wards his adverfaries. And fuch as are of the contrary character, fuch as think that they do God fervice, when they deftroy his creatures upon pretence of religion, let us ever efteem them as the worst fellow-fubjects in Chrift's kingdom, if they can be called fellow-fubjects who thus exercife dominion where they should only practife obedience.'

The remaining fermons in this volume are upon the fol lowing fubjects: Is any fick among you,' &c. James v. 14, 15. The Son of Man came to fave that which was loft; If in this Life only we have Hope in Chrift, we are of all Men most miserable; Chrift, a true and proper Object of Divine Worship, and God properly and truly, by Nature and from all Eternity; The Scriptural Rule of Submiffion to Government explained.

Our author's general fentiments on this head are contained in the following paragraph.

In arbitrary governments, neither the confent of the people is afked, nor always their inclination confidered. There the law is forced upon them; and it is, it must be their rule, whether they think it reasonable or not, prudent or the contrary.

This was the cafe of the Roman empire when Chrift and his apoftles lived and gave the rules which I before mentioned to you, about the duty of fubjects to their princes: the will of the fovereign was the law at that time, or if the fenate of Rome had any share in the confirming any law, yet the great body of the Roman empire had nothing to do with it, but to receive it when published, and obey it when tranfmitted to them; but in a free and limited monarchy like ours, the people's confent is neceffary before any law can be established; and therefore the more thare we have in the making the law, the lefs we should have in the breaking it, and he furely cannot be thought to practife the fcriptural rule of fubmiffion who will not be obedient even to the laws which he himself has made, nor be fubject even to thofe whom he himself has helped to or dain the higher powers.'

These are the fubjects, which his lordship has difcuffed in the prefent collection of fermons. His mode of writing is calm and argumentative. His reafoning clear and obvious to the meanest capacity. His practical inferences and exhortations are serious and important, but feldom animated. His explanations of Scripture are in general learned and judicious, His notions of Chriftianity, and its peculiar doctrines, are of an ambiguous nature, for the most part rational, but fometimes intermixed with the relics of Calvinifin, the doctrines of original fin, the reconciliation of God to man, the fatisfaction

fatisfaction made by Chrift to Divine juftice, and the like., In the popish controverfy he has produced his authority for the errors which he aftribes to the Roman Catholic church, and has refuted them in a masterly manner.

A Philofophical Inquiry into the Caufe of Animal Heat: with incidental Obfervations on feveral phifiological and chymical Queftions, connected with the Subject. By P. Dugud Leflie, M. D. 8vo. 65. Boards. Crowder.

To determine the caufe of animal heat is a problem which has much exerciled the invention of phyfiologifts, and given rife to various hypothefes. Mechanical and chemical powers have each had their refpective abettors, whofe theories, however, are liable to fo many ftrong objections, that they can. afford but little fatisfaction to an inquifitive mind. The author under confideration feems to have entered upon this curious enquiry with a thorough knowlege of all that has been written on the fubject, and a decifive opinion, founded on arguments, of the fallacy of every hypothefis which has hi therto been propofed. The work is divided into two parts, each of which is fubdivided into chapters, and these occafionally into fections.

The firft chapter treats of, animal heat in general, and the fecond, of the phenomena of animal heat. The latter is divided into four fections, in the firft of which the author evinces, that the latitude in the temperature of animals is confiderable; and in the fecond, that there is a remarkable uniformity in the temperature of animals.

Though we have found, fays our author, a confiderable latitude of temperature in the different claffes of animals, there is a furprising uniformity in that, which is peculiar to each genus and fpecies. The difference between the fpecies of the fame genus never exceeds a few degrees; and the distinction between the loweft genus, and the higheft, is not greater. Thus in the whole variety of the bird kind, the temperature is nearly one and the fame; and as far as our experiments go, it is likewife fteady in the amphibia. With respect to the more imperfect animals, they are too dependent on the influence of external circumftances to preferve uniformity of heat.

But one of the most remarkable properties of animal heat, is the uniformity which it is obferved to maintain under the greatest irregularity of fize. In all the variety of quadrupeds, birds, and cetaceous fishes, we find nothing depending on that circumftance; for the thermometer rifes to the fame degree, whether applied to the moufe or the elephant, the wren or the oftridge,

oftridge, the fea-calf or the whale and we cannot perceive that age, fize, or temperament, produce any material difference. That this at leaft is the cafe with respect to man, De Haen has rendered fufficiently plain, by a courfe of accurate experiments on fubjects of both fexes, from the earliest infancy, to extreme old age: And if we be allowed to reafon from analogy, we met fuppofe that the fame uniformity of temperature extends to all the more perfect tribes of animals.

Before the days of the immortal Harvey, it was the general opinion of phyfiologifts, that certain parts of the body, in particular the thoracic vifcera, were a temperature fuperiour to the other parts of the animal; but it is now, I think, evinced by the most accurate obfervations, that in every individual, it is uniformly the fame over the whole body; and if any difference has at any time feemed to fubfift in a healthy animal, between the external and internal parts, it is to be entirely attributed to the communication with the colder furrounding medium, and the difficulty of preventing the thermometer from being affected by it. With refpect to thole parts, which are without the courfe of circulation, the cuticle, hair, nails, &c. they are always ac a mean degree betwixt the heat of the animal and the ambient air.'

In the third divifion of this chapter Dr. Leflie displays the connection between the ftate of refpiration, the colour of the blood, and the degree of heat in animals; and in the fourth he confiders the connection, between the ftate of circulation, and the degree of heat in animals.

