And if the nitrous particles in the air be en- ‘pt ged ina grear cold, as cannot eafily be denied, they mutt of confequence have a lefs fhare of ve-. locity ; but the product of their maffes thus aug- mented by the velocity remaining, muft {till give hereeit ; them
310 The History and Memoirs of the
them a greater quantity of motion. Nothing further is required to make the falt act more for- cibly againft the particles of the fluid; and this I apprehend the real caufe of the great evapora. tion they undergo in cold weather.
Yet this aerial nitre cannot hinder a fluid from’ turning into ice, but on the contrary muft be a means of promoting the fame; for it is noc the air or the nitre contained in it, but the ztherial matter that gives fluids their motion, and confe- quently *tis on a diminution of the torce of this Jatter, that the lofs or diminution of the motion of the former depends. . Now the ztherial mat- ter, befide its natural feeblenefs in the winter, mutt loofe a great part of its force, by aécting a- gainft the condenfed air, which is further replete with large molecules of falt; and thus muft ne- ceflarily be rendered feeble in a fevere cold, and by no means in a condition for maintaining the motion of fluids; in a word, we may confider the air in frofty weather, as that ice charged with falt, commonly ufed for the freezing of certain liquors in fummer... ‘Thefe liquors probably freeze by a diminution of the motion of the etherial matter, which acting againit the ice, and the fale mixed together, the air, with all its heat, cannot hinder the concretion.
It may perhaps be urged, that fluids contain particles of air, which, according to M. Ma- riotte’s obfervations, are ina ftate of compreffion 10 times greater than in the open atmofphere ; that the fprings of the air thus comprefied, un- bend themfelves in the froft by a diminution of the motion of the fluid ; and that ’tis to the explo- fion of thefe fprings, that the evaporation of the particles of fluids in the froft are owing.
Now
Rovat ACADEMY of SCIENCES, 311
-NowI allow, that fluids contain a great deal of air; that this air 1s more comprefied in the fluids than in the open airs; that the froft gives occafion for its {prings to unbend themfelves 5 and that thefe fprings unbend with the more force, on account of the compreffion they are in, and what is more, that this unbending of the fprings of the air is the caufe of the lightnefs and rarefaction of ice, as well as of the bubbles and tubules men- tioned in my obfervations; but I cannot allow, that the action of thefe fprings is the caufe of eva- poration, when I confider that both the fluids which freeze, and fuch as withftand the froft, un- dergo an evaporation proportional to the tenuity of their parts, -and that ice, feveral days old, Joofes full as much as water juft beginning to freeze. In fluids which do not freeze, the un- bendings of the fprings of air cannot be very confiderable; and in ice, formed many days, thofe fprings muft have had their full play, and now left incapable of any further action.
It has been obferved, that when the ice begins to form, its furface is full of wrinkles, which are fometimes difpofed in parallel lines, and fometimes after the manner of radii, under which furface is a multitude of little frozen particles, in form of needles, or rather of funnels, whofe {mail end is turned to the furface of the water. Thefe funnels are eafily perceived in a cylindri- cal phial, when the liquor contained in it is in- tirely froze.
Now this difpofition of the ice thus beginning to be formed, is favourable to the contained air’s efcaping out upon the fpring’s beginning to un- bend, and feems at the fame time to prohibit the entrance of the external air, which might otherwife take its place. Thus the air which re-
I mains
312 The History aid Memorrs of the mains in the freezing water, muft dilate with the more- freedom, as being no longer compreffed by the external air 5° and hence probably arife the levity and rarefaction of ice, but not the eva- poration of its particles. ee he dele It would be tedious to enter into an explication of all F have obferved upon ice 5. befides, that it may eafily be deduced from the principals al- ready laid down. From hence, for inftance, it appears, that the particles of oil Of olives are more ramofe than thofe of oil of wallnuts 3 and that ’tis owing to thefe branches, which lock the parts faft together, that the aerial nitre is not able to carry them off; that the particles of wall- nuts are more grofs, though lefs branchy, than thofe of oil of olives; and that it arifes hence, that the former is heavier, and dries quicker than the latter; and further, that the particles of the oil of wallnuts muft be fmoother, and more flippery, and only touch in a few points of their furface; whence it is, that the ztherial matter, with all its weaknefs, can eafily move them, and hinder the oil from freezing ; and hence it is, thofe particles are not firm enough to refift the impulfe of the aerial nitre, which carries them off 5 hence alfo appears that the tenuity of the particles of brandy and oil of turpentine, favours their’ fluidity and evaporation ; as for the heavy and globular particles of mercury, it appears, that. fome more powerful agent, than the nitre of the air, is required to feparate them from theit mafs. Since the atherial matter {till maintains the fluidity of oil of wallmuts, tis no wonder, that’ the water covered with. it, fhoul¢ withftand the froft ; oil of wallnuts, on this occafion, dome the. Gffieie of a kind of filtre, and giving entrance to. a quantity of this matter, fafficient to maintain the
RoyAt Acabemy of SCIENCES. 313
the fluidity of water ; and if oil of olives likewife defend water a little while from the froft, ’tis by reafon this oil, which only condenfes by the cold, contains a little of the etherial matter in its branches, by means whereof the water thus co- vered with oil of olives, is able to fuftain the cold longer, than if entirely deftitute of that affiftance ; and if hot water freeze half an hour later than cold, *tis by reafon fome time is fpent in laying afide the motion which the fire had given it ; and as to the palenefs of the fun in a fevere froft, who does not perceive, that the condenfation of the air, and the groffnefs of the nitrous particles contained in it, muft reflect abundance of its rays, and prevent their penetrating tous. Laftly, if a kind of gangreen appear on the frozen parts of trees and other plants, is not this owing to a cor- rofive falt, corrupting the texture thereof? The relation is fo near, between this gangreen, and that which befalls the parts of animals, that their caufe muft be near a-kin; corofive humours burn the parts of animals, and the aerial nitre has the {ame effect on the parts of plants penetrabile frigus aaxrit.
I fhall clofe this memoir with fome reflections upoa the epidemical catarrh, which fueceeded the thaws of the 23d of Fan. and the 26th of Feb, —~—So many perfons were feized with it all at once, that it can be owing to nothing lefs than fome general caufe, which acted at the fame time upon all men. This caufe we find in the air re- fpired after the thaw, whofe nitre having been much divided, was now reftored to its natural form: to explain myfelf, _ The air conveyed into the lungs by the tra- chea, fills the veficles, whereof that vi/cus is com- pofed ; and tho’ the blood do not enter into thefe
mou. I N°. 31. Na veficles
314 The History and Memorrs of the
veficles, excepting a preternatural cafe; yet the blood in the pulmonary vein, being found more brifk and florid, than that in the artery, fhews, that it has undergone a confiderable change from the air in refpiration. Hence, as the air has no im- mediate action upon the blood, we may fuppofe, that the texture of the veficles of the Jungs does the office of a kind of filtre, by feparating the nitrous part of the air; and that’tis this nitrous part to which the florid lively ftate of the blood in the pulmonary vein is owing, if now the ni- trous particles in the air happen to be groffer than ufual, as we have fhewn muft be the cafe in a fevere cold, their proportion will be changed with refpect to the filtre, which is to feparate them ; and hence only a fmall quantity will enter the blood, which, together with the external cold, will occafion that fluid to remain ina ftate of in- activity, during which the paffages of perfpira- tion being ftopped, the blood muft retain moft of is ferous and ymphatick part, which will re- main inclofed in its fulphurous ones, and only to be extricated threfrom by a general lique- faction. This 1] iuefaction of the humours muft happen upon a thaw; for the nitre on this occa- fion dividing into little molecules, a great quan- tity of this fale muft mix haftily with the blood, and animating it, excite a fermentation, which fuffices to make an inftant feparation of a large quantity of lymph and ferum, which being thrown upon all the glands of the body, produces a head- ach, naufea, ftoppage of the nofe, cough, crudi- ty, and abundance of urine, wearinefs, and fome- times a little feverifhneds. °
The catarrh above defcribed is very different from what happens in a violent cold; in this Jatter, the humours circulate with difficulty ; and
I
Royat AcADEMY @f SCIENCES. 315
by their thickening, occafion fome ferous parts. to be feparated from them; whence the hoarfenefs and cough, which are frequent!y accompanied with an involuntary weeping, by reafon_ of the lachrymal points, which are ftopped by the thick- ening of the mucus in the nofe.
Accordingly the two catarrhs are to be treated after a very different manner ; thofe from co'd, are cured by remedies, which reftore the humours to their fluidity ; and where there is a ftoppage of the head, the readicft remedy I know is, the perfume of amber, which doubtlefs acts by the quantity of volatile falr, and fulphur, con- tained therein ; wine and brandy burnt with fugar, and tea, coffee, and chocolate, are proper for the fame reafon; feveral violent and very obftinate colds I alfo knew cured that winter with chicken broth, wherein an ounce of fnakes flefh dried, with a handful of creffes had been boiled about ; of an hour. '
As to catarrhs caught in the thaw, care mult be taken to prevent the too great diffolution of the humours, by boiled emulfions, rice-milk, water- -gtuel, barley-water, and yolks of eggs, with fu- gar-candy, whey, and milk itfelf, narcotics, and phlebotomy, are proper in either kind of catarrh ; and efpecially where the patient is harraffed with a cough, or any inflammation of the breaft is ap- prehended. »
XIV. The variation of the needle at Nurem- berg, dy M. Wurtzelbaur,
M. Wurizelbaur finds the variation of the nee- dle at Nuremberg, to be near 11 degrees; and obferves, that it has not increafed fince the year
Nn 2 1702,
316 The History and Memoirs of the 1703, when he obferved it alfo to be 11 de> grees. -
XV. A comparifon of the obfervation of the eclipfe of the moon, Sept. 29, 1708, made at, Nuremberg, Genoa, aud Marfeilles, by M. Cafiini the fon*.
8 43 36 Beginning of the eclipfe at Nurem- erg.
8 33 49 paint of the eclipfe at Genoa. .
8 20 45 Beginning of the eclipfe at Mar- feilles. —
© 9 47 Difference of the meridians between Genoa and Nuremberg.
© 22 51 Difference of the meridians between Marfeilles and Nuremberg.
11 6 34 End of theeclipfe at Nuremberg.
10 57 21 At Genoa.
10 41 26 At Marfeilles.
o g 13 Difference of the meridians between
| Genoa and Nuremberg.
© 25 8 Difference of the meridians between
Marfeilles and Nuremberg.
XVI. Reflections on the obfervations of the — echpfe of the fun, March 11,1709, made tn different countries, by M. Caflini the
fon*. At Montpellier the end of the eclipfe was obferved exactly at 2 55 49 We find by the figure drawn up for the meridian of Paris, that ic muft have happened there at 2 49 30
* March 2, 17099. + April 17, 1709. . Which
n
Royal ACADEMY of SCIENCES, 317
Which gives the difference of the meridians
At Genoa the beginning of the eclipfe was obferved exactly at
It muft have happened by the fi- gure at
Which gives the difference of the meridians
At Bolonia the end was obferved with fome ambiguity at
It muft have happened by the fi- gure at
Which gives the difference of the meridians
apie PT,
o 6 19 O 59 52 Oo 34 0 9.260162 3 34 35 2 58 40
01.35) 55
. A OF THE PAPERS contained in the ABRIDGMENT of the History and Memoirs of the
RoyraL ACADEMY of ScIENCES at Paris, for the Year Mpccx.
In the HISTORY.
I. N the progrefive motion of feveral [pe- O cies of fhell-fifhes.
Il. Of the gla/s ware of India.
III. Of a fort of acorn from Coromandel.
IV. Of the virtues of a nut called Bicuiba.
V. Of a woman delivered of a child, when above 80 years of age.
V1. Of the fatal effects of fome vapours in a baker’s cellar.
VII. Of @ remarkable echo.
VIII. Of figured fiones.
IX. Of M. John James Scheuckzer’s Herbarium diluvianum.
X. Of the count Marfighi’s philofophical effay to- wards a biftory of the fea.
XI. Of a tenia found in a tench.
XII. The difcovery of an extraordinary fort of infect.
XIII. On the pond mufcles.
In the MEMOIRS.
I, Experiments on the elaftteity of the air, by M. Carré. | II. Qd-
A Taste, &e. 319
II. Obfervations of the quantity of water which fell at the obfervatory during the year 1709, with the fiate of the thermometer and barometer, by M. de la Hire.
{Il. 4 comparifon of the obfervations which we have made here at the obfervatory on the rain and winds, with thofe which M. le Marquis de ~Pontbriand: made at bis caftle near St. Malo, during the year 1709, by M. de \a Hire.
IV. A comparifon of my obfervations with thofe of M. Scheuchzer, on the rain and conftitution of the air during the year 1709, at Zurich, in Switzerland, 4y M. de la Hire.
V. Of the neceffity of centering well the objet glafs of atelefcope, by M. Cafiini the fon.
VI. Od/ervations on the bezoar, and on other fub- frances, which come near to it, by M. Geoftroy,
un.
vir An infect of {nails, by M. de Reaumur.
VIII. Reflections on the obfervations of the flux, and reflux of the fea, made at Dunkirk, by M. Baert, profeffor of bydrography, during the years 1701 and 1702, by M. Caffini the fon.
IX. Odfervations on a fort of talc, which is com- monly found near Paris, upon banks of plaijter- ftones, by M, de Ja Hire.
X. Obfervations on the variation of the needle, with regard to Dr. Halley’s map, with fome geographical remarks made upon fome fea-jour- nals, by M. de Lifle.
XI. Reflections on the obfzrvations of the flux and reflux of the fea, made at Havre de Grace, by M. Boiffaye du Bocage, profeffor of bydro- graphy, during the years 1701, aud 1702, dy M., Caffini the fon. ba Re
XII. Refleions on the obfervations of the tides made at Breft, and at Bayonne, dy M, Caffini the fon, XII.
320 A Tage, &e.
XIE. Aw examination of the filk of fpiders, by M. de Reaumur.
XIV. Experiments on the effects of the wind, with regard to the thermometer, by M. Caffint the fon.
AV. Experiments on the thermometers, by M. de la Hire the fon.
XVI. An obfervation on the little ben-eggs without yolk, which are commonly called cock’s-eggs, by M. Lapeyronie.
XVIL. 4 comparison of the obfervations of the eclipfe of the moan, Feb. 13, 1710, maae in different places by M, Maraldi.
nr iy AN | ABRIDGMENT
PuILosopHICAL DiscovEeRIES and Op- SERVATIONS in the HisTory of the RovaL ACADEMY of SCIENCES «at
~ Paris, forthe Year 17:0.
1. On the progreffive motion of feveral fpecies of frellfifhes.
Ltho’ animals in general have an indifpen- fable occafion for the progreffive motion, either to feek for food, or for the males and fe- males to meet together; yet many of them feem incapable of it meerly by their figure : of this fore are feveral fpecies of fhell-fifhes; and therefore M. de Reaumur has obferved them with a great deal of care, for they might walk in fecret; and an external action is often as difficult to difcover, as the internal ftruCture of a part.
The late M. Poupart™ had obferved, that the river-mufcles being laid upon the flat of their fhells, thru out at pleafure a part, which on ac- éount of its ufe, may be called a leg or an arm, that they made ufe of it to hollow the fand under them, and confequently to fink foftly on one fide, fo as to be found at laft upon the edge of their fhell; after which, they advanced this arm as far as poffible, and then refted upon its extremity to draw their fhell to them, and fo to trail them- felves in a fort of groove which they themfelves formed in the fand, and which fuftained the fhel!
* Vol. Il. p. 376, of this abridgment. gon. 1H. N*. 32. Oo on
322 The History and Memoirs of the
on both fides. In looking at a mufcle, we fhould not guefs at this expedient, this mechanical re- fource.
M. de Reaumur has feen a like motion in the fea-mulcles, what may be called their leg or their arm, and which tn its natural ftate is 2 lines long, may come 2 inches out of the fhell; and the ani- mal having feized upon fome fixed point with this arm fo extended, contracts it afterwards, and con- fequently advances by trailing.
By an almoft fimilar mechanifm, which M. de Reaumur has been very minute in defcribing, the chama, or parr, another fort of fhell-fith, walks upon the mud, or plunges into it. But he has obferved, that if it plunges therein, it is no farther than is admitted by the length of two horns, or tubes, which it can pufh out of its fhell, and with which it takes in, and throws out the water, which in all probability it ftands in need of for its refpiration. Thefe horns muft al- ways be able to communicate with the water that is above it, and thence it happens, that even when it does not make ufe of them, for they are not always in action, there is in the mud which covers it, one or two little holes of the diameter of its horns, which difcovers it.
The length of thefe horns in the other fhell- fithes, determines alfo the depth to which they fink in the mud.
The patella, lepas or limpet, which is an univalve fhell-fifh, always faftened to a ftone upon which the lower circumference of the fhell may be ex- actly applied, feems to have no other motion than the raifing of this fhell the height of a line, sfo that its body may have a circumference of this magnitude, uncovered and naked. As foon as
one touches it, the fhell falls and covers ic. But I vet
RoyaL AcADEmMy of SCIENCEs, 323
yet M. de Reaumur has found in this animal, a progreflive motion upon the ftone to which it iticks.
The fea-nettle, which has the figure of a truncated cone, is in like manner always ap- plied to a ftone, by the greateft bafe of this cone. Some circular mufcles form the plane of the two bafes, and fome ftrait mufcles go from one bafe to the other. The whole play of the progreffive motion confifts in general in this, that one half of the mufcles both ftrait and circular, on that fide to which the animal would go, {wells and extends itfelf, and confequently occupies a fmall part of a new place, whilft the other half finks, and is drawn by that which advances, or pufhes itthe fame way. This motion is no more quick, nor more fenfible than that of the hand of a clock.
There is another fea-nettle, which faftens itfelf to nothing, and isthe moft odd of all animals with regard to its figure ; and is the moft fingular in the thinnefs of its confiftence, for it melts in one’s hands. It would not be reckoned in the number of animals, if we did not fee in it a motion of /y- ftole and diaftole, the only fign of life that it
tyes. ~ /.
In the laft place, the fea-ftar with its 304 legs toeach of the 5 rays of which it is compofed, eoes never the fafter. Its 1520 legs give it no advantage over the mufcle, which has but one. _ What a prodigious variety is there in the works of nature! not only the great quicknefs of the motion, but even the extreme flownefS is executed after different manners.
Qo2 Ay
4
224 The History and Memoirs of the Ln explanation of the figures. | “Plate TV, fig. 1. a fea-mufcle opened after the natural manner, . satis” tee, Fig, 2. a fea-mufdle Babin, § and putting forth | its leg, 4
Fig ig. 3. a chama or purr epened, to thew the | parts ferving for the progreffive motion. ~ |
S the vertex of the fhell.
“MM « two mufcles, which are cut thro’.
I the leg, placed in the middle of the fhell,. proceding trom the vertex. Its whole extremity Vis, ftrait and fharp, it is only rounded over- apainft the 2 ficthy tubes marked CC; whereas, on the other fide it advances a little, val forms a fort of blunted point marked P. | ~
“© O the inner aperture of the tubes CC.
. Fig. 4..a purr embracing the mud wath i its leg Li, DB gt
Fig. 5. A purr prolonging the horns or tubes ia CF to draw in the water.
S the vertex.
B.BB the bate.
SB the breadth.
LL the length.
Fig. 6. a fort of fhell-fith found. on, the coafts of Poitou, Aunis, and Saintonge, and there called. palourde: {tis different from the chama peloris, and from the pelorde of the coafts of Provence.
CC the two horns or tubes,
Fig. 7. a palourde opened.
O the interior aperture of that horn which is fartheft from the vertex.
I the leg.
Fig. 8. afort of fhell-fifh found on the coafts of Poitou and Aunis, where it is called fourcon. “CC the horns or tubes.
Fig.
“Rovat AvAbE Me of” ScIENCES. “395C
Fig. 9. a fourdon opened.
I a part refembling 2 leg.
P the foot. |
~'T the heel.
Fig. 10. a fourdon, with the lee, foot, and heel thruft out for-walking. :
fig. 11. a tellina opened fo as fhew the leg.”
» Fig. 12.a tellina with the leg thraft son ready to open a way in the fand.
~S the verter.
CC. the horns or tubes. 7
Fig. 13. a tellina bending its leg to raife iefelf. ~ Fag. 14.° another fpecies of tellina imc
‘thetles.< -
CC the horns or tubes.
Fig. 15. a tellina, with its leg thruft forth, ready to enter the fand.
AA the bounds of growth, marked fo di- ftinétly on the fhell, that they look like {mall pieces ftuck upon larger. ~ CC the horns or tubes.
I the leg. -
Fig. 16, the fhell of a Jempet faftened to a
ne.
Fig. 17. the anima] taken out of the fhell. AAA, &ec, that part of the animal which is uncovered by the fhell.
T the head,
CC two little horns bent towards it. '
P a thick fiefhy part in the middle of the opening of the’ fhell, whtich it makes ufe of for its progreffive motion.
Fig. 18. a {mall whelk, in which the organ of progreffion, or leg, is like that of a fnail,
FE. the leg.
’ C the lid'with which it fhuts ‘its thell:
326 The History and Memoirs of the
_ P the part which it puts upon its head, when it draws its leg into the hell.
Fig. 19. the cancellus, called in Englifh, the wrong heir, or Bernard the hermit. It isa fea- animal without any fhell of its own, which lodges in the fhells of whelks, and other turbinated fhell- fifhes.' -
DG its claws, like thofe of crabs and lob- fters. :
Fig. 20. I11 three little bodies near its thorax, with which it faftens itfelf to the fhell.
AO is that part of the animal, which is co- vered only with a thin fkin, the reft having a fofter fhell than that of cray-fithes.
Fig. 21. 2 fea-nettle.
