Apoplexy, we believe, is little altered from the former edition; so that we look for more information on this important subject in the future articles referred to. A few antiquarian articles occur, which have afforded us much pleasure. Archery and Armour are so excellent, that we wish they had been longer; they appear to have been drawn up by the late ingenious Mr. Strutt. A like praise and a like regret may be extended to Arms in heraldry. The ecclesiastical and theological articles, Apocalypse, Apocrypha, and Arians, appear to be drawn up with perfect impartiality, and contain all the information to be required or expected on these topics. CHAPTER XXIII. EXPERIMENTAL PHILOSOPHY. THE works included in this department of our present volume are not numerous, nor of first-rate importance; they bear, however, a considerable value, and we doubt not will be received by the public with complacence. Professor Aldini's volume on Galvanism exhibits a full detail of the wonderful effects produced by this newly-discovered agent on the nerves and muscles of animals recently killed. Mr. Johnson's laborious compilation of the scattered facts, illustrative of animal chemistry, merits great praise for its accuracy and minuteness, and will be acknowledged as a most useful body of facts and opinions by all those who are engaged in this interesting pursuit. Mr. Cavallo's Experimental Philosophy is well calculated to inspire young people with a desire of penetrating further into the majestic temple of Nature; and Mr. Accum's System of Chemistry will be welcomed by the amateur, and may be gleaned with profit by the more experienced chemist. Dr. Black's Lectures, which some years ago would have deserved the first rank among the popular systems of this science, from the delay in their public appearance, are likely to engage the attention of those principally who have enjoyed the pleasure and advantage of his personal instructions, and of those who are anxious to become acquainted with the style and manner of this eminent philosopher. ART. I. The Elements of Natural and Experimental Philosophy. By TIBERIUS CAVALLO, F.R.S. Illustrated with Copper Plates. 4 vol. 8vo. THE phænomena of nature cannot fail of making an impression in various degrees on every mind: some will acquiesce in the idlest surmises, whilst others, by a comparison of various effects, will be enabled to class them together, and thus arrive to some general property to which these appearances may be refered. In making this classification it will appear, that number and extension are two qualities which enter into the consideration of most of these effects; and hence, without the study of the mathematics, the knowledge of the cause of effects in nature must remain very imperfect. As many persons are unwilling to take the labour which is required to make the necessary progress in these studies, it becomes an object of some importance to devise means of rendering the science as popular as possible, and great praise is due to those who exert themselves in this manner. At the same time all readers should be informed, that not only their ideas must be very imperfect, but that they in the end take more trouble in investigating any subject in the popular way, than they would do by examining it on its true principles. Thus in explaining the motion of the heavenly bodies, the great principles are, that a body acted upon by two powers will describe the diagonal of a parallelogram, whose sides are the lines of directions of the powers; and that a body revolving round a center of force will describe equal areas in equal times about that centre. Now to him to whom parallelograms and triangles are familiar, the demonstration is simple and easy; to others the ideas must be always confused, and it will be very dif ficult to make them comprehend the nature of the curvilinear motion. The author of this very valuable work has done, however, as much as could be expected from any one, for the general reader. He goes through every branch of natural philosophy, whether it can be referred or not to mixed mathematics, and in both parts shews himself eminently qualified for the work which he has un. dertaken. If in his text he consults the ease of the general reader, he gives information sufficient in his notes to exercise the talents of, at times, even the higher class of mathematicians. The first volume is assigned to mechanicks; the second to hydrostatics, pneumatics, and the general principles of chemistry; the third to caloric, optics, electricity, and magnetism; the fourth to astronomy, aerostation, meteors, weights and measures. This arrangement does not appear to us to have any advantage over the common mode in which the phænomena to be explained on mathematical principles are kept by themselves, under the heads of mechanics, hydrostatics, optics, and astro nomy. The first volume begins with a general description of natural philosophy, and points out the true rules of philosophising, not omitting to hold out a necessary degree of scepticism, at the same time that the student is put on his guard "not to become a blind believer or a useless sceptick." The general properties of matter are then explained, with the nature of the laws of motion; and we were rather surprised at finding ourselves precipitated in the next chapter into the difficulties of centripetal and centrifugal forces, and the centre of gravity, which generally remain till the student has familiarised himself with the more simple effects of mechanical motion. The the ory of percutiert motion then follows, and we are brought next to the nature of compound curvilinear motion; in the latter of which the fourth proposition of the second section of Newton is explained. These, to us appearing very difficult chapters, are followed by the doctrine of motions on inclined planes and of pendulums; and then we are introduced to the mechanical powers, which in most books of this kind are