420 



THE POPULAR SCIENCE MONTHLY. 



once so minute and complex that its action 

 is inconceivable." Appendix II is devoted to 

 a discussion of telegony, much of which has 

 appeared in this magazine. Dr. Romanes be- 

 lieves in centripetal heredity, and therefore 

 cannot agree with Mr. Spencer, whose theory 

 is of the centrifugal order. 



Electric Waves : Being Researches on 

 THE Propagation of Electric Action 

 WITH Finite Velocity through Space. 

 By Dr. Heinrich Hertz. London and 

 New York: Macmillan & Co. Pp. xv-f- 

 278. Price, $2.50. 



The impossibility of reviewing in brief a 

 work of such transcendent importance to 

 electrical science as this volume undoubtedly 

 is, will become apparent to the reader when 

 we declare that the progress exclusive of 

 the author's own discoveries so concise- 

 ly recounted, not only embraces the names 

 and experiments of and from Newton and 

 Bernoulli and their day, down through a line 

 of seventy-five prominent men of genius, 

 but also includes with Faraday and Ampere 

 of late years Helmholtz, Lodge, Maxwell, 

 Siemens, and Sir W. Thomson in our own 

 day. The volume before us is the aijthor- 

 ized English translation from the German 

 work, by Prof. D. E. Jones, B. Sc, and in- 

 cludes an able preface by Lord Kelvin, Pres- 

 ident of the Royal Society. 



Dr. Hertz was primarily induced to carry 

 out the experiments elucidated in this vol- 

 ume through the proffered prize in 1879 of 

 the Berlin Academy of Science, for a solu- 

 tion of the problem to establish by experi- 

 ments " any relation between electromag- 

 netic forces and the dielectric polarization 

 of insulators," which simply meant that a 

 force electromagnetic in itself might be ex- 

 erted in non-conductors by polarizations, 

 or that electromagnetic induction is the 

 cause of the polarization of a non-conductor. 

 The attention of the professor was first 

 drawn to the problem by Herr von Helm- 

 holtz, who promised the assistance of the 

 Physical Institute in Berlin if Dr. Hertz 

 determined upon making the research and 

 necessary experimentation. After many fail- 

 ures, and his first abandonment of the solu- 

 tion, he finally gives to the world the impress- 

 ive deductions of the original papers now in 

 the form of fourteen chapters contributed 

 to Wiedemann's Annalen. These are, in the 



present volume, supplemented by an ample 

 introduction and various explanatory notes 

 of vast import. Proceeding from the intro- 

 duction, which emphasizes the experimental 

 and theoretical phases of the subject, we 

 gather from chapter to chapter the crown- 

 ing results embodied in such phenomena as 

 rapid electric oscillations, the effect of ultra- 

 violet light upon the electric discharge, the 

 action of rectilinear electric oscillations upon 

 a neighboring circuit, the finite velocity of 

 propagation of electromagnetic actions, elec- 

 tric radiation, the fundamental equations of 

 electromagnetics for bodies at rest, and 

 other all-important subdivisions. The work 

 in the aggregate represents the fervid ex- 

 pression of a scientific explorer, whose heart 

 was indubitably in his work, and who now 

 presents us at minimum cost a wealth of 

 labor and a store of new knowledge. 



Romance of the Insect World. By L. N. 

 Badenoch. New York : Macmillan & Co. 

 Pp. 341. Price, $1.25. 



This volume contains one of the best ef- 

 forts that have been made recently to put 

 scientific facts into an attractive form. If 

 one can be interested at all in the wonderful 

 ways of insects, this book will spur to better 

 acquaintance. Valuable data have been 

 culled from every quarter, not neglecting the 

 investigations of our American naturalists. 

 Dr. McCook, Mrs. Treat, and the Peckhams. 

 These are grouped under the four topics of 

 metamorphoses of insects, their food, home- 

 building, and defenses. 



The transformations of insects, although 

 seemingly abrupt transitions, are but pro- 

 gressive stages toward maturity, mainly due 

 to the nature of an insect's skin, which does 

 not permit enlargement of form. 



The bill of fare relished by insects ex- 

 ceeds in variety that demanded by the larger 

 members of the animal kingdom. Anytiiing 

 from a nettle to a fungus may be acceptable, 

 horn, cork, or grease being the favored diet 

 of some species. There is also a long list of 

 insects that are parasitic, and others who 

 breed their own cattle. 



Among those who build hermit homes are 

 described the mining, carpenter, and mason 

 bees ; the wasps, making nests of clay ; the 

 gall-makers ; the lictor moths that carry their 

 curious dwellings about with them, and the 



