From Abstract: "This report describes the occurrence of the mica and its physical properties among which is an unusually wide range of colors. A table is presented showing the results of power-factor measurements made by the National Bureau of Standards on 196 samples of sheet mica from 109 mica mines and 15 feldspar mines.It is concluded that more systematic planning of mica mining, for the district as a whole. would result in an average yearly production of at least 90,000 pounds of relatively clear sheet and possibly much more."

From Summary: "A method for calculating the rate of heat transfer from the surface of an airfoil or streamline body is presented. A comparison with the results of an experimental investigation indicates that the accuracy of the method is good. This method may be used to calculate the heat supply necessary for heat de-icing or in ascertaining the heat loss from the fuselage of an aircraft operating at great altitude, for example."

Investigations were undertaken to improve the ailerons of a P-51 fighter so as to obtain greater effectiveness without increasing the stick forces. Modifications consisted of increasing the deflection range of the aileron to 70 percent and changing the original concave section to a thick section with beveled trailing edge. Results of the modified ailerons showed an increase in effectiveness over the original aileron of 70 percent at low speed and 55 percent at high speeds.

Report presenting a new method for obtaining the velocity potential of the flow about a solid of revolution moving uniformly in the direction of its axis of symmetry in a fluid otherwise at rest. The method is based essentially on the fact that the form of the differential equation for the velocity potential is invariant with regard to conformal transformations in a meridian plane. The general results are applied to a body of revolution obtained by revolving a symmetrical Joukowski profile about its axis of symmetry.

Report presenting an analysis of the effects of heat and compressibility in the flow through the internal systems of aircraft. Equations and charts are developed whereby the flow characteristics at key stations in a typical internal system may be readily obtained.

Report presenting tests on a single-cylinder, air-cooled engine to determine the effect of several different exhaust-stack shapes on the design and performance of the individual cylinder exhaust-gas jet-propulsion systems. Results regarding the effect of nozzle area and stack shape on exhaust-gas jet thrust, effect of nozzle area and stack shape on overall performance for the S-shape, the 90 degree bend, and the 180 degree bend, the effect on the shape on engine power and volumetric efficiency, and the effect of a branched stack on engine power are provided.

Report presenting a practical method for determining the chordwise distribution of the rate of heat transfer from the surface of a wing or body of revolution to air. The method is limited to use to the determination of heat transfer fro the forward section of such bodies when the flow is laminar.

Report issued by the U.S. Bureau of Mines on the progress made in metal-mine stemming. Previous reports have been presented impartially, or under different procedures. This report contains updated progress results from current procedures and mine conditions. The report includes tables, and illustrations.

Report issued by the U.S. Bureau of Mines over the ongoing issue of heaving-shale in the Gulf Coast area. The operations and potential causes of incompetent heaving-shale are listed. This report includes tables, and a map.

Report issued by the U.S. Bureau of Mines on the differing conditions of oxygen in explosives. Results from explosives samples with oxygen variations are presented. This report includes tables.

Report issued by the U.S. Bureau of Mines on investigations conducted on manganese ore used for smelting. Experimental methods and results are presented. This report includes tables, and a photograph.

Report issued by the U.S. Bureau of Mines regarding laboratory tests conducted on acid leaching of manganese ore. Descriptions of the methods used in testing and results are presented. This report contains tables, and graphs.

Report issued by the U.S. Bureau of Mines on testing of sub-audible noises and accuracy of rock burst predictions. The history of this study, and the results of these investigations are presented. This report includes tables, graphs, illustrations, and diagrams.

Report issued by the U.S. Bureau of Mines on sub-bituminous slack from Denver, Colorado. The characteristics and properties of 2-1/2 inch slack samples are listed. This report includes tables, graphs, maps, illustrations, and photographs.

Report issued by the U.S. Bureau of Mines on the annual work conducted by the Mining Division during 1942. Descriptions of projects and operations during the fiscal year are listed. This report contains tables, and photographs.

Report issued by the U.S. Bureau of Mines on the annual report of work conducted by the Explosives Division during the fiscal year of 1942. Descriptions of testing projects and operations are presented. This report includes tables, graphs, illustrations, and photographs.