A a part of the fea-nettle, reprefented in this and the two following figures, refembling the vent of a large beaft, on which account thefe ani- mals are called, by the common people in France, culs de chevaux, €8 culs d’anes.
BB the bafe which does not appear in this figure, becaufe the animal refts upon it; but it may be feen diftinétly in fig. 24.
Fig. 22. a fea-nettle with all its horns ex- tended.
- Fig. 23. another fea-nettle.
AIIFBD a fpace where only the ftrait canals appear.
ACIFRA a fpace where only the circular cgnals, appear.
_ TFTO a fpace where the ftrait canals’ partly appear, the circular canals being but partly fwoln. Ete
COTR a fpace where the circular canals are fwoln.
Fig. 24, a fea-nettle reverfed, to fhew its 7
Fig.
=| :
Royvat AcADEMY of SCIENCES. 327
Fig. 25. the mouth reverfed.
CC the circumference where the horns: are fattened.
OOOO the circumference of the mouth re- verfed.
It is by this mouth, that the animal takes in its food, and excludes its young.
I a little fort of inteftine turned fpirally.
Plate V. fig. 27. another fort of {fea-nettle called fea-blubber, or fea-gelly.
DD the circumference or bafe.
CD the grand refervoirs or canals.
The circular circumferences DDD, &@c. EFEF, &c, receive the water only by the portion ED of the canals D; whereas the band CCCC, &c. EFEF, &c. the thicknefs of which increafes gra- dually EFEF, &c. to CCCC, &c. receives the water from 16 canals marked CE and CF.
BBBB four columns, which divide the fea- nettle as it were into 4 parts.
T a trunk, in which the 4 columns are united.
RR, Gc. the trunk divided into 8 branches.
P P an appendage to one of thefe branches.
L. a fmall part of the canal left between the apertures of the columns.
Fig. 28. reprefents fome of thefe parts more at large.
T the trunk of the canal.
- RR, &c. the branches into which the trunk is divided. - OO, Ge. the apertures of each of thefe branches. _ Fig. 29. a fea-ftar.
RR one of its rays laid open.
BB two rows of tranfparent bodies like pearls.
Fig. 30. another fea-ftar reverfed, creeping un- der a ftone.
AA
328 The History aud Memoirs ofthe
AA in thief two rays. the ends of the legs ap- ar. S the mou dd or fucker. DD, ce. five teeth about the fucker. Fig. 31. an end of a ray magnified. Ce é, bundies of tubes. RRR « the fkin.
Il, Of the glafi-ware of India.
M. de Ja Hire has been informed by a, memoir that has been'fent him from Pondichery, in the Indies, by” F. Yachard, a miffionary jefuit in 1709, that the glafs-ware of India, which is noe, fo fine as that of China, or Japan, is made of the gum of a tree of the colour of white amber or karabé, which they meit in two ors of lin- feed ott,
ML, Of a fort of acorn from Coromandel. y2
.M. de dz Mare, a fea-officer, having brought from the Eaft-Indies, Brazil, and Pros feveral forts of drugs, gave them: to.M. Sauveur, who fhewed them to the academy. M. Geoffrey took. upon himfelf the examination of them. They were roots, feeds, woods, ftones, &c. He compared thefe drugs,’ ashe’ faw them himfelf, and whatiwas faid.of them in the memoirs of M. de la Mare, with what was faid of them by ‘the; authors,» who have treated. of thefe fubje ets) and by that he endeavoured to find out, if what he had before him was what thofe authors +haye de- fcribed. We fhall fupprefs the principal. part of this. work, altho”? inquired into with a great deal ~ of care, being only mere erudition, and we oe only
LV. Vol, i,
Ro¥At ACADEMY of ScTENCES, 329 Only take from it here, and in fome other places what belongs to philofophy.
Fhere is on the coaft of Coromandel, a tree pretty much like our oaks, which bears a fort of acorn, out of whicli they draw an oil, like oil of olives. The Malabars make ufe of -it in their food, for burning, and:to colour their linnen. M, de la Mare, by their example eat of it in fallads, and fifh fried with it; and he had’ taught all the other officers of the coaft to eat it, who found it tobe very good.
IV. Of the virtues of a nut called Bicuiba.
The nuts called dicuzba burn like cloth foaked in pitch, and itis in burning that they extract the oil, as M. de la Mare has tried at M. Boudin’s, firft phyfician to the late Dauphinefs. M. Fean Verdois, contul of the Frezch nation affirms, that he has cured many cancers with this oil, and that by eating one of thefe nuts, the colick is eafed.
V. Of @ woman delivered of a child, when above 80 years of age.
The late bifhop of Sees has affirmed, that a man in his diocefe, whom he knew, being 94 years of age, had married a woman of 83, who in due time was delivered of a boy.
VI. Of the fatal effet of fome vapours in a
baker’s cellar.
A baker of Chartres had put into his cellar, which was 36 {teps deep, and well vaulted, 7 or 8 tubs of embers out of his oven. His fon, ‘a {trong and robuft young man, going to carry
Fou. N°, 32. Pp fome
330 The History and Memoirs of the
fome more embers, with a candle in his hand, the candle went out half way the ftairs, he came up, lighted ic and went down again. When he was at the bottom of the cellar, he cried out for help, after which they heard no more of him. His brother, as ftrong as he, went down quickly, cried in the fame manner, and then ceafed. His wife went down after him, and a maid fervant ‘after her, and it was ftill the fame thing. So {trange an accident alarmed the whole neigh- bourhood ; but no body was in hafte to go down into the cellar. There was only one neighbour, more zealous and bold, who not believing that thefe four perfons were dead, went down to give them his hand, and help them out. He cried out, and they faw no more of him. A paffen- ‘ger, a very vigorous man, afked for a hook to draw fome of the people out of the cellar, with- out going down to the bottom, he threw the hook and drew up the maid, who, upon coming to the air, gave a figh: they opened a vein, but fhe did not bleed, and died upon the fpot.
- The next day a friend of the baker’s out of the country, faid, that he would draw up all the bodies with a hook, but for fear that he fhould find himfelf ill, without being able to get up a- gain,. he was let down into the cellar with a rope upon a wooden pully, and as foon as he fhould cry out, they were to draw him up again: he very foon cried out; but as they drew him up, the rope unhappily broke, aad he fell back again; they mended as faft as they could this rope, which was broken pretty near the top-of the cellar, but they could Only bring him up dead, They opened him, his brains were. in a manner dry, the meninges exceffively ftretched, the lungs matked with black fpots, the bowels blown up,
and
Royat ACADEMY of SCIENCES. 331
and as thick as one’s arm, inflamed, and as red as blood; and what was the moft particular, all the mufcles of the arms, thighs and legs, as it were, feparated from their parts.
The magiftrates took cognifance of this acci- dent, for the publick intereft, and forbid aay one’s going into the cellar, till they had taken the advice of phyficians, furgeons, and even of mafons. It was concluded, that the embers, which the baker had put into his cellar, were not well extinguifhed, that as there is a great deal of falt-petre in all the cellars of Chartres, the ‘great heat had raifed in that a very malignant vapour, which had caufed fo many fatal effects, that they ought to throw a great quantity of wa- ter into it, which would extinguifh the fire, and make the nitrous vapours fall. This was execu- ted, and at the end of fome days they let down into the cellar a dog, tied to a plank, with a lighted candle. The dog did not die, and the candle did not go out, certain figns that all the danger was over. They took up the dead bodies, but fo corrupted by the water, that they could “not be examined ; they were very much fwoln, and one had his tongue out of his mouth, as if he had been ftrangled. The academy had this hiftory from M. de /a Hire. There is one almoft of the fame fort in the hiftory of 1701-*,
VII. Of « remarkable echo,
M. /? Abbé Teinturier, the arch-deacon @f Ver- dun, has tent to M. Caffni the fon, the account of an echo, that he has feen-3 leagues from Ver- dun, tis formed by’two thick towers, detach’d from the body of the houfe, and 26 toifes diftant
_* Vol. I. pag 253 of this abridgment. 463 Pp2 fran
332 The History aud Memorrs of the
from one another. One has a lower apartment of free-ftone vaulted ; the other has only the porch fo. Each has its ftair-cafe. As all that belongs to echos may be called. catoptricks of found, becaufe the found reflects itfelf according to the fame laws, asthe light does, we may look upoa thefe two towers as two looking-glaffes, placed over-againft one another, which mutually fending back the rays of a light object, multiply the image of it, altho’ continually weakening it, and make it always appear farther diftant. Thus when we are upon the line that joins the two towers, and pronounce a word with a pretty high voice, we hear it repeated 12 or 13 times, by equal intervals, and always weaker and weaker. If we go out of this line to a certain diftance, we hear no more of this echo, from the fame reafon, that we fhould fee no more of the image, if we fhould remove ourfelves too much from the fpace which is between the two looking-glafies. If we are upon the line, which joins one of the towers to the body of the houfe, we only hear one repe- tition, becaufe the two echos de not any more play together with regard to thofe that f{peak, but one alone.
VIL. Of figured flones.
M. Yobn Schuchzer being come to Peris, and having been prefent many times at the affemblies of the academy, of which he is one of the moft Jearned, and ufeful correfpondents, read a Latin differtation, which he addrefied to it, upon the figured ftones, that he has objerved in his jour- ney into Flanders and France.
The quarries about Paris have at different depths of the beds, fometimes pretty thick, dif-
ferent
RovaAL ACADEMY Of SGIENCES. 333
ferent forts of fhells, ftrongly. bound together either by earth or fand, hen thefe fhells have wreferved their fubftance, or their natural con- fiftence, they do mot. yet merit the name of j- gured ftones, that is only proper when they are petrified ; but they deferve it ftill better, when after having ferved for a mould to a fubftance yet fluid, which has intirely filled them, and af- rerwards grown hard, their fubftance has been ab- folutely deftroyed by time, and there remains only this petrified matter, which very exactly re- prefents their interior figure. Then the whole that we fee is, in reality, only a figured ftone ; and this probability is fo ftrong, that there is need only to prove, that fome part of an animal has contributed to the formation of this ftone. The perfect conformity of the figures is a demontftra- tion of it; to which M. Scheuchzer adds, that about thefe ftones there is always in the quarries an empty fpace, which is exactly that which the fhells filled.
There may figured ftones be found, whofe moulds may be unknown to us at prefent. The fhells, which have formed them, are not any more ia our feas, or they have efcaped us. The great quantity of ftones, which certainly have been moulded in this manner, gives us a-right to make this {uppofition. Perhaps even fome mouids may have been loft; thatis, fome {pecies of fhell may have perifhed; but to admit this thought, which is a littl. bold, we muft per- ceive in a {tone pretty fenfible traces of this fort of formation. :
Thus we do not admit it at prefent in explain. ing a ftone, which was thought to be found only in Hungary and Tranfy/vania, but has been found by M. Scheuchzer in Swifferland, and in a fil
greater
334 The History and MEMorIRS of the
gteater quantity in Picardy about Noyon. Clu- Jius has called it Numifmale, becaufe of its figure s however, it does not fo much refemble a medal, or piece of money, as a glafs convex on both fides, but more elevated in the middle than the {pherical curve requires. Its two convex halves eafily feparate, and fometimes are found natu- rally feparated. Then we fee in the ftone turns made fpirally, like thofe of a cord twifted about itfelf. Thefe turns are faftened by a fort of little filaments, which extend themfelves obliquely to- ward the circumference. The exterior furface of the ftone is fometimes polifhed, but oftner fet round wich little points, whofe different feries are forts of irregular flutings. The generation of thefe forts of ftones, if we could never fufpect them to have been moulded, will perhaps reduce the philofophers to the hypothefis of feeds, ven- tured by the late M. Tournefort *.
To explain the fhells-petrified, and fometimes buried under ground at great depths, or thofe which by a long feries of ages are confumed, after having left only the print of their figures, M. Scheuchzer has recourfe to his hypothefis of the deluge already explained in the hiftory of 1708 +, which he has in common with his bro- ther upon thefe forts of fubjeéts. If what we have related after M. Sau/mon, in the hiftory of 1707 t; does not abfolutely require this hypo- thefis, at leaft a confiderable part of what is land now, mutt formerly have been fea. ~ We fhall not here pafs over in filence an idea, upon which, however, M. Scheuchzer has de- clared that he did not pretend to infift, and which he has only propofed asa fort of philofophical dream. If we make-a great round bafon half ¥ Vol. I. pag. 410. FT Vol. Ill. pag. 77. t Vol. IIE. p 6.
3 tull
Rovat ACADEMY of SCIENCES, 335
full of water, turn pretty faft round its centre? till at laft the water has taken all the fwiftnefs the bafon, and ftop it fuddenly, the water will not ceafe continuing to move, and even with fo much force, that it would furmount the edge of the veffel. Thus if God fhould, at an inftant, {top the turning of the earth about its axis, the waters of the fea would fpread themfelves with violence over the whole earth. This manner of expiaining the deluge is not lefs fimple than new ; even when God exerts his extraordinary power, and fuperfedes thefe laws which he has framed with fo much fimplicity, we may imagine, that the miracle is performed alfo with the greateft fimplicity poffible.
IX, Of M. John James Scheuchzer’s Her-
barium Dilu, janum.,
M. John Fames Scheuchaer? s Herbarium Dilu- vianum, printed at Zurick in 1709, and fent to the academy by the author, turns upon the fame principle with the work which. we have juft men- tioned, and with all thofe of both thefe brothers, mentioned in the hiftory of 1708+. This ex- traordinary herbal is only compofed of plants, which, from the time of the deluge, having been ‘buried in foft fubftances, have left the print of their figure upon them, when they were after- wards become petrified. They are only fimple figures without fubftance, but fo perfeét and fo exact, even in the moft minute. particulars of what they reprefent, that it is impoffible to mif- take them. Among a great number of plants, which are all of. thefe countries, there is an Ja-
+ Vol, III. pag, 77, 81, 82. dian
246 The History and Memoirs of the 4tan one, ‘the ftone of which was fotind ih Saxony, which agrees with an obfervation already made inthe hiftory of 2706 *. The ftrange ¢onfufion that the deluge muft have caufed upon the fur- face of the earth, renders the tranfportation of an Indian plant into Germany very poffible. Ac- cording to the manner in which the holy feripture explains it, we may equally place the beginning of the deluge, either in the fpring or the autumn ; but M. Scheachzer rémoves this uncertainty by fome of the plants-o6f his herbal, and chiefly by an ear of barley. Their age is only that which they have here at the end of May. This is alfo confirmed by an infect or two, of which we alfo know the life fufficiently, an@ which are not older. Thefe are a new fort of medals, whofe dates are without comparifon more ancient, more important, and more fure, than thofe of all the Greek and Roman medals.
There are certain ftones which reprefent upon their furface, not like thofe of this herbal, a fin- gle part of a plant, or a finele leaf, but fhrubs and little forrefts very beautiful. ‘Thofe repre- fent fomuch, that they reprefent nothing, and in effect on examining them ever fo little, we fee that thefe trees, or fhrubs, do not reprefent any real plant. They are even fometimes accom- panied with little caftles, or figures, which adorn the piévure indeed, but render it unworthy of thé herbal of the deluge. ‘Thefe are true fports of nature. M, Scheuchzer undertakes to'explain the — philofophy of thefe fports; that is; how certain juices which exuded from the pores of a ftone, as faft as i¢ was formed, could fpread themfelves Hetween two of the leaves, or firata, which com- pod it, and trace there certain reprefentations
ol TT. pag. 357. ve almoft
Royal ACADEMY of SciENCES. 337
almoft regular, to which afterwards our imagi- nation lends a little of what it wants. He has even rendered his explication fenfible to the eyes, by an experiment quite like it of two flabs of po- lifhed marble, which he rubs together, after having put fome oil between them. It {preads there fo as to form trunks and branches.
Among the remains of the deluge, M. Scheuchzer reckons a great trunk of a tree, which he knows to be laid upon the fummit of mount _ Stella, the higheft mountain of the d/ps. M. Fobn Scheuchzer has twice attempted to go and fee it with his own eyes, altho’ the moft deter- mined hunters have never been there but with fear ; but the fnows have been an invincible ob- ftacle. According to his eftimate, this trunk is raifed 4000 feet above the moft elevated place of thefe mountains, where any trees naturally grow, for-beyond a certain height there grow none. Who could have carried it thither? With what defign? And what machine muft they have ufed?
X. Of the count Marfigli’s philofophical effay towards a biftory of the fea.
The count Marfgli has fent to the academy a manulcript work, intitled, 4 Phyfcal Ejjay on the Hiftory of the Sea, of which He has done it the honour of a dedication. He turned to the advantage of philofophy a ftay that he made on the coaft of Provence and Languedoc, and took that opportunity of ftudying the fea particularly. The manner in which he engaged in it, is fuffi- cient to fhew what the genius of obfervation is ; and to give a model of it, he has formed a defign as extenfive as the fubjeét, he has em- braced-all the parts of ir, and has undertaken to
Vor. III. N°. 32. Qq make
338 The History and Memoirs of the
make by himfelf all the experiments which can have relation to it. If we hada fufficient num- ber of as good memoirs made by obfervers, who had been placed in ditferent parts of the world, we fhould at Jaft have a natural hiftory.
_ The work of count Marfigli is fo confiderable, that the extracts which the academy has caufed to be made from it, by M. Mara/di and Geoffroy, were themfelves pretty large works. We fhall here only givean idea of it incomparably fhorter, and we fhall be greatly affifted by their labours. The hiftory of the fea is divided into 5 parts. The firft treats of the difpofition of the bottom, or bafon of the fea. The fecond, of the nature of the water. The third, of its motions. The fourth, of the plantsthat grow there. The fifth, of the fifhes. This laft part is not finifhed, and the academy have not yet feen any thing of it. The whole is accompanied with a great number of figures, made with a great deal of care.
To difcover the nature and difpofition of the coafts, he has made different fmall voyages in barks, which are all contained between the cape of Siffe near Toulon, and the cape a’Agde in Lan- guedoc. He has made others at fea, and fome- times at 11 leagues diftance, to examine. the depth and nature of the bottom. He has found that the gulph of Lyons is cut afunder by a ridge, hid under the water, that the part which is from the land to this ridge is not above 70 braces deep, and that the other which is towards the main is 150 in fome places, and fometimes fo much that it cannot be founded. He calls it the abyfs*; he has fearched what the difpofition of the {oil was, that is to fay, the order of different banks, or beds of earth, fand-rocks, €@¢. not only in the coatt, but alfo in the iflands or neighbouring fhelves.
I ’ This
Royat ACADEMY of SCIENCES. 339
This difpofition is found alike, fo that all the Wands are only fragments of the firm land, and probably the bottom of the fea is a continua- tion of it. From hence we may conjecture, with count Marfiglt, that the globe of the earth has a determinate organical ftructure, which has not fuffered great alterations, at leaft in a confiderable time.
He fhews, that fome beds of falt and bitumen are mixed among the beds of ftone; and that upon the natural bottom of the fea there is formed an accidental bottom, by the mixture of different matters, fand, fhells, mud, &c. which the glu- tinofity of the fea has ftrongly united, and ftuck together, and which are afterwards har- dened fornetimes even till it petrifies. As thefe incruftations are neceffarily formed in rata, there are fome in which the fifhers diftinguifh the an- nual augmentations ; they have a furprizing va- riety of colours, which fometimes penetrate even into the ftony fubftance, but are oftener only fu- perficial, and diffipate out of the water.
Some of the matters which form thefe incrufta- tions, have afforded by chymiftry, principles fo like to thofe of marine plants, that we might fuf- pect them to be fo; and much more, as they are fometimes wholly fibrous. Such are the hard fea moffes, or /ichens which fatten to the ftone, and have almoft the fame hardnefs,
Count Marfigli found by a_ thermometer
- plunged in the water, that the degree of heat there is equal at different depths; that in the winter it is fomething greater in this fea, than in the air; and on the contrary in fummer ; but pretty often equal. Neverthele!s count Marfgli has obferved allo, that many marine plants agree with thofe of the and, in {hooting in the fpring oftener than in
Qq 2 other
340 The History and Memoirs of the
other feafons. An accident prevented the expe- riments of the heat of the fea from being conti- nued fo long as they fhould have been.
According to him, the fea-water, fuppofing it to be well chofen, is more clear and bright than any other water. As to its colour, it depends both upon its bottom, and the fky ; and fo many other circumftances hitherto lefs known, that all the experiments of count Mar/gli leave him ftill a great deal to defire upon this fubjec. ,
It is more eafy to determine the caufes of its ‘faltnefs and bitternefs, for we may well obferve the bitternefs as different from the faltnefs. One is produced by the diffolution of beds, or banks of falt, the other by the diffolution of beds of bitumen. .
Water is much more proper to diffolve the fale, than the bitumen, which is an oily matter: and in the fea-water the dofe of falt is much ftronger than the bitumen. Count Mar/gii having taken 23 ounces 2 drams of ciftern-water, to make fea- water of it, he put 6 drams of common falt into it, and only 48 -grains of fpirit of pit-coal; for pit-coal is bituminous; and befides there are mines of it found in the mountains of Provence: and with this mixture he had an artificial fea- water of the fame tafte with the natural. Thefe 48 grains did not at all increafe the weight of the water weighed by the areometer.
The {mall quantity and lightnefs of this bitu- minous matter, are the cautfes, that the fea-water diltilled, fo as to loofe its faltnefs, has not how- ever loft its bitternefs, and a difagreeable tafte, nor even as is pretended an unwholfom quality. The diftillation which is naturally made by the fun, and which is very different from that an
alem-
Rovat Acapvemy of Sciences, 341
alembic, perfectly purges the fea-water from its bitumen.
