Describes the importance of nitrogen-fixing bacteria on crops of legumes.

Report presenting testing of rectangular Clark-Y biplane cellules with zero and -0.25 stagger, the gap equal to the chord, and 0 degrees decalage were tested on the NACA spinning balance in the 5-foot vertical tunnel.

"An investigation was made in the N.A.C.A. 7 by 10 foot wind tunnel of the distribution of air pressure over one chord section of a Clark Y-H airfoil with a split flap. The results obtained are given in the form of diagrams showing the chordwise distribution of pressure on both airfoil and flap as plots of calculated aerodynamic coefficients for both airfoil and flap" (p. 1).

The purpose here is to consider the mechanical characteristics of reinforced phenol-formaldehyde resin as related to its use as structural material for aircraft. Data and graphs that have appeared in the literature are reproduced to illustrate the comparative behavior of plastics and materials commonly used in aircraft construction. Materials are characterized as to density, static strength, modulus of elasticity, resistance to long-time loading, strength under repeated impact, energy absorption, corrosion resistance, and ease of fabrication.

"The N.A.C.A. has developed a simple pressure-level meter for the measurement of sound-pressure levels above 70 db. The instrument employs a carbon microphone but has no amplification. The source of power is five flashlight batteries. Measurements may be made up to the threshold of feeling with an accuracy of plus or minus 2 db; band analysis of complex spectra may be made if desired" (p. 1).

Report presenting a study of eight wings and three tails covering a wide range of aerodynamic characteristics in 24 wing-tail combinations. Observations were made of the steady spin for four control settings and of recoveries for five control manipulations. The effect of wing shape, tail arrangement, control settings, relationships between spin characteristics, and comparison with results for basic loading are provided.

"This report presents the results of a combined theoretical and experimental investigation conducted at the Georgia School of Technology on the static thrust of the lifting air screw of the type used in modern autogiros and helicopters. The theoretical part of this study is based on Glauert's analysis but certain modifications are made that further clarify and simplify the problem. Of these changes the elimination of the solidity as an independent parameter is the most important" (p. 1).

A brief guide to growing, harvesting, and using roselle. Includes recipes for making jelly, jam, or drinks from the plant.

Discusses effective timing for harvesting rice, taking into consideration milling quality, moisture content, and other factors.

This paper is a critical analysis of the methods of determination of the tendency to detonation. No attempt has been made to describe in detail the different fuels and the different methods proposed.

"An investigation was undertaken to determine the character and importance of the transition phase between the ground run and steady climb in the takeoff of an airplane and the effects of various factors on this phase and on the airborne part of the takeoff as a whole. The information was obtained from a series of step-by-step integrations, which defined the motion of the airplane during the transition and which were based on data derived from actual takeoff tests of a Verville AT airplane. Both normal and zoom takeoffs under several loading and takeoff speed conditions were considered" (p. 1).

Report presents the results of a photographic study of the combustion in a spark-ignition engine using both Schlieren and flame photographs taken at high rates of speed. Although shock waves are present after knock occurs, there was no evidence of any type of sonic or supersonic compression waves existing in the combustion gases prior to the occurrence of knock. Artificially induced shock waves in the engine did not in themselves cause knock.

Data complied regarding wells and other water resources, including water quality analysis, measurements, and other relevant information.