der proceeds to its maximum, the hygroscope moves from 80 to 100, and fometimes a little farther. Then we have alfo a certain proof that extreme moisture exists in the air; for every folid body expofed to it is wet. But it is only in that moment we can depend on extreme moisture exifting; for, if in the other defcribed ftages of the phænomenon, the appearance of water on the furface of fome folids has proceeded from a spontaneous precipitation in the air, all the other folids ought to have been wet; but they only become wer in a certain fucceffion, and in the mean time the flip of quill, and all the other above mentioned hygroscopes, move more and more towards their point 100, in fign of moisture increasing in the air. Confequently (as I had concluded from my first obfervations), inftead of having in dew an hygroscopic standard for the hygrometer, we have in its phænomena many circumstances which will only be explained with the affiftance of that inftrument.'

The general conclufion is,

• The maximum of evaporation in a mafs of inclofed air is far from being identical with the maximum of moisture; this being dependent alfo, even to a very great degree, on the temperature of the Space, fuppofed to be the fame, or nearly fo, as that of the wa ter which evaporates in it. Moisture may arrive to its extreme in an inclofed air, if that common temperature is near the freezing point; but it becomes lefs and lefs, even to a very dry ftate, as that temperature rifes, though the product of evaporation, thereby increafing, continues to be at its different maxima, correfpondent to the different temperatures."

The different claffes of hygrofcopes are either flips or threads; in other words, laminæ cut across the fibres of animal or vegetable fubftances; or thefe fubftances divided lengthways. The former are most steady in their march, for the latter, as analogous to the twisted ftrings, are found to be anomalous in their motions, and shortened by the moisture which at other periods lengthens them. The reft of the paper relates to the formation of hygrometrical fcales, and the different marches of flips and threads. Like many of M. de Luc's works, it is too copious. It is needlefs to relate experiments which have failed; ideas, which been given up; and fancies which a little reflection has fhown to be vifionary. On the whole, those who have read our author's former work, and M. de Sauffure's effays, will not think that much is added to our knowledge of hygrometry from the lucubrations before us.

Art. II. On the Production of Ambergris. A Communication from the Committee of Council appointed for the Confideration of all Matters relating to Trade and Foreign Plantations; with a prefatory Letter from William Fawkenes, Efq.

to

to Sir Jofeph Banks, Bart. P. R. S.-Three hundred and fixty two ounces of ambergris were found in one whale, and it is certainly the cause or effect of disease. Cow whales are chiefly found in low latitudes, where they feemingly go to calve. Whales, our author tells us, often are feen in fcools; he has feen from 15 to perhaps 1000 together.' This ambergris was fold for nineteen thillings and nine pence per ounce: about one half was bought for exportation to Turkey, Germany, and France.

Art. III. Obfervations on the Affinity between Bafaltes and Granite. By Thomas Beddoes, M. D.; communicated by Sir Jofeph Banks, Bart. P. R. S.-Dr. Beddoes, we think, fails in almoft every step of his proof. He fees granite in every ftone, where he can difcern mica and feld fpar, and where, as in one inftance, he fancies that he perceives quartz (note to p. 51.) In general, he does not advert to the flight connection between lavas and bafaltes; the real difference between ftones, compounded of mica, &c. where black and white fhining fpots are difcernible, and the true compacted granites; between pieces of real granite, accidentally combined with tufa or lava, and this fubftance in a fused ftate. Thefe different circumftances will, in general, explain the approximations which our author has adduced; though it would have been fufficient to have obferved, that Dr.Beddoes' ideas feem to have been taken wholly from fpecimens: he appears never to have examined granite, bafaltic or volcanic countries, and fometimes not to have attended with fufficient accuracy to defcriptions. He would not surely, unless blinded by his eagerness in the pursuit of an hypothesis, have told us that, in the ufual fituations, bafaltes takes the place of granite, fupporting fucceffively fchiftus and limeftone? Bafaltes are often found, particularly in the Giant's Causeway, and in fome of the bafaltic countries in Germany, refting on limestone. If our author would attend to Sauffure's Travels, and Dolmieu's Memoir, in a late volume of the Journal de Phyfique*, he would find that much the greater part of his doctrine, and of course of his conclufions, was vifionary.