There are in the earth fo many different matters,
that the fea wafhes, and of which it mutt raife fome particles, that we may pretty juftly believe, that bitumen is not the only principle which mixes with the falt. _ By what has been juft faid, we fee that in 24 ounces of fea-water, there are 6 drams of falt; or, which is the fame thing, that it contains the 32d part of its weight of falt. But this is only true of tne water taken at the furface of the fea, that at the bottom is more falt, and has the 29th part of its weight of falt. The falteft waters are alfo the heavieft. ‘Thofe which are upon the furface of the fea at the outlet of the Rone, are lighter by ;3;, than the waters farther diftant, and e- qually fuperficial ; and thefe ftill lighter than thofe which are farther diftant from land.
It is furprifing that the water of the fea, which does not want falt, has not diffolved all that it can diffolve. By count Mar/fgli’s experiments, a quantity of water which ought to contain 6 drams of it, diffolved 4 4 more; and the arti- ficial fea-water 5. He conjectures, that the ani- mals and plants of the fea, confume part of its falt.; that another part of it diffipates in the air; that the foft waters, which it receives not only from the rivers,but from the fprings of its bottom alfo, frefhen it; but with all this he does not pre- tend, that the difficulty is intirely removed.
He has made 14]b. of fea-water pafs through 15 earthen pots, which he fucceffively filled with garden-mould and fea-fand. Hf they had been joined together, they would have made a cafcade of 75 inches long, and 5 broad. The 14]b. of water having pafled both through the fand, and
through
342 The History and Memoirs of the
through the mould, were equally reduced to 5 Ib. 2 ounces ; but they were better frefhened by the fand, and deprived of a greater part of their weight. If the cafcade of fand had been twice as Jong, we might believe, that it would become al- moft infipid. | By this means the fea-water might become frefh by filtering through the bowels of the earth, if at’ the end of a certain time the filters fhould not fill with the falt which has been depofited in them.
The falt of the fuperficial waters is white, and that of the deep waters of a dark afh-colour. The firft is the only one in which there is found an acid, and is of a more biting faltnefs, and a much lefs fenfible bitternefs. From hence it comes, that at Peccais, in Languedoc, where they extract falt from deep well-waters, it muft be left expofed to the air for 2 years at leaft, before it is vended. This time is neceffary for it to lofe a bitternefs which would be infupportable. We fhall fupprefs a great number of obfervations upon the marine falt, becaufe this fubject is more known.
‘Count A/arfigli has not had leifure to content himfelf fully upon the fact of the bitumen con- tained in the fea-water: however he believes it is this which produces the natural unctuoufnefs of this water, which even the diftillation does not take away from it. The great quantity of glue which fixes upon the {tones and plants, the union of fo many heterogeneous bodies which glue -to- gether, the tartar which hardens in fome places the bottom of the fea, or inclofes feveral forts of matters, and chiefly the lithophytons, a marine plant. He has begun experiments at different times upon the tartarifations of the fea, which could not be carried far enough,
He
Royat ACADEMY of SCIENCES. 343
He has obferved, that pulfe boiled in fea-water, came out of it more hard than when it was put in; that the flefh of mutton becomes white, and more tender than in foft water, but very falt and bitter; that the bread made with fea-water is falt, and may very well be eaten while it is new 5 but when it is ftale, it acquires an exceffive bit- ternefs.
The fea has three forts of motions, the flux and reflux, the currents, and the undulations. We know that the Mediterranean has no flux.or reflux, at leaft univerfally ; and in effect, according to the common fyftem, it muft not have any, fince it is not under the courfe of the moon. However, as an almoft infenfible flux and reflux might ea-- fily efcape the obfervations which are commonly made, count Mar/igli has made new ones, which this motion could not have efcaped; and it was not at all perceived in the places where the obfer- vations were made. -
Count Marfigli has not difcovered any rule in the currents, altho’ he has not fpared his voyages, nor his trouble. He has not been able to verify what is commonly faid of this famous current, which coafts the whole Mediterranean, as if it was formed by the entrance of the waters of the ocean, and by their return. But he believes he has dif- covered fomething very fingular. During the fummer, and in the time of the coral fithing, they perceive at the fide of the abyfs, a current which feems to have a relation tothe motion of the fun upon the horizon, but fo that it is always oppofite to it. When the fun is in the eaftern part of its diurnal courfe, that is to fay, from its rifing till noon, the current goes to the weft ; and at noon jt turns to the north, and afterwards to the eaft. They have not obferved if it goes to the fouth at
mid-
344 The HisTory and Memoirs of the
midnight ; this would agree with the reft, and even appears neceffary.
As to the undulation, it is fufficient to know the exceffes of it. Count Marfigli has obferved be- tween Maguelone and Peyrole, that in a great tempeft the waves rofe 7 feet above the common evel of the fea. At the mountainous fhores, fuch as thofe of Provence, a furious fouth-weft wind raifes the water only 5 feet, but the percuffion that it makes againft the rocks, drives it fome- times to8. This is not comparable to the poetic tempetts.
XT. Of a tenia found in a tench.
M. Geoffroy, junior, fhewed a tenia found ina very found and fat tench, like to thofe which are found in man, only it was not divided by rings. It had only ftripes, or folds, perpendicular to its Jength, according to which another great ftripe went from the head to the tail, dividing it into equal halves. It was intire, and 2 feet 4 long. We do not know that there has been hitherto any ‘euia found in fifhes.
XII. The difcovery of an extraordinary fort of tnfeé.
We muft be furprifed to fee that a little body pretty exactly oval, and whofe great diameter, which is of above a line, is to the fmall as 3 to 2 3 which has a very polifhed furface of the colour of roafted coffee, with a fmall pearl-coloured band in the middle; and which, with thefe appear- ances, would hardly be taken for an animal, and at moft but for an ege, fhould however leap in a garden, raifing itfelf = an inch, and fometimes
. leap-
~
Rovat AcADEMy of SciEncEés. 346 leaping as high as. 2.W hen we would have it leap,. we'need only expofe it to the fun, or-hold it in the hand when it is hot. M. Carré, to whom we owe this obfervation; opened the bag of one of thefe little bodies, it is thick and folid in pro- portion to its bignefs, and ir had need be fo: to bear their leaps, and it inclofes a very white little worm, of which the back is cut with tranfverfe and parallel rings, and the belly very flat, and without feet. We perceive two little black. points: on the fide of the head. As the figure of its belly hinders it from entirely filling the bag, it has room to make a leap there by gathering up its body, and afterwards opening it haftily. It is thus that it raifes up its houfe in the air. It muft be very vigorous, for this houfe is a very great weight in proportion to it; and yet it raifesit very high, and Catries it a great way; and that very often. M. Carré kept one for two months in.a box, without perceiving any alteration init. This little animal. is a riddle pretty difficult to explain. How does it nourifh itfelf in this bag fo well clofed? How does it multiply in this prifon? For, although it fhould multiply in the manner that mufcles do*,, how fhould its eggs get out?
XIII. On the pond mufcles,
We know well enough, at leaft to a certain point, the animals that are moft expofed to our eyes, and with which we have the greateft coms merce, But there ts an infinite number of others, which the little need that we have of them,- the difficulty of obferving them, a certain contempt which we have for them on account of their little-
* See the following article.
Wo. I. N°.32. Re nels,
346 The Hystory and MEmorrs of the
nefs, or their figure makes us neglect them, or abfolutely deprive us of them. Thefe are chiefly infects, and fhells.
Who would imagine that there is an animal which receives its nourifhment, and refpires only at the azus, which has neither veins nor arteries, and has no circulation in it?) We need not mention its being a hermaphrodite, for that is a wonder at prefent too commons; but it differs from ali the other hermaphrodites hitherto known, in its multiplying independently of another ani- mal of its own /pecies, and is itfelf alone both fa- ther and mother of what it produces. Here is a quite new idea of an animal; it is the pond muf- cle, the ftruéture of which, M. Mery has difco- vered, notwithftanding its fhape is fo odd, and difcourageing, on account of its exceffive: fin- guiarity.
What we may call the head of the mufcle, tho’ we can find neither eyes, nor ears, nor tongue in it, but only an aperture which may be called its mouth, isan immoveable part, faftened to one of the fhells, in.fuch a manner, that it cannot go out to feek for nourifhment, but nourifhment mu(t come to it. This nourifhment is nothing but water, which, when the fhells open, enters
into the amus of the mufcle, which opens at the
fame time, and paffes thence into certain refer- voirs or canals contained between the interior fur- face of the fhell, and the exterior furface of the animal, and at laft goes into the mouth, when compelled by a certain motion.
At the bottom of the mouth are two ca-
. nals to receive the water. One throws feve- ral branches into the body 6P®the mufcle, one of which terminates in the heart. The other is a fort of ingeftine, which firft pafles through
3 the
Rovat AcapEmy of SCIENCES. 347
the brain, then makes feveral circumvolutioms in the liver, and at parting from thence, traverfes the heart in a right line, and ends in the anus.
This brain and liver are fuch no otherwife than as we pleafe to call them fo, but the heart deferves that name a little better. Jc has a ventricle, and 2 auricles ; and the alternate motions of /y/fole and diaftole in the ventricle and auricles; but it has neither veins, nor arteries: the water brought to it by its canal, enters from the ventricle into the auricles, and returns from the auricles into the ventricle, and makes a flight reprefentation of cir- culation, without any apparent effect ; for being once arrived at this heart, it has no way to get out again. What muft become then of the quan- tity there collected? Probably there is no collection made, becaufe the animal does not make the wa- ter flow continually thro’ the mouth into the heart; and when a certain quantity has entered, the contractions of the heart fqueeze it thro’ the pores, and drive it into the neighbouring parts, which abforb it, and are thereby nourifhed.
The canal which M. Mery calls the inteftine, and which, as well as the other, receives the water immediately from the mouth, does not feem fit to carry the nourifhment to the parts, becaufe it has no branches to diftribute it. However it contains at its beginning and end, two different fubftances ; the firft of which may be water di- gefted, that is, the nutritious juices drawn from it; and the others may be the excrement.
The mufcle cannot breath, till it is raifed upon the furface of the water, and it raifes itfelf like other fifhes, by dilating the cavity in which it contains the air. Then it is its azus too that re- ceives the air from without, and carries it into the RE oS lungs,
348 The History and Memoirs of the
lungs, for isis generally funk at the bottom of the water.
It has ovaries, and feminal veficles. Thefe two forts of organs are equally compofed of tubes ranged by the fide of each other, ail fhut at the fame end, and opened at the oppofite end. We do not diftinguifh thefe parts by their ftructure, which is all alike to the eye, but the difference of their contents, and fo much the more as the ovaries are always full of eggs in winter, and empty in fummer, and as the veficles are in all feafons in like manner, but little filled with their milt, which confequently feems to flow out con- tinually. All the cubes difcharge themfelves into the anus, and M. Mery imagines, that when the eggs are depoficed in their feafon, they cannot fail of meeting with the mile or feed which ferti- lizgesthem. ‘Ihe animal therefore has no need of another to affift in its generation.
M. Mery does not agree with the late M. Pow- part concerning the progreffive motion of pond mufcles*. He apprehends, that their whole belly, which comes two inches out of their fhells whenfoever they will, in the form of a keel of a fhip, creeps upon the mud, juft as the belly of a ferpent does upon the ground. He defcribes the mufcles, which, by their alternate contractions, make the whole play of this mechanifm.
He is alfo of opinion, that the fhell of the mufcle is not formed as M. de Reaumur has found the fnail-fhell to be formed}. Here the firft cir- cumvolutions are no Jarger in a great old {fnail, which proves that the fhell is not a member of the animal, and that it is formed by a fucceffive addition of foreign parts; buc fome bands that
% See p. 321 of this yolume. + See p. 250 of this volume.
we ta
Roya ACADEMY of SCEINCEsS. 349
we perceive on a mufcle fhell, are largeft in the biggeft mufcles. Befidesthe mufcle has 8 ten- dons faftened to the inner furface of its fhell ; if the fhells did not grow in the fame manner as the flefh, thefe -which are faftened at firft in certain places of thegrowing mufcle, muft continally change their faftening to the laft growth of the animal ; and how could that be poffible? The difficulty is confiderable, but perhaps it is no more than a difficulty. .
AN
ABRIDGMENT
OF THE.
PuiLosoPpHicaL Memoirs of the Roya AcaADEMy of SCIENCEs at Paris, for the Year 1710.
I. Experiments upon the elafticity of the air, by M. Carré * ; tranflated by Mr. Cham- bers.
M. Parent gives us fome experiments in the
hiftory of the academy for the year 1708, whereby he pretends to prove, that the air has no {pring; but the point feems of too much impor- tance to be given up, either upon M. Pareni’s experiments, or his reafonings without fome fur- ther examination ; for it can never be too much confidered, how liable we are to fall into errors, in drawing conclufions from one or two experi- ments, which may have fucceeded agreeably to our opinion; efpecially when they go counter to an eftablifhed doctrine, warranted by a multitude of experiments.
My intention therefore is to repeat M. Pareni’s experiments, together with fome others tending to the fame matter, in order to which it may ‘be neceffary to tranfcribe the account thereof, given by M. Fontenelle. —— “A very extraor- «¢ dinary and furprifing experiment, agrees with ‘© or rather proves this fentiment. M. Parent ‘© took feveral round glafs phials about an inch in ‘¢ diameter, and having long narrow necks, from *« 8 to 10 inches long, and a line wide; in each
* July 1709. é6 of
aA Lal
es
vn wa eR ROR
«6
al ba
a Lal
€¢ «ec 66
Rovat Acapbemy of SCIENCES. 351
of thefe, he put a little quantity of a different liquor as water, wine, fpirit of wine, oil of tartar, petrol and mercury ; then putting their necks thro” holes made in the receiver of an air-pump, he exhaufted the air, after which melting that part of the neck, which was on the outfide, with a lamp, and twifting it about the weight of the ambient air quickly fealed it hermetica'ly ; fo that there could be no doubt but the phials were all well emptied of air. Atthe fame time there were other like phials, fealed after the fame manner, but full of air, both the one and the other were laid upon burning coals, whereupon thofe full of air,
‘by the great augmentation which the heat muft
have occafioned in the {trength of the fpring,
-fhould have burft with great noife ; whereas,
in reality, they only melted gently through the aperture ; and onthe contrary, thofe which contained no air, “but only a little liquor, made all a great detonation, and burft in pieces. Now, what becomes of the fpring of the air in this experiment? The etherial matter car- ried by the fire into the former phials, could not make fo great an effort againft their inter- nal parietes, by means of fuch fubtile and deli- cate particles, as thofe of air are, as by means of more maffive particles of the other liquors. ‘© Hereby we can eafilv explain how moifture may produce thofe extraordinary effects, com- monly attributed to the {pring of the air, nor need we any longer be in pain to underftand how fuch a fpring fhould act in great rarefacti- ons, where the particles of air do not feem to touch, or bear upon one another; but this perhaps would be to extend our confequences further, than as yet may be allowed of. There 6s is
353 The History andMemorrsof the *¢ 3s a certain maturity required'in phyfical truths; ** which time alone can give them.”
Here follow my experiments. I pro- cured: 4 little glafs phials to be made with Jong necks, like thofe ufed by M. Parent, and pre- pared after the fame manner. The firft was full of common air; the 2d exhaufted of its air; the 3d’ Full of air, witha little common water ; and the ath empty of air, but containing a little quantity of water. I fealed them all hermetically, and lay- ing one after another upon’ the burning coals, the confequence was, that the phial, which contained nothing but common air, and which remained fome time without fhewing any effect, as being fomewhat thicker than the reft, opened at a place where it was fomewhat ftretched before, and pro- duced a kind of hiffing by the air iffuing from it, without’ any great violence. The fecond had pretty much the fame effect, but the hiffing was fomewhat more confiderable, the part of the phial moft heated having ftretched fomewhat further, and yielded more quickly. The third made a violent detonation, and burtt into very little pieces in avery fhort time. The fourth likewife burft with fome noife, and very quickly, tho’ only a very fmall hole was made in it. 7
After this, I made 4 other little phials like the former. The firft, which was full of air, remained on. the coals a confiderable time, ere it produted its effect; but it ftretched till at length it burit, with a confiderable noife, and difcovered a large aperture.
The fecond, which was likewife full of air, produced much the fame effect, but with lefs noife, the part at which it opened was ftretched more, and the hole fmaller.
The third and fourth, which were emptied of air, funk inwards withcut burfting ; and efpe-
cially
Royat ACADEMY of SCIENCES. 353
cially the fourth, infuch manner, as that half the convexity which touched the coals became clofed exactly to the other half, and only made a hollow hemifphere. The fame fhould always happen in this experiment, fince the external air, though much dilated by the heat, muft prefs more ftrongly than. the thin air included can poffibly refift, and confequently the part moft heated muft be driven inwards ; and if the fame did not hold in the firft experiment, “twas probable, by reafon there was air, or fome other matter enough left in the phial to make it burft.
Not being yet fully fatisfied with thefe experi- ments, I made 15 other little phials like the for- mer; an account whereof, and of the effects they yielded in the fire, follows.
The firft, which'was full of common air, being laid on the coals burft in pieces in a very fhort time, and with a little noile, which had not been found in any fimilar experiment before.
The fecond, which was emptied of its air, melted without burfting, and turned into a hol- low hemifphere, as eee §
The third, which was full of air with a little water, burft quickly with a great noife.
The fourth, which was void of air, but had a little water, burft in a fhort time, with a noife fomewhat greater than the former. .
The fifth, which was full of water, remained but a little time on the coals ere it burft, and threw them all around with a very great noife.
The fixth, being full of water, exhaufted of air, itsmeck broke off, and it became a kind of eolipile, which continued a confiderable time ; and tho’ the fire were very vehement, the phial futfered no change.
Vou. I. N°. 32. Sf Thg
3c4. The History and Memoirs of the
The feventh, being exhaufted of air, had a little coloured fpirit of wine in it, this burf{t almoft as foon as laid on the coals with confiderable noife.
Theeighth, which was full of air, with a little fea-fale in powder therein, melted, and yielded a Jictle hole with fome noife.
The ninth, being full of air, with a little fale- petre, made a fmall hole in a very fhort time, with a little noife.
The tenth, which was full of air, with a little urine, burft ina fhort time, wiih a confiderable noife.
The eleventh, having no air, but a little fale wa- ter in it, burft in a fhort time, with a great noife.
The twelfth, having no air, but a little au- rum fulminans, burit as {con as laid on the coals, with a little noife.
The thirteenth, having no air, but a little ful- phur, melted and funk inwards, without burft- ing, the fulphur alfo melted, and rofe to the top of the neck of the phial.
_ The fourteenth, being full of air, together with alittle Jamp-oil, remained a confiderable time-on the coal, but burft at length with a confiderable noife.
‘The fifteenth, was exhaufted of air, but had a little drop of mercury about a line in diameter therein, this remained 3 minutes on the coals without undergoing any change, and when it had been cooled, was laid on the fire again for 7 or
8 minutes without any effect, the mercury ftill keeping to the top of the neck, only a little ‘flaw was perceived in it. nil
It appears therefore, that all thefe experiments,
-snftead of deftroying the fpring of the air, tend rather to confirm it; but ic likewife appears,
ne that
Royvat ACADEMY of SCIENECS. 355
that neither the fpring nor the dilatation of the ircluded air, are the immediate caufe of the noife and fracture of the glaffes; fince fome of the phials, which were full of air, burft without mak- ing any noife; the reafon whereof may be, that the ftreneth of the air’s fpring, as well as that of other bodies, confifting only in the unbending of its parts, and acting equally every way, and this fucceflively in proportion to theaction of the fubtil matter, in its pores. ‘This power diftributing it- felf thro’ all the parts of the, phial it is contained in, that moft heated coming at length to melt, yields and gives the air paffage, which accord- ly iffyes out much after the manner as out of an eolipile ; for that ic does not dilate fuddenly e- nough to burft the fides of the phial ; but when the air is mixed with other particles of matter fufceptible of a great motion, and a quick and fudden dilatation, it then produces the noife above-mentioned, and {fhatters the veffel to pieces. We donot well conceive the mechanifm, whereby thefe little particles of matter make this havock,~ and it muft be confefied, the fmalleft experiments are often fufficient to perplex a naturalift, who owns no other power, or virtue in bodies, but what arifes from the motion and figure of their parts. ,
Not foreign to this purpofe, are two other ex- periments, which prove the furprizing force of the dilatation of air, which thofe who deal jn fuch experiments, will do well to obferve, for fear of taking harm. An eolipile, being placed on the coals, and the fire raifed to a con- fiderable pitch, it flew from off the trevit againft the foot of atable, a yard off, with force fuffi- cient to batter it, and continued whirling for fome time after,
© {2 The
366 The History and Memoirs of the
The fecond experiment was made in the aca- demy Del Cimento, where a glafs tube was taken about a foot and half long, whofe extremities terminated in two globules of equal capacity ; one whereof was open, as if the tube had been | continued thro’ it, then a quantity of brandy was poured into the tube, fufficient to fill the lower globule and half the tube; after which the aperture of the upper globule was fealed her- metically, the whole being plunged in a veffel full of oil, which was made boiling hot, by continually blowing on the fire, the brandy rofe into the upper globule, and burft the whole with fo much violence, that ufing another time a cop- per vefiel, in lieu of a glafs one, its bottom was broke out; and another time when an iron veffel was made ufe of, near the thicknefs of a crown- piece, it burft in like manner, and carried with it a fplinter broke off from the pavement.
II. Odbfervations of the quantity of water, which fell at the obfervatory during the year 1709, with the ftate of the thermo- meter and barometer, by M. de la Hire *.
The quantity of water which fell, either in rain or. melted {now was in.
Lin. Lin. Jan. 22... 4... July OME 2 Feb. H3ourse) AU, LOv a March 20 9 Sept. 29. 2 April Bee Ses. OCT. LZ, _ May 32 Novem, Li ia June AS tics inldet. IL 3
The fum of the water of the whole year 1709, is261 lines ;, or 21 inches, g lines 5, which is #” Jan. 8, 1710. a
Roya ACADEMY of SCIENCES. 357
a little more than the mean years, which we have determined to be 19 inches.
