ment, he fufpended the execution of his intended voyage to America. In the year 1796, he was appointed profeffor in Anderfon's Inftitution at Glafgow, where his lectures were attended in an unparalleled manner. In confequence of this he was invited to read at other places, which not only proved profitable at the time, but alfo gave him great hopes of future fuccefs. This tranfient gleam of profperity, however, foon received a ferious check by the death of Mrs. Garnett, which happened in December 1798. From that time, the remainder of the doctor's life feems to have received very fhort refpites from a series of unpleasant, and unfortunate Occurrences. In 1799, Dr. G. was appointed profeffor of philofophy, chemistry, and mechanics at the Royal Inftitution, which was at that time eftablished in London. But even in that fituation, which might have been expected to offer a perma nent provifion, fortune proved adverfe to him; for a variety of irritating circumftances which he met with in that Inftitu tion, foon induced him to refign his place in it. Thus, being once more left unprovided, he procured a house in Great Marlborough Street, and began to read public lectures in it. He was allo engaged to read lectures at other places; and was at the fame time (1802) elected phyfician to St Mary le Bonne Difpenfary. But this accumulation of employment, however flattering it might be to his hopes, exceeded the powers of his weak conftitution, and in fact his health fuf. fered confiderably from it. Yet he might have lived fome years longer, had not a typhous fever, which he caught in the courfe of his attendance at the Difpenfary, put a period to his life on the 28th of June, 1802. "Thus was loft to fociety a man, the ornament of his country, and the general friend of humanity. In his perfonal attachments, he was warm and zealous. In his religion he was fincere, yet liberal to the profeffors of contrary doctrines. In his political principles, he faw no end, but the general good of mankind; and, confcious of the infirmity of human judgment, he never failed to make allowances for error. As a philofopher, and a man of fcience, he was candid, ingenuous, and open to conviction; he never dealt in mystery, or pretended to any fecret in art; he was always ready in explanation, and defirous of affifting every perfon willing to acquire knowledge. Virtue was the bafis of all his actions; fcience never poffeiled a fairer fabric, nor did fociety ever fuftain a greater lofs.' P. xxi. Lecture 1. Introduction. In this introductory lecture Dr. G. Tt 3 Dr. G. flates the difficuly of explaining, in a popular courfe of lectures, a fubject fo complicated and fo extenfive as that of the animal economy. On this confideration he hopes to obtain the indulgence of his hearers. He adduces feveral ar guments to prove the interefting nature of the fubject, and the very great ufe of the inveftigation; fince by the knowledge of phyfiology, i. e. of the proper actions of the parts of the human body, we are enabled to avoid noxious, and to adopt ufeful practices, for the prefervation of our health, and conflitutions. After thefe confiderations, the author gives a fhort and comprehenfive, but elegant, view of the hunan body; namely, of the different parts of which it is compofed, the bones, the mufcles, the nerves, the fanguiferous vefiels, the brain, &c; briefly mentioning the principal ufes of those parts, their mutual actions, and their dependence upon each other; as well as upon external objects. The latter part of this lecture contains a fketch of the fubfequent lectures. In the fecond lecture Dr. G. explains the procefs of refpiration, and for this purpose, he firft defcribes, in a fummary way, thofe parts of the animal body which are more immediately fubfervient to refpiration; viz. the larynx, the wind pipe, and the lungs. He then flates the principal properties of the air, and thus fhows that the nature of the atmospherical fluid, is the caufe of the admirable effects which are produced in the courfe of refpiration; fuch as the maintenance of the animal heat, the abforption of the pureft part of the air, which is neceffary for the formation of certain animal fluids; alfo the production of other gafes, and fo forth. This he explains entirely upon that theory of refpiration, which is at prefent almoft univerfally acknowledged by men of fcience. "All thefe circumftances," this author fays, may be accounted for, by the principle we have laid down; the decompofition of oxygen in the lungs. "There have not been wanting, however, fome very eminent phyfiologifts, who have contended that animal heat is produced chiefly by the nerves. They have brought forward in proof of this the well known fact, that when the fpinal marrow is injured, the temperature of the body generally becomes diminished; and that in a paralytic limb the heat is lefs than ordinary, though the ftrength and velocity of the pulfe remain the fame. Thefe facts, and others of a fimilar nature, have induced them to be. lieve, that the nervous fyftem is the chief caufe and effential organ of heat; and they have adduced fimilar arguments, to prove that nutrition is performed by the nerves, for a limb which is paralytic from an injury of the nerves, waftes, though the circu lation continues. The truth is, that the nerves exert their in- The fubject of the third lecture is the circulation of the blood, and in order to explain this most important function, Dr. G. begins by defcribing, in his ufual concife and elegant manner, the organs which nature has formed for this purpofe. He then fhows how the action of thofe organs, namely, the heart, the arteries, and the veins, forces the blood to move in a conftant circuit through every part of the animal body. This he compares, though not with very ftriking fimilarity, to the circulation of the aqueous fluid over the furface of the earth. The principal circumftances which are apt to accelerate, or to retard the ufual circulation of this blood through the fanguiferous veffels, are likewife pointed out in this lecture; and among these we find the explanation of a phenomenon which has always been attended with difficulty, and which, however, is ftill in want of further examination and illuftration, notwithstanding Dr. Garnett's explanation, which is as follows, "While we are on this fubject, it