Art. IV. Nebulous Stars, properly fo called. By William Herfchell, LL. D. F. R. S.-The apparent nebulæ, refolvable by good telescopes, were found to confift of the accumulated light of fixed stars, and it was no unprobable supposition, that the more diftant ones were of the fame kind. Numerous phanomena have, however, occurred to our very able and enterpiling obferver, to render this conclufion doubtful. In many inftances, the ftar has been in the center, and the nebulofity

• Shortly noticed in our Foreign Intelligence of last month.

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around

around it fo diluted, faint, and equabie, that he hesitates not to fuppofe it luminous matter connected with the ftar, collected perhaps from myriads of rays darted into the vaft expanfe, and defigned probably for the formation or regeneration of a fun. This vaft and fublime idea is highly interesting, and fills the mind with the most awful views of a fuperintending providence. Yet, though the object is fpecious, we must be allowed to hesitate; and, as it is a well founded rule in philofophy, to admit of no other caufes for phænomena than are neceflary, we may be allowed to fuggeft, that it is poflible, on a starry nebulosity, too diftant to be refolvable, to have by ac cident a ftar in the line drawn from the center to the eye, as there are certainly stars which coincide with other points of a diftant nebula. Thefe nebulous ftars alfo are the very small ones; and we fufpect, that even Mr. Herschell's skill cannot determine, in fuch vaft distances, that the one is equally near with the other. Let us attend, however, to his conclufions,

But what a field of novelty is here opened to our conception! a fhining fluid, of a brightnefs fufficient to reach us from the remote region of a ftar of the 8th, 9th, 10th, 11th, or 12th, magnitude, and of an extent fo contiderable as to take up 3, 4, 5, cr 6 minutes in diameter! Can we compare it to the corufcations of the electrical fluid in the aurora borealis? Or to the more magnificent cone of the zodiacal light, as we fee it in fpring or autumn? The latter, notwithstanding I have obferved it to reach at leaft go degrees from the fun, is yet of fo little extent and brightness as probably not to be perceived even by the inhabitants of Saturn or the Georgian planet, and must be utterly invifible at the remoteness of the nearelt fixed ftar.

More extenfive views may be derived from this proof of the existence of a shining matter. Perhaps it has been too hastily furmifed that all milky nebulofity, of which there is so much in the heavens, is owing to ftarlight only. Thefe nebulous stars may ferve as a clue to unravel other myfterious phænomena. If the fhining fluid that furrounds them is not fo effentially connected with thefe nebulous ftars but that it can alfo exist without them, which. feems to be fufficiently probable, and will be examined hereafter, we may with great facility explain that very extenfive, telescopic nebulosity, which, as I mentioned before, is expanded over more than fixty degrees of the heavens, about the constellation of Orion; a luminous matter accounting much better for it than clustering ftars at a distance. In this cafe we may alfo pretty nearly guefs at its fituation, which mult commence fomewhere about the range of the ftars of the 7th magnitude; or a little farther from us, and extend unequally in fome places, perhaps to the regions of thofe of the 9th, 10th, 11th, and 12th. The foundation for this furmife

is, that, not unlikely, fome of the fixed ftars that happen to be fituated in a more condenfed part of it, or that perhaps by their own attraction draw together fome quantity of this fluid, greater than what they are intitled to by their fituation in it, will, of courfe, affume the appearance of cloudy ftars; and many of those I have named are either in this ftratum of lumineus matter, or very near it.

