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Heat transfer resistance of the air layer is severely influenced by the state of motion in the air layer. In this report, the state of motion is observed by using both TiCl4 and NH3OH, and the coefficient of heat transfer through the air layer is measured as the first report. According to our experiments, the convective motion in the air layer is cellular motion and the breadth of a cell is about twice of the thickness of the air layer and the ratio between the thickness of the air layer and the breadth of a cell increases with Grashoff number. And then the heat transfer is theoretically analyzed and it is found that theoretical results agree well with the experimental data.

Experiments were carried out to determine the resistance of rubber products to vibration. There were no essential changes in mechanical properties as a result of vibration for 50 to 100 hours. There were on the other hand considerable changes in electrical properties, e. g., the insulation resistance decreased with increase in time of vibration. Further experiments in connection with this problem will be carried out to obtain data on the effects of vibration for prolonged periods. The authors wish to thank Messrs. Endo, Taguma, Hamono, and Wada for their aid in the experimentation.