Page:Popular Science Monthly Volume 42.djvu/289

Rh evolutions called the Irving School March Drill. An illustrated chapter is devoted to Delsartean posturing. Apparatus drills with wands, Indian clubs, rings, dumb-bells, etc., are described, and a great many additional evolutions are suggested. The volume includes thirty-two pages of music suitable for evolutions of classes. We are somewhat astonished to see in the front of the book a poetical quotation ascribed to Herbert Spencer!

This is a brief elementary manual consisting of two parts, the first devoted to characters of minerals, and the second being descriptive. In the first part the crystalline forms of minerals are described quite fully, and the chemical composition, specific gravity, and other characters are treated briefly. In the descriptive part the minerals are grouped under these heads: rock-forming minerals, ores and veinstones, salts and other useful minerals, gems or precious stones. The text is illustrated with many cuts showing the forms of crystals or amorphous minerals and the occurrence of minerals in veins.

The extensive work of which the first installment is before us is made on the plan of having the several subjects included in its scope treated by authors having special qualifications for their respective tasks. In the selection of subjects the editors have been guided mainly by the needs of the English officials known as Medical Officers of Health, but there is much information in the essays which is applicable to sanitary conditions the world over. The first volume comprises sixteen essays dealing separately with air, water, food, clothing, baths, the dwelling, physical education, offensive and noxious businesses, etc. The most space is given to the treatise on The Dwelling, by P. Gordon Smith and Keith D. Young. The authors deal with the subjects of site, the arrangement of laborers' dwellings, prisons, barracks, schools, workhouses, and hospitals, both general and special, and the drainage of the dwelling. The Disposal of Refuse is also treated with much fullness in a separate article by W. H. Corfield, M. D., and Louis C. Parkes, M. D. In the essay on Warming and Ventilation, the author, W. N. Shaw, F. R. S., gives formulas and describes methods for calculating the movement of air in various systems of ventilation, and gives a summary of the conditions to be satisfied to secure a proper change of air. He also compares the efficiency of the ordinary modes of heating, and gives various numerical data concerning heating in the climate of England. The volume is illustrated with nearly two hundred cuts and plates, and has a separate index.

has chosen a very attractive topic, and has made a book interesting to both the zoologist and the general reader. After an introductory chapter giving the principal facts of animal coloration, he cites a number of cases in which the coloration of an animal appears to be in part due directly to the influence of the surroundings, among which are the prevalence of green in the animals of verdant Ceylon, the white fur of polar animals, and the absence of color among cave-dwelling species. Coming to the purposes of color in animals, the author finds much to discuss under the head of protective coloration. While on this subject he raises the question whether as a matter of fact animals are concealed from their foes by their protective resemblances, and shows that there is much evidence on the negative side. He contends, also, that in some cases so-called protective coloration is produced more simply and directly than by the operation of natural selection. Warning coloration, first explained by Mr. Wallace, next receives attention. The author is inclined to give much weight to the suggestion of Dr. Eisig that in caterpillars which are distasteful to their enemies the usual bright pigments cause the inedibility of the species instead of being produced to advertise it. Alluring colors receive attention in the same chapter. Allied to coloration like the surroundings is mimetic coloration or