the first things taught, and the deviation from the general method does not appear to be followed by any advantage to either teacher or learnThe chapter on compound engines er. and machines deserves commendation, both in itself and as pointing out fit objects for study; for many persons who pursue in theory the doctrine of motion, find themselves much at a loss when they are called upon to apply their knowledge to any practical purpose. The very excellent work of Cotes on hydrostatics leaves little to be said on the theory; but many improvements have been made since his time, particu larly in discovering the specific gravi ties of bodies, and the motion and properties of air, which are in this work dilated upon with great propriety. In treating the doctrine of optics, we were agreeably surprised at finding inserted the observations of, as he is called, a recent anonymous writer, concerning the inflections of light. They were publish ed in the year 1799, and proceed, we understand, from the pen of a gentleman who studied the Newtonian theory with great diligence at Cambridge, and after an absence of several years returned about that time to this country. The observations have not been noticed so much as they deserved; the experiments are in a high degree ingenious, and the result is far from establishing the New tonian theory. The author of the work before us makes the following remark upon the whole of this intricate subject this doctrine to a variety of phenomena, "A close examination and application of which have been observed by various inge nious persons, especially of the present age, render this theory of colours doubtful in almost all its parts. In the first place, it may be doubted whether there really are only seven distinct primitive colours, or an indefi duced by some unknown modifications of nite number of them, which are perhaps pro white light. The breadths and the gradations of the supposed seven primitive colours, in the prismatic spectrum, are the greatest foundation for the above-mentioned doubt. With respect to the thin transparent plates of which all bodies are supposed to consist, we are greatly in want of experimental contirmation; and even if we were sure of their plain, how are the fixed and unchangeable existence, it would be difficult thereby to ex colours produced by them in all directions.— Such doubts may be seen in all the modern writers on optics, to whose works, which are principally to be found in Transactions of Societies, Journals, &c. I shall refer the inquisitive reader, who may wish to be informed on the subject, or to extend our knowledge of nature." The passage of light through glasses, or reflected by mirrors, may fill volumes, and cannot indeed be rendered very intelligible, without more attention to figures than will be bestowed by the general reader. This part of the subject is therefore very properly brought into a narrow compass, and the volume that might have been employed upon light alone, surrenders up one half to electricity, galvanism, and magnetism. In the fourth volume, the system of the world is explained in the usual manner, and the latest discoveries are inserted. The addition of two new planets to the system and of the discoveries of Herschel and Schroeter, give an additional interest to this part of the work, and of them the author has very judiciously availed himself. Aerostation is well known; as to its general facts, as a science, it remains still in its infancy. The child sees its bubble rise with the same pleasure as the multitude the balloon; the direction of the progress of either still depends on the breath of the lad, or the caprice of the winds. It is, however, a curious subject; and with that of meteors, and the falling of stones in different parts of the world, will be perused with plea sure. On the whole, the work is admirably well adapted to give a general idea of a number of interesting topics. From its size, it cannot be supposed to dilate sufficiently upon any article to satisfy the diligent enquirer; but as a book of reference, and an easy explanation of philosophical subjects, it merits the attention of the general reader, and does great credit to the author. ART. II. An Account of the late Improvements in Galvanism, with a Series of curious and interesting Experiments, performed before the Commissioners of the French National Institute, and repeated lately in the Anatomical Theatres of London. By JoHN ALDINI, Professor of experimental Philosophy in the University of Bologna, Member of the Medical and Galvanic Societies of Paris, of the Medical Society of London, Sc. To which is added, an Appendix, containing the Author's Experiments on the Body of a Malefactor executed at Newgate, &c. &c. Illustrated with Engravings. THE impression made by the experiments of Professor Aldini will not easily be effaced from the memory of those who were fortunate enough to be witnesses of them. When this ingenious foreigner left England, he put his manuscripts into the hands of the editor of this work, (whose name does not appear) partly in French, partly in Latin. They are here all collected and published in English, and, together, form a series of most curious and interesting experiments, more surprising perhaps than were ever presented in one point of view, and afford ing abundant matter for present contemplation and future enquiry. The subject being as yet but new, no more of theoretical reasoning accompanies the recital of matter of fact, than necessarily attends the researches of ingenious men; it is therefore to the facts and original discoveries that the reader's attention will be chiefly directed. A few of them we shall mention, not as an abstract of the whole, (which ought to be consulted in the work itself, and with the assistance of the plates) but as an inducement to those of our readers who -pursue the fascinating science of physi ology, to attend to a subject which promises so rich