Page:Popular Science Monthly Volume 41.djvu/875

Rh, the puzzle of fifteen, the tower of Hanoi, Chinese rings, and the like; the knight's path on the chess-board, the art of traversing mazes, geometrical trees; the speculations on spaces of one, two, and four dimensions; and hypotheses concerning matter and gravity. Some of these problems are trivial; others are associated with the names of distinguished mathematicians; while several of the memoirs quoted have hitherto not been accessible to English readers.

is a book of general interest and considerable historical value. Many interesting articles on its subject have been published in various periodicals, but none that in themselves have covered the whole ground, and given, as the author says, an idea of the routine, forethought, and general arrangements necessary to carry on such a far reaching organization as a great steamship line, and which would set forth the efforts of the men who have instituted and maintained such enterprises, and the nature and results of the more remarkable examples of vessels and machinery which they have employed. The effort has been made in this book to cover this ground; and the book gives the history, from the earliest institution of Atlantic steamers, of the several lines; chapters descriptive of the working, sailing experiences, and machinery of the Atlantic lines; notices of the men who have made and conduct the Atlantic ferry; sketches of eventful passages and scenes, etc.; facts concerning the manning, expenses, and cost of Atlantic lines; and Atlantic records and tables.

In the Elementary Geography of the British Colonies, published by Macmillan & Co. as one of their Geographical Series (price, 80 cents), the part relating to the British possessions in North America, the West Indies, and the southern part of the South Atlantic Ocean, is contributed by Dr. George M. Dawson, of the Geological Survey of Canada; and that concerning the colonies, dependencies, and protectorates in the northern part of the South Atlantic, Mediterranean Sea, Africa, Asia, Australasia, and Oceania is contributed by Mr. Alexander Sutherland, of Melbourne. India and Ceylon are not included, but are described in a separate volume of the Geographical Scries. In both departments the descriptions are systematic, full, and satisfactory; and the geography is a valuable manual for whatever purpose such a work may be required.

In his book on Electric Railway Engineering (Rubier Publishing Company, Lynn, Mass.) the author, Mr. Edward Trevert, has endeavored to make the subject as plain and interesting as the present advance in the science will admit. The book is written wholly from an electrical point of view, and aims to make clear all the points connected with the management of electric railways. The powerhouse and its apparatus, generators, the construction of the line, motors, rheostats, electric heaters, trolleys, locomotives for heavy traction, trucks, car-wiring, and the storage-battery system are described and illustrated in the chapters severally assigned to them. Accounts are given of some illustrative roads, and remarks for motor men and station men; and some miscellaneous matters are treated of in the appendix. The author predicts a brilliant future for electric railroading.

We published a few months ago a paper by M. Charles Henry on Odors and the Sense of Smell, which included many facts and principles of great interest—some of them, doubtless, novel to most of our readers. Prof. Henry's full discussion of these subjects, with technical observations, tables, etc., which were not appropriate to a popular article, with descriptions of some special apparatus he has invented and applied, are given in a hand-book, Les Odeurs; Démonstrations pratiques avec l'Olfactomètre et le Pèse-vapeur (Odors; Practical Demonstrations with the Olfactometer and Vapor-Balance), which is published in Paris as a number of the Forney Municipal Professional Library of Art and Industry.

The Etiology, Diagnosis, and Treatment of the Prevalent Epidemic of Quackery—an address before the graduating class of a medical school—by Dr. George M. Gould, is devoted very largely to the denunciation of homoeopathy. The offer of a prize of $100 is made for the best essay that shall,