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TH±] POPULAR SCIENCE MONTHLY. 



energy. The one of these is 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 oscil- 

 latory disturbance of the particles of a body : in vir- 

 tue of this molecular movement a body may appear 

 to our cutaneous sense of heat (a sense quite dis- 

 tinct li-om 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 mag- 

 netism, the author states that they '' are not 

 forms of energy ; neither are they forms of 

 matter. They may, perhaps, be provision- 

 ally defined as properties or conditions of 

 matter ; but whether this matter be the or- 

 dinary matter, or whether it be, on the other 

 hand, that all-pervading ether by which or- 

 dinary matter is everywhere surrounded, is 

 a question which has been under discussion, 

 and which may now be fairly held to be set- 

 tled in favor of the latter view." Although 

 the author, in his preface to this solid vol- 

 ume, 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. 



The Relation of Animal Diseases to the 

 PcBLic Health. By Frank S. Billings, 

 D. V. S., etc. New York: D. Appleton 

 & Co. Pp. 446. Price, $4. 



The 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 emi- 

 nent standing, a graduate of the Royal Vet- 

 erinary Institute of Berlin, and honored by 

 various kindred institutions and societies. 

 In addition to the qualifications thus attest- 

 ed, Dr. Billings has another excellent requi- 

 site for the task he has undertaken, which 

 is deep feeling upon the subject — an inter- 

 est 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 dis- 

 eased 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 inter- 

 est in them that shall lead to private and 

 public action, and for this purpose strong 

 language is entirely justifiable. His sub- 

 ject, 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 165 pages, describes the "History of Vet- 

 erinary 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 vet- 

 erinary police system in the United States. 

 The first part is taken up with a considera- 

 tion of some of the most important infec- 

 tious and contagious diseases of animals — 

 those which require both scientific knowl- 

 edge 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 espe- 

 cially important. But the author has Bismarctian 

 views about the'" great American hop," which may 

 raise an unjust howl from those whose pockets 

 will be touched. "We hope they will, for the in- 

 trepid doctor Is fully capable of dealing with them, 

 and he should have his chance. It will be a hard 

 light and a good one. Before Government acts in 

 the matter, all large pork-packers should have 

 skilled examiners, licensed from some good vet- 

 erinary 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 po- 

 htical reasons only or mainly. 



Next to hogs, trichina! are apt to infest rats, 

 and the doctor says : " Continued examinations of 

 rats should be made in all parts of the country, and 