a harvest in an unexhausted field. The first part of this volume treats of the nature and general properties of galvanism. The facts are reduced to a number of general propositions, each of which is proved by an appropriate experiment. In all, the ultimate object is to produce, by various methods, muscular motion in different parts of animals recently killed. Thus the first proposition is, that mus cular contractions are excited by the development of a fluid in the animal machine, which is conducted from the nerves to the muscles, without the action of metals. This is proved in the following experiment: Having provided the head of an ox which had been recently killed, I thrust a fin ger of one of my hands, moistened with salt water, into one of the ears, at the same time that I held a prepared frog in the other hand, in such a manner, that its spinal marrow touched the upper part of the tongue. When this arrangement was made, strong convulsions were observed in the frog; but on separating the are, all the contractions ceased. This experiment will succeed still better, if the arc be conveyed from the tongue of the ox to the spinal marrow of the frog." A real attraction, never before observed, between muscle and nerve, is proved by the following experiment: "I held the muscles of a prepared frog in one of my hands, moistened by salt water, and brought a finger of the other hand, well moistened, near to the crural nerves. When the frog possessed a great deal of vitality, the crural nerves gradually approached my hand, and strong contractions took place at the point of contact. This experiment proves the existence of a very remarkable kind of attraction observed, not only by myself, but also by those whom I requested to repeat the experiment." This, however, requires much delicacy and accuracy in the preparation to succeed. Galvanism is excited by the simple contact of the nerve of an animal with its own muscle. It is thus proved: "Having prepared a frog in the usual manner, I hold the spinal marrow in one hand, and with the other form an angle with the leg and foot, in such a manner, that the muscles of the leg touch the crural nerves. On this contact, strong contractions, forming a real electrico-animal alarum, (carillon) which continue longer or shorter, according to the degree of vitality, are produced in the extremity left to itself. In this experiment, as well as the following, it is necessary that the frogs should be strong and full of vitality, and that the muscles should not be overcharged with blood.” Many curious facts are given, to shew the general relation between galvanism and electricity; and the author inclines to the hypothesis of an animal pile existing with every animated body, and acting similarly to the voltaic pile. In the second part, Professor Aldini treats of the influence which galvanism has on the vital powers, and under this head are contained those astonishing and celebrated experiments, of exciting commotions in the decapitated trunks, or the heads of large animals, by means of the voltaic pile conveyed to the nervous and muscular systems. The Professor has employed both the larger brutes and human subjects; the latter, criminals deca pitated by the sentence of the law in Bologna, whom the alarmed and astonished spectators saw again rolling the eyes, gnashing the teeth, menacing with the arms, and for an instant resuming the actions of life. nova desuetis subrepens vita medullis ments as examples of these astonishing phenomena: "The first of these decapitated criminal, being conveyed to the apartment proce for my experiments, in the neighbourhood of the place of execution, the head was re subjected to the galvanic action. For t purpose I had constructed a pile, consistir of one hundred pieces of silver and zincHaving moistened the inside of the ears with salt water, I formed an are with two meile wires, which, proceeding from the two e were applied, one to the summit, and the other to the bottom of the pile. When the communication was established, I obser strong contractions in all the muscles of or face, which were contorted in so irregular. manner, that they exhibited the appearances of the most horrid grimaces. The action the eye-lids was exceedingly striking, th... less sensible in the human head than in La of the ox." The larger animal shewed equat powerful commotions. Having provided an ox recently Li the head of which was not cut off, I fams an are from one ear to the other, interposi the pile. The immediate result was o motion, so violent in all the extremities of tanimal, that several of the spectators we much alarmed, and thought it prudent to s tire to some distance. I then cut off t. head, and formed an are from the spinal row, first to the diaphragm, and then to dsphincter aai. In the first case the diaphra experienced violent contractions, in thick thr I obtained a very strong action on the rectur, which even produced an expulsion of th fæces." could excite no contraction in the heat It is remarkable that Professor Aldiri of any of the subjects by the galvant pile. However, on carefully repeating the experiments, some other Italian phi losophers have succeeded in this point, the heart therefore is susceptible of g vanic influence, but with difficulty. view of the medicinal powers to be exThe third chapter contains a short pected from galvanism; they appear to be very similar to those of electricity. The following use of one or the other is new and singular: "Before I conclude this article, I must suggest a hint respecting the application of galvanism to diseases of the teeth, found d on information communicated to me on this subject by Mr. Fowler, an eminent dentist in London, when the caries is concealed from the sight. Mr. Fowler employs the fo!lowing method to discover the affected tooth: He first insulates the patient, and having put We must relate two of the experi- into his hand the electric chain, he applies a |