Page:Popular Science Monthly Volume 51.djvu/141

Rh, the technical, and the diplomatic situations of to-day with regard to the two chief routes. In his concluding chapters he argues for the construction of a canal as of transcendent importance to the economic development of America, and gives his reasons why the United States should control the passage. The volume is carefully indexed and contains four maps.

Among the papers accompanying the Report of the United States Commissioner of Education for 1894-’95 are two dealing with important subjects connected with the educational system of Great Britain. One of these is the question of religious instruction in the free schools, and the other is the organization of secondary education as shown by the report of a royal commission. The legal aspects of the Manitoba school case are given in another contribution. Foreign matters of interest treated in other papers are the university education of women in England, the educational status of women in various countries, and English teaching on the history of the American Revolution. Of domestic interest are the chapters on teachers' pensions, Chautauqua education, and early educational history in the United States.

The book on Alternating Currents and Alternating Current Machinery, by ''Profs. Dugald C and John P. Jackson,'' forms Volume II of their textbook on Electromagnetism and the Construction of Dynamos (Macmillan, $3.50). The authors have followed in it methods that have been found advantageous in teaching other branches of engineering. The volume is designed to present the fundamental phenomena of alternating currents as met with in engineering practice, and to point out their controlling principles and applications. Descriptions and illustrations of commercial machinery are not included per se, though where practical data may be useful in illustrating deductions in the text they are copiously used. For the fuller information of the reader, a large number of references are given in footnotes. In the chapters on polyphase currents the authors could not hope to supply a list of references that would remain long adequate, as material of overshadowing importance is being constantly published. Descriptions of experiments having only historical interest have been carefully excluded. In the use of mathematics the authors have sought to avoid presenting unnecessary formulas on the one hand, or giving results without reasons on the other. Numerous original demonstrations of the standard formulas have been introduced and a few additions have been made to the nomenclature. The volume contains over three hundred diagrams and other figures, and is adequately indexed.

In a neatly printed little pamphlet H. Edwin Lewis has discussed The Philosophy of Sex scientifically, delicately, and impressively. His chapter on Reproduction and the Origin of Sex and that on the Nature and Relation of Sex lead up to an earnest appeal for sexual purity, which can not fail to help well-intentioned persons who are weak or thoughtless or who do not know where to turn for guidance. (Vermont Medical Publishing Co., Burlington, 35 cents.)

Much out of the common run of textbooks is Number and its Algebra, by Arthur Lefevre (Heath, $1.25). It deals with the theory of numerical operations, and is designed to be introductory to a collegiate course in algebra. It thus bears a similar relation to algebra that the chapters on chemical philosophy in books on chemistry bear to their main subject. The mathematical operations whose natures are explained range from counting up to work with radical surds, undetermined coefficients, roots of integral and quadratic equations, radix fractions, and functions. The several chapters are based on lectures which the author has given for a number of years to his university students with the especial design of aiding the large part of them who were preparing to teach, hence pedagogical applications will be found throughout the book. "Plainly the first step," says the author, "to the understanding of the algebra of number is to understand the nature and laws of number. It is hoped that these lectures have been a fairly adequate guide and stimulus to this step. After mastering what may be called the vocabulary of the language (proficiency in this matter has been assumed), the next step is to grasp the idea of algebraic form. In the study of algebra this should be the main standpoint. It is only by following out the problems which arise in a systematic