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Show Titles and Abstracts 11 with those techniques developed at the Wisconsin Experiment Sta tion, has shown exceptional promise in the control of some crop ... insects. The insecticide is prepared by activating or finally grinding the seed and diluting with sulphur or talc (pyrophyllite), the nature of the dilutant depending upon the crop for which the in secticide is intended. The dust at varying concentrations has exhibited strong toxic properties against some of the most resistant insects to commer cial control methods. Such insects as the squash bug (Anasa tristis De Geer ), Lygus bugs and the Harlequin bug (Murgantia histrionica Hahn). In 1944 trials were conducted on the control of squash bug. Nine commercial varieties of squash were observed. Two appli cations of dust were made, fifteen days apart. Typical of the obtained is that of the Golden Delicious, a yields variety which yielded approximately eleven tons, while the check averaged only 3.75 to 4 tons per acre. Experimental evidence would indicate that Sabadilla, ap plied well around all vines, will give excellent control of the in sect. For the squash bug a concentrate of 20 to 30 per cent of activated material gave satisfactory control. ... ... ... ... ... Mine Ventilation as Affected by Roughness of Wall of a Two-Compartment Rectangular Shaft ROBERT S. LEWIS, Professor of Mining, and HUSEYIN OZUKURT, Graduate Fellow, Department of Mining and Metallurgical Research, University 0/ Utah A two compartment shaft, on aI/12th natural scale, was made of sheet steel. It measured 8x 12 inches in section. It was lined with timber sets made of wood strips one inch square .. Rough ness of wall between the sets was obtained by crushing a biotite granite, and screening the product into certain sizes, one size being used for on test. The crushed rock was glued either to pieces of paper or to wood blocks. In turn, the paper or blocks were glued to the shaft walls between the sets. Resistance to the .flow of air through the shaft was measured by a sensitive gauge connected to two pitot tubes, placed 20 feet apart in the shaft. Resistance to the flow of air increased as the rock parti des were placed farther and farther back from the inside face of the shaft timbers. ... ... ... The Future of the Mining Industry . Dr. Robert S. Lewis Professor of Mining, University of Utah, Salt Lake City, Utah Utah is preeminently a mining state. A study, made a few • |
