Rotary Valve Engines

"A practical treatise on the principles of rotary valves, with examples of application to the early gas engine, the steam engine, and to modern petrol motors". Black cloth with gilt lettering on the spine. Undated , with no edition details given. War economy standard. Preface dated 1946. 216 pages, illustrated with photographs, diagrams and graphs etc. on 118 figures. 6 X 8.5 inches. The book is rubbed, with wear to the cloth at the corners and spine ends.Some marking to the cloth and a lean to the spine. Quite a sound copy, inside all in good order, pages clean and unmarked. Good copy. No dustwrapper.