may not be improper to take notice of the effects of fwinging on the circulation, which have been found by Dr. Carmichael Smyth, and others, to diminish the ftrength and velocity to fuch a degree, as to bring on fainting. Thefe effects have never been fatisfactorily accounted for; but they would feem to admit of an eafy explanation on mechanical principles: they are undoubtedly owing, at leaft in a great mea fure, to the centrifugal force acquired by the blood. "By a centrifugal force, I mean, the tendency which revolv ing bodies have to fly off from the centre, which arifes from their tendency to move in a ftraight line, agreeably to the laws of motion. Hence a tumbler of water may be whirled in a circle vertically without fpilling it; the centrifugal force pufhing the In the fame manner water against the bottom of the tumbler. when the human body is made to revolve vertically in the arch of a circle, this centrifugal force will propel the blood from the head and heart towards the extremities; hence the circulation of the blood will be weakened, and the energy of the brain diminished. The contrary, however, will take place on a horizontal fwing, as I have frequently obferved, both on myfelf and others;" for for the centrifugal force in this cafe will propel the blood from the extremities towards the head." P. 46. After the above paffage, the author speaks of the pulfation of the arteries, and of the indications arifing from the frequency, the ftrength, the regularity, and other qualities of thofe pulfations. He remarks, that the conclufions concerning the fate of the body, which are derived from those peculiar qualities of the pulfations, are frequently wrong, when they are entirely dependent upon obfervation, without the aid of reafoning. He then lays down certain poftulates, upon which he grounds his reafoning and his obfervations concerning the above-mentioned indications. The fourth lecture treats of digeftion and nutrition, together with fome other functions which are more immediately connected with them. This branch of phyfiology is likewife treated in a manner fimilar to the fubjects of the preceding lectures. The parts fubfervient to maftication, swallowing, and digeftion, are first described, and then their ac tions in the proceffes of digeftion, nutrition, &c. are briefly, but very intelligibly explained. In the fifth lecture, which treats of the fenfes in general, this author endeavours to explain how the human being becomes acquainted with the external world; that is, with the objects which furround him; by means of the senses; for he becomes acquainted with their hardness by the sense of feeling, of their colours by his fight, of their odoriferous qualities by the smell, and fo forth. After fome general obfervations on the powers of the human mind, Dr. G. defcribes the organifms of the fenfes, together with their actions, as far as the prefent flate of knowledge will enable us to understand this moft difficult part of phyfiology. In this he proceeds with great regularity and perfpicuity; confidering, in the firfi place, the general laws of fenfation, and then proceeding to examine the laws which are peculiar to each fenfe. But in this lecture the laws peculiar to the touch only are noticed. The laft paragraph of it is here fubjoined. "Feeling is by far the most useful, extenfive, and important of the fenfes, and may be faid, indeed, to be the basis of them all. Vifion would be of very little ufe to us, if it were not aided by the fenfe of feeling; we fhall afterwards fee that the fame obfervation may be applied to the other fenfes. In fhort, it is to this fenfe that we are indebted, either immediately or indirectly, for by far the greateft part of our knowledge; for with at it we hould not be able to procure any idea with refpect to the magni tude, tude, distance, shape, heat, hardness or foftnefs, afperity or fmoothnefs of bodies; indeed, if we were deprived of this fenfe, it is dif ficult to fay whether we should have any idea of the existence of any external bodies; on the contrary, it feems probable that we fhould not." P. 91. The fenfes of tafte and of fmell are examined in the fixth lecture; and the feventh treats of found and of hearing. The eighth lecture, which is rather longer than any of the preceding, contains the admirable fubject of vifion; and here, in conformity to the other lectures, Dr. G. firft defcribes the human eye in all its parts, and then proceeds to explain the nature and properties of light; how vision in general is performed, and in what manner the eye conforms itfelf to fee diftin&tly at different diftances. Concerning what is called the feat of vifion, this author confiders the opinions of the principal philofophers who have bestowed their attention on the fubject, to which he briefly adds his own. It is mentioned in almoft every elementary work on natural philofophy or on optics, that there is a place in the bottom of the eye, which is infenfible of light; fo that we cannot perceive that object, the image of which falls exactly on that spot; fuppofing that the other eye is kept fhut This fpot is where the optic nerve enters the eye, and in which place only the choroides is deficient. Speaking of this fpot, Dr. G. fays, up. "M. Le Cat, though he ftrenuously fupports Mariotte's opi nion, takes notice of a circumftance, which, if he had properly confidered it, might have led him to a contrary conclufion: from a beautiful experiment he obtains data, which enable him with confiderable accuracy to determine the fize of the infenfible fpot in his eye, which he finds to be about or of an inch in diameter, and confequently only about or of the diameter of the optic nerve, that nerve being about of an inch in diameter. I find that in my eye likewife, the diameter of the infenfi ble fpot is about of an inch, or fomething lefs. Whence it is evident that vifion exifts where the choroid coat is not present, and confequently that the choroid coat is not the organ of vifion." P. 151. In the fequel, this author likewife takes notice of other interefting questions respecting vifion. Having thus, in the preceding lectures, taken a view first of the general structure, and of the functions of the living body, and then of the fenfes through which we become acquainted with the external objects, this judicious author ex |