Mr. G. C. Whipple, Director of the Mount Prospect Laboratory of the Brooklyn Waterworks, has prepared a handbook for the water analyst and the waterworks engineer, with the title given above. It deals with the purposes, methods and results of the biological examination of drinking-water, affording means for the identification of the microscopic life found in water supplies and suggesting means for the elimination or control of those organisms which disagreeably affect the color or odor of potable waters. The construction of reservoirs, the storage of surface and of ground waters and the growth of organisms in pipes are also discussed. Though the motive of the book is thus technical, the subject is developed by the author along broad lines in a thoroughly scientific manner, and he has brought together a great deal of information, not only for the sanitary engineer, but also for the physicist, the chemist and the biologist. The problems in limnology, such as the temperature, stagnation and circulation of reservoir waters; the distribution and relative numbers of different organisms and their relation to chemical analyses are discussed in the light of the results of many years’ investigation of water-supplies. The seasonal succession of organisms, their movements with respect to light and other stimuli, and their horizontal and vertical distribution, are in like manner fully treated. The scope of the work and the treatment of the subject make the book a valuable one alike for engineering and biological laboratories and for the general library. THE PROGRESS OF SCIENCE.