- We fee by thefe obfervations, that the 3 months of April, May, and Fune have afforded almoft as much water as the other g, and it is what gene- rally happens in June, Fuly, and Auguf; and this is the reafon that the fummer corn, which is fown very late, has yielded a great deal. The great quantity of fnow, which fell during the winter, has perhaps contributed to the fertility of the land ; and if the wheat and rye had not been frozen in the root, this year would have been very plentiful.
The thermometer which I ufe for meafuring the heat and cold, is the fame which I have pre- ferved for about 40 years; but as it has been placed at different expofures to the heavens, ex- cept for the laft 15 years, we cannot make a very exact comparifon of the firft obfervations with the laft. However all thefe obfervations being al- ways made at the day-break when the air is the coldeft, we may conclude by them pretty exaétly all that we can know by the means of this inftru- ment. I fhall only obferve, that the judgment, which we commonly make of the cold, depends upon many particular circumftances, as the wind, the humidity of the air, the heat or cold of the preceding days, the expofure of the place where one is, and the conftitution of bodies, which may confiderably alter it ; therefore it will be always: more fure to refer to the thermometer.
The cold, at the beginning of this year, was exceffive, with a great deal of fnow; for my thermometer fell to 5 parts, the 13th and 14th of Fanuary; and the following days being a little rifen, it returned to 6 parts the 20th, and the 2aftto 5.3, but afterwards the cold diminifhed
gradually.
358 The History and Memoirs of the
gradually. This great cold was very fenfible, for the 4th of this month this thermometer was at 42 parts, which is very near a mean ftate, which 1 have determined to 48 ; the 6th, it came to 30; the 7th, to 22; the 1oth, to 93 and at Jaft, the 13th, to 5. It was without doubt this fudden change which appeared fo extraordinary, and what is {till more furprizing is, that this great cold came without any confiderable wind, or it had only a gentle one towards the fouth, and then when the wind increafed, and turned to- wards the N. the cold leffened.. This cold S. wind muft fhew us what really happened in the countries to the fouth of us, where the fea was frozen in fome parts of the coaft of Provence, and where the greateft part of the fruit-trees, died as well as in this country.
I had never obferved this thermometer to fall folow as this year. I only find in my regifters, that the 6th of February, 1695, the thermometer was fallen to 7 parts in the place where it is at prefent ; and the cold of that year, which had begun in 1694, was looked upon as one of the greateft that had been for a great while, but we fee that it is not at all to compare to that of this year. J have alfo obferved fometimes this ther- mometer at 13 parts, butvery feldom.
The winter of this year lafted a great while ; for the 13th of March it froze again very hard, the thermometer being at 24 parts, and the froft beginning when it is at 32.
We find in Mezeray’s Hilt. of France, that the winter of the year 1608 was very long and very fevere, and that the greateft part of the young trees were frozen: however that year was very plentiful, altho’ they call it the year of the great troft; but by the comparifon of the ap
ant
Roya ACADEMY of SCIENCES. 359
and of the lofs of trees, the laft winter muft have furpaffed it.
The thermometer was at the higheft at 63 parts the 11th of Auguff, half an hour after 4 in the morning, and towards 3 in the afternoon at 75 parts. In the mean ftate, it is at 48 degrees at the bottom of the caves of the obfervatory. The heat of this year has been much lefs than that of 1707, when the thermometer rofe to al- moft 70 parts, Fu/y 21, in the morning, and in the afternoon to 82, which is the higheft it has been in this country, without being expofed to the fun. ‘
To compare the obfervations of my thermo- meter with thofe that fhould be made with M. Amontons’s, of which he has had a great many dittributed in feveral places, I have placed one, which he has made with a great deal of care, next to that which I commonly ule; bur as ic had ferved for fomie particular obfervations, I had not put it clofe to mine till laft May, We know that all M. dmontons’s thermometers have their 54th degree, or 54 inches, which marks the temperature of the air of the caves of the obferva- tory, as in mine the 48th does. { obferved thea, that when M. Amontens’s thermometer was at 55 inches, 8 lines, minz was at 63 parts ;.fo that 15 parts of mine anfwer to 20 lines of M Amon- tons’s. But when mine marked 28 parts laft De- cember, M. Amontons’s marked 51 inches, 6 lin. which gives in mine 20 parts below the mean ftate, and in that. of M. Amontens’s 30 parts, which is a very different proportion from the firft, and might be cauied by the inequality of the in- fide of the tubes; and as that of M. Amontons’s is very {mall, and mine middling, I fhould be- lieve that the inequality might be greater in
360 The History and Memorrs of the
M. Amontons, than in mine. However, we may know by this, that we can have nothing very exact in the comparifon of thermometers in different countries, and for the fame time, unlefs the thermometers have been rectified by one ano- ther in all forts of degrees of heat and cold, and I believe it will not be poffible to find two equal ; that is, of which equal degrees in the divifions anfwer to equal degrees of heat or cold.
As for my barometer, it is always placed at the top of the great hall of the obfervatory ; I found it at the higheft at 28 inches, 3 lines 2 Fan. 19, with acalm and ferene sky, which was about the time of the greateft cold; and the 31ft of December, it was at 28 inches, 3 lines 4, witha very thick fog and calm. It was alfo feveral times beyond 28 inches, with different winds, partaking rather of the N. than of the S. and always without rain. I[ obferved this barometer at the loweft at 26 inches, 7 lines 4, witha ftrong fouth wind, and moderate rain, Dec. 16. The difference between the greateft and leaft heights of the barometer, was therefore 1 inch, 8 lines, which is a little more than the mean difference that is obferved here, and is 1 inch, 6 lines. This inftrument was pretty exact in foretelling rain and fair weather, according to the common no- tion.
I obferved the declination of the loadftone with the fame needle of 8 inches Jong, and in the fame place where I ufed, and as I have fhewed in the memoirs of the preceding years. The 2ath of Dec. laft, I found this declination 10° 30! toward the W. from whence we know that this declination irtcreafes almoft the fame quantity each year.
Ii.
Rovat AcabDEmy of Sc1ENcEs. 361
III. 4 comparifon of the obfervations which qwe made here at the obfervatory on the rain and winds, with thofe which M. \e Mar- quis de Pontbriand made at bis cafile near S. Malo, during the year 1709, by M. de la Hire *.
It is for fome years, that M. dz Torar has communicated to us the obfervations, that M. le Marquis de Pontbriand makes at his caftle, in the fame manner that I make them here, upon the rain. He found, that there fell in melted {now and water in the month of
Lines. Lines.
_ Jan. 33 4 July 18 4
Feb. 17.2. Aug. 5% March 20. «...seps. 5 April | 30 + Odéctob. 14
May 26.4% Nov. Dr
June 23 4 Decem. a
and during the whole year 225 lines, or 18 in- ches, g lines. .
This quantity of water is lefs than what we found here, which was 21 inches, g lines, and this is extraordinary ; for we had obferved the preceding years that it rained much lefs here than in that country, which is upon the border of the fea.
We fee by the memoirs of M. de Pontbriand, that the hard froft began fome days fooner in that place than at Paris ; but it {nowed here at the fame time with a N. W. wind, There was
* March t, 1710.
wet, La NY. 323. Fe but
362 The History and Memoirs of the
but little wind at Paris, and that was towards the fouth.
The month of Fan. gave there 33 lines { of water, and at Paris only 22 lines!. The me- moir fays, that the hard froft diminifhed at the end of Fan, and began again in Fed, and that the night between the 23d and 24th, it was as hard as from the 6th to the 18th of Fam. At Paris, it began again alfo in Fed. pretty near the fame time ; but it was much lefs than in Faz.
He adds alfo that the winds were very violent at N. W. but at Paris they were only very gentle, and toward the S.
He fays, in fine, that the cold has not been fo great with him, as in the middle of Bretagne ; which muft appear to have been fo, becaule of the proximity of the fea, the humid vapours of which abforb a part of the great colds, as ,we learn from all the experiments ; for during the hard froft, the air is extremely dry, and as foon as it becomes damp, it thaws.
I fhall alfo here obferve that I faw, in 1679, in the king’s garden at Breft, fome very fine ana- nas, or pine-apples in the open ground, and I believe they had paffed the winter there; per- haps the maritime foil contributed to it, for I do not believe they can be raifed in this country.
In June they had at Pontbriand only 23 lines + of water, and at Paris 45 lines $ : alfo at Pa- ris the 25th and 26th, it rained g lines, and at Pontbriand only 2 4
In Auguft we had a ftorm in the night between the 11th and 12th, with 7 lines + of water, and they had none at Pontbriand.
In September we had again a ftorm here the night between the 13th and 14, which gave g Jines of water, and none at Pontbriand ; befides
there
Royat ACADEMY of ScIENCES, 363
there fell only 5 lines of water during this whole month at Pontbriand, and above 29 lines at Paris.
In Nov. the quantity of water at Pontoriand was 3 lines 4, and at Paris a little lefs than x line =.
In Dec. we had here during the night of the 15th and 16th a fort of hurricane.
In general, all the winds of the year are a little different at Pontbriand and at Paris, and pretty often they tend more to the N. at Poxtbriand than at Paris; which may be occafioned by the di- re€tion of the Englifh channel, and by all the coafts of Germany, Denmark and Norway, and chiefly when the wind comes between the N. and W.
IV. A comparifin of my obfervations with thofe of M. Scheuchzer, on the rain and and conftitution of the air, during the year 1709, at Zurick, zz Switzerland, dy M. de la Hire *.
9M. Scheuchzer has fent me the obfervations that he has made upon the quancity of water which fell at Zurick, where he ftayed during the year 17093 by which we fee that the firft fix months have given him 172 lines + of water, Pa- ris meafure, and the laft 208 lines, which make in all 3904 lines, or 32 inches, 6 lines $3 but at Paris, there fell only: 21 inches, 9 lines : he adds, that this year has furnifhed 1 inch, 10 = Jines more than the preceding.
By the comparifon of thefe obfervations we
® May 24, 1710. T te know,
364. The History and Memotrs of the
know, that it rains much more in Switzerland thanat Paris. )
I had already remarked by the obfervations of the rain made at Lyons, that it rained there much more than at Paris, which I attributed to the mountains of Switzerland, which are not very diftant from it; and which is confirmed by thefe laft obfervations. For it is not to be doubted but that the vapours, which are fupported in the air ina flat country, and are much lower than the high mountains, when they come to meet, ftop, and condenfe there in a cold feafon into {now, which muft produce much more water, being driven by the winds againft the rocks, than in the places where they do not ftop at all; and if the air is hot enough to hinder thefe vapours from freezing, they gather together and fall in rain, befides the fnow which then melts, and of which one part rifes alfo in vapour, caufes there very great rains,
As for M. Scheuchzer’s obfervations upon the increafes and diminutions of the river Limage, they naturally follow thofe of the rains and melt- ings of the {now in the feafon when that happens.
“He alfo adds his obfervations upon the baro- meter and thermometer, where he fhews that the greateft height of the quickfilver of the barome- ter was 26 inches, 10 lines 4, the 19th of Fan. and the loweft 26 inches the 20th and 28th of Feb, and confequently the difference was only 10 lines 4, asin the year 1708.
The moft remarkable thing is, that my baro- meter was alfo at the higheft the toth of Fan. at 28 inches, 3 lines £, with a calm, which is the fame day that it was at the higheft at Zurick, and that the difference is 17 lines; and if we would conclude from hence the different heights
of
Rovat AcADEmy of Screnegs. 365
of the places where thefe obfervations have been made, in fuppofing for one line of this difference r2 toifes, 3 feet, as I have determined in thefa
uarters, we fhould fay, that the place where M. Eivoridie obferved, is higher than the middle of the obfervatory where my barometer is, by 212 toifes+. But the different heights at which we fee the fame quickfilver keep in different tubes, altho’ in the fame place, may leave us fome fuf- picion of the true differehce of the heights of thefe places.
As to the leaft heights of M. Scheuchkzer’s ba= rometer, which was at 26 inches the 2oth and 28th of Fed. it does not altogether agree with mine inthe fame days; for fed. the 28th, I had 27 inches, 2 lines, with a moderate wind, and confequently the difference of our barometers will be that day 14 lines iriftead of 15,which I found in the greateft height: perhaps our obfervations were not made in the fame hour, and the wind might alfo occafion fome alteration ; M. Scheuch- zer does not mark thefe circumftances. But Fed. 20, mine was at 26 inches, 10 lines, witha high wind at fun-rifing ; thus the difference would be only 10 lines, inftead of 14 or 15 by the other obfervations, and mine would be lower than it ought by 4 or 5 lines. Nor was my barometer at the loweft on thofe days, for I obferved it Dec. 16, at 26 inches, 7 lines 4, with a high fouth wind ; thus the quickfilver of the barome- ter has much greater alterations at Paris, than at Zurick in Switzerland.
I think we might attribute thefe forts of inequa- lities, to particular caufes ; for it is not probable that they can come from the different heights of the atmofphere, which make the weight of it, in places not very diftant from one another. May
we
366 The History and Memorrs of the
we not believe, that when there is a high wind and
many clouds, and chiefly in the mountains, as in Switzerland,the wind fhouldcomprefs and condenfe the air inclofed between the furface of the earth, the rocks and the clouds ; fo that it will then make a much ftronger impreffion upon the guickfilver of the barometer, than if there had not been any wind? But as in thefe forts of places, where there is a great deal of water, it is feldom that they have neither winds nor clouds, fo the quick- filver of the barometer will for thefe reafons fup- port itfelf there almoft always higher than in the plains.
I can fay nothing to M. Scheuchzer’s obferva- tions of the thermometer, altho’ I have one of M. Amonions’s \ike his, which ts a thick glafs phial with a little quickfilver, which rifes into a little tube open at the top, as he had conftructed them to make the experiment of boiling water, but I never make ufe of it, becaufe it is fubjeét to the different changes of the weight of the air.
v. Of the neceffity of centring well the object glafs of a telefcope, by M. Caflini the fon*.
For the obferving the apparent diftances of the ftars, they formerly made ufe of circles, femi-ciicles, or quadrants, divided into degrees and minutes, and furnifhed with four fights, of which two were fixed and placed, one at the be- ginning of the divifion, and the other diametri- cally oppofite. ‘The other two were born upon a rule moveable about the centre of the inftrument, by the moderns called alhidade.
Since the invention of telefcopes, they have fubftituted to the fights two telefcopes, one of
* March 26, 1710. ; i which
Royal ACADEMY of ScIENCES, 367
which is fixed upon a line parallel to the radius, which paffes through the beginning of the divi- fion, the other is placed upon a rule which turns about the centre. They place at the focus of the object-glaffes of thefe telefcopes, two threads which crofs one another in the axis at right an- gles, one of which is parallel to the plane of the inftrument, and the other is perpendicular to it. They put the eye-glafs into a tube, which finks into that of the telefcope, fo that the threads which crofs one another are at its focus, that their interfection may be well diftinguifhed.
Thefe telefcopes thus difpofed have a great ad- vantage over fights, becaufe we diftinguifh by their means the terreftrial and celeftial objects, with much more perfpicuity, and obferve more exactly their diftance between themfelves, by placing them exactly in the interfection of the threads which crofs one another at their focus at right angles; but it is neceffary, that the object-glaffes be well centred, that is to fay, that they be every where of equal thicknefs at their circumference. For let, 1, 2, 3,4 *, be the tube of a telefcope, which has at one end of its extremities an object- glafs A, B, C, D well centred, fo that the centre E of this glafs be exactly in the axis S, E, I, O, of the telefcope ; let there be at the other extre- mity an eye-glafs G H, of which let the centre I be alfo in the axis of the telefcope. Let S bea very diftant objeét, out of which proceed the rays S.B, SD fuppofed to be parallel, which falling upon the furface of the glafs BD, are refracted and reunited in the axis in L, which is the inter- fection of the two threads of flk MN, PR, which cut one another at right angles, and of which MN is vertical, and P R horizontal. We
* Plate VI. Fig. 1. fuppofe
368 The History and Memoirs of the
fuppofe the point L to be placed to the focus of the lens GH, in fuch a manner, that the rays GL, HL, which proceed from this point, and fall upon the furface of the lens GH, are re- united in O. The eye being at O will fee the object S in L in the axis of the telefcope, and confequently in its true fituation.
If we move the object-glafs A BC Dtoabecd, fo that the centre of the glafs be, for example, in F; then the rays, that proceed from the object S, will be reunited at the point T, to the extre- mity of the axis SFT, which paffes through the centre of the glafs F, and the rays which proceed from the point T, and fall upon the eye- glafs GH, will be reunited atthe point V, where the eye being placed, will fee the objeét S in T, in a very different fituation from that where it appeared, when the object-glafs was at the centre of the telefcope.
If we now fuppofe, that we would obferve the diftance between two ftars with two telefcopes, one of which has its object-glafs well centred, and the other not; if we incline the inftrument to obferve the apparent diftance of the two ftars, the well-centred telefcope turning by this motion about its axis, the centre E of the object-glafs refts in the axis of the telefcope, and its focus falls upon the point L the interfeétion of the threads ; but the centre F of the object-glais not well cen- tred, will, by this motion defcribe a little circle about the avis E L of the telefcope, and the point T, where the rays are then reunited will defcribe alfo a like circle about the centre L ; fo that the apparent diftance between thefe two ftars obferved with two telefcopes, one of which has its object- glafs well centred, and the other not, will not be their true diftance, and will be fubject to irregu-
larities,
Royat AcaDEMY of SCIENCES, 369
larities, which cannot be remnedied, but by cen- ring the two object-glaffs exactly, or directing them one upon the other to the fame object, which comes to the fame thing.
VI. Obfervations on the bezoar, and on other Jubfiances which come near to tt, by M. Geoffroy, junior.
The dezoar is thought by fome to derive its name from the Perfian word pazar or pazan, which fignifies a goai: and according to fome others, it comes from the Hebrew or Chaldean word beluzaar, which fignifies counterpoifon.
The firft ftones, Known under the name of Je- zoar, were brought from the eaft. After the difcovery of America, there came fome, which bearing fome refemblance to the former, both in ftructure and virtue,-had the fame name alfo, with this difference, that the firft are called orien- tal, and the others occidental bezoars. ‘There are other ftony fubftances alfo taken from animals and difpofed in ftrata, which have been called bezoar, with the addition of the name of the ani- mal, as bezoar of the ape, and bezoar of the cayman. Some taking the word bezoar in the fignification of counterpoifon, have applied it in- differently to all fubftances endued with that vir- tue; hence it has been given to chymical compo- fitions, as mineral and jovial bezoar. Others have called the powder of the heart and liver of vipers, animal bezoar. The name of bezcar or bezoartic, has alfo been given to fome artificial powders or ftones, in which bezoar is an ingre- dient. Such are the different bezoartic powders, the countefs of Kens powder, the ftones formed of this powder, and the Goa ftone,
Vor. Ill. N°. 33. Uu As
370 The History and Memoirs of the
_ As the bezoar has been obferved to be difpofed in ftrata, the name has been given to a fort of fi- gured ftone, found in America in feveral places, to which alfo the fame virtues are afcribed. There are bezoars found alfo in Italy, Sicily, feveral parts of France, and efpecially in Languedoc.
Thefe are the different fubftances in general, which we know under the name of dezoar. But » properly fpeaking, the bezoar is a ftony fubftance taken from fome animal, compofed of feveral firata, or coats like onions, and endowed with fome power of refifting poifon. The two prin- cipal fpecies of it are, as we have faid, the orien- taland occidental. It is:not eafy to diftinguifh what animals they are that produce them; be- caufe what agrees with only one of them, may have been afcribed to both. We know in general, that this ftone is found in the ftomach of a fort of wild goat which browzes upon aromatic plants. If we may believe Tavernier, there are feveral found in the fame animal, as may be known by feeling. ‘Thefe ftones are of different fhapes and fizes: fome are fhaped like a kidney ; others are round, or oblong, or of an irregular figure. Each {tone is compoted of fevera] plates, and formed of a greenifh or olive-coloured fubftance, fpeckled with white. Thefe plates adhere to each other in fuch a manner, as to fhew upon breaking feveral firata of fubftances of a different thicknefs, and fometimes of a different colour. In breaking thefe ftones, fome plates part with great evennefs from the reft. The fame thing happens upon rubbing them pretty brifkly. The middle or centre of the ftone is commonly a hard, gravelly, {mooth fubftance. The bezoartic /frata, which cover this mafs, are eafily crufhed by the teeth;
and
Roya AcapeEmy of SCIENCES. 371
and ftick to them as if they were fomething glu- tinous, and tinge the fpittle.
They kindle eafily in the fire, and feem to con- tain fome volatile falt and oil. The matter which remains is like the caput mortuum \eft in the re- tort after the diftiilation of animal fubftances. Thefe ftones are very {mooth on the ourfide, but fometimes a little rugged, and like fhagreen in fome of their circumvoiutions, They are pretty tender, and give a yellow, greenifh, or olive- coloured tinge to paper rubbed with chalk, cerufe, or lime, on being drawn pretty hard over them, becaufe they wear away, and leave fome of their parts upon thofe materials. I have fteeped 2 of thefe ftones cold ; 1 in water, and the other in fpirits of wine, for 12 hours, without finding any alteration in them. J have left the fame ftone in water for feveral days, and there came only a little matter from it, which juft troubled the water, and yet the water or fpirit of wine had penetrated both of them.
