24 MARCH 1923, Page 20

A. Dictionary of Applied Physics. Vol. III. Edited by Sir

Richard Glazebrook, K.C.B. (Macmillan. 63s. net.) The third volume of Sir Richard Glazebrook's most useful encyclopaedia of applied physics deals exhaustively in a single alphabet with Meteorology, Metrology and Measuring Apparatus. It would have been still better for the student, perhaps, if the two main subjects here treated could have been sold separately at a lower price. The articles are all written by acknowledged specialists. As a model of concise exposition we may mention that by . Mr. J. E. Sears on Metrology, describing those austere principles of exact measurement of mass, length and time on which all modern physics and their engineering corollaries depend.