23 JUNE 1923, Page 20

Letters of a Radio-Engineer to His Son. By John Mills.

(Routledge. 10s. 6(1. net.) Letters of a Radio-Engineer to His Son. By John Mills. (Routledge. 10s. 6(1. net.)

A lucid and competent description of the principles and methods of wireless telegraphy in an unnecessary disguise. It is one of the best popular books on the subject.