A study is made on the illumination of viewing screen for radiography by the theory of vision. It is concluded that. 1) The min. discriminating difference of uniform objects which can be appreciated in radiograph decreases with increasing film density, film constant and illumination of the view-ing screen. 2) The subjective sharpness depends on the illumination and the film density or distribu-tion of densities, is almost always better than physical sharpness, and rises with decreasing illumination of the viewing screen. 3) The max. value of subjective contrast is influenced by the phenomenon of irradiation, and depends on the illumination and the film density, rises with decreasing illumination of the viewing screen. 4) The subjective contrast rises, if the shortwave-length light of the viewing screen is cut off by filter up to approximately 500mμ. 5) It is to be desired that the intensity of illumination of the viewing screen for radio-graphy be widely adjustable.
In the studies on mass spectrometer of magnetic scanning type so far reported, the power source stabilization and the scanning control are treated as independent subjects. In this paper, two standard voltages are used, and by coupling them and by mechanical control, the source stabilization and the scanning control achieved in union. Principle of the device and results of experiment are given.
Glass powder is packed in a tube joining two vessels, and water vapour is made to flow through it. After the vapour is let enter one end of the tube, there is a time lag for the vapour to come out of the other end in steady state. By measuring this time lag in setting up the steady state of flow, it is estimated that the amounts adsorbed at 10-510-6 mmHg, 0125°C are 0.510 and 150×10-8 c, c.S.T.P, /cm2 for lead borosilicate and soda lime glass surfaces respectively. It seems that the adsorption in this region is not of simple physical nature. Using the time lag method, it is possible to eliminate the influence of ionization gauge. The residual gas pressure was about 1×10-8 mmHg. Surface areas of glass samples were determined by the B. E. T. method.
Method of preparing large single crystals of alkali-halide in laboratory had been reported by the author1). Using these crystals, various optical parts have been made. In response to the requirement of physicists engaged in the research of infra-red spectroscopy and the study of ionic crystals, the method of polishing is given which is similar to the polishing of glass but with special caution on account of deliquescence and softness.
As the previous experiments indicated that the current noise is the principal factor which determines the ultimate sensitivity of a bolometer made by vacum evaporation, investigations are carried out to trace the origine of this noise and by eliminating it, the performance of the bolometer is remarkably improved. A typical bolometer possesses a resistance of about 1 KΩ and shows a sensitivity between 20 and 30μV/μW if the electric current of 2mA is passed through it. As the bolometer is damaged if the current exceeds about 10mA in the atmosphere of about 15°C, its maximum sensitivity would be much higher than this. When it is used as a detector of the usual infrared spectrometer with a quartz prism, the fine structure of the vibration-rotation band of HCI at 3.46μ can be easily resolved.
A series of basic researches was formerly made by the authors on static frictional phenomena. Recently, some experiments have been carried out with special reference to high-polymeric specimens in order to show the existence of minute deformation of the contact part before breaking in static frictional measurements. Various micro-flow curves are observed, each one of which seems to correspond to the bulk properties of specimens used. The method of applying external driving force is also studied in regard to its effect upon the value of maximum static frinctional force obtained thereby. As for the time rate of applying force, no remarkable differnce is found in the range between 0.5gr/sec. and 8, 000gr/sec. The negative dynamic load continuing for longer than 1/200 sec. is found to behave quite similarly as static load for the measurement of static friction.
Using the authors' previously reported method, concentrations of two different pulp solutions (G. P. and S. P.) are determined and it is found that the “Time to stop” is longer for G. P. than for S. P. As a check, the flowing speeds through a tube are compared which gives parallel results. Length distributions of fibers are also compared.