Prochnow, Dr. Oskar. Vogelflug und Flugmaschinen. Leipzig, Theo.Thomas, 1910. 101pp, illus, hardcover, 5x8", attractive pictorial cover of stork in flight and a Wright aeroplane behind. Chapters on bird flight, analysis of bird wings, propellers, and early heavier-than-air machines with nice illustrations and early photos. German text. Very good condition.