7 io 



THE POPULAR SCIENCE MONTHLY. 



that " it is easier to learn the differential cal- 

 culus than to follow a demonstration which 

 attempts to avoid its use." Pneumatics and 

 hydraulics have been included as divisions 

 of hydrostatics, and there is a chapter on the 

 mechanical theory of heat. 



Dr. Daniel G. Brinton has reprinted from 

 the Proceedings of the American Philosoph- 

 ical Society his account of Nagualum a 

 mystic cult that flourished in Mexico and 

 Central America in the times of conquest 

 and colonization (David McKay, Philadelphia, 

 $1). The nagualists were of various tribes 

 and languages, united in a powerful secret 

 organization ; they exercised necromantic 

 powers and held occult doctrines. They were 

 animated by an intense hatred of the Spanish 

 explorers, and their one purpose was the de- 

 struction of the invaders and the annihilation 

 of the government and religion introduced 

 by them. 



A recent bulletin of the United States 

 National Museum is A Monograph of the Bats 

 of North America, by Harrison Allen, M. D., 

 being designed to take the place of the 

 author's monograph on the same subject 

 issued thirty years ago. The new work is 

 made larger than the old by the addition of 

 species and by elaboration of the descriptions. 

 Thirty-eight plates, showing anatomical de- 

 tails, accompany the text. 



A sketch of travel in California, by Rev. 

 Dr. Charles A. Stoddard, has been published 

 under the title Beyond the Rockies (Scribners, 

 $1.50). Dr. Stoddard describes the fruit 

 orchards, the wonderful climate, the big 

 trees, the Yosemite Valley, the old missions, 

 San Francisco and other Californian cities, 

 etc., in a chatty and entertaining style. In- 

 cidents of travel are also mingled with the 

 descriptions, and there are accounts of the 

 Bcenery and stopping places in Texas, New 

 Mexico, Arizona, Utah, and Colorado, which 

 were passed through either in going or com- 

 ing. The volume is copiously illustrated 

 with photo-engravings of the places de- 

 scribed. 



A new translation of The Social Contract, 

 of Jean Jacques Rousseau, with an introduc- 

 tion and notes by Prof. Edward L. Walter, 

 has been issued (Putnam, $1.25). Students 

 of political science will find in this book 

 " the most striking statement of a theory 

 destined to mold profoundly the history of 



nations," and will discover within it, also, 

 " the weapons which are first sharpened and 

 polished, and then directed against the whole 

 framework of the modern state." The in- 

 troduction reviews the political circumstances 

 in which the treatise appeared, and the notes 

 give historical facts concerning the persons 

 and events referred to in the text, or refer- 

 ences to books from which full information 

 may be obtained. 



In David T. Day's report on the Mineral 

 Resources of the United States for 1892, the 

 ninth of the series, the statistical tables of 

 previous years are carried forward. Instead 

 of chapters, the book is divided by mineral 

 topics, which are so arranged as to bring 

 kindred subjects together. The work is the 

 result of a census conducted by the principal 

 experts on each subject. 



The Report of the Chief of the Weather 

 Bureau for 1891-9% is the first volume of 

 the meteorological data published by the of- 

 fice as now constituted, and continues the 

 series heretofore published by the War De- 

 partment. The necessity of crowding two 

 years' work into one report has compelled 

 condensation by the omission of the detailed 

 hourly and twice daily observations ; but this 

 omission is partly supplied on the daily 

 weather maps. Tables of monthly and an- 

 nual normal pressure, temperature, and pre- 

 cipitation are given. A description of the 

 instrumental equipment of observing stations 

 by Prof. C. F. Marvin, and a report by Prof. 

 Cleveland Abbe on the instrumental correc- 

 tions, methods of reduction, and the prob- 

 able resulting accuracy of the observations 

 and the mean, add much to the value of the 

 volume. Mark W. Harrington, chief of the 

 bureau. 



The Commissioner of Labor of the United 

 States publishes a special report on Compul- 

 sory Insurance in Germany, which has been 

 prepared at his request by Mr. John Graham 

 Brooks, after residing in Germany and mak- 

 ing a careful and broad study of the subject 

 and all the circumstances surrounding. The 

 author was commissioned to collect all the 

 official information available with reference 

 to the system, and to ascertain in all legiti- 

 mate ways its real workings, its effect upon 

 labor and the workingman, and its general 

 tendencies. Neither approving nor condemn- 

 ing the system, Mr. Brooks has given the 



