Page:Popular Science Monthly Volume 25.djvu/282

272 energy. The one of these la the energy of a wave motion in the ether, passing from a hot body to surrounding objects across the intervening space, as from the sun to our earth, or from a hot fire to the colder objects upon which it shines: this we call radiant heat. The other form is a confused oscillatory disturbance of the particles of a body: in virtue of this molecular movement a body may appear to our cutaneous sense of heat (a sense quite distinct from that of touch) to be more or less hot or warm; or, in the converse case it may, on account of the small amount of this movement, appear to be relatively cool or cold. The latter form of heat may be called sensible heat, or heat simply, and of it we shall proceed to treat in this chapter.

"Of Ether-Waves" is the heading under which the phenomena of radiation, including reflection, refraction, and interference, are treated. In defining electricity and magnetism, the author states that they "are not forms of energy; neither are they forms of matter. They may, perhaps, be provisionally defined as properties or conditions of matter; but whether this matter be the ordinary matter, or whether it be, on the other hand, that all-pervading ether by which ordinary matter is everywhere surrounded, is a question which has been under discussion, and which may now be fairly held to be settled in favor of the latter view." Although the author, in his preface to this solid volume, expresses the modest hope that it may "be found fitted to serve as an elementary introduction" to a course of wider reading and practical study, it is by no means a book for immature students. It is illustrated with about two hundred and fifty diagrams.

subject considered in this volume is one of great practical importance both to individuals and to the community at large. The author is a veterinary surgeon of eminent standing, a graduate of the Royal Veterinary Institute of Berlin, and honored by various kindred institutions and societies. In addition to the qualifications thus attested. Dr. Billings has another excellent requisite for the task he has undertaken, which is deep feeling upon the subject—an interest inspired of large knowledge—in fact, an intense enthusiasm well suited to the kind of work he has in hand. He writes with vigor, and often with a vehemence that might involve exaggerated statement; but we must remember that his work is not a treatise on veterinary practice, or a manual of medical and surgical treatment of diseased animals, addressed to the profession. It is a work on the prevention of disease, addressed to the general intelligence of the community, and designed to draw attention to questions and to stir up a popular interest in them that shall lead to private and public action, and for this purpose strong language is entirely justifiable. His subject, moreover, is one upon which there is not only much ignorance among otherwise well-informed people, but upon which there is also a great deal of narrow and unworthy prejudice, deserving of unsparing exposure and severe denunciation.

The work is divided into three parts. The first, of 208 pages, is devoted to "The Diseases of Domestic Animals"; Part II, of 155 pages, describes the "History of Veterinary Medicine" and the establishment of veterinary schools; Part III, of 51 pages, treats of "The Means of Prevention" by veterinary schools and institutes and a veterinary police system in the United States. The first part is taken up with a consideration of some of the most important infectious and contagious diseases of animals—those which require both scientific knowledge and official authority for examination and repression. An intelligent writer in "The Journal of Comparative Medicine and Surgery" thus refers to the subjects here discussed:

"Trichiniasis" in men and animals is dealt with in pages 1 to 40, and is a capital study indeed. The ready detection of the disease in slaughtered hogs, about the pillars of the diaphragm, is especially important. But the author has Bismarckian views about the "great American hog," which may raise an unjust howl from those whose pockets will be touched. We hope they will, for the intrepid doctor is fully capable of dealing with them, and he should have his chance. It will be a hard fight and a good one. Before Government acts in the matter, all large pork-packers should have skilled examiners, licensed from some good veterinary college, to inspect and mark their products. These will find a more ready sale, at higher prices, than less well-attested articles. These certificates will doubtless have a higher standing than those of some Government officials, appointed for some political reasons only or mainly.

Next to hogs, trichinæ are apt to infest rats, and the doctor says: "Continued examinations of rats should be made in all parts of the country, and