Misfortune had only to form her claim, in order to found her right to the ufe of his purfe, or the exercise of his talents. His houfe was an afylum for the unhappy, beyond what a regard to personal convenience would have allowed; and his income was diftributed in the fupport of his inmates, to an extent greater than general prudence would have permitted. The moft honourable teftimony to his moral and focial character, is the cordial efteem of his friends and acquaintances. He was known by no man by whom his lofs was not regretted." P. 188.

After defcribing the man, Dr. A. proceeds to characterize his works, which tafk he alfo performs with a general foundnefs of judgment, with elegance of tafte, and confiderable felicity of language. One hyper-Johnsonic word, obtenebration, comes in rather awkwardly in his eftimate of the profe ftyle of his author, which in other refpects exhibits a good example of merits fimilar to thofe he celebrates. It abounds with proofs of accurate perception and juft difcrimination. We could with pleasure increase the number of our extracts from this account of a man, of whom our age is justly proud. but that we have already extended the article as far as is convenient. Dr. Anderson concludes the Life of Johnson with characters of him, taken from other authors, but none of them in accuracy or merit furpaffing his own; and it may perhaps be thought extraordinary, as it certainly is meritorious, that from a North-Briton and a Whig, this great author, who, it must be owned, gave many unreasonable provocations to both, fhould obtain fo juft a tribute to his merits, fo candid an account of his failings, and, for the most part, fo unexceptionable a history of his life and writings.

ART. VII. Philofophical Tranfactions of the Royal Swiety of London. For the Year 1795. Part. I. 4to. 11s. Elmily. 1795.

As man is formed for fociety, it is in this ftate only that his

faculties are called into action, and his exertions meet with due fuccefs and reward. By fociety his manners become polifhed, and by competition thofe powers for invention and improvement are roufed and rendered productive, which in folitude would either be dormant, or for want of due nourishment would languish and die away. Such reflections naturally occur upon entering on an examination of the publication now before us, as the articles contained in it afford a ftrong proof of the utility of combined exertion, and of the propriety of uni

ting, at ftated periods, the endeavours of philofophers to extend and improve human knowledge. The articles fucceed in the following order:

I. The Croonian Lecture on mufcular Motion. By Everard Home, F. R. S. Read, November 13, 1794. P. 1-23.

One Plate.

Several eminent modern philofophers have endeavoured to afcertain in what part of the eye the power refides, by which it accommodates itfelf to a diftinét view of objects at different diftances. The paper before us is the fourth on the subject, which we have had occafion to examine*; for the whole of its tendency is to determine this curious and important point; and in the prosecution of it, the ingenuity, fcience, and perfeverance of Mr. Home, Mr. Ramfden, and Sir Henry Englefield, were happily united.

While Mr. Home's mind was ftrongly impreffed with Mr. J. Hunter's Experiments on the cryftalline lens, and some opinions of Mr. Ramfden, refpecting the ufe of that part, the following opportunity, highly favourable for profecuting an enquiry into the fubject occurred: A young man came into St. George's Hofpital with a cataract in the right eye, and as he cheerfully fubmitted to an operation, he was put under the care of Mr. Home for that purpose.

"In performing the operation," fays Mr. H. "the cryftalline lens was very readily extracted, and the union of the wound in the cornea took place unattended by inflammation, fo that the eye fuffered the smallest degree of injury that can attend so severe an operation; thefe circumftances it is proper to mention, as they contributed to render the patient a more favourable fubject of experiment.

"The man's name was Benjamin Clerk; he was a fea-faring man, 21 years of age, and in perfect health. Both his eyes were free from complaint till about the 11th of April, 1793, at which time he was on a voyage home from the Eaft-Indies; a fudden mift or dimness appeared before his right eye; this increased very rapidly, and on the 18th of the fame month the fight was entirely obfcured. This crystalline humour was extracted on the 25th of November; and 27 days after the operation, the eye was fo far recovered, as to admit of obfervations and experiments being made upon it.

"In this man we had all the circumftances combined, which feemed to be required to determine how far the cryftalline lens was the principal agent in adjufting the eye. The man himself was in health, young, intelligent, and his left eye perfect; the other had been an uncommonly fhort time in a difeafed ftate, and appeared to be free from every other defect but the lofs of the cryftalline lens."

* See Brit. Crit, vol. iv. 250, and vol. v. pp. 340 and 600.

After

After this account of the man, experiments are related, made by the three gentlemen mentioned above. Objects being prefented both to the perfect and imperfect eye, affifted by glaffes of different focal lengths, it was found that the imperfect eye not only had the power of adjusting itself to diftinct vision at different diftances, but that its range of adjuftment, when the two eyes were made to fee at nearly the fame focal distance, exceeded that of the perfect eye. The facts and arguments adduced in Mr. Hunter's letter on this fubject, publifhed in the volume of the Philofophical Tranfactions for 1794, alfo convinced them, that the power of the eye, by which it is adjusted to fee at different diftances, does not arife from a change in the general form of the globe of the eye. The power was therefore to be fought for in another part of the eye, and the cornea next became the object of examination.

A portion of the cornea being removed from the eye of a perfon of 40 years of age, two days after death, Mr. Home found by experiment, that it was elastic; and proceeding in the anatomical investigation, he found that the cornea is compofed of two portions; the external, a continuation of the tendons of the four straight mufcles of the eye; the other a continuation of the fclerotic coat, and the uniting medium between them, not unlike very fine cellular membrane. He alfo afcertained, that the cornea grows thicker towards the centre; that this increase of thickness is principally in the external lamina; and that in ftretching the cornea, the central part yields most readily to the powers applied.

