1 AUGUST 1914, Page 23

Flight Without Formulae. By Commandant Duch&e. Translated by J. H.

Ledeboer. (Longmans and Co. 7s. 6d. net.)—This discussion of the mechanics of the aeroplane, by a French military engineer, is written in the simplest possible language, without the use of mathematical formulae or equations. The chapters on stability set forth several new and important theories on this fundamental problem. The translation is excellent, and the book should be helpful to all who wish to understand the principles of flight.