The principle of operation of the NACA high-speed camera is completely explained. This camera, operating at the rate of 40,000 photographs per second, took the photographs presented in numerous NACA reports concerning combustion, preignition, and knock in the spark-ignition engine. Many design details are presented and discussed, details of an entirely conventional nature are omitted. The inherent aberrations of the camera are discussed and partly evaluated. The focal-plane-shutter effect of the camera is explained. Photographs of the camera are presented. Some high-speed motion pictures of familiar objects -- photoflash bulb, firecrackers, camera shutter -- are reproduced as an illustration of the quality of the photographs taken by the camera.

Report discussing flight tests on a low-drag wing pursuit airplane to determine the effects of Mach and Reynolds numbers on the maximum lift coefficient obtainable in gradual and abrupt stalls. The obtainable maximum lift coefficient was found to be greatly affected by the Mach and Reynolds numbers in gradual stall. In abrupt stalls, the maximum lift coefficient was affected by the Mach number, but not the Reynolds number.

The following report presents data from the investigations on discovering factors affecting the precipitation of tubanyl peroxide from Alpha and Beta gunk solutions at reduced temperatures.

Abstract: The possibilities for the removal of tuballoy from diffusion pump oil and reclamation of the oils for reuse are discussed. The report includes specifications of practical equipment, operating instructions, photographs and diagrams of the necessary construction details.

Report discussing testing of 2-percent additions of seven aromatic amines on the knock-limited performance of 28-R fuel in a CFR engine. The most effective antiknock additives are described.

Abstract. In order to anticipate radiation - chemical effects in solutions of active lanthanum, various solutions and suspensions containing lanthanum were irradiated with an electron beam. Separation of lanthanum from barium by the alcoholic HCl method is not rendered less efficient by radiation, although considerable gas evolution occurs. Suspensions of lanthanum as hydroxide and as ferrocyanide are not appreciably solubilized by radiation. Lanthanum oxalate is decomposed by radiation, is partially thrown into solution, and finally dissolves completely when all the excess oxalate ion in the solution has been destroyed.

Abstract. the fluctuation in pile intensity caused by an oscillating point absorber is calculation. It is found that the nature of the response depends on the frequency of the impressed oscillation. If the frequency is high compared to the decay rate of the high harmonics, the response consists of a wave which is propagated away from the oscillator. If the frequency is low, the propagated wave character of the response disappears and the intensity of the whole pile tends to oscillate with the same phase. The amplitude of the response decreases with increasing frequency.