Circular presenting a description of the Bernard 120, which is a seaplane. Descriptions of the structural elements, engine, and fuel distribution system are provided.

Report presenting a description of the Dyle and Balaclan DB 70, which is a commercial airplane with a very thick wing. Details of the fuselages, wings, passenger and pilot spaces, ability to function as an ambulance airplane, and flying qualities are provided.

Circular presenting a description of the Latécoère 521, which was the largest aircraft built in France at the time. A more detailed description of the wings, hull, accommodation for passengers and officers, fuel system, controls, and flight characteristics is provided.

According to one of the main propositions of the boundary layer theory the scarcely noticeable boundary layer may, under certain conditions, have a decisive influence on the form of the external flow by causing it to separate from the wing surface. These phenomena are known to be caused by a kind of stagnation of the boundary layer at the point of separation. The present report deals with similar phenomena. It is important to note that usually the cause (external interference) directly affects only the layer close to the wall, while its indirect effect extends to a large portion of the external flow.

Circular presenting Les Mureaux 130.A2, which is a high-wing two-seat observation monoplane. A description of the design, performances, components, performance qualities, photographs, and drawings are provided.

Circular presenting a description of the Bleriot 110 which is a long-distance airplane mainly distinguished by its fineness and lightness. Details of the fuselage, shape, wing, and power plant are provided.

Report presenting a description of the Latécoère 28, a commercial monoplane. A detailed description of the design, flight characteristics, and special features are provided.

Circular presenting a description of the Boulton Paul P.71A, which is a new type of two-engine biplane. Details of the design, fuel tanks, materials, fuselage, passenger seating, tail, and flying qualities are provided.

Circular presenting a description of the Wibault 280 T.10, which is an all-metal cantilever low-wing monoplane. The flight characteristics, design, blueprints, and photographs are provided.

Circular describing the Polish P.I and P.VIII airplanes, which are both all-metal gull-type wing monoplanes that differ in the type of engine used, their wing area, and their landing gears. Details of the components, design, differences, characteristics, load distribution, performance, drawings, and photographs are provided.

The stability conditions of Ente (duck) airplanes are investigated in this report. In developing the formulas, which afford an approximate solution, the unimportant effect of the height of the C.G. and the moment of the residual resistance are neglected. The effect of downwash from the forward horizontal empennage on the wing are also disregarded.

"The stability of an airplane can be easily determined by wind-tunnel tests, especially by simple tests with models mounted wind-vane fashion. However, each stability curve plotted by this method is valid only for a certain setting of the corresponding control surface, i.e., it characterizes the stability of the airplane with the control stick in a given position. The problems thus defined are studied from the point of view of longitudinal and transverse stability. Directional stability is not included in this study" (p. 1).

In the present report the computation is actually carried through for the case of parallel spars of equal resistance in bending without direct loading, including plotting of the influence lines; for other cases the method of calculation is explained. The development of large size airplanes can be speeded up by accurate methods of calculation such as this.

This report details the Elmira, New York soaring contest of 1930 and provides up-current maps, experiences in piloting, distance flights, and a few details on glider design.

Circular describing the Avro Anson, which is a two-engine low-wing cantilever monoplane of the general-purpose type. Details regarding the wing, landing gear, controls, fuselage, pilot's equipment, power plant, armament, characteristics, performance, drawings, and photographs are provided.

Circular presenting a description of the Loire 11 military airplane, which is a landplane. Information regarding the materials, wing, fuselage, power plant, flight characteristics, and some photographs are provided.

Circular presenting a description of the C.A.M.S. 80, which is a shipboard or observation patrol, light-bombing, long-range amphibian. Details of the hull, landing gear, wing, tail surfaces, power plant, front cockpit, pilot's compartment, photographer's compartment, radio cabinet, rear gunner's cockpit, stern compartment, and flying qualities are provided.

Report issued by the Bureau of Mines over the Salt Flat fields in East Central Texas. As stated in the introduction, "this report deals with the development and production history of the Salt Flat field and gives comparative data on five outstanding fault fields. Two of these fields are producing from limestone and three from sandstone reservoirs" (p. 2-3). This report includes tables, maps, photographs, and illustrations.

Report issued by the U.S. Bureau of Mines on the coal mine related deaths during the month of February, 1931. The number of fatalities and the causes of each are presented. This report includes tables.

Introduction: In anticipation of the design of equipment for heat transfer tests, a series of short exposure corrosion tests was initiated in an effort to determine the order of magnitude of the corrosion involved. Information was required on the effect on corrosion rates of applying a potential between two concentric tubes, the annulus between them containing condensate water.

The investigation of all serious accidents, involving technical defects in the airplane or engine, is undertaken by the D.V.L. in conjunction with the imperial traffic minister and other interested parties. All accidents not clearly explained in the reports are subsequently cleared up.

"The deformation of aircraft wings is measured by photographically recording a series of bright shots on a moving paper band sensitive to light. Alternating deformations, especially vibrations, can thus be measured in operation, unaffected by inertia. A handy recording camera, the optograph, was developed by the static division of the D.V.L. (German Experimental Institute for Aeronautics) for the employment of this method of measurement on airplanes in flight" (p. 1).

This investigation shows the attempt to improve the electrodynamomoter designed by Mr. Villey. The force to be measured acts on a flexible steel plate which is placed in front of a fixed plate. The deformation varies the original thickness of the layer of air between the two plates, thus causing a more rapid variation in the coefficient of electrostatic attraction of the two plates than in the capacity of the condenser formed by the dynamometer.

Report presenting tests made in the variable-density wind tunnel of airfoils of the NACA 4400 series modified by reflex at the trailing edge designed to reduce the pitching moment to the value of -0.03. The modified airfoils are designated the NACA 4400R series.