Previously the anther measured the resistance of a single wheel rolling on dry sand and made a report. From that experiment, he obtained the following results: 1. The depth of the wheel sinking into the sand and the horizontal or the vertical component of the resistance stand in logarithmic linear relationship. 2. In the case of a constant sinking depth, the larger the diameter and the thickness of the wheel, or the bigger the grain size of the sand, or the harder the state of the sand, the more the resistance with increasing rate. 3. Variation of the resistance accaording to the velocity is negligibly small. As the vertical and horizontal components of the resistance depend on the weight of a car and on the pulling resistance, the data for the single wheel can be applied for a car. In this paper, relations between the traction resistance and the weight, the center of gravity, the velocity of the car, the shape of the wheel, the grain size and the state of sand are observed.
Details of the construction and practical limitations of an X-ray shadow microscope are described. It had two electro-magnetic lenses and the focus of the electron beam could be reduced to 5×10-5mm in diameter. Projecting shadow images of the specimen were obtained at a primary magnification up to 100× with exposure time of one or three hours. A resolution of several hundred Å should be practicable.
Effect of radiation on the starting potential was studied experimentally on various low presseur Ar-Hg discharge tubes with hot cathode. At the optimum argon presseur (about 4 mmHg) and wall temperature (40_??_80°C), remarkable rising of starting potential by faint u. v. ray and visible light was observed. When the intensity of irradiation is stronger than a certain value, the starting potential V_??_r gives somewhat a statnrated constant voltage (V_??_r)_??_at. Regardless of the kind of light source, strong irradiations by such as incandescent lamp, Ne lamp and Ar light give the same (V_??_r)_??_at as by Hg light.
Lead case-shots were pulverized under various conditions by using specially designed pulveri-zers. The process of fine disintegration was made clear for every experimental pulverizing con-dition, which might have had remarkable effect on the process. The course of study for the faculty of metal pulverizer was discussed from the results of the present experiments.