In the great number of bezoar ftones which I have opened, I have found that many, as fome authors relate, had chaff, hair, marcafites, ftones, or gravelly fubftances united together, and as hard asa ftone in the middle. I have alfo found talc, wood, kernels almoft like cherry ftones, alfo myrobalan ftones, quarters of other fruit-ftones, kernels of caffia, and kidney-beans inclofed in a coat, or outer membrane, hardened by the mat- ter which has ‘ormed the bezoar, and having their own membrane drawn back, and dried, after having been fwoln. In others, the firft coat of the kidney-bean was confumed; and the ftones founded like eagle-{tones. I have attempted to prick fome of thefe ftones with a red-hot needle to fee whethey were counterfeit, but it did
U2 not
372 Thelistory and Memoirs of the
not enter, and only imbrowned the place where it was applied; which authors propofe as one of the principal marks by which the good bezoar may be known, imagining that thofe are to be rejected, in which kidney-beans are found, which they look upon as a proof that they have been falfified by the people of the country.
They advife us to choofe the bezoar in ftones of a middling bignefs, of a brown colour, turn- ing, quick lime yellow, and chalk green, not diffolving in water, and not rifing in bubbles about the part pierced with a red-hot iron, for that would fhew it to be mixed with fome refins. The plates alfo muft be fine, difpofed in frrata, and the ftones muft be taken from animals which Jive upon the mountains, fuch as thofe of Perjia. After all it feems pretty difficult to me, to coun- terfeit the bezoar ; and with a little practice we may eafily difcover the cheat; if there is any. For if it was counterfeited with plafter, or any - fuch like matter, it wou!d not change either with the fire or water, it might colour the quick-lime with any tinéture that was given it; and, in a word, undergo all the proofs, though it was counterfeit.
Nor is it to be imagined, that in order to counterfeit them, they pick out all thefe different fubftances which ferve as a bafe to the firata, of which they are compofed, fince they need only begin a little ball of the fame pafte, which pro- bably is not fo rare, that they have occafion to be faving of it.
I think the fubftances inclofed in the bezoar ferve perfectly well to inform us of the manner in which it is produced, as is obferved by Tavernier who tells us, thefe {tones are formed about little
-
buds, or tops of the branches of a plant: tele
Royal AcApDEMY of SCIENCES. 373
buds of Zavernier may be the kidney-beans fpoken of by Monard, which 1 have obferved. Thefe folid and undigefted bodies remaining in the fto- mach of the animal, may irritate its glands, of which the lymph thickened with the leaven of the ftomach, ftill loaded with the juice of the aroma- tic plants on which it has juft brouzed, may have been able to form the /rata, fo fmooth and ex- actly united, that art would find a difficulty in imitating it. I obferve alfo, that whatfoever body makes the centre of this ftone, the frata of it are fo fine, and fo well turned, that the ftone out- wardly takes the figure of the fubftance contained within,
If, for example, there is a ftraw, the ftone will be long; if it is a ftone, it will preferve the figure of it; if it is a kidney-bean, the radicle will appear on the outfide; and a line which fe- parates very diftinétly the 2 lobes of the bean; in fhort, we may know by the fhape and weight of them, what they contain. ‘Thus, as in the choice of fo precious a fubflance as the bezoar, we have not the liberty of opening all, after having been well affured of a certain number of the. moft doubtful, upon which we fhall have made the preceding experiments, we mutt refer to the fight and feeling. By the fight we examine the colour immediately, which muft neither be too pale, nor too deep ; in the fecond place, the finenefs of the grain, the {moothnefs, and the clofenefs of its texture, which keeps the plates from rifing eafily above one another. It muft alio be obferved, that they have a regular fhape, as of a kidney, a bird’s egg, or fomething like thefe. The touch may alio judge of the matter inclofed within the bezoar, which we may eafily determine by the weight of it. If, for example,
| the
374. The History and Memorrs of the
the bezoar is heavy, the bafis will be a ftone, or fome other matter, which fills up the greateft part of it; but if it is light, it will be hollow within, or contain only fome light matter, as hair, or fome of the vegetable fubftances already mentioned. The ftones which rattle, fhew there is a fruit within, which being dried, takes up lefs room; and fometimes it is rotted or broken into a duft, which fome authors greatly efteem.
I have alfo obferved, that when bezoars are. fhaped like kidneys, are light and rattle, they have ufually a kidney-bean in the middle. Thofe which are light, round, and a little flatred, con- tain a round flat fruit, almoft of the thape of a caffia ftone. Moreover, though thefe ftones fhould inclofe a ligneous kernel, or even bits of wood, the lightnels thould make them preferable to thofe which contain ftones, which alio will be a great deal heavier, provided the bezoartic mat- ter anfwers the other proofs.
The whole preparation of bezoar for common > ufe in medicine is, to reduce it to a fine powder, either to give it in fubftance, or to make it enter into fome compofitions, obferving to powder only the bezoartic part, and to fepirate all the foreign matters which may be found in the heart of the bezoar, efpecially when they are ftones or other fubftances, which have no bezoartic virtue.
There is a great diverfity of opinions about the animal which yields the bezoar. It appears, that the oriental, which is brought to us from Egypt, Perfia, India, and China, 1s produced by a fort of goat, called by the Per,ians, Pazan, or by a He goat of a larger fize thaa ordinary, as nimble as a ftag, wich its horns reverfed on its back, whence Clufius calis 10 Capricerva.
That
Roya Acapemy of ScIENCEs. 375
That which is brought from America, is pro- duced by a fort of goat, alieh 1 is not at all, or but very little different from the other, except in its horns.
The different opinion of authors concerning the names and figure of this animal make me believe, that thefe ftones may be found in feveral fpecies of animals, and that each has defcribed what he has feen. The fame reafon may ferve to prove the caufe of the different colours of the bezoar.
The occidental bezoar is eafily diftingufhed by its being paler. It is fometimes of a hehe grey, ingendered upon foreign fubftances, like the ori- ental bezoar. The plates are fometimes thicker and ftriped in their thicknefs,
The foffi] bezoars are a fort of ftones formed in ftrata, having the figure of the animal bezoar. They are ufually of a light grey, their rata are very thin, they have no {mell, and are ufed in the fame difeafes with the other bezoars. America, as I have already faid, furnifhes us with a great many of thefe bezoars, as well as Jta/y, and fe- veral parts of France.
Thofe who have treated of the bezoar, as Ca/- par Baubinus have comprehended under this name, a great many fubftances that have no re- lation to it, which can only caufe confufion in na- tural hiftory. If therefore we would range in a convenient order, all that can partake of he the name of bezoar, I believe it would be proper - to make 5 clafles of them.
The firft would contain the true bezoars, which are the oriental and occidental.
In the fecond we might place-all the ftones taken from animals, which refemble the bezoar in their ftructure and vertue, as the bezoar. of the ape, that of the Cayman, alfo the different forts of pearls, and the crab’s eyes, In
376 The History and Memorrs of the
In the third, the different forts of foffil' be- zoars. In the fourth, fubftances figured like the be- zoar without its virtues, as the human ftone, either of the bladder, kidneys, or gall-bladder, with thofe which are found in the gall-bladder of oxen,
and other animals.
In the fifth, the egagropile, which are a fort of balls of different figures, pretty light, formed of a mafs of hairs and fibres of plants, which the animals could not digeft. Thefe fibres and hairs are fo interwoven as to form but one body, which refembles a ball of felt. There are fome which are covered again with a thin bezoartic cruft. They commonly grow in the firft ftomach of alf ruminating animals, or in the ftomach of thofe which do not ruminate. ‘Such are the ftone of the wild porcupine, and the other balls of hair found in goats, cows, oxen, and other animals.
VIL. Ax infect upon fnails, by M. de Reau- _mur; * ¢ranflated by Mr. Chambers.
All the animals hitherto obferved which live upon other animals, may be reduced to two kinds; for either they live on the external furface of the body of the animal, as the lice found on quadrupeds, birds, and even feveral infects, as flies, beetles, hornets, &c. or they live in the body of the ‘animal, under which kind may be ranged the feveral forts of worms which have been difcovered by diffection in the bodies of feveral animals.
The new infects I have obferved on {nails does not come under either of thefe kinds, but has fomething in common to both; for it fometimes
* July 9, BF TO, % in-
Rovan AcaDEMY of SCIENCES, 377 inhabits the external furface of the body of the fnail, and fometimes hides itfelf in the vi/cera thereof.
By the collar of a {nail is meant, that part which encompaffes its neck. This collar is of a confiderable thicknefs; and ’tis little other than the thicknefs of this collar we perceive when the {nail fhrinks into its fhell, fo as neither to let its head nor bafis be feen; of which you may con- ceive an idea by jig. 2, the triangular {pace B fi- tuate in the middle of the aperture of the fhell is a remainder of the bafis of the animal; which is furrounded on al] fides by the thicknefs of the col- lar ; and ’tis on this part of the collar, chat the in- fects we areto fpeak off are found, they are reprefented in the fame figure by the letters €CCC, Ge. or rather by the dotted lines which proceeding from thofe letters, terminate in thefe animalcules 5 they are never eafier to obferve, than when the fnail is thus totally inclofed in its fhell, tho’ they may be perceived in feveral other cir- cumftances. The bare eye without any affiftance of the microfcope, fuffices to difcover them; but they are rarely feen at reft, being in a continual hurry, running about with great agility, which is fomewhat fingular; the motion of fuch kinds of infects being ufually very flow.
Notwithftanding the fmallnefs of thefe animal- cules, there is not room for them to go upon the upper furfaces of the body of the fnail, the fhelt- being too exactly fitted thereon 3 but there is terri- tory enough befides to travel in; the fnail giving them entratice, as oft as it opens its azus. This anus is likewife placed in the thicknefs of the col- lar, in the place marked by A; it is here repre: fented fhut ; but the animal rarely comes out of its thell without opening it 5. befides, that it opens
Vor. UI. N°. 32. XX it
378 The History and Memorrs of the
it on feveral other occafions, it may be feen open in jig. 3. where it isalfo denoted by the letter A.
It feems as if the little infeéts waited with im- patience for the favourable minute, when en- trance fhould be given them into the ample theatre of the inteftines of the fnail, at leaft they never mifs the opportunity of prefenting themfelves when occafion offers ; gathering to the edge of the hole, they immediately flip into the fame, running along the parzetes thereot, fo that a few minutes after, not one infect is Jeft on the cellar. The letter D in jig. 3. fhews fome of thefe animalcules preparing to enter into the inteftines by the anus.
The eagernefs wherewith they endeavour to get in, feems an indication that this is their moft commodious place of refidence, how then fhould they come on the collar? ‘is poffible they never do it but againft their inclination, of which the continual hurry they are under feems a proof. In effect the {nail obliges them to go lodge there, as often as it voids its excrements ; for thofe excre- ments poffeffing almoft the whole width of the inteftine, muft neceffarily drive before them every thing they meet in their way. ‘The little infects therefore upon their arrival at the edge of the anus, are forced to go upon: the collar, and in regard this operation of the fnail continues fome time they walk about al] this while on the col- lar, as having it not in their power to re-enter when they pleafe, in regard the jnail has fre- quently fhut the door, while they were frifking on the outfide. |
What has been hitherto faid, may be obferved of all the fpecies of {nails, tho’ moft frequently: of the large garden {nails reprefented in fig. 2 and 3. But there are fome forts wherein this infect may be difeovered, even in the middle of the. inted-
tines 5
Rovat ACADEMY of SCIENCES. 379 tines ; as in the little {pecies of {nails reprefented by fig. 4 and 5. The Charatteriftick of this fpecies is a kind of lid denoted by O, confitting of a matter equally folid with that of the fhell, and by means whereof the animal can inclofe it- felf all around when it pleafes, as fea inails do, whereas the collar of the common Jand-fnails is bare, unlefs in winter and fome dry feafons, when they ftop the aperture of their fhell with a kind of foam which comes to a confiftence as it dries ; but this occafional lid never adheres to the body of the animal, Jike that above mentioned ; nor is it comparable thereto in folidity, Breaking the fhell of one of thefe little fnails about the place E jig. 4. and thus laying the fkin of the animal bare as in. fig. 5. the infect will be frequently dif- covered in the very body of the fnail, by reafon this coat or fkin is tran{parent, and lets us fee thro’ it, as thro’ aglafs ; the letter C reprefents two. in- feéts, as viewed thro’ the fkins of the fnail.
+ Tho’ we find thefe infects on all the fpecies. of fnails, yet not at all times indifferently, and very. rarely in rainy feafons. Not to give our felves ufe- lefS trouble, we are only to‘look for them after a drought, which perhaps may be proper to hatch. them, or even to prevent the deftruction of thofe already formed. When the earth is very moift, the body of the fnail is faturated with water, which afterwards oozing much more vifcid thro’ the col- Jar and bife of the fnail, forms feveral drops thereon, the {malleft of which drops fuffices. to deftroy feveral of thefe infects ; not that they are afraid of being drowned therein, as ina kind of little fea, this liquor is ta them a folid body, and each drop may be to them, what the fall of a building isto us. I mean it may overwhelm and, crufh, them by its weight, whenever by the motion > oF
380 Fke History aid Memorns¢ the of the fhail, one of th2fe drops happén to be tum- bled from oné place to another.
Be this as it will, *tis certain that dfynefs pro- motes their formation, as appears from the ‘fol= lowing fact, which I have repeated feveral times 5 gathering fails in moift weather, and after a careful examination finding no infeéts in them, I put them in veffels where the lof the watry hu- mour, continually evaporating from them, could not be repaired, and viewing the fame {nails fome- time after, I never failed to find feveral infects thereon, havire fometimes to!d twenty on the fame animal. Th 5 OF 6 day ; }have fometitmes found 4 few, but in 3 weeks never failed of a large quantity.
The body alone of the fnail is a foil proper for: thefe infects, which are never feén on the fhell 5 or if they be compelled thither are not long ’eré they recover the collar, from whence they were driven.
- To the bare eye they ufually appear of a dery white colour, though fome of them feem a little brownifh, and others lightly tirged with red.
' A good microfeope is neceffary to perceive their feveral parts diftinétly ; by this they appear as in fig. 6 and 7; the former whereof reprefents their upper fide, and the latter their under fide. The letter T in each figure fhews their trunk, which however only appears in part in fig. 6% but the manner in which it bends under may be feén, This trunk in all Jikelihood ferves them to fack the fnail 5 it is placed in the middle between two little horns CC, which are very movable, hike thofe of ether infeéts, both upwards, down- wards, and laterally ; and what is more, are ca- pable of extending and contracting, like the
| horns
Royvat ACADEMY of ScrENCES. 384 horns of ‘fnails; whence the animalcule is. frees quently feen without perceiving its horns, . _..
Its body is divided into 6 axnuli, and the an- terior part to which the trunk and horns. are joyned. Itshas 4 legs on each fide, the 2 foremott whereof are articulated to the anterior part; and the 2 hind ones to the firft ring; the fecond and third are faftened further from each other, than the frft and fecond; or the third and fourth: thefe legs are befet with large hairs, and feem to terminate ih three or four points, much like the legs of fevetal kinds of beetles, when the iaft.arti- culation is removed, which terminates in two little hooks. Their back is round,.and raifed with regard to their fides, which are likewife rounded, and have 3 or 4 large hairs upon them ; their auus is likewife furrounded with 4 or 5 hairs of an e- qual length ; but there are none on its belly.
VII. Reflections on the obfervations of the frux and reflux of the fea made at Dunkirk, by M. Baert, profeffor of bydrography, during the years 1701, and 17025 by sd Caflini, jun. * HARES by M. Chamn- _bers,
OSfervations of the ebbing and flowing of the fea, being of great importance for the fecurity of navigation, and for the choice of times molt fuitable for coming in, or going out of ports, and it being withal of great “confequence to the fei- ences, to Jearn whether they have any connection with the motions of the moon; and whether the Variations to which they are fubjcct, are reduci-
le to any rules, a circular memoir was drawn up
* jJulyi12, 171°.
by
382 The History and Memoirs of the by the academy, and at their requeft, fent by
the count de Pontchartrane, into feveral ports of France, with orders‘to make exact journals of fach obfervations.
Among others, M. Baert, profeffor of hydro-
graphy at Daakirk, was intrufted with this care, of which he acquitted -himfelf with all the applica: tion and accuracy that could be defired. He chofe a place for his obfervations im the inclo- fure of the admiralty, where the fea has no other confiderable motion, ‘but that of the fluxsand re- flux ; here he butlt a lodge both for fhelter from the weather, and to prevent being’ difturbed in his “obfervations:. this done, he fixed a iquare tube * E FGH, perpendicular to the furface of the fea, being compofed'of 4 boards open: at bot- tom in GH, that the water might enter-freely in, and rife to a‘level with the fea, and:clofed a-top in EF, by a lid EAF, which had a little hole in A, 14 lines in diameter, thro’ which paffed 2 wooden ruler T K, on the lower extremity whereof was a little {quare board LM, fomewhat blunted at the corners to prevent friction; under which board was faftened a piece of cork 4 inches thick, which floating-on the furface of the water, made the wooden ruler TK rife and fall according asthe tide rofe and fell. This-ruler was divided into feet and inches, whereby to eftimate the in- creafe or diminution of the tide. —-——~ We omit in this account feveral circumftances of this ma- chine, which fhews the great accuracy of M: Ba- eri’s obfervations, and are related at large in a letter to father Gouye.
Tt may be neceffary here ta obferve, that all the meafures of the height of the fea were taken with regard to a fixed point, which is on a level with
we yn Ae . wy the
RovaL ACADEMY of SCIENCES. 383 the top of the boards bordering the -key, near the fluice of the bafon, directly on the afcent towards the citadel,: which is a part of the key which the fea never goes beyond ; nor mutt it be omitted, that the dire€tion of the canal at Dunkirk, is north-weft by north, that its length from the mole-heads near the read to the place of obferva- tion is 1435 fathoms, and its breadth 36 fathoms at the mouth, and 16 where narreweft ; notwith- ftanding which, there is no confaderable difference between the ume of high water at the place of ob- fervation, and that againft Risbanc, as was found 5 feveral times, by the fineft days of fummer, by minute watches. For underftanding of what follows, it muft be obferved, that we call it high water when the flood is rofe to its greateft height; and low water when the ebb is fallen to its greateit depth. The greateft tides are thofe when the ficod is the higheft poffible; and the fmallei tides thofe when the flood is the loweft pofble.
The journal of M. Baeri’s obfervations of tire tides, begins on the 24th of March, 1701, and ends on the 31ft of Mey, 1702; it expreffes for every day the height of the water in the time of flood, and fome hours before and after, with re- gard to the fixed point abovementioned, in- creafing in number downwards, in order to. find the proportion between all the heights of tides which he had occafion to obferve. To find the pre- cife time he had drawn a meridian line with great exactnefs, whereby to regulate his clock trom time to time; thus obferving the hour and mi- nute wherein the water was at the fame height, both in rifing and falling, he took the middie between the two obfervations which were neareit the high water, the one before, and the other after it, for the precife time of high water, which te
found
384 The History and Memorrs of the found more convenient than to make ufe of ré= moter diftances, having obferved in many expe- riments, that the fea falls fomewhat. more flowly than it rifes. He alfo obferved the winds, and the temperature of the air on each day of obfer- vation.
As to the irregularity of the progreffion ob- ferved both in the rifing and falling of the tide; M. Baert dares not determine, whether the winds be the caufe, or whether we are to fuppofe that the fea is moved by waves far diftant from each other ; and by others which follow clofe together. As to that balancing upwards and down- wards, obferved at each high-water, he takes the caufe to be natural ; for as the fea in approaching the coafts meets with an obftacle, it may rife a little above its level, which will oblige it to return again; and thus makea flow fort of vibrations near the place where the obftacle is, which will {carce be perceivable elfewhere, by reafon of the winds.
To be able to compare the obfervations of high water, and fee whether their irregularity be redu- cible to any rule more certain than has yet been done, M. Baert has drawn a table wherein is ex- preffed for every day from the 24th of March; 1701, to the laft of May 1702, the moon’s place at noon in longitude and latitude in two feparate columns; her age at the time of high water in a third column ; the precife time of high water in a fourth ; the height of water below the fixed point in the fifth ; the moon’s paflage over the meridianj in the fixth, and in the feventh, and eighth, the direction and ftrength of the wind and ftate of the - Weather.
. The firft thing that occurs upon confidering the times of high water at Dunkirk is, that on the
days
Rovat Acapemy of Sciences, 395
days of full moon the flood happens about noon, though not fo exactly, but that we fometimes find a difference of a whole hour, as may be obferved in the 15 fucceflive obfervations made thereof ; the high water which came the earlieft, was on the 19th of Fuly, at 24 minutes paft 11 in the morn- ing ; and the lateft on the 17th of September, at 24 minutes paft 12 in the afternoon, which gives a variation of an hour inthe times of the tides on the days of full moon 5, which variation being di- vided into 2, gives the meantime of high water at Dunkirk, about 6 minutes before noon,
To fix fome rule in this variation of the time of the tides, on the days of full moon it muft be obferved, that the retardations of the tide from one day to another, bears fome analogy to the motion of the moon, whofe paflage over the me- ridian is retarded about 49 minutes daily, On this footing, when the times of full moon concurs with the time of high watér, there muft neither be an- ticipation, nor retardation, in the time of high water ; but when the full moon happens in the morning before high water, the moon’s paflage over a horary circle, is retarded two minutes in an hour, with regard to the fun; and confequently there muft be an equal retardation in the time of high water ; whereas, when the full moon hap- pens after high water, the moon being not yet at its full, when the water is at its height, there muft be an acceleration in the time of high water obferved. |
Suppofing this acceleration, or retardation of 2 minutes in an hour, we have a rule for deter- mining the variation of the tides on the days of full moon.——-For an inftance, on the roth of Fuly, 1701, the high water was found at 24
Wom. N°.33.. Yy mi-
386 The History and Memorrs of thé
minutes paft 11 in the morning, which is the greateft acceleration obferved by M. Baert; and full moon for that day is marked in the alma- nack at 50 minutes paft 13 in the evening; hence the high water muft have gained about 24 minutes, which being fubftracted from 11 hours, 54min, the mean time of the tides at Dunkirk, gives 11 hours, 30 minutes for the time of high water, within 6 minutes of that found by obferva- tion, — Again, on the 17th of Sept. 1701, the day on which the greateft retardation of the tides was found, high water happened at 24 min. paft 12, and full moon at 56 min. paft 5 in the morning, confequently high water, by the rule above affigned, mutt have been retarded 12 min. which added to 11 hours, 54 min. give 12 hours, 6 min. for the time of high water, within 18 min. of that found by obfervaticn.