Report issued by the U.S. Bureau of Mines on the experiments conducted on stemming in metal-mines. As stated in the introduction, "its purpose is to compare the amount of dust and gases produced as a result of blasting charges of dynamite (1) in drill holes, (2) in bombs, and (3) in mud-cap or adobe shots" (p. 1). Dust and gas concentrations gathered from the experiments are listed. This report includes tables.

Report issued by the Bureau of Mines over the operations of the Nonmetals Division during 1942. The work done by the division is discussed. This report includes tables, illustrations, and photographs.

From abstract: The Carrizo Mountains vanadium district is in the Navajo Indian Reservation, northeastern Arizona and northwestern New Mexico. From May through October, 1942, two mining companies, operating under lease agreements with the Navajo Service, opened several mines in the district and produced a total of about 6,000 tons of ore, averaging approximately 2.2 percent.

Abstract: In the accompanying report reference is made to all of the deposits in Alaska in which molybdenum minerals have been definitely recognized and reported. None of the deposits have been mined commercially, and none of them have been prospected thoroughly enough to afford quantitative estimates as to their tenor and potential reserves ; in fact, at only a few of the localities has there been more than surficial testing. Forty-one separate and distinct localities where molybdenum minerals occur are listed, and the available information on factors of geologic significance regarding each occurrence is given. A small-scale map of Alaska on which the various localities are indicated forms part of the bulletin, and in the text are extensive references to the various published reports and records of the Survey upon which the statements are based. In spite of the widespread distribution of molybdenum mineralization in Alaska, the remoteness of many of the localities, their handicap through dearth of transportation facilities and labor supplies, and the already wellsupplied condition of the American market for molybdenum ores discourage the early development of any of the known deposits or search for them in unsurveyed areas. These draw-backs will doubtless become -less important factors …

This report is part of a series describing the structural features, the character of the oil- and gas-producing beds, and the localities where additional oil and gas may be found in parts of Osage County, Oklahoma. This part provides an overview of the discussions in the previous 10 publications and provides a summary of relevant information.

From abstract: Tin-bearing veinlets are exposed in a small area near Izenhood Ranch, 22 miles north of Battle Mountain, Nev. They occur in thick rhyolitic flows of Miocene (?) age, and wood tin, found in the gravels of arroyos that head in the surrounding rhyolite, presumably comes from -other veinlets not yet discovered. The exposed veinlets are about 20 feet in maximum length and a quarter of an inch in average thickness. Parallel and reticulating veinlets form lodes 4 to 6 feet thick and 15 or 20 feet long. Virtually no cassiterite is disseminated in the wall rock.

From abstract: Mica has been mined in New Hampshire since 1803. Production from 1908 through 1939 has aggregated 13,326,990 pounds of sheet and punch mica, an annual average of 416,470 pounds. Since 1931 production has been below this average, because of economic conditions rather than depletions. The mica-bearing pegmatites of the Grafton and Keene districts occur mostly in sillimanite-mica schist adjacent to large areas of biotite gneiss. The pegmatite bodies range from a fraction of an inch to more than 200 feet in thickness; most of them are crosscutting, and about 75 percent strike northeast. Mica occurs sporadically in most of them but where present in commercial quantities it is localized in one or more of the following zones: (1) In quartz-plagioclase-muscovite zones 2 to 10 feet from the walls of large pegmatite bodies, (2) in or near quartz masses that occur mostly near the centers of the bodies, (3) in thin dikes 5 to 15 feet thick or in similar offshoots from larger bodies, (4) within large pegmatite bodies, in more or less tabular streaks or zones composed principally of plagioclase, quartz, and muscovite.

Report on operations given by Fred Harmon of the Harmon Flying School at Ballinger, Texas. The report states that there are 210 students per class, 110 mechanics for 94 airplanes with 45 women who start at $65 per month. Women took night school course, 2 hours per night, 4 nights a week, while paid $1 per night, for 30 days. The women mechanics proved very steady, very capable, and efficient.