The cornea was now examined, while the eye was adapting itfelf to different distances. This was done by means of an apparatus, contrived by Mr. Ramfden, in which the head was kept as fteadily as poffible, and the lateral part of the front of the cornea was viewed through a fixed microfcope, furnished with a micrometer wire in the focus of the eye glafs, fo placed as accurately to oppose the anterior edge of the cornea. gentlemen already mentioned thus made experiments on each other's eyes; and from the whole Mr. Home concludes,

The

"That in changing the focus of the eye from feeing with parallel rays to a near distance, there is a vifible alteration produced in the figure of the cornea, rendering it more couvex: and when the eye is again adapted to parallel rays, the alteration by which the cornea is brought back to its former ftate, is equally visible."

Having established thefe facts, Mr. Home proceeds to make fome obfervations upon the mufcular and elaftic power, by which fo very curious an effect as the adjuftment of the eye is produced. The ftate of the eye fitted for parallel rays, he con

fiders as the effect of elafticity in the cornea, but that for nearer diftances, which is lefs frequently wanted, as the effect of mufcular action. Thefe opinions he fupports by a series of judicious obfervations upon the eye itfelf, and upon elaftic and mufcular action in general. A detail of thefe, however, cannot be expected in this place. In our number for April last, we announced the difcovery, which to us appeared important; and we truft we have now afforded to our readers that fatisfaction which we gave them reafon to expect.

II. The Bakerian Lecture. Obfervations on the Theory of the Motion and Refiftance of Fluids; with a Defcription of the Conftruction of Experiments, in order to obtain fome fundamental Principles. By the Rev. Samuel Vince, A. M. F. R. S. Read, November 27, 1794. P. 24-45. Three Plates.

We deem it unneceffary to state the difficulties attending an inquiry into the nature of the motion and refiftance of fluids. They are well known to those who have made any confiderable advancement in mathematical philofophy, and, as the title of the paper before us implies, a theory is ftill wanting, which will bear the teft of experiment. In this fubject the keen penetration and perfeverance even of Sir Ifaac Newton, D. Bernouilli, D'Alembert, Buat, and others, have not fucceeded; and this failure of fuccefs is to be attributed to a want of knowledge of the conftitution of fluids, which perhaps the moft ftrenuous endeavours of man will not be able entirely to fupply.

The beginning of the paper before us confifts of clear and judicious reafoning on the nature of fluids, but it tends only to enforce a conviction that fundamental principles are not to be obtained, except from experiments; a conviction under which Sir Ifaac Newton and others have confidered the fubject. Mr. Vince next confines his attention to the time of emptying a veffel through an orifice at the bottom, and the determination of the velocity of the effluent fluid, under various circumftances, by theory and by experiment. Thefe determinations lead him to conclude, either that the common principles of motion cannot be applied to fluids, and that the agreement is accidental; or, that under certain circumstances, and reftrictions the application is juft. Which of thefe is the cafe, is not per haps eafy for the mind to fatisfy itfelf about."

Having examined the circumftances which he propofed, res fpecting the emptying of veffels, Mr. V. proceeds to a confide ration of the doctrine of the refiftance of bodies moving in fluids. This doctrine, as it has hitherto been admitted for

want of a better, is evidently defective. For it is founded upon this fuppofition, that when a body moves in a fluid, each particle acts upon it undisturbed by the reft, or the fluid is conceived to act as if each particle, after the ftroke, were annihilated. Between this theory and experiment there is confequently very little agreement, and therefore Mr. V. conftructed a machine, of which he has here given a defcription and a figure; and by this machine, he says, "the abfolute quantity of reliftance in all cafes may be very accurately determined, and the law of its variation under different degrees of velocity."

We defer offering any remark on this machine, as Mr. V. concludes the paper with a promife of laying before the Royal Society, at a future opportunity, an account of all the experiments which can be made by it, fome of which he believes have never yet been attempted.

II. On the Nature and Conftruction of the Sun and fixed Stars. By William Herfchel, L. L. D. F. R. S. Read, December 18, 1794. P. 46—72.

Every lover of rational inquiry will doubtlefs confider the opinions ftated in this paper, as a valuable addition to the acknowledged properties of the great luminary of our system. As the most eminent philofophers have attended to the fubject, various discoveries have been made in it, the principal of which Dr. H. concifely enumerates in the following words:

"Sir Ifaac Newton has shown that the Sun, by its attractive power, retains the planets of our fyftem in their orbits. He has alfo pointed out the method whereby the quantity of matter it contains may be accurately determined. Dr. Bradley has affigned the velocity of the folar light, with a degree of precision exceeding our utmost expectation. Galileo, Scheiner, Hevelius, Caffini, and others, have afcertained the rotation of the Sun upon its axis, and determined the pofition of its equator. By means of the tranfit of Venus over the difc of the fun, our mathematicians have calculated its diftance from the earth; its real diameter and magnitude; the denfity of the matter of which it is compofed; and the fall of heavy bodies on its furface." P. 46.

The truth of thefe difcoveries refts on foundations as firm as any to which we can recur for certainty in our inquiries. Mathematical inveftigations, grounded on fuch principles of motion as reafon mult ever acknowledge, lead to conclufions which claim our belief; and thele conclufions being confirmed by obfervation enable us to affirm, without hesitation, that the laws derived from theory are really fuch as regulate the motions of the heavenly bodies. But concerning the in

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BRIT. CRIT. VOL, VII. JAN. 1796.

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