Circular presenting a description of the De Havilland Dragon Moth, or D.H. 84, which is the first twin-engine airplane built by this particular company. Details of the design, components, flight characteristics, performance, drawings, and photographs are provided.

Circular describing the Dewoitine D.500 pursuit airplane, which is an all-metal cantilever low-wing monoplane. Details of the fuselage, cockpit, control surfaces, weapons, landing gear, fuel tanks, wing, engine, characteristics, performances, drawings, and photographs are provided.

Circular presenting a description of the light airplane SM-1, which was designed by W. S. Shackleton and Lee Murray. Information regarding the design and flight characteristics and some photographs of the airplane are provided.

Circular describing the Comper "Mouse" commercial airplane, which is a three-seat cabin low-wing monoplane. Details regarding the landing gear, wings, cabin, seating, fuselage, tail, power plant, controls, characteristics, performance, drawings, and photographs are provided.

Circular presenting a description of the Hanriot-Biche 110 C1 airplane, which is a French all-metal low-wing pursuit monoplane. Details regarding the wing, girders and tail surfaces, pilot's cockpit, power plant, landing gear, flying qualities, and photographs are provided.

Circular describing the De Havilland "Leopard Moth", which is a three-seat cabin high-wing monoplane with a good cruising speed and fuel efficiency. Details of the components, controls, characteristics, performance, drawings, and photographs are provided.

Circular describing the Dewoitine D.332, which is a commercial three-engine all-metal low-wing monoplane form France. Details of the construction history, wing, fuselage, power plant, landing gear, characteristics, performance, drawings, and photographs are provided.

Circular presenting a description of the Boulton and Paul P.64 high-performance mail-carrier. It is a two-engine tractor biplane that has been designed to give the specified normal speed with each engine throttled down to approximately half its output. Details of the landing gear, structural features, pilots' compartment, accommodation for mails, controls, power plant, and some flying qualities are provided.

Circular presenting an overview of the Westland Wallace, which is a general purpose aircraft used by the British Royal Air Force. A description of the design, flight characteristics, blueprints, and photographs are provided.

Circular presenting a description of the Caudron P.V. 200 touring amphibian, which is a two-place cantilever monoplane with folding wings and dual controls. Details of the wing, fuselage, controls, landing gear, flying qualities, and photographs are provided.

Circular presenting a description of the first British airplane with a retractable landing gear, which is a small and aerodynamically clean monoplane. A description of the design and flight characteristics is provided.

Report issued by the U.S. Bureau of Mines on the exploration of the Oklahoma City oil field for natural gas reserves. This report includes tables, maps, and illustrations.

Report issued by the U.S. Bureau of Mines on the specifications and development of methods used in plain-carbon steel production. Proposed methods and experiment results are presented. This report includes tables, graphs, and photographs.

Report discussing earthquake activity in the United States during 1933. The report is broken down by regions and has sections for specific earthquakes.

From introduction: In the following report the species of Foraminifera found in the Miocene of the Coastal Plain region of the eastern United States from Florida to Maryland are described and recorded. Numerous papers have been published on this region, some of which, however, are largely lists. Where the original material on which a paper was based has not been available for the present study, the records have been omitted, as it is very difficult to place the species in their proper position without seeing the actual specimens.

From abstract: The thesis of this paper is that the anhydrite cap rock of salt domes originated by the residual accumulation and consolidation, on top of a salt stock, of sedimentary anhydrite freed from the salt by solution of the top of the stock. This hypothesis is compared with that of origin from a bed of sedimentary anhydrite supposed to have overlain the salt of the salt stock in depth and to have been forced up on top of the stock as it rose. The strongest basis for the hypothesis of residual accumulation is the presence, between the anhydrite cap rock and the top of the salt stock on many salt domes, of a flat solution surface, the "salt table," decapitating anhydrite-bearing folds in the salt. The paper considers other general geologic evidence and internal petrographic evidence with a view to ascertaining to what extent they confirm or at least fit this interpretation.