It muft be obferved, that whereas in the ob- fervation of the 19th of Fu/y, the wind was north- _ north-eaft ; on the 17th of September, it was fouth and very frefh at the time of high water, which might have contributed to the retardation of the tide; for the waves being driven by the tide againft the coafts of Dunkirk, from north to fouth, their motion might eafily be retarded by the fouthern wind, which coming from fhore, blew directly againft the tide; furmifing from this obfervation, that the winds, according to their different directions, may occafion either accele- rations, or retardations of the tide, we examined the obfervations made on the 15thof Nov. 1701, the day of full moon, the wind being at fouth, and very frefh, according to the rule above laid down, full moon having happened at 4 minutes paft 5 in the evening, we mutt fubitract 10 bed
rom
Roya ACADEMY of SCIENCES. 387
from 11 hours, 54 min. which gives the time of high water at 11 hours, 44 min. in the morn- ing, 16 min. earlier than in the obfervation, which fixed it at 12 hours, o min. In this obfervation therefore, as well as in that of September, there was a retardation in the tide, which may likewife be attributed to the wind, which blowing at fouth-weft, muft have checked the motion of the tide. On the contrary, in the high water on the 12th of dpril, 1702, full moon happened at o'—13/in the evening, and it was high water at 11"—45/ inthe morning,the wind being at north- north-weft, and very frefh. By the rule there- fore, high water fhould have happened at 11°— 54, which is 9/ later than was actually obferved : fo that in this obfervation was an acceleration, which may be attributed to the north-north-weft wind, which blowing direétly on the coaft, con- curred with the tide, and made it earlier than it would otherwife have been.
In the other tides, obferved by M. Baert at full moons, the winds were either weak, or fo difpofed, that they could neither hinder nor pro- mote the motion of the tide any thing confidera- bly, fo that no regard was had to the effects pro- duced by them.
When a like comparifon of M. Baeri’s obfer- vations of high water for 15 fucceffive new moons, from the 8th of April, 1701, to the 26th of May, 1702, we find, that the earlieft came on the 29th of Nov. at 11° 20/ ¢ in the morning, the new moon for that day being at 10° Oo in the evening ; and that the lateft was found on the 27th of April, 1702, at o —47' in the even- ing. A new moon happening that day at 3 — 54 in the morning, the difference between the
Xy-2 times
388 The History and Memorrs of the
times of thefe two tides being, divided into two, we have the mean time of high water at Dunkirk in the new moons, at 12 —4', which only differs 10! from the mean time of the tides at full moon.
This difference being inconfiderable, high water at Dunkirk may be fuppofed in the new moons, as well as in the full moons, to happen at 11'—54' in the morning; fo that ufing the rule above prefcribed for determining the variations of the tides, on the days of full moon, we fhall have the time of high water on the 8th of May, 1701, at 12"—-15, which is within 20 min. of what was actually obferved; and the time of high water on the 27th of April, 1701, at 12°— 20, within 37’ of the obfervation, which, in fome meafure, reconciles thofe two obfervations, which were 1"—26 diftant from each other.
As to the winds obferved at the time of high water in the new moons, they do not feem to haften or retard the flood, fo regularly as was ob- ferved in the full moons, which may arife hence, that the motion of the tide arifes from a compli- cation of feveral caufes, fome whereof may be unknown; befides, that ’tis difficult to afcertain the precife time of high water. The time while it remains full flood, without either fenfibly rifing, or falling, being according to M. Baeri’s obfer- vation, from 12 to 20, or 30’, it muft be ob- ferved, that the tides happening on the days of full and new moons, are not the higheft tides; but that the higheft happen 1, 2, or 3 days af- ter, as appears from 30 obfervations made there- of, only two of which happened the day before full moon ; fo that upon a medium, one may fuppofe, that the higheft tide at Dunkirk hap-
pens
Royat AcapeEmy of Sciences, 389
pens two days after new or full moon, as M. Baert has obierved. *Tis commonly fuppofed, that the higheft tides happen in the new and full moons next the equi- noxes, and yet by comparing the obfervations made at Dumkirk, we find, that the higheft tide happened on the 3oth of Nov. 1701, when its height above the fixed point a day after full moon, was found 3 feet, 2 inches; and on the 27th and 28th of Fed, 1702, when it was
found 3 feet, 3 inches.
The great height of thefe two tides, ’tis true, may be attributed to fome extraordinary caule 5 for onthe 29th of Nov. 1701, the day of new moon, the high water was found 6 feet, 8 in- ches, below the fixed point, which was one of the loweft tides that had been obferved; and on the day following, it was found 3 feet, 2 inches, which, as above noted, was the higheft tide that had been known at Dunkirk. On this and the preceding day, there was a violent fouth-weft wind, which on the day of new moon, might have driven back the waters, and hindered their rifing to the ufual height, till returning with more impetuoftty on the day following, they rofe even beyond their cuftomary pitch, and thus made a kindof balance; in effect on the next day, viz, the firft of December was obferved 4 feet, 2 inches below the fixed point, which is above a foot lower. than on the day before; and on the fecond of December, it was 3 feet, 11 in- ches higher than on the firft ; whereas, according to the common rule, it fhould all along have been on the finking hand, fo that we may fup- pofe this alternate motion caufed by a violent
fouth-weft wind to have lafted 4 days. Much
390 The History and Memoirs of the
Much the fame fluctuation was obferved on the 27th a0 28th of Feb, 1702, when the height of the fixed point above the fea was found 3 feet, 3 inches; for on the 26th of Fed. the day of new moon, the high water was obferved 5 feet, 6 inches below the fame fixed point, occafioned by a great north-weft wind. On the 27th in the morning, the wind was fouth-weft, and at 10 a-clock turned to north-weft, high water on this day was obferved 3 feet, 3 inches below the fixed point, which is 2 fect, 3 inches higher, than on the day preceding. On the 28th, it was found at the fame height; but on the firft of March, high water was found 2 feet, 7 inches Tower, than on the 28th of Feb. and on the fe- cond of March, it was a full foot higher, than on the firft, tho’ it fhould rather have funk ; fo that here was a kind of vibration, excepting that there was no variation between the heights of the 27th and 28th of Feb. which might be owing to the winds fhifting fo fuddenly, from fouth-eaft to north-weft, on the 27th in the morning.
We have fufficient grounds therefore to fup- pofe, that the winds may increafe or diminifh the height of the tides, after the fame manner as they have been fhewn to occafion accelerations and re- tardations therein; and ’tis probable likewife, that the difpofition of the channel of the fea, and the fituation of the fhores, may contribute their fhare to the producing variations very difficult to be reduced to any certain rules.
As the higheft tides after new and full moon, do not always happen at Dunkirk about the equi- noxes, it has been enquired, whether fome other caufe, for inftance, the different diftance of the
moon
Royat AcADEMY of SCIENCES. 39%
moon from the earth, might not contribute to their increafe, or diminution. — For fuppofing, as we may very eafily do, that the caufe of the ebbing and flowing of the fea arifes from the pref- fion of the moon, upon the fluid matter between the moon and the earth, it will follow, that the further diftant the moon is from the earth, the lefs will this preffion be, and confequently the tide the lower; on the contrary, the nearer the moon is to the earth, the greater will be its preffion, and confequently the tide higher.
According to our theory of the moon, which gives an exact reprefentation of the motion of that planet, and its feveral diftances from the earth, fuch as found from the apparent variation of its diameter, ’tis fuppofed, that when the fun’s place meets with the place of the moon’s apogee, the moon being now in conjunction, is at her greateft diftance from the earth; and, on the contrary, at its {malleft diftance, when in oppo- fition. About 6 months after, when the fun meets with the moon’s perigee, the moon is then at her leaft diftance from the earth in conjunctions, and at the greateft in oppofitions; and when the fun is 3 figns diftant from the moon’s apogee or pe- rigee, on each fide the moon is at the fame di- ftance from the earth, whether fhe be in conjunc. tion or oppofition.
If we now compare M. Baeri’s obfervations, made when: the fun was near the apogee and pe- rigee of the moon, for about the mean diftances, we fhall find, that the high and low tides, both in the new and full moons, correfpond to the different diftances of the moon from the earth; and that when the fun is in the mean diftances, the tides are pretty nearly of an equal height in
the
392 The History and Memorrs of the
the conjunctions or oppofitions immediately fol- lowing. —
For.an inftance, in the full moon which hap- pened on the 21ft of March, 1701, the fun was near the moon’s apogee, being 17 degrees 16/ therefrom, the moon therefore being then in op- pofition, was according to our theory near the earth, and confequently the tide muft have been high accordingly. On the 26th of March, two days after full moon, the height of the fixed point above the furface of the water, was 4 feet, 3 inches, which was one of the higheft tides that had been obferved. And in the next new moon that happened on the 8th of April, the diftance of the fun from the moon’s apogee being. 1” oO) 21’ the moon was far- ther diftant from the earth than in the preceding oppofition ; whence it follows, that the tide mutt have been lower, as it was obferved accordingly, the height of the fixed point above the level of the feaon the 10th of Apri] being found 5 feet, 8 inches.
Tis true, according to the common opinion, which fuppofes that the higheft tides happen neareft the equinoxes, the tide muft have been higher on the 26th of March, than on the roth of 4- pril; but for the fame reafon, in the following full moon of the 22d of April, the diftance from the equinox being increafed, the tide fhould have been lower than on the roth of 4pri/3 whereas it was really higher by 1 foot, 1 inch, conformably to what fhould have been from the fituation of the moon, which was farther from the earth on the 8th of April, than on the 22d: whence it ap- pears, that the higheft or loweft tides bear a nearer relation to the diftance of the moon from
I the
- Rovat Acanemy of Sciences, 393
the earth, than to the diftance of the fun from the equinoxes. © | | .
For the eafier making this comparifon, we ‘have drawn up the following table ; in the firft ‘column whereof are expreffed.the days and hours ‘of the new and full moons; in the 2d, the time of high water obferved at Dynkirk, on the days of new and -full moon; in the. gd, the time of nige water calculated according to the preceding rule 5 in the 4th, the height of the fixed point above the furface of the fea at the time of high ‘water; in. the 5th, the fun’s diftance frem the apogee of the moon; inthe 6th, the diftance of the moon from the earth, atthe time of new and full moon, with regard to the mean diftance, which is fuppoled to be TQ0000,parts; in the th, the day of the higheit tide ; and in the Sth, the height of the Axed point above the furface of ithe fea, ~ . |
Vor. HI.N®. 33 2 A
394 The History and Memorrs of the
A TABLE of the times and heights of the
Time cf higt pFune ot hgbpAcagit. vu
E water founc§vater found}the fixed
Time of new and full |by obférva-}y calcula. }pvint. ction.
© 24 Mar.at 8 36
@ Ss Apr. 105 5 11 (-) 22 Apr. 5 ys ae @ 8 May, I ORE () 22 May, 2 [5 3 @ 6 June, 2z 6 6 (-) 20 June, ° (6 2 @ 6 July, re) 5.10 @ 19 July, m1 é 6 @ 4 Aug. 10 15 eae © 18 Aug 2 5 10 @ z Sept 6 ; 7 ©) 17 Sept 5 6 1 @ 2 O€. 2 411 eo), touOck: Il 6 5 @ 31 O8€. 1I ‘ ay = ©) 15 Nov. 5 F 5 Io @ 29 Nov. 10 11 E.jrr 20 211 33 2/6 8 -) 15 Dec. 10 36Milnre55 [11 57) 6 11 @ 29 Dec. 10 47 Mant 51 211 56 [5 ©
1702
14 Jan. 112 Mij1z g |12 16 {5. 6- @ 28 Jan. 138 M.jtr 46 |12 15 [5 Qs (-) 12 Feb. 3 2E.fsa.32 [11 48 |6 2 @ 26 Feb. 615 E.ftr 57 {11 41 [5 6 © 14 Mar, 4 48 M.jr2 13 L1iz14 |5_ 6 @ 28 Mar. - 11 7 Mjrz2 10 try 56 {5 10 =) 12 Apr. o 13 E.jat 45) [tt 53 14 Se @ 27 Apr 3 49 M.j12. 47 |12 10 j§ 11 -) 11 May, 4 59 E.|11 36 |1t 44 jg 6 ® 26 May, 8 27 E.Jir 47 |11 37 {6 10
Rovat ACADEMY of SCIENCES. 395
rides, in the new end full moons at Dunkirk.
Distance 0: we} vuttance ot deight o1
fea from te] he moon the water
moon’s apogee om the Day of the [|therein. | arth in : ;
compan, higheft tide.
Opp
— P m
17 16193778 ||26 March, O 21}105589)|10 April. 24 April. 11 May. 23 May. 7 June. 2 33!99713 |{2z1 June. 3 16 2/98372 || 7 July. 22 July. 6 Augutt. 22 Augutt. 6 September. 18 10 106340) 1g September. L313} 93460,| 2 October. 17 O&tober. 30 Odtober. 16 November, |5 30 November. ;3 17 and 18 Dec. 6 30 December. /3 ! 1702. 9 4 37}/100013 |14 January. |5 9 17 19|100477/|30 January. {5 ; 13 February [4 27 and 28 Feb. 3 15 March. 30 March
~~ ~ NAN OO
nvr PPP OKNH AW AAD NWOn AO OHH OW OMN O BNI COW
OPOMOMmMpbUIMIMN” AMY AP uh by
a Or
4 : 5
wt 22 55193519 {115 April. 3 10 4 © ~ § 52/106496 j26 April. 5 13 May. '4 1]29 May. ‘6
Zz2 By
396 The History and Memoirs of the
By this table it appears, that when the fun’s diftance fromthe apogee of the moon is about. 3 or 9 figns, the height of the water on the day of the higheft tide, is nearly equal both in cone. junctions and oppofitions.
As to the loweft tides,’ out of the new and full moons, they do not ufually happen in the qua- dratures, but 1, 2, or 3 days after; fo that we may fuppofe them at a medium, to happen 2 days after the firft and laft quarter ; as we like- wife obferve, that the higheft tides commonly happen 2 days after the new and full moon,
The loweft tide happened on the 8th of Feb. 1702, the high water being then 10 feet, 2 in- ches below the fixed point ; and the higheft tide, as already obferved, was on the 30th of Novem. 1701, when the high water was 3 feet, 2 inches below the fame point; fo that the difference be- tween the higheft and loweft tides at Dunkirk was 7 fect. — But what is further remark- able is, that the height of the tides, which hap- pen in the quadratures, feems likewife to depend on the diftance of the moon from the earth, the flood being found higher when the moon is near the earth, and lower when fhe is farther diftant from it; foas the height is much the fame in the. firft and Jaft quarter, when the moon is equally diftant from the earth.
According to the theory of the moon, when the fun is about three figns diftant from the , moon’s apogeé, the moon in her quarter is in perigee, and in her laft quarter in apogee, and confequently the flood fhould be higher in the. firft quarter, and lower in the laft. On the con- trary, when the fun is about g figns diftant from the moon’s apogee, the moon, if in her firft quar-
; ter,
Roya ACADEMY of SCIENCES, 397
ter, is in apogee, and in her laft in perigee 3 con- fequently high water muft be lower in the firft than in the laft quarter ; and when the fun is either in the moon’s apogee, or perigee, the moon is at an equal diftance from the earth, both:in the firft and laft quarter, and confequently the tides _ muft be equal in each.
But the agreement between the heights of the tides, and the different diftances. of the moon from the earth in the quadratures, will be more eafily obferved, by means of the following table.
398 The History andMemorrs of the
ATABLE of the times and heights of
———
© Woo +tTONOHMDOO a 20. 9. ae
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wt OO Om EO CO Oe
Om Oe TOs CORK COs OO OOS OH TH OF
Rovan AcADEMY-¢f ScEINCES. 399
_ the anne in the quadratures at Dunkirk,
a. od le apa Awol : ihe a un from the $|itancetrumfiow H the fixe water, ‘ Time of the int above.
mcon’s apc=- jthée earth Bee. inthe qua- ratures.
the water,
loweft tide.
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pe
—- DAP mM AST BST OO em = Pp woOoMn *
~ t
ON
131 September. 5 25 8102165 27 September. 6 6 30102275 11 Oétober. 26 O€ober.
9 November. 26 November. 8 December. 23 December
WOO 0D 0 WONT & NYO WOOD O OID WO WO MOUND: nO
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8 28 20106425 5 January. 9 10 2 97717 20 January. 8 February. 21 February. 8 March 22 March.
8 April. 20 April.
5 May.
19 May.
- =
—_ mM ONT = NN OM
at 28 56101725 © 12 4010085
400 The History and Memoirs of the
If now we confider the retardation of the tides, from day to day, we fhall find it liable to feveral irregularities, there being a retardation of 1'—54’, between the 2d and 3d of April, 1701, and an anticipation of 30’, between the 35th and 16th of Offober ; fo that it would be difficult to give rules for finding the time of high water daily at Dunkirk, within a few minutes of truth, as we have done for the days of new and full moon.
Our firft enquiry was, whether thofe irregularities bore any analogy to thofe of the true motion of the moon, which gains or lofes, with regard to the mean motion; but finding, that they were frequently a contrary way, I have been obliged to look elfewhere for the caufes of fuch variations. — In order hereto, we have compared the times of high water, obferved on the days of the qua- dratures, and find, that on the day of the firft and laft quarter of the moon high water happens at Dunkirk, nearly about the fame time as we had before obferved, that high water happens nearly at the fame time in the new and full moons,
Among the 29 obfervations made at the quadra- tures, that, wherein the flood was moft accele- rated, happened on the 26th of duguft, 1701, at 4h 31’; and that wherein it was moft re- tarded, on the 7th of December, 1701, at 5°— 58’: fo that there is a variation of 1'——27/, in the time of high water at the quadratures, which is greater by 1', than that obferved at new and full moons, 2
To affign fome rule for this variation, we fup- pofe, that the mean time of high water in the quadratuses happens at Dunkirk at 5°—6' in the evening, and to or from this time add, or fub-
{tract 2! for every hour, which the time of the quadrature,
RoyAt ACADEMY of SCIENCES. 401
quadrature, expreffed in the almanack, antici- pates or comes behind this mean time of high water.——For an inftance on the 31{t of March, 1701, the day of the quadrature, high water was obferved at Dunkirk at 5'——36' in the evening, Now the laft quarter of the moon is fixed for that day at 6 32 inthe morning, by the al- manack ; and the difference between 6 —32! in the morning, and 5 —6’ in the evening, the mean time of high water in the quadratures is to —-34'; to which, at the rate of 2/ per hour, anfwer 21’, which added to 5'°—6’, give 5 —27’ for the time of high water on the 31{t of March, 1701, which is within 9! of the time obferved. The mean time of high water at Dunkirk, in the ew and full moons, being at 11°——54! in the morning, and in the quadratures at 11 --6/, we have 5°—12’ for the interval between the times of the tides from the new and full moons to the quadra- tures, which is much Iefs than that of the quadra- tures, to the new and full moons; accordingly a greater retardation, from. one day to another, is obferved in the tides fucceeding the quadratures, than in thofe which fucceed the newand full moons ; the caufe whereof may be attributed to this, that the tides being lower about the quadratures, than about the full moons, the fea, which grows higher every day, as it approaches the new or full moon, fpends more time in furpaffing the height of the preceding day; whereas, from the new and full moons to the quadratures, the fea finding no obftacle, but being affifted by its own weight, defcends with the greater velocity, and confequently renders the intervals between the tides fhorter. After afcertaining the time of high water in the new and full moons, and quadratures, we confi- Range N@.94,° “Aaa dered
402 The History and Memoirs of the
dered anew all the obfervations made at Dun- kirk, during the fpace of 14 months, and deter- mined the mean time of high water for eyer, both after new and full moon, oad after the quadra- tures. We alfo formed rules of the variations they are liable to, with regard to the times of the new and full moons, and quadratures preced- ing the given day.
By thefe rules, among 434 obfervations related by M. Baert, there are only two wherein the time of high water, determined by the rule, is 54 minutes different from the time obferved. This difference will not appear very great, confider- ing what a number of irregularities may occur in the obfervations, there being fometimes a doubt of a whole hour in determining the time of high water, as was obferved on the 27th of February, 17023 when it was firft found high water at o°— 8’ in the evening. After which the fea funk fome inches, but rofe again at o°—57’ to the fame height; it had been at 49! before, where it remained till 1°—10'; and M. Baert fixed the time of high water for this day at 1°—7/.
For the eafier finding the time of high water on any given day, we prefent the following table of the retardation of the tides, both after the new and full moons, and after the quadratures ; the tides are here laid down for every 12 a-clock, for the conveniency of finding the morning and even- ing tides. By means of this table, and of the rules fubjoined, the true time of high water may be found at Dunkirk for any given day, which may be of fervice to pilots for chufing the moft proper times to enter, or come out of that port.
De ie
Royat AcapEmy of SCIENCES. 403
a / h II 54 mean|5 6 mean time of high wa |time of high wa- ter at Dunkirk,\ter at Dunkirk, ontheday ofnewjon the days of, and full moon. | the quadratures.