After these preliminary enquiries, the author proceeds, in the third chapter to take a view of the prevailing opinions on the cause of animal heat; and of thefe the firit that he refutes is the doctrine of chymical mixture.

When Chymical Philofophy, fays he, came into vogue, and prevailed in the theory, as well as the practice of medicine, almost every operation in the animal machine was attributed to the effect of ferment, or mixture. We need not be at all furprized that men, who never extended their views beyond the bounds of their laboratory, nor ever contemplated the other parts of nature, became poffeffed of the idea of the univerfal application of thofe energies, which they had perceived in fuch a variety of inftances; and that imagining their influence unbounded, they attempted to explain even the functions peculiar to life, on principles deduced from their acquaintance with that one fet of caufes.

Thus, from obferving that on mixing certain bodies far below the temperature of the human body, a degree of heat fometimes rifing to actual inflammation was produced, they, without farther inveftigation, pronounced mixture the fole caute of animal heat. Various, however, were the opinions not only

refpcci

respecting the place where the mixare happened, but also concerning the nature of the fluids of which it confifted.

Vanhelmont, Sylvius, and feveral other chymico-phyfiologifts, fuppofed that the mixture took place in the intestinal tube, and afcribed it to an efferverfcence betwixt the pancreatic juice and the bile. Others difcovered acids in one place, and alkalis in another; but the general opinion for near two centu ries was, that acefcent fluids taken in, meeting with alkaline already prepared in different parts parts of body, gave rise to the degree of heat peculiar to animals. But all who are in the leaft converfant with the laws of the animal economy, need not be told that thefe opinions are mere conjectures, founded on facts gratuitoufly affumed. No experiments have fhewn either an acefcency or alkalefcency in the bile, that is fufficient to unite with the other animal juices, and generate the heat of animals. But to avoid much difcuffion, did we even admit the fuppofition in its full extent, ftill it would be found by no means fufficient to account for the ftability of animal heat in different climates and feafons; its equability all over the body when in health; its partial increase in topical inflammations, or hardly indeed for, any one phenomenon attending its production.

Since then it appears that the fluids fuppofed to be mixed, the place in which the mixture is made, and every other circumftance pertaining to it, are equally ill afcertained, and feconded by analogy, none will, we prefume, hesitate to reject every hypothefis of the caufe of animal heat, founded on the effects of mixture.'

The theory which fucceeded to the former was that of fermentation; and of this opinion, as our author observes, there were various modifications; but of late the putrefactive species of fermentation has been moft generally adopted. He justly obferves, however, that the efficacy of this process in producing animal heat, is far from being well afcertained.

In the third fection Dr. Leflie enquires into the mechanical generation of animal heat. From obferving that the circulation of the blood, and the temperature of the body are clofely connected with each other, phyfiologifts have been induced to afcribe the generation of heat in animals to the more mechanical effects of motion. The inquirer admits this principle to have the force of a fecondary caufe, but rejects the opinion of its being fufficient for folving the problem. He confiders this doctrine under the two divifions into which it has been diftinguished. The former fuppofes animal heat to depend on the reciprocal action of the fluids upon the folids; and the other upon the inteftine motion of the globules of blood among them.felves. Both thefe opinions our author endeavours to refute,

The

The next opinion noticed is that of Dr. Cullen, which is delivered only as a conjecture, in the following terms.

"May it not (fays he) be fuppofed, that there is fome circumftance in the vital principle of animals, which is in common to thofe of the fame clafs, and of like economy; and which determines the effect of motion upon the vital principle, to be the fame, though the motion acting upon it may be in different circumftances."

By this, fays our author, Dr. Cullen means, for to thofe who never heard him on the subject fome illuftration of the text may not be unacceptable, that the different temperature of different animals is owing to a difference of the vital principle, infomuch, that the velocity of the blood may be the fame in a frog, as in a man, yet in confequence of the different vital principle, the heat produced be different. The facts, upon which he feems to lay greatest stress are, that neither where the furrounding medium confiderably furpaffes the temperature of the living body, nor where it is far below it, is there any fenfible change in the heat of animals. Thefe, and fome fimilar facts, feemingly countenance his hypothefis, but they will, it is prefumed, be hereafter explained on principles more obvious, and confiftent with the fimplicity of nature; for while we admire the fingular ingenuity, which ftamps every part of the Cullenian doctrine, we must be permitted to confider it, in this particular, as founded on a more fpecious, than folid bafis. What juft grounds have we to imagine the principle of life different in different animals? And how are we to conceive, that the fame degree of motion fhould in one ciafs of animals always produce a certain degree of heat, and in another clafs as regularly a different? A propofition of fuch a nature should, no doubt, require the most obvious facts and conclefive arguments to establish it; but in the prefent instance we do not even perceive any probable reafon from analogy. Befides, to fay that the principle of life can generate heat or cold, independent of chymical or mechanical means, is contrary to experience, and feems in itfelf abfurd. Upon the whole, from thefe few of the many objections that tend to overturn Dr. Cullen's theory of animal heat, we do not hesitate to account it a mere hypothefis, and entirely abandon it.'

The examination of the various hypothefes concludes with that of Dr. Black, which is the laft, and Dr. Leflie acknowleges, perhaps, the moft ingenious and beft fupported theory which has ever been proposed on the subject of animal heat. Dr. Black having obferved, that not only breathing. animals are of all others the warmeft, but also that there fubfifts fo clofe and ftriking a conne&ion, betwixt the state of refpiration and the degree of heat in animals, that they appear