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 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.

Report issued by the U.S. Bureau of Mines discussing safety hazards in western mines. Mine hoisting and haulage accidents are presented. Accident prevention is also discussed. This report includes tables.

Technical report. Photomicrographs showing the effect of heating polished uranium surface at 600, 700, 850, and 1000 degrees C, and sandblasted and cut surface at 1000 degrees C are included.

The yield of 49, the efficiency of production of 49, and poisoning in a power plant are discussed. Only the crudest of estimates of the poisoning are possible: these indicated that production will probably not be hampered by poisoning. In this case the yield of 49 could be as high as 3 kg/ton but only about 2 kg/ton is compatible with a fairly high efficiency. In the case that production is stopped by poisoning, smaller yields, proportional to the tolerable loss in k, are obtained. In this case the yield will be improved by a factor of 2 or 3 if only the most poisoned parts are extracted and replaced by new uranium.