A TABLE of the retardation of the tides.
aoa td Day anc 2ctard
acur at rion of cec new jthe tides v ful
Retarda ton o ‘ the tid dif.
cre hour af y+ ficer firft
D. H/H.M|M|.D H.'D. H./M
0 ~ oOo z6/.0° "OO O32 12/0 26/24]; 12.0 32/36 1 90 soft ot Blgr 12 1uj2u{ 12,1 49 i]
EQ|22) 9). O12 32143 18}| 12'3 11|39 13) 3 | 44133
122 24114 1214 14130
4 O2 42/1814 olf 40/26
12/3, urgi| —t2i5 424 Sen 2si205 (OG. 2a 24! 1213 44/20]; 12/5 = 50/22
Or eA VESI29T GO Sor e161 zi22 12/4 21\r9] | 1216 34|22
Pawo VO WS Gris C16 54120
Rule firft, To find the time of high water at Dunkirk for the days of new and full moon, and of the quadratures.
_Find in the almanack the time of new or full moon, and of the quadratures, and take the dif- _ ference between this and the mean time of high water, exprefled for the day of that phafis, the double of this difference will be the number of minutes to be added to the mean time of high water, in cafe the time of the phafis anticipate the
Aaa2 mean
404 The History and Memoirs of the
mean time of high water, or, on the contrary, to be fubftracted in cafe fuch time come after that of high water, the refult whereof will be the true tine of high water required.
For an inftance, firft, fuppofe the time of high water required for the day of full moon in April ago
Full moon by the almanack falls on the 22d of April, at 5 —16’ in the evening, the difference between this 5 —16' inthe evening, and 11°—s4! in the morning, the mean time of high water in the new and full moons at Dunkirk, as laid down in the table, is 5 —22!; the double whereof, viz. 10'—44" is the number of minutes to be fub- {tracted from 11'—54, on account of the full moon’s coming after the time of high water, the remainder is 11?—43', the true time of high wa- ter inthe morning of the 22d of April. M. Baert obferved it that day at 11'—4 4’.
For a feoond inftance, fuppofe the time of high water required forthe day of the firft quadra- ture of the moon in 4pri/, 1701.
~ The almanack fixes the firft quadrature of the moon to the 16th of April, at 2°—8’ in the morning, the difference between which time and 5 —6'in the evening, the mean time of high water in the quadratures at Dunkirk is 14'—58', whofe double zo isthe number of min.to be added to 5 ——6', by reafon the time of quadrature an- ticipates the mean time of high water. The fum, viz. 5'—~36' in the evening, gives the true time of high water on the 16th of April. M. Baert found it that day at 5 —4o’.
Second rule to find the time of high water at Dunkirk, for any given day. ;
Find by the firft rule the time of high water, the day of full or new moon, or of one of the
qua-
Roya Acavemy of ScIENCES. 405
quadratures, immediately preceding the given day ; to this add the retardation of the tides, cor- refponding to the difference between the given day, and the day of the preceding phafis, the fum will be the time of high water for the day required. To find the time of high water immediately preceding, or following that now found, we mutt fubftract or add the difference cor- refponding to 12.
For an inftance, fuppofe the hour of high wa- ter required for the 26th of March, 1701.
In the almanack, we find that the phafs im- mediately preceding the 26th of March, is full moon, which happens on the 24th of March, at 8°—36 in the morning, the difference between $°—36/ in the morning, and 11'—5,!/ the mean time of high water at Dunkirk, is 3'/—18"; the double whereof 6’/—36", being added to 1 1"—54. gives the time of high water at 12 —1', on the 24th of March, the day of full moon. To this add, 1°—3o0", the retardation of the tides cor- refponding to two days after full moon, the refule gives the time of high water, on the 26th of March, 1701, at 1'—31'in the evening, the very fame as was obferved by M. Baert. ‘To find the time of high water, which happened in the morning, and the fame day, take the dif- ference between 1'—30! and 1 —14', viz. 109/, which fubftraéted from 1'——21', the time of high water in the evening, gives 1°—12' for the true time of high water in the morning.
For a fecond inftance, fuppofe the time of high water required for the 6th of Apri], 1701.
By the almanack we learn, that the third qua- drature of the moon, which is the phafis imme- diately preceding the given day, happened on the gift of March, 1701, at 6 —32'in the morn-
ing,
406 The History and Memorrs of the
ing, the difference between this 6°—32! in the morning, and s5’'—6' in the evening, the mean time of high water at Dunkirk, in the quadratures, is 10 —34! 3 whofe double 21/—8” being added to 5 —6', by reafon the time of the 3d quadra- ture comes before 5'—6', gives the time of high water at Dunkirk, On the 31ft of March, 1701, the day of the Jaft quadrature, at 5°\—27! in the evening, the difference between the 31ft of Mar. the day of the third quadrature, and the 6th of April, the day given, is 6 days the correfpond- ing retardation, to which in the table is 6°—12', which added to 5"—27', gives the time of high water at Dunkirk, for the 6th of Apri/, 1701, at ¥1"——39' in the evening. ———— To find the time of high water, which happened in the morn- ing, take the difference between 6’—12', and 5 —50', viz. 22’, which fubftracted from 11°— 39, the time of high water on the 6th of Apri/, mn the evening, gives 11°—17’, for the true time of high water in the morning of the fame day. M. Baert found it 11 —21' this morning .
Third rule, to find in any given month the times of the higheft tides, moft proper for enter- ing or coming out of the port of Dunkirk.
Find, by the preceding rule, the time of high water for the 2d days after the new andfull moons of that month, and you will have the time re- quired,
For an inftance, the full moon of the month of March, happening on the 24th at § —36' in the morning, we feek by the 2d rule the time of high water on the 26th of March, which, in the inftance there given, is found at 1'—31' in the evening. M. Baert obferved it high wa- ter this day at 1°——31' in the evening ; and the
t1ae
RoyaL ACADEMY of SCIENCES. 407
tide was higher than in any of the preceding or following days.
Fourth rule,to find the day and hour of the high- eft tide, which will happen in any given month.
By the aftronomical tables, take the moon’s diameter for the day of new and full moon; if this diameter be greater on the day of the new than of the full moon, the tide will be higheft this month 2 days after the new moon 3 but if the moon’s diameter be greater on the day of full than of new moon, the tide will be higheft this month 2 days after the full moon.
For an inftance, fuppofe the higheft tide re- quired in the month of April, 1701
By the table, we find the diameter of the moon, on the 8th of April, the day of new moon, to be 14’——53", and on the 22d of 4 pril, the day of full moon, to be 16/——24", confequently the higheft tide in this month. will be on the 24th, which agrees with M. Baeri’s obfervation.
Fifth rule, to find the day and hour of the loweft: tide, which will happen in any given month.
Find, by the aflronomical tables, the moon’s diameter for the day of the firft and laft quadra- ture, if this diameter be {maller on the day of the firft quadrature, the leaft tide this month will be 2 days after the firft quadrature. On the con- trary, if the moon’s diameter be the Jeaft on the day of the laft quadrature, the Joweft tide that month will be 2 days after the laft quadrature.
For an inftance, fuppofe the leaft tide required for the month of Fuze, 1701.
By the tables, we find the diameter of the moon, on the 13th of Fane, the day of the firft quadrature, to be 16/ 6", and on the 28th of
I Tune,
408 The History and Memoirs of the
Fune, the day of the laft quadrature, to be 14'——47", confequently the {malleft tide in the month of une, 1701, muft have happened on the 30th of that month, agreeably to the obfer- vations of M. Baert.
IX. Ob/fervations on a kind of tale, commonly found near Paris, over the banks of plajter- frones, by M. de la Hire*; tranflated by Mr. Chambers.
One of the moft curious among tranfparent ftones, and that which may give moft employ- ment to the naturalifts to account for its effects is what we commonly call ‘Mand cryftal. ’Tis ex- tremely tranfparent, and clearer even than the fineft glafs ; but might be more properly called a talc than a cryftal, for the reafons alledged here- after. Its difcovery we owe to Erafmus Bar- tholin, a celebrated Danifh mathematician, who firft laid it before the publick, in a treatife upon the fubject, printed in 1670. M. Huygens has alfo been very large on the properties of this {tone, in his treatife of light, printed in 1690. .
Having two large pieces of this ftone in my poffeffion, I was willing to examine it, by feve- ral experiments, and in different manners, both for my own fatisfaCtion, and for the afcertaining of what thofe gentlemen have faid of it. It ought, as already hinted, to be called a talc, ra- ther than a cryftal, it being one of its chief pro- perties to cleave readily every way, but ftill pa- rallel to one of thofe 6 phafes, whereof its figure confifts, which is always an oblique angled paral- - lelipiped, and confequently its fragments will
* July 19, 1710. all
Royat AcADEMY of SCIENECS. 40g
all be parallelipipeds, whofe 8 folid angles are placed fimilarly in the fmalleft pieces, as in the largeft.
The 6 faces, whereof it is formed, are oblique angled parallelograms, whofe two oppofite obtufe angles are each ror degrees, 30/, and confe- quently the two others being the complements thereof, muft be each 78°-——30/: this ] have learnt by my obfervations,
In this para'lelipiped are only 2 folid angles, which are oppofite to each other, and formed by 3 of the obtufe angles of the faces; the other 6 are each comprehended between one obtufe angle and two acute ones, there being in all 12 equal _ obtufe angles, and as many equal acute ones.
The inclinations of the faces make two kinds of angles ; 6 whereof are obtufe, comprehending each 105 degrees, and 6 acute ones of 75° each, which are the complements of the former. Thefe meafures are fomewhat different from thofe of Meff. Bartbolin and Huygens, which may a- rife from the difficulty of making exact obferva- tions thereof, by reafon the acute angles are not fo well defined as the obtufe ones.
Thus much for the figure of the ftone.
But what is more remarkable in it is, that it re- prefents all the objeéts feen thro’ two of its pa- rallel faces double ; the diftance between the two images appearing fo much the greater, vas the faces are further diftant from each other, or the cryftal thicker. This phenomenon is the moft fenfible, when the object is a black point, ora line drawn on the face of the ftone.
The doubling of the object, however, is not the only thing to be confidered in this ftone ; bur the manner wherein this is done, which is always in the line paffing thro’ the objeét, which is ee
‘Vou. PT NP 94. Bbb rallel
410 The HisTory and MEmorRs of the
rallel to that whereby the obtufe angle of the face the object is upon is bifeéted.
This double image of the fame object fhews, that there muft be a double refraction in thefe bodies, and accordingly two very different ones have been diftinétly obferved. The firft, com- mon to that found in all tranfparent bodies, and depending on the inclination of the incident ray, to the line perpendicular to the face of the body when the refraction is made. The fecond, pecu- liar to this cryftal, and arifing from another in- clination of the incident ray, to another line in- clined to the fame face. Hence it follows, that if the incident ray be united with one of thefe lines, it will not undergo the refraction belonging to that line, but will undergo that depending on the other; and confequently the image will al- ways be double in every other inclination.
I have made feveral experiments, and have likewife repeated them feveral ways; the refult whereof is, that in the firft of the two refractions, the fine of the angle of incidence in the air, is to the fine of the angle refracted in the body as 5 to 33 whence we learn, that this refraction of the body, notwithftanding its foftnefs, furpaffes that of the glafs, which is only as 4 # to 3.
As*eo the 2d refraction which is peculiar to this body, and makes the object double, Barthe- lin takes it to depend upon a line, or ray, always parallel to the edges of the faces next thofe where’ the refraction is made; but Huygens denies this iine to be parallel to thofe edges; for myfelf, af- ter examining the point with great attention, I find this line more perpendicular to the furface of the cry{tal by 1°, which is no great matter in an enquiry of this kind: further I find the fines of the
angles
RoYAL ACADEMY of SCIENCES. 411
angles of incidence in the air with regard to this line ; and in this 2d refraction to be to the fines of the refracted angles nearly as 44 to 3, which is much like that of glafs.
’Tis obfervable, that the image produced by the fecond refraction, always appears lower than that produced by the firft; the reafon whereof is eafily affigned from the laws of dioptricks, as alfo why each of the two images only appears with # the ftrength it would have, if viewed with- Out the interpofition of any other body. Hence it is, that when the parts of the two images cover each other, as will happen in a certain fituation ta a black ftroke upon the cryftal, this part will ap- pear twice as {trong as any where elfe.
Myj examination of the Ifland talc led me to confider that found in this country over the banks of plafter-ftone ; for we muft not neglect what is committed unto us, and which would ap- pear curious in a foreign country to beftow all our attention upon what comes afar.
This plafter tale is a tranfparent ftone which bears a near refemblance to that brought from the Levant, except in point of figure, which is very fingular, and is conftantly the fame in all the pieces we have feen ; its relation to the real talc confifts in its cleaving readily into thin leaves, or lameile, equally traniparent with thofe of com- mon talc, but fmaller, and more brittle.
We meet with ftore of pieces of this ftone, of a moderate bulk, in a ftratum of white fatty earth, over the blocks of ftone whereof the plafter of Paris is made; they are diftributed thro’ this earth, wherein it is known they are formed with- out any order or uniformity, being thrown as it were at random, and feveral almaft joining one to
Bbb2 another
412 The History and Memoirs of the
another with the intervention only of a little of the fatty earth.
The figure * of this talc refembles the barbed point of an arrow, as appears by ABCD which reprefents one of its faces; for there are always two parallel to each other, according to which the ftone cleaves into leaves ; and one of thefe faces is bigger than the other. We find pieces from 12 to 15 inches long, all forked at the broad end as in CAD, the other end B terminating in a point ; the pieces in thicknefsof a moderate fize, are about i inch: thro’ the 2 parallel faces we perceive ob- jects very clearly, at leaft in the white pieces; for there are fome yellow and brownifh ones which are but little tranfparent.
Each piece is naturally divided into two length- ways, as appears by the right line AB, proced- ing from the cleft A to the point B; and the plane which parts them is perpendicular to the faces ; but the two pieces are ufually united, be- ing only diftinguifhed from each other by the inequality of the fubftance found in this part, where there is fometimes likewife found, a little of the earth wherein the talc is formed: in fome parts of it we alfo find a hard itony kind of cruft.
The fides which terminate this ftone, do not ufually make right angles with the faces; but an acute angle of 75 degrees on the broad fide of the face, and itscomplement on the other; and hence it is, that the two faces are not of the fame big- nefs in every piece: the fides naturally are not fmooth and polifhed, being only formed of the extremities of the feveral /amive, which are al- ways covered with a thin yellowifh cruf% ; and
* Plate VI. fig. 9, hence
RoyaL ACADEMY of SCIENCES. 413
hence objects only appear very confufedly thro’ thefe fides unlefs the cruft be removed, and a var- nifh laid over, which is not eafy to execute, by reafon of the {mall connection between the /a- Ming.
One of the points of the fork is fometimes found a little feparate from its piece, being only joined irregularly thereto, by a little of the fatty earth ; and upon feparating them quite, we find that thefe points only adhered to the reft by pieces of /aminz, about a line thick, which enter. more or lefs into the body of the ftone, and make bond as the mafons call it therewith.
Upon removing fome of the rough /amelle on the furface of this talc, we clearly difcern lines therein, as EF proceeding from the middle line AB, towards the edges on either fide; and making an acute angle AEF, with the fame middle line towards the fork A,-of about 60°: we alfo per- ceive other lines as GH proceeding from the middle towards the edges, and making an acute angle BGH towards the point B of 50°, fo that the acute angle formed at the meeting of thofe 2 lines is 70°.
Hence it always happens, that upon cleaving the talc into thin pieces, which can only be done with a fharp knife, beginning at the exterior edges after firft removing the cruft: moft of thefe lamine breal into triangles, whofe angles are conftantly 50, 60, and 70 degrees, which is a very fingular property of this ftone. We alfo find certain fragments of thole thin /amelle, in figure of a parallellogram compofed of 2 of thefe triangles joyned together.
Hence we may probably infer, that the mafs of thefe talc ftones, confifts only of thin /amelle flenderly faftened to each other, each whereof is
formed
414 The History and Memot1rs of the
formed of little triangular /amel/z, as the elements thereof which are ftrongly faftened to each other at their edges, whence they have a confiderable firmnefs ; each of which little elementary trian- gles has 3 unequal acute angles; wiz. of 50, 60, and 70°, as appears from the pieces of broken © lamelle, which are only affemblages of the fame elementary triangles, and form triangles like their elements ; for thefe /amellze are very brittle, and yet afford the fame angle, when, or howfoever broken.
If the fides of thefe elementary triangles do not make a right angle with their face, but an angle of 75 degrees on one fide, and its complement on the other, which however is more than can be obferved, it would likewife follow, that upon joining together in the fame order, the whole fide of a piece formed by them, would have this incli- nation to the face, which is eafily obferved.
From the difference of the angles in the ele- mentary triangles, it will likewife follow, that according to their feveral arangements in forming the /amelle, the fides of thofe /amelle will either be parallel to the line in the middle, or inclined thereto in 10°, which alfo forms the point of the piece ; the faces whereof are always inclined 10° to the middle line on either fide, when they are inclined at all, which happens almoft univerfally 5 for the angle AEF being conftantly 60°, and the angle BGH, or BEJ, or BEK 50°, the angle FEI or FEK, will neceffarily be 70°; and if the triangle FEI, whofe angle FEI fhould be 70°, have its angle EFI 60°, and confe- quently the other EIF of 50, it will follow, that the fide FI will be parallel to AB; but if the angle EFI, or EFK be 50 degrees, and the other EKF 60, the line FK will make an angle
with
Rovat ACADEMY of SCIENCES. 41¥
with the middle an angle of 10°, which we ufually find accordingly. Thefe 2 cafes may happen in the firft formation of the leaves by the triangles, as FEK taking an inverted fituation, the angle in FE, ftill remaining the fame; and as we may fup- pofe, that before the forming of thefe leaves, their elementary triangles floated in a liquid fub- ftance ; by the motion whereof they were ranged afide of each other, in a certain order, agreeable to their figure; whence it happened, that the fides of the /amelle might become inclined to each other, in an angle of 10 degrees; for I only here confider $ the intire /amel/e which is always di- vided into two by a line, as AB; but if in fuch formation of the /amel/, one of them by any ac- cident happened to take a different pofition, the reft adapting themfelves thereto by the motion of the fluid,” formed the fides of the /awze//e parallel to each other. ;
Tt was in.this formation of the /amelZe, that they acquired their hardnefs, which became pretty confiderable by their elements joining to each other at their fides ; but the /ame//e having ftill a liquid matter between them, which could only be drained off in time, it hence happened that they did not adhere any thing confiderably to each other by their furfaces; fo that if there be the leaft foreign matter left between them, they will always be eafier to feparate from each other than to be broke a-crofs.
' As to the fork CAD, its formation feems to be as follows, the angle formed by each horn as ACH or ADH 1s ufually 50° which is the fmal- left of the 3 angles of the element, and if the ex- terior fide of the piece make an angle with the middle line of 10% towards the point, it follows, that the angle of the fork CAD muft be 120 de- I
OTees,
416 The HisTorY aud Memoirs of the
grees, which is very near what we actually find in fome pieces of this talc-————Now if any foreign body have been found about A to hinder the 2 elementary triangles, which fhould have been difpofed therein from uniting to thofe of the fides (fomething of which kind we actually find in the difunion of the horns, from the body of the talc by a piece of earth as abovementioned) in this cafe, the connection between the /amine being interrupted, the reft muft have continued forming, and terminate at length in the point of the horn, by lines parallel on one fide to EF, and on the other in AC and AD ; for the natural figure of the elementary triangles in joining together, will always form triangles fimilar to the elements. What has hitherto been obferved of the quan- tities of the angles in the talc, is only what ob- tains in the general, there being feveral"irregula- rities found therein, occafioned in the formation by foreign bodies, which diverting the elementary triangles, have made them affume external figures different from what would naturally have arofe from the affemblage of elements; yet without any fuch thing being perceivable in the body, on account of the fmallnefs of thofe elements, as we find by fome of the fides which are a little crook- ed, and by certain angles which are lefs or greater than thofe of the elements, in which cafe thefe fides muft have little dentures ; fome whereof are perceivable in the irregular fractures of the /a- melle : in fine, we find fome pieces of tale which have others faftened on their fides; in others the point is extended into-a paralellipiped only on one fide, and towards the point of others, we find another piece form’d as ufual, but oppofite to the firft, with a thoufand other varieties which are as it were the /uz/us of this formation. After
Royat ACADEMY of SCIENCES. 417
After examining the figure of this talc, I ap- plied my felf to the obfervation of its refractions, Thefe, I firft confidered between the 2 parallel faces, the only way wherein the ftone is naturally tranfparent ; and then in planes perpendicular to thofe faces, as is ufually done in meafuring the refraction. Then in all the other directions, as lengthwife from the middie of the point, towards the fork ; then fide-wife, breadth-wife, perpen- dicularly to the middle line, €&c. and every where under all the different angles of inclination, found the fine of the angle of incidence in the air, to the fine of the angle refracted in the body as 5 to 33, which is the fame as that from air into glafs ; and the fame likewife with that peculiar to Ifland cryftal, which deferves a {pecial attention ; Jaftly, feparating a.piece of talc into two, by the plane which divides its length, and is perpendicu- Jar to the faces, I examined what the refra¢tion would be a-crofs the thicknefs of its fide, fuch refraction being made in a plane parallel to the faces, which is impracticable while the two halfs are joyned together, both by reafon of the too great thicknefs, and of the foulnefs of the middle part where the feparation is ; but having cleanfed this part, and fmeared it over with a litle gum- water, as alfo the outer edge which is commonly rough, till a black body might be difcerned thro’ it, I found, that the refraction this way was the fame as before ; viz. as 5 to 3 }.
