Another engine manual reprint from World War I for the aero engine historian and the model engineer. World War I resulted in considerable development in aero engines in general, but the rotary’s high power to weight ratio resulted in it being extensively used in fighter or ‘scout’ aircraft where speed and manoeuverability were major requirements. Clerget-Blin & Cie was one three French firms which developed rotary aero engines, the demand for which reached such a level that they reached a licensing agreement with British manufacturer Gwynnes Ltd. who published this manual, probably in 1917. Clerget engines were perhaps the best designed of the three makes and were well regarded by pilots and fitters alike. Their 9B and 9BF engines covered here developed 134 bhp at normal revolutions - power enough to make the Sopwith Camel, to which they were fitted, the most successful fighter/scout aircraft of the war. This detailed manual was for use by personnel at major maintenance facilities who would have had to rebuild the engines, and it is the detail which makes this book so fascinating. The first 26 pages cover the general setting up, dismantling and servicing of the engine, and include 13 drawings, many highly detailed. There then follow 8 blank pages for note taking, but then there are 32 pages which form an “Illustrated List of Parts”. Of these, 14 pages contain illustrations of component parts etc. Finally there are another 8 blank pages for your notes. For anyone with an interest in early aero engines, these details makes this book something they should have. Additionally, although only one of the drawings (a GA) carries any dimensions, I suspect that there is enough information here for a replica, or model, of one of these engines to be built. 74 page, high quality paperback. Camden