From Summary: "An investigation was made in the NACA 7 by 10 foot wind tunnel to find the increase in maximum lift coefficient which could be obtained by providing a model wing with both a Fowler trailing-edge extension flap and a Handley Page type leading-edge slot. A conventional Handley page slot proportioned to operate on the plain wing without a flap gave but a slight increase with the flap; so a special form of slot was developed to work more effectively with the flap. With the best combined arrangement the maximum lift coefficient based on the original area was increased from 3.17, for the Fowler wing, to 3.62."

"Preliminary results are given of drag tests of streamline wires. Full-size wires were tested over a wide range of speeds in the N.A.C.A. high speed tunnel. The results are thus directly applicable to full-scale problems and include any compressibility effects encountered at the higher speeds. The results show how protuberances may be employed on conventional streamline wires to reduce the drag, and also show how the conventional wires compare with others having sections more like strut or symmetrical airfoil sections" (p. 1).

A simplified aerodynamic theory of the cyclogiro rotating wing is presented herein. In addition, examples have been calculated showing the effect on the rotor characteristics of varying the design parameters of the rotor. A performance prediction, on the basis of the theory here developed, is appended, showing the performance to be expected of a machine employing this system of sustentation. The aerodynamic principles of the cyclogiro are sound; hovering flight, vertical climb, and a reasonable forward speed may be obtained with a normal expenditure of power. Auto rotation in a gliding descent is available in the event of a power-plant failure.

"This paper gives results of a short investigation of the drag of a forward-sloping closed-cabin windshield. The drag of the windshield in both the original and a final modified form was determined from tests in the variable-density wind tunnel. The final form of the windshield was arrived at by modifying the original as the result of flow observations in the N.A.C.A. smoke tunnel. The investigation studied the utility of the N.A.C.A. smoke tunnel as applied to reducing the drag of objects for which the full dynamic scale could not be approached in the smoke tunnel, but designers should find the results of the flow observations and drag measurements of value" (p. 1).

"At the request of the Bureau of Aeronautics, Navy Department, a study of the design of floats especially suitable for use on high-speed seaplanes was undertaken in the N.A.C.A. tank. This note give the results obtained in tests of one-quarter full-size models of two floats for high-speed seaplanes. One was a float similar to that used on the Macchi high-speed seaplane which competed in the 1926 Schneider Trophy races, and the other a float designed at the N.A.C.A. tank in an attempt to improve on the water performance of the Macchi float. The model of the latter showed considerably better water performance than the model of the Macchi float" (p. 1).

"This report gives a comparison of the accuracy of the three methods for calculating the compressive strength of flat sheet and stiffener combinations such as occur in stressed-skin or monocoque structures for aircraft. Of the three methods based upon various assumptions with regard to the interaction of sheet and stiffener, the method based upon mutual action of the stiffener and an effective width as a column gave the best agreement with the results of the tests. An investigation of the effect of small curvature resulted in the conclusion that the compressive strength of the curved panels is, for all practical purposes, equal to the strength of flat panels except for thick sheet where non-uniform curvature throughout the length may cause the strength of the curved panel to be 10 to 15 percent less than that of a corresponding flat panel" (p. 1).

Tests were made with the spinning balance in a 5-foot wind tunnel to study the effect of stabilizer location upon the pitching and yawing moments given by the tail surfaces in spinning attitudes. The tests revealed that the horizontal surfaces, when in a normal location, seriously reduced the effectiveness of the fin and rudder, particularly at angles of attack of 50 degrees or more. The tests also revealed that a more forward or more rearward location gave no consistent or decided improvement; that a lower location greatly increased the shielding so that the yawing moment from the combination was in general less than that given by the bare fuselage; and that a higher location decreased the shielding and gave a favorable interference effect, particularly at the high angles of attack. Additional results regarding the stabilizer and the elevator are given.

"Tests were conducted in the N.A.C.A. full scale wind tunnel at the request of the Army Air Corps to determine the effect of retractable landing gear openings in the bottom surface of a wing upon the characteristics of a Lockheed Altair airplane. The tests were extended to include the determination of the lift and drag characteristics throughout the angle-of-attack range with the landing gear both retracted and extended. Covering the wheel openings in the wing with sheet metal when the wheels were extended reduced the drag only 2 percent at a lift coefficient of 1.0, which was assumed for the take-off condition" (p. 1).