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It appears, therefore, that mineral expect, from the generosity and gratiwaters may not only be perfectly imi- tude of the public.” tated, but may even be rendered more Mr. Magellan next enters on the eshcacious, wholesome, and agreeable, subject of Ludiometers, or instruments than the natural ones. We can not for meafuring the goodness of respi. only make them stronger of the folid rabie air. Dr. Prieitley discovered ingredients, if occasion requires, but that if nitroust, and common or respithey may be made to imbibe double rable air, are mixed together, they will, the quantity of fixed or sulphureous after union, occupy less space than air, that the natural waters are ever they did before; and that their confound to contain, as our author hath traction or diminution of buik is amply shown.

greater as the common air is purer. Mr. Magellan then proceeds to give Several contrivances have been proposed (from Bergman, &c.) the recipes for by philosophers, for measuring this making the principal of those mineral contraction; but none seem to answer waters; specifying the feveral ingre- better than the eudiometers invented by dients, and their quantities, with pro- our ingenious author, and which are per directions for the processes. But described at length in the present pamas it would, perhaps, be unfair to phlet. We cannot, in a work of this tranfcribe them, we must refer the in- nature, follow him in his defcriptions quisitive reader to the work itself*. of these instruments, for want of room;

We shall conclude this part of our and because they continually refer to account of Mr. Magellan's work with plates. In former editions of this observing, after Dr. Priestley, that pamphlet (for this is the third, though “ by means of these discoveries, the the work has not yet been noticed in trouble and expence of importing the any Review) Mr. Magellan described foreign mineral waters may now be three different eudiometers: but in the faved.” The trouble, indeed, we have present, he has supprefled the account reason to think, is fometimes faved; of one of them, as being too complex but the public is as yet very little be- and coftly, “ fimplicity in philofophi. nefited thereby, as the artificial waters cal experiments (as the author jultly are, at least, in some instances, sold for observes) and cheapness of the inftruthe real ones, and at the same price. It ments required for their proceiles, is probable, however, that if the arti- being two of the most desirable circumficial waters were sold as such, the stances in the investigation of natural public is not as yet fufficiently diveíted phenomena.” The first of these inof prejudice to give them the preference. itruments confits of a glass, tube 12 or These prejudices, however, the work 15 inches long, and of an equal diabefore us will tend to remove.

A glafs ftopple is fitted to the We cannot withhold the concluding upper end; and a hollow glass veifel, paragraph of this part of Mr. Magellan's of a forewhat globular form, to the ingenious pamphlet: “. Put this being lower, but by means of a neck, so as a new branch of medical knowledge, to form a right angle with the tube. which I am not qualified to , ursue, 1 To this resiel two small and equal heartily will, that some young phy- vials are fitted. fician, endued with talents equal to The ftopple and vials being taken the talk, and actuated by a warm zeal out, the eudiometer is to be filled with for the benefit of mankind, should ap- water, its lower part, qreren the whole ply himself to this new branch of the instrument, being immersed in the same medical profession; in which, no fluid. Close its mouth with the doubt, he will meet with all the en- stopple. Then fill one of the vials ccuragement he may have a right to with nitrous air, the other with the

air * A Treatise on Mineral Waters, both natural and artificial, has lately been published by Die Elliot; which allo contains the recipes for making the artificial waters.

+ Nitrous air may be obtaised by diffolving iron or copper in spirit of nitre (aqua fertis.) The air flies oil, and may be caught by means of a bladder, or other proper contrivancobThe spirit of altre ihould be diluted with almost thrice its weight of water.

meter.

air whose purity is to be ascertained, These defcriptions will, perhaps, be and affix them to the instrument. The fufficient to give the reader a general stopple may then be taken out again. idea of our author's eudiometers: but, The vials have hitherto been superior for a more ample account of them, as to the globular vessel of the Eudiometer. well as for a number of particulars But that refsel being now turned, and and circumstances necessary to be obthe vials, of course, being beneath it, served in making the experiments, we the airs which they contain, will, by must refer him to the work itself. the less specific gravity, rise above the The invention of eudiometers is a water and remain in the upper part of very important acquisition to natural the vessel, where they will mix. Their philofophy. By means of these inunion may be expedited by gently agi- struments, we are enabled to measure tating the vessel. This being done, the purity of the air (so far at least as the tube is to be accurately filled with its phlogistication is concerned) with water, and shut with the stopple. And almost as great exactness as we measure then being fufficiently inclined for- its weight by the barometer, or its heat ward, the air will quit the globular by the thermometer. Not to mention vefcl

, and rise to the top of the tube, the great advantages which will be dedriving downwards a proportionable rived from them by the experiments quantity of water.

in Natural Philosophy, we can (to use The space which the two vials of the words of our author) by this means air would have occupied in the tube form a proper judgment concerning is known by means of a graduated those places where people may be able ruler, on which it is marked. And to liie without danger of hurting their from the difference between that and constitutions, by breathing, and being the space which the mixed airs now continually furrounded by noxious air; poilers, the parity of the respirabie air which they have not yet been able to on which the trial was made is de distinguish from the inost wholesome, ternined.

except by a long and too late expeOur author's other cudiometer is ftill rience.” Previous to building houses, more fiinple. It consists of a Itraight of any new situation, recourse will, in glass tube, of an uniform diameter, and future, be had to the eudiometer, to about one or two feet long, ground discover whether or not such situation air-tight, to the neck of a glass globe, is healthful: and were this only adabout 3 inches in diameter, with a vantage to be derived from these inhole, and a glass itopple. A ftopple is ítruments it would be great indeed! also fitted to the other end of the tube, On this occasion, the author very the mouth of which resembles a funnel. properly addresses himself to Dr.

