A Text-Book of Hygiene.

This book is a valuable compilation of the most important matters relating to the subject of hygiene. It is comprehensive in scope, well condensed, clear in style, and abundantly supplied with references. A work of this sort is necessary and will undoubtedly be improved by future editions. In the consideration of the matter of ventilation the author is somewhat at fault. He assumes the general principle that foul air rises, and recommends rules for ventilation accordingly. The fact is, that in artificially heated buildings of all classes, public as well as private, the middle layer of air is that containing the least impurity and the best adapted as to temperature and humidity to the use of the inhabitants. Impurities that rise can not be dangerous, as they occupy an inaccessible part of the room, while the denser impurities and cold air resulting from the loss of heat by connection as