- But being fearce fatisfied with all thefe obferva- tions, I was further willing to know whether the clefts or flaws, perceived on the fide of this ftone, might not produce fome particular effect ; to mike which the more apparent, I applied an iron wire lengthwife over thefe clefts, and looking thro’ the
Werth, N°oz4..; Cece talg,
418 The History and Memoirs of the
talc, found its image appear in ‘two different places, or at Jeaft much larger than it really was, with a clear fpace between the two; then moving the wire gently, but ftill in its former direétion, I perceived the image jump, as it were, from one place to another, bur {till double ; to render thefe obfervations the more confpicuous, by reafon the talc is. very dim when viewed fideways, it muft be held near the light of a candle, and the iron wier applied full upon it.
Here it will be required to produce phyfical reafons of all thefe effeéts, not only of the talc, but of /fand cryftal, which it fo nearly refembles; from whence light might perhaps be let into moft other tranfparent bodies, as diamond rock, cry- ftal, allom, €@¢. which are all natural produs- tions; and in al] appearance are formed of an aflemblage of elements, fimilar to each other, which determine their figure: but this I referve for another memoir.
At Paffy near Paris, round the mineral fpring, are likewife found little pieces of talc, of the fame fpecies as that of the plafter quarries, be- ing fiffile like them into thin /amelle; *tis very clear and tranfparent, and fenfibly formed of the fame triangular elements, as that of plafter; but the figure of its two parallel faces, according to which it cleaves, is a parallelogram with two acute angles of 50 degrees each. Its fides make an angle, with the faces of 125 degrees on each fide, tho’ ’tis difficult to meafure them exactly, by reafon the fides are not {mooth, as being only formed of the extremities of /amellz, which leaves feveral inequalities along the fides.
What is moft remarkable in this talc, is a prominent angle, of about rro°, which it makes about the middle of its thicknefs on a
ide ;
Royat ACADEMY of ScIENCES. 419 fide ; fo that its figure would be a parallelipiped, with 6 faces, provided its two ends, or bafes, were plain; but they alfo make a prominant angle abour the middle of 140 degrees.
As to the refraction of this talc, I have not been able to find the exact quantity thereof, by reafon the pieces are too fmall; nor do I find, that objects appear double through its parallel faces.
_ Sir I/faae Newton gives his, obfervations- upon ifland cryftal, with an abftrufe fort of folution of its effects in his opticks.
Coc2 An:
420 The History and Memorrs of the
An Exeianation of the Terms of Art wed in this volume, which were not explained at the end of the former volumes.
A Lhidade, is an Arabic word, ufed to ex- prefs a moveable rule applied to an inftru- ment for obferving heights and lengths. It is alfo called a diopter.
Apogeum, or apogee, is a point in the heavens, in which the fun, moon, or any planet, is at its greateft poffible diftance from the earth.
Areometer is an inftrument ufed to meafure the denfity or gravity of fluids. That which is ufed by the royal academy of fciences at Paris, isa glafs bottle balanced with quickfilver, having a very narrow neck, divided all along into equal parts. It is immerged in liquors, which they would compare together, and the weight of them is determined by the degree to which the areo- meter finks; that in which it finks moft being the lighteft liquor.
Brace, a meafure of 5 Paris feet and 4 inches, or about 5 feet, 7 inches 3 of our meafure.
G Caliber, the bore or width ofa fire-arm, or the diameter of its mouth, or of the ball that it car- riés, Chamber, or fourneau, or furnace of a mine, is that part in which the powder is placed. The 2 cavity
2
Pi A
‘LAS a SF ; gb ee ee
Roya AcADEMY of SCIENCES, 421
cavity of it is about 5 or 6 cubical feet, and is charged with about 1000 /d. of powder, or lefs, according to the earth that is to be raifed. Choroides, the inner coat of the eye. Cornea, one of the coats of the eye, fo called, becaufe it is tranfparent like horn.
Diaftole, the motion of the heart, by which it dilates itfelf: it is oppofite to the /y/fole, by which it contracts itfelf.
E
Eolipyle, a hydraulic inftrument, confifting of a hollow metalline ball, with a flender neck or pipe, having a very {mall aperture. It is heated red hot, in order to rarefy the air, and then thrown into water. There will enter as much water into it, as may ferve to fill the vacuum left by the air condenfed by the coldnefs of the wa- ter. It is then fet before the fire again, and the air rufhes out with a furprifing impetuofity, and for a confiderable time. |
F
Fougade, or fougaffe, is a little fourneau, or chamber of a mine made in form of a well, 8 or 40 feet broad, and 10 or 12 deep, which is digged under fome work intended to be blown up. It is charged with facks or barrels of gun- powder, and is fet fire to like other mines witha fauciffe.
Fourneau of amine, /ee chamber.
M Mortife, or mortoife, an incifion into the thick- nefs of a piece of wood, which is to receive ano- ther piece called a tenon. O
422 The History and Memorrsiof the
O Os hyotdes, a bone fo called, becaufe it re- fembles the Greek letter Y. It lies at the root of the tongue. P
Perigeum, or perigee, is a point of the heavens, in which the fun, moon, or any planet is at its leaft poffible diftance from the earth.
Pia mater, a thin and delicate double mem- brane, which lies under the dura mater,. and im- mediately covers the fubftance of the brain,
Sauciffe, or faufage, is. a little roll of pitched cloth, 2 inches in diameter, filled with good powder, and having a flow fufee faftened: to it. It reaches quite to the chamber of the mine, and is ufed to fet it on fire.
Syftole, that motion of the heart, by which, it contracts itfelf. It is oppofite to the diafale, by which it dilates itfelf.
A
GENERAL INDEX
CON TENTS
tua) RD. VOLUM E.
A pag. CORN from Coromandel — 328 Air, the dilatation of it by beiling water confidered. 110 ——— Experiments on the elafticity of it. 359 America, remarks on the navigation of its coafts. 125 Amplitude, what it is. 15 Animalcules, the multiplication of them. io Aftaboras of the ancients thought to be the Tacaze. 137 Aftape of the ancients thoucht to be the Dender. 138 Atbara, @ name given to the Tacaze. id. Atmofphere, the weight of it. 229 Aurora borealis /een at Berlin. 13 B
Baker’s cellar, the fatal effects of fome vapours there. 329 Barometer ob/erved. 225953 T71, 360, 364 — — luminus. 23 — anew one deferibed. 6 —— the method of meafuring the heights of places by
tt. 7 Barometrical obfervations, made at Paris and at Zurick, compared, 177
Baro-
EAN iD: Ex:
; pag: Barometical obfervations upon St. Baum, and the neigh- bouring mountams. _ 142
— infeveral places compared. 229 Batavia, the difference of the milk of European women
there, and that of Negrefles. 12
St. Baum, barometical obfervations made there. 142 Beguignes, the height of it. 142 Berlin, az aurora borealis /een there. 133 Bezoar, obfervations an it. 369 Bernard the hermit, a fort of ff. 326 Bicuiba, @ fort of nut, its virtues. 329 Bitumen contained in the fea-water. 342 Boca Cinca, its latitude. 152 Blood, circulation of it in infeéts. II Bolonia, ‘the difference of its meridian from that of Paris.
I Bombs con/fidered. A Brazil, its pofition in the maps erroneous. 130 Burning-giafles of the ancients. $8 Cc
Cancellus, a fort of fih- 326 Cencers cured. 329 Candace, the common name of the queens of Meroe. 130 Cape Horn, its pofition in the maps erroneous. 128 Cartefian fy/tem of the caufe of gravity vindicated. 201 Carthagena, its latitude. 153 —— longitude. 153, 154,155 Catarrh, an epidemical one, which fucceeded a thaw. 313 Cats, the particular ftrudture of thetr eyes. 192
—— plunged in water, the effect on their eyes confidered. 793 Centring well the objedt-glafs of a telefcope, the neceffity
rey. ss 366 Chama or purr, a fort of frell-fp. 322 Circulation of blood in injects. Ir Cobwebs, how made. 33. Cold, cominz with a fouth wind. 165 Colick eafed 329 Coromandel, a fort of acorn from that country. 328 Crabs-eyes, obfervations on them. 245
Cray-
TyNe Di EX:
pag:
Cray-fith, obfervations on them. 244 Cryftal, 2 differtation on it. 81 of Ifland. 408 Cuttle-fifh, the eggs of it confidered, 87
D
Declination of the needle obferved. 23> 955 105, 17%
: i 315, 360 Dender, a confiderable river flowing into the Nile. 137
thought to be the Aftape of the ancien. 138
Dunkirk, the tides obferved there. 381 E
Echo, @ remarkable one near Verdun. ae
Eclipfe, of the moon at Nuremberg, Genoa, and Mar-
feilles. 316
fun in different countries. 316
Egagropile, what they are.
376 Ethiopia, the maps of that country very erroneous. 131 ay Fire, conjectures on the matter of it. 287 Fire-arms differently charged. 6 Fifhes petrified. 82 Flints, their generation. 8 Fluids, the evaporation of them in cold weather. 305 Flux and reflux of the fea obferved at Dunkirk. 381 Fridtion, light of bodies produced thereby. 3 Frofts, fome effects of them. 305 | seu
Galets, a fort of /lones.
6
Genoa, difference of its meridian from thofe of Marfeilles and Nuremberg. 316 from that of Paris. 317
I Glafles, why the tendereft are leaft fubje& to break by fire.67 Glafs ware of India.
328° VoL. IV. NY. 34, Ddd Gojame
—
INDEX.
pag. Gojame faify /uppofed to be the Meroe of the ancients. 133
Golfo-trifte, obfervations made there. Gravel expelled from the kidnies.
149
Gravity, the Cartefian (/tem of the caufe of sanisadblonedh
201
Gueguere fal/ly /uppofed to be the Meroe of the ancients.133
uerre, @ city of Ethiopia.
Gunpowder, the effec? of it, chiefty im mines.
H
Hearts, two in a pullet. Hogs, injurious to cray-fifh.
141 44.
167 250
Horizon of the fea, the irregularities of its apparent de-
pr cffion. 27 ——— the apparent depreffion of it 146 Horfes, a method of topping them /uddenly. gt
I
Ice, why it melts fafler in vacuo, than in air. — at Copenhagen, its thickne/s in the hard winter F
1709. 167
— the thicknefs of it on the Thames iz 1683. ibid.
Iguana, a fort of American dzard. 12
India, the gla/s-ware of that country. 328
Infects, circulation of the blood in them. Ik
—— an extraordinary fort. 344
—— upon fnails. 376
Tfland, a@ new one near Santerini.. 13, 79 L
Latitude of Bocachica. 152
— Carthagena. 153
— Fort St. Louis in Dostnge 155
»———— Santa Marthe. 150
-——— — Martinico. 156
— Porto-Cabeillo. 149, 150
— Porto-Bello. 151
"59
, ——— St. Thomas Wand. eietets
Lepas,
LAD E x.
ag. Lepas, 2 fort of fhell-fifh. pas Light of bodies produced by friftion. 3 —— of the barometer. 23 —— conjectures on the matter of it. 287 Limat, a river of Switzerland, the augmentation and di- minution of it obferved. 177 Limpet, a fort of fhell-fifh. 322 Longitude of Car:hagena. 153, 154, 155 -—_ Martinico. 157 = Porto-Bello, ISI St. Louis, a fort in St. Domingo, #ts latitude. 155 Lyons, the quantity of rain observed there. 176 M Machine to retain the wheel, which ferves to raife the rammer to drives piles. 23 Malaca, the air dilates otherwife there than in France. 242 Map of @ country, anew way of conft udfing it. 14 Marteilles, difference of its meridian from thofe of Genoa and Nuremberg. 316 St. Marthe, its latitude. 150 Martinico, 7ts latitude. 156 Meroe, conjectures on the pofition of that ifland. 130 governed only by queens. ibid. its true fituation. 332, 135 —— not an ifland but a peninfula. 132 fufpected by fome to be animaginary ifland. 134 ———— its diftance from Syene. 136 ——— its pojition by the climates. 137 ——— by what rivers formed. ibide -——— its figure. 138 _ Milk, the difference between that of European women and Negrefles. 12
Mines, the effed? of gunpowder 1n them. 44 Montpellier, the difference of its meridian from that of Paris. 316 Moon eclipfed at Nuremberg, Genoa, and Marfeilles. 316 Motion pragreffive of feveral /pecies of fhell-fifbes. 321 Mountains, the origin of them. 4
77 Ddd2 Mufcles
| ISNSD*E"X.
pag. Mutcles of the pond. . 346
— alittle fhell-fifh that feeds upon them. 75 Mufick, an extraordinary cure performed by it. 9; 68
N
Needle magnetical, its declination 23, 95, 105, 125, 150, £52, 15551725 315, 360
Negrefles, the difference between their milk and that of European women. 12 Nile, the fources of it where fituated. 133 Nuremberg, the variation of the needle obferved there. 315 — difference of its meridian from thofe of Mar-
feilles and Genoa. 316 O Obiett-glafs of a telefeope, the nece(fity of centring it well. 366 Opticks, /ome facts in them explained. 190 RP Palourde, a@ fort of fhell-fyh. 324 Patella, @ fort of shell-fifh. 322 Pendulum, the length of it at Porto-Bello. 151 ——- Martinico. . 160 Piles, @ machine to retain the wheel, which ferves to raife the rammer to drive them. 23 St. Pilon, darometrical obfervations made there. 142 Pont-briand, the weather. obferved there. 173 Porto-Bello, zts longitude.and latitude. I5t Porto-cabeillo, obfervations made there. 149 Port de Paix, zmSt. Domingo, its lagitude. 160 Progreffive motion of feveral /pecies of frell-fifhes. 321 Pullet wth tio hearts. 167 Purr, a fort of fhell-fiph. 322 R
Rain, the quantity of it obferued. 19, 92,170, 172, 176, ’ q yy / i> “9
35 301, 363 NS)
TN: D E> X,.
Ss Rai pag. Santerini, a new ifland near it. 13,71 Sea, the phyfical hiftory of it. 337 —- nettles, their progreffive motion. ae —- urchins, confider ations on their legs. 168 Seine, why it was not entirely frozen in the bard winter of 1709. 166 Shagreen, an account of it. 165 Shells inclofed in ftone. 66 ——of land and water animals, how they are formed ana grow. 250 Shell-fith, @ fmall one that feeds upon mujiles. 75 ——-— the progreffive motion of feveral of them. 321 Sight, the principal organ of it. 198 Sluices, @ new confiruction of them. 57 Snails, their generation. 83 an infect upon them. 376 Solium, @ worm in thehuman body, It Sourdon, a fort of fhell-fifp. 324 South-fea, @ voyage thither. 125 Spectacles, when difcovered. go Spider, the circulation of blood in its leg. i — obfervations on thefe infeé:. 29 —— their manner of making their webs, 33 —— their manner of catching flies. 7,40 their different foecies. 38 Spinner, a fort of /pider. 4t Stone expelled from the kidneys. 12 Stones of the fea. 6 figured. 332 Sun eclipfed in different countries. 316 — a luminous circle obferved about it. 148 _— the force of its rays in prefjing and pufhing. 66
— the effcét of its heat on a pafte, laid upon a piece of po- lifbed glafs. 68 Supprefiion of urine cured. 12
Switzerland, a great deal of cry/tal found in the mountains there. og
Syene, its pofition, 136 y
IN DE X.
Fz ! : , Page Tacaze, a confiderable river, that flows into the Nile. 137 called alfo Atbora. : 138 thought to be the Aftabora of the ancients. 137 "Fania found in a tench, 344 Talc, obfervations on a fort of it. 408 Tarantula, a /pectes of fpider. 42 Felefcope, the neceffity of centring well its objeét-glafs. 366 Tench, a tenia found in one. 344 Tersadel Fuego, remarks on the navigation of its coafts. 125 Thermometer sbferved. 205 945 1715 357 St. Thomas ifland its latitude. 155 Thunder con/idered. 64 Tides obferved at Dunkirk, 381 ¥: Vapours in a baker’s cellar, the fatal effects of them. 329 Veficaria Marina not the eggs of the cuttle-fifb, 87 Vifion, the principal organ of it. 198 Ww Wett-Indies, ob/ervations made there. 349 Whelk or buccinugh, @ fort of shell-fyp. 325 Winds cbferved. 22 955170, 174 Woman delivered of a child, when above 80 years of age.329 Woodpecker, obfervations on its tongue. 183 Worms voided by /tool. II Wrong-heir, @ fort of fy. 326 Z Zurick, baremetrical obfervations made there. 177
AWN
nN
ran. oD OE xX:
OF
AUTHORS NAMES.
A.
Gricola 245. F. Francifco Almeyda 139. M. Amontons 47, 110 to 113, 115, I19, 121, 124, 225, 227, 305, 306, 307, 359, 366. Archimedes 88. Ariftophanes 88, 89,
B.
M. Baert 381 to 384, 386 to 389, 3@r, 402, 404, 405, 406, 408. Juan de Barros 137. Bartholin 408, 409, 410. Bafilis 135. Cafpar Bauhinus 375. Bellonius 245. ‘Mz. Bernier 9g. M. Bernouli 3, 4. F. de Beze 238, 240, 242. M. l’Abbe Bignon 13, 125. Bion 134. . M. Borelli 183, 187, 188. M, Boudin 328. F. Bourg-
An InvEx of AuTHoRs Names.
F. Bourgnon, 70, 72. Mr. Boyle 4.
F. Brevedent 139. Burnet 77,78.
C.
M. Carré 5, 10, 45, 345.
M. Caffini 4, 5, 27, 74, 105, 125, 142, 149, 167, 215, 316, 331, 366, 381. ,
Cellarius 134.
M. de Chafteuil Gallaup 14.
M. Chevalier 14, 16, 18, 44.
M. Clairambaut 128,
Clufius 334, 374. M. Couplet 153.
v
M. Dalefme 92. Dampier 127.
M. Delifle 128, 129.
M. Defcartes 77, 78,204. Diodorus 131, 138,
M. Dodart to.
M. Felibien8. @
M. de Feriol 70, 165.
F. Feuillée 149, 150, 151, 153, 155) 156, 159, 160, 161.
M. Fontenelle 350,
G.
Gandolphe 168, rég. Gaiflendi 13,
M. Gauteron 305.
M. Geoffroy 68, 244, 328, 338, 344) 369 Gefner 245.
An Invex of AuTHors Names?:
M. des Glos 156.
F, Je Gobiens 139.
F. Nicola Godinho 131.
Pieter Goos 105.
F. Gouye 238, 382.
Dr. Halley 106, 107, 108, 109, 125, 126, 128, 129, Egy 452, 155:
M. des Hayes 156.
Heliodorus 141.
Van Helmont 245, 246, 250.
M. de la Hire 19, 57, 88, 93, 96, 110, 148, 154, 165, pe 173, 179, 190; 220; 328, 331, 356, 361, 363,
08.
4
M. Homberg 11, 12, 29, 64, 65, 66, 67, 103, 166, - 289.
Sieur Houffaye 105, 106, 107.
M. Huygens 20, 45, 97, 98, 99, 100, I0T, 202, 203, 204, 206, 212, 217, 220, 223, 225, 408, 400, 410.
I, M. Jaugeon 165. Jofephus 141.
K. Kepler 215 to 219.
L.
Latantius go.
M. des Landes 12.
M. de la Lanne 13, 14. . F. Laval 27, 28, 74, 75, 141, 145, 147, 236, 237. M. Leibnits 13. -
M. Lemery, jun. 287.
M. Lewenhoeck 11.
M. Littre 167.
F. Hieronymo Lobo 139,
Abbé de Louvois 220.
M, Ludolf 131, 135.
7 Eee M.
An InpEx of AuTHoRS NaMEs,
M.
M. de Mandajor 69.
M. Manfart 24.
M. Maraldi 73, 177, 229, 338.
M. de la Mare 328, 329.
M. Mariotte 113, 170, 198, 199, 207, 208, 238, 239, 243, 310.
Count Marfigli 337 to 344.
Mercator 133.
M. Mery 183, 273, 346, 3475 348.
Mezeray 358.
Monard 373.
N.
Sir Ifaac Newton 20%, 111, 214, 218, 219, 419. M. Nuguet 118, 119, 1206
O. Ortelius 133.
M. Parent 350, 352.
M. de Pas 12.
F. Paulet 140.
M. Perrault 183, 188.
M. Picard 23.
Pifo 12.
M. Plantade 167.
Plautus go.
Pliny 89, 131, 1355136, 1375 139) 140, 141- Sieur Poncet 139, 140.
M. la Comte de Pontbriand 173, 175, 301. M. de Pontchartrain 382.
M. Poupart 84, 321, 348.
Prolemy 136, 138.
An Inpex of AuTuors NAMES,
R, M. de Reaumur 75,76, 77, 250, 321, 322, 323, 348, 6
379. M. Richer 152. M. du Roule 132, 137, 139, 140.
S.
Marquis Salvago 229, 231.
M. Saulmon, 6, 7, 8, 87, 334.
M. Saurin 201, 295.
M. Sauveur 328.
M. John Scheuckzer, 77, 78, 79, 80, 177, 178, 180, 132, 236, 33%, 333, 334, 3372 363 to 366.
M. john James Scheuchzer 73, 74, 81, 82, 83, 3355 336, 337.
Steno 77, 78.
S:rabo 136, 137, 138, 139, 141. aL;
F. Tachard 328.
Tavernier 370, 373.
Abbe Teinturier 331.
F, Balthazar Tellez 131, 134, 135. M. du Torar 173, 361.
M. Tournefort 66, 334.
M. de Vauban 19, 44.
M: Jean Verdois 328.
M du Verney 84, 85.
M. de la Verune 125, 129. Ifaac Voffius 134.
Ww. Woodward 77, 78. M. Wurtzelbaur 315. Ee 2
- BOOKS Printed for J. and P. Knapton, at the Crown in Ludgate-ftreet.
NHE WORKS of Samus Crarke, D.D. late ReCtor of St. Fames’s, Weftminfter. Witha Preface, giving fome Account of the Life, Writings, and Character of the Author, by Benjamin Lord Bi- thop of Vinchefter. In Four Volumes, Folio. A {mall Number is printed on Large Paper.
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