The initrument being filled with Priestley, in the following strain: water, and closed at the globular end, “ The happy discorery which you is to be held in a vertical position, have made for the general benefit of nianwith the funnel part open, and under kind, and perhaps of almost the whole water. A vial of each kind of air is animal creation of this globe, by findthen to be thrown into it. These ing that nitrous air is a true toft of the purising through the water in the tube, rity of rejsirable air, which is absolutemix together in the globular part; and ly necellary to life, and without which after the expansion arising from the it is presently extinct, gives a moit heat generated by their mixture is striking instance of the blameable forover, the atopple must be put into the ness of mankind to pay a proper attenmouth of the instrument, which is then tion to those objects, the importance to be inverted. The ftopple of the of which is infinitely superior to that globuiar part nust now be taken out, of the numerous triling novelties, i liat part being under water; and the which fo often spread, with prodigious space which the air occupies in the tube rapidity, through remote provinces, measured, by means of a graduated and even to the molt diitint countries ruler, as was defcribed before.

of the earth."

In that part of our author's work he had the generosity of availing himself, which treats of Eudiometers, he has by disclofing it to the public, to exexamined, and very ably refuted feve- pose my poor eudiometers. If so, be ral animadversions of Mr. Cavallo, on was guilty of an unhappy oversight, inhis instruments above described. He deed! infinuates, and feemingly with justice, Now, if we combine with this that Mr. Cavallo has been improperly probable fact, the peculiar advantage influenced to establith the credit of Mr. that Mr. Carallo has endeavoured to Fontana's eudiometer, by depreciating draw from the anguarded experiments be his*. He certainly appears to write came to see in a friendly manner at my with prejudice; and in his zeal againit lodgings:--when it is considered, that our author, has fallen into blunders I was treating him with the most friend. which one would imagine a man of his ly regard, whilft he was mustering togeacknowledged abilities could hardly ther such a heap of doughty arguments have been guilty of. He also appears againít my poor eudiometers: and that to have acted disingenuously and un- I have continued ever since the farne candidly, as the following quotation behaviour towards him, whenever we will thew :

met together, without his having ut“ There is something remarkable tered a single word of what he was doin what Mr. Cavallo says (p. 327) viz. ing, or ever afterwards making the least that I acknow ledged to him, that I had excuse for what he had done :- I candespaired of obtaining a constant result

not help judging these circumstances from these experiments with nitrous deserve to be known, that the public air. But, after my having acknow- may form a true estimate of the whole," ledged the fame uncertainty to all the Mr. Magellan is certainly an ingeworld, in the very first (page 26) and nious, and what is more, an useful man: following editions of this letter; one and, if we are rightly informed, his may be apt to think, that Mr. Cavallo fimplicity of manners, and goodness of has overlooked it; and that he miftook heart, are at least equal to his ingenui. what I had said to him, as if it was a ty. Such a man ought not to be wansecret or a friendly confidence, of which tonly persecuted.

* See Mr. Cavallo's Treatise on different kinds of Air.

A S T R O N O M Y. ACCOUNT OF THE MEASURES TAKEN BY SOME PERSONS ABROAD, TO PERFECT THE THEORY OF THE MOTIONS OF THE GEOR

GIUM SIDUS. EXTRACTED FROM A LETTER OF M. DE LA LANDE TO THE AUTHORS OF

THE JOURNAL DES SCAVANS, PRINTED PARIS. GENTLEMEN, I N your Journal for February, 1782, seconds, 98151; the place of the aphe

you have given the elements of the lion, on the 2: it of December, 1581, circular orbit which I had calculated 11° 23° 22' 58"; the true anomaly of for the new planet which has been dif- the planet, at 18" 5' 40", mean time covered by Mr. Herschel. That at l'aris, 97° 29' 19'', and its mean calculation was found to err z' about anomaly 102° 52'7". the beginning of the prefent year; and M. bode having remarked, in the the errors were such as thewed that the cpheineris of Berlin for 1784, that the planet had accelerated its motion. A- tiar, No.964, of Mayor's catalogue, hout that time M. DE LA PLACE, by could not well be any thing else than an analytical method of his own inven- the Georgium Sidus, as that itar cannot tion, calculated the elements of its el- be now found in the place where May

