Page:Popular Science Monthly Volume 39.djvu/873

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to water. The Leyden jar is an example of two conductors separated by an insulating medium and may be used to exhibit some of the recent discoveries as well as simpler phenomena. An analogy is found for the charged Leyden jar in the atmospheric condition preceding a thunderstorm when the air between the earth and clouds is under the same strain as the glass.

The theory of molecular magnetization accounts best for the properties of magnets and the study of terrestrial magnetism confirms the coincidence of magnetic storms and sun-spots. All electrical manifestation results in discharge, but current electricity consists in a continuous flow. The usual way of producing this by galvanic battery, the chemical, physiological, and magnetic effects are next examined. The practical units of measurement, the volt, ohm, ampère, and coulomb, are usually employed with prefixes signifying a million-fold or millionth, thousand-fold or thosuandth. In the last section various magneto-electric, dynamo machines, and electric motors are described and illustrated; also, electric lighting, railways, telpherage, the telephone, and many minor electrical devices; and the application of electricity to metallurgy in electro-plating, electrotyping and welding. The nature of electricity is discussed. Since the detection of electro-magnetic waves that can be reflected, refracted, and polarized like those of light, the "electro-magnetic theory of light" has been accepted and "we may say that electrical science includes the whole of optics, or that optics includes the whole of electrical science, whichever way we like to put it."

The Criminal Jurisprudence of the Ancient Hebrews. Compiled from the Talmud and other Rabbinical Writings, and compared with Roman and English Criminal Jurisprudence. By S. Mendelsohn. Baltimore: M. Curlander. Pp. 270. Price, $2.50.

The author of this book is Rabbi of the Jewish congregation "Temple of Israel," at Wilmington, N. C. He is described as a man of great learning, and the accuracy of his work is testified to by prominent Hebrew clergymen on the side of Talmudic data, and by "lawyers of renown" on that of the civil and common law. His purpose in preparing it has been to acquaint the world with the system of criminal jurisprudence unfolded in the Talmud, and to contribute to the vindication of the Israelitish people's ancient literature from aspersions which have been cast upon it. His language on the latter point leads us to infer that he hardly realizes the attention Talmudic literature has received in later days from students, and underrates the respect in which it is held by theologians and scholars. In the course of his essay he unfolds the thesis that the system of criminal jurisprudence of the ancient Hebrews, as recorded in the Talmud and contemporaneous rabbinic literature, was one which enforced civil order and secured the safety and peace of society by mildness and consideration; and this in an age of savagery and violence, of wars and uncertainty. While in England, one hundred years ago, one hundred and sixty offenses were punishable with death, that penalty was inflicted among the Hebrews for only thirty-six offenses. The lex talionis, an eye for an eye, etc., prescribed by Moses, and not unknown to the old English law, gave way, under the rabbis, to a pecuniary compensation; and it was the custom of the rabbis, sitting in judgment over a human being, to lay every possible legitimate obstacle in the way of conviction. In the body of the work a syllabus is furnished of the principal penal statutes established by the ancient Jews and preserved in the Talmud and contemporaneous rabbinical books, under the headings of Crimes and Punishments, The Synhedrion, The Trial, and The Execution. An account of the Talmud, historical and analytical, is given in an appendix.

An Introduction to the Study of Botany. By Edward Aveling. New York: Macmillan & Co. Pp. 363. Price, $1.10.

This volume is intended as a guide to the practical study of the subject, and assumes no knowledge of it on the part of the reader. The syllabus of the Science and Art Department at South Kensington is taken as a basis for the general plan of the work, but it is intended to help all who enter upon the study, no matter what particular end they may have in view. The lessons are expected to be taken from the plant, and