We have faid above, that in nebulous ftars the existence of the thining fluid does not feem to be fo effentially connected with the central points that it might not also exift without them. For this opinion we may affign feveral reafons. One of them is the great refemblance between the chevelure of these stars and the diffused extenfive nebulofity mentioned before, which reader it highly p:obable that they are of the fame nature. Now, if this be admitted, the feparate exiftence of the luminous matter, or its independence on a central ftar, is fully proved. We may also judge, very confidently, that the light of this fhining fluid is no kind of reflection from the ftar in the center; for, as we have already obferved, reflected light could never reach us at the great distance we are from fuch objects. Befides, how impenetrable would be an atmosphere of a fufficient density to reflect fo great a quamity of light? And yet we obferve, that the outward parts of the chevelure are nearly as bright as thofe that are clofe to the ftar; fo that this fuppofed atmosphere ought to give no obstruction to the paffage of the central rays. If, therefore, this matter is felf-lumincus, it feems more fit to produce a ftar by its condenfation than to depend on the ftar for its existence.'

On the whole, in whatever light we view the fubject, it muft lower the pride of grovelling terreftrial mortals, who think the univerfe their own, and dare to dictate to the unverfal Lord what he ought to do, or explain minutely what he has done.

Art. V. Abstract of a Register of the Barometer, Thermometer, and Rain, at Lyndon in Rutland. By Thomas Barker, Efq. with the Rain in Hampshire and Surrey; for the year 1789. Communicated by Thomas White, Efq. F. R. S.The thermometer was from 78 to 131; the mean heat of April 48. The barometer from 30.25 to 28; each cecurring in January. The rain at Lyndon was 28.002; at Selborne 42.00; at Fyfield 35.61 inches. Our author compares the cold of the winter 1740 with the prefent, and finds the effect of the former more confiderable; but, in the influence on vegetables, he does not advert to the previous wet autumn of 1739. Fish were lefs commonly killed in ponds in 1740, which he very properly attributes to this cause.

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Art. VI.

Art. VI. Obfervations on certain horny Excrefcences of the human Body. By Everard Home, Efq. F. R. S.-Our author's lift of these phænomena is very incomplete; and he attributes horn to an extraordinary and fuperfluous effort of nature to extend the cuticle over a wound. The gritty fubftance found in the previous fwelling, from the bottom of which the horn ufually rifes, he does not explain. The fubject is yet very little understood; and it is firft necessary to enquire what the nature of this horny fubftance is, and how it is connected with the bones. Our author has not facts fufficient before him; nor is it, for this reason, surprising that his difquifition ends in words.

Art. VII. Confiderations on the Convenience of measuring an Arch of the Meridian, and of the Parallel of Longitude, having the Obfervatory of Geneva for their common Interfection. By Mark Auguftus Pictet, Profeffor of Philofophy in the Academy of Geneva; in a Letter to Sir Jofeph Banks, Bart. P. R. S.-The polar and equatorial diameters of the earth, as afcertained by different menfurations of a degree of the meridian, differ greatly. Thefe numbers are fo diftant as

and for the difference between the two diameters; and we now know that many irregularities must have arifen from the hygrofcopic or pyrometrical affinities of the fubftances employed to measure the bafe. Since general Le Roy's experiments, in the late attempt, greater accuracy will be at tained. It is neceflary, however, to proceed anew with the mensuration; and M. Pictet gives many reafons, generally fas tisfactory ones, for preferring the neighbourhood of Geneva for the operation. He propofes to measure 84" of the arch, and the parallel of longitude eastward.

'The re-union of the two measurements (of latitude and lon gitude) in the fame fpot, is an advantageous circumstance; and the more fo, if we confider that this fpot lies between the 45th and 46th degree, that is, in the mean latitude between the pole and the equator, near which latitude the mean radius of the earth takes place in the well founded fuppofition of its being a spheroid. This radius, found by the most accurate measurement hitherto attempted, would become a ftandard, and to which the refults of the equatorial and northern measurements being compared, the true figure of the earth would be the better afcertained.

The pofition or relative longitude of the meridian of Geneva is well determined by a great number of obferved immersions and emerfions of the fatellites of Jupiter, and by fome ocultation of flars by the moon. Thefe obfervations were performed by the late profeffor J. H. Mallet, Mr. J. Trembley, and myself. The greater part of them are already calculated, and their mean refult