He makes the grater Er observed it, pains have been taken feini-axe 19.0818 semi-diameters of the to examine the manuscripts of that ceearth's orbit; the half-excentricity, in lebrated astronomer, which are pre

4

served

liptic orbit.

served at Gottingen; and the date of orbit of this new planet as already the observation on which the position known to a very considerable degree of that star was grounded, is Septem- of exaciness. ber the 25th, 1756, at 10" 21' 18";

From this observation of MAYER's, mean time, at Paris; and gives its lon- we find, with great exactness, the pogitude, at that time, 11' 16' 37'43", fition of the node for the year 1781, and its latitude 43' 23",

to be II 12° 47', and the inclination This observation, at once fo com- of the orbit, to the plane of the eclipplete and circumstantial, and found by tic, 46° 13'. The greatest equation a kind of accident which we could not is 5° 27'17'; and is at 33° 24' 31" even have hoped for, is near 25 years of the mean anomaly. At the time prior to that of Mr. HERSCHEL; and when Mayer observed it, it was exis found to accord very exactly with ceeding near its aphelion; and it is computations made from the elements now not far from being at its mean of M. DE LA PLACE, recited above; distance from the fun. and, therefore, we may look on the

TO THE EDITOR OF THE LONDON MAGAZINE.
SIR,
I

Am happy to find your Magazine open to Mathematical Correspondence.

To see a miscellany amply supported and supplied with the daily improvements in that moft useful science has long been my most ardent with, and I Ihould esteem it a peculiar happiness if any communication of mine should be thought to merit a place in it, or tend to the advancement of science.

I fubmit the following Observations on the late Lunar Eclipse to your des kermination, whether they are worthy insertion in your next. Sept. 19, 1783.

W. G. OBSERVATIONS ON THE LUNAR ECLIPSE WHICH HAPPENED

ŏ SEPT. 10, 1783:

TAKEN IN TOWER-STE E T. THE 'HE time-keeper was regulated to my own meridian by the mean of the

transits of the two limbs of the sun on the same day; aliowing 3' 12'' for the equation of time. Sept. 10, mean tiine. gh 35m 0" the moon had a cloudy appearance, especially on the N. E. limb.

the cloudiness much increased. 9 40 46 the eclipse began on the limb between the two radü which pals

through Grimaldus and Infula Ventorum. 9 42

cloudy.
9 45

ditto.
the convex of darkness approaching Insula Vextorum,
vet approaching
cloudy.

clearing off.
54 33 Copernicus immergirig.
56 20 ditto quite in the Ihadow.
7 50 Insula in Maré l'aporum and Tycho both immerging.

o I judged the moon to be half obscured.
27 43 Mare Criium 3 of the convex of darkness from the northern horn,
37 30 approaching total darkness.
33 oditto,

o ditto.
o total dark.
Sometime during the total darkness the moon suite disappeared

by the fogginess of the air.
Loxd, Mag, Oct. 1783,

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43 very light on the N. E. limb.

53 total darkness ended.
24 23 Grimaldus energing.
28 43 center of Infila Ventorum.

cloudy.
35

Night ricw of Copernicus emerging.
cloudy.

laft of Tycho emerging.
48 13 a right line from Injula Ventorum through Tycho will touch the

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Μ Ε DICI Ν Ε. TO THE EDITOR OF THE LONDON MAGAZINE. SIR, CEVERAL years ago, in attempting terwards that if I but opened my mouth

to * piece of one of my large under teeth, ly disappeared though it was at fint by which means the medullary part of plainly visible; and this, anil a mere the tooth became distinctly visible. I particular examination of its form and felt no inconrenience from it for a colour, convinced me that it was a lilong time.

But about two months ving insect. I im.nediately mixed up ago it began to trouble me; and, on a little calomel with mucillage of gum examination, the hole became gradual- arabic into a paite, and filled up the ly enlarged. Examining the tooth by tooth with it. The pain ccale in means of a looking-glais, I faw, among about a quarter of an hour, and on the medulla, a fmall portion of fub- searching the tooth afterwards, the 1tance of a black cocur, which I at first worm was found deal, and taken out. thought mig lit have buin part of the I have not lince felt the least unealinefs food that had bageri there. I endea- in the tooth; and, therefore, conclude voured to remote it. But not being that the pain had been caused by the able to do it hv the means which I infect, which the mercury killed. then usel, conclure:t it to be rocher a I remember, when quite a boy, to decayed splinter of the tooth.

have heard a tooth-drawer in the coun. deavouring rematedlsfreund ti gurt trv affirm that the tooth-ach was occait out, I fornuti: a vien as I touch. fored by a worm which preved on the ed it with a needle or other inftru- ner e of the tooth, and that the decay mene, it elade iny attempt, and funk of the teeth was oving, at least in ma. beneath the marriw. I obienied af- ny cases, to the luine insect *. I have

in en

not

* lle derived the cure of the footh-ach byamila forti', and the preferration of the teeth by tobacco,

from this theory,

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