National Advisory Committee for Aeronautics: Technical Notes No. 34, The 300 H.P. Benz Aircraft Engine, by Dr. A. Heller. 10 pages, illustrations, diagrams. Technical Notes No. 35, The Optical Wing Aligning Device of the Langley Field Tunnel, by F. H. Norton and D. L. Bacon. 3 pages, illustrations. Technical Notes No. 36, N. A. C. A. Langley Field Wind Tunnel Apparatus. The Tilting Manometer, by F. H. Norton and D. L. Bacon. 3 pages, illustrations. Technical Notes No. 38, Measurements of Rudder Moments on an Airplane During Flight, by von Heidelberg. 23 pages, illustrations. Technical Paper No. 40, Effect of the Reversal of Air Flow Upon the Discharge Coefficient of Durley Orifices, by Marsden Ware. 12 pages, illustrations. Technical Notes No. 42, The Determination of Downwash. by Walter S. Diehl. 8 pages, diagrams. 6 pamphlets, quarto. Washington, 1921.

Reference Data:

Journal of the Franklin Institute, Vol. 191, by Franklin Institute, Philadelphia, Pa, 1921, page 436