Bolometers using antimony, bismuth and tellurium have been prepared by coating, mem-branes of collodion with these metals by evaporation and their properties, especially the tem-perature coefficient of electrical resistance, are investigated. The temperature coefficient of antimony bolometer is positive, and almost independent of the film thickness, but its measured value is not reproducible when the thickness becomes less than about 1000A. As for the film of bismuth, the temperature coefficient is negative whereas its bulk value is positive. Its absolute value decreases as the thickness of the film is reduced, and like antimony, its value is not reproducible when the thickness becomes less than about 1000A. Furthermore, such an unstable film shows a large amount of noise when electric current is passed through it. Tellurium, which is a semiconducting material, possesses also negative temperature coefficient when it takes the form of thin film. Its temperature coefficient of resistance is relatively high, but the current noise is rather considerable and the result of this the sensiti-vity of the tellurium bolometer is not superior to noise of Bi and Sb. The average minimum detectable energy of these bolometers is about 10-8 watt.
For stereographic roentogenograph, two photographs are taken from two optically determined positions and viewed with a stereoscope. A film changer for exposures and a prism type stereoscope have been devised to be attached to an ordinary X-ray apparatus for medical examination. A factor T0 is conceived with which the stereoscopic perception can be controlled. Manipulation is made easy by an adjusting device to suit different individuals. An attachment for measuring the exact position of any particular object in the visual field is provided.
Crystal structures of CdSe prepared by several different methods have been investigated by the method of electron diffraction. It has been observed that the CdSe crystal of cubic structure changes into hexagonal form when reduced in vacuum or in hydrogen atmosphere. The dependence of electrical conductivity, thermo-electric effect, optical absorption and photoconductivity of CdSe upon crystal structure, has also been investigated. In hexagonal CdSe, various complicated phenomena have been observed, which have never appeared in cubic form specimens. It seems probable that hexagonal CdSe contains stoichio-metrically excess cadmium in the crystal which causes the difference in the physical properties of the two crystal forms of CdSe.
Characteristics of threshold vibration tangible to the tips of fingers have been observed over a range from 5 cps to 1000 cps with a vertical vibration generator. It is found that the thershold amplitude of vibration φ is proportional to d2φ/dt2 in the range of 5_??_150 cps, to φ in the range of 200_??_400 cps and to ∫∫φ(dt)2 in the range of 500_??_1000 cps where φ is the displacement and is represented approximately by _??_ where φ: the threshold vibration amplitude in μ, K: the minimum value of φ in μ, ƒ: the frequency per sec, h: a damping constant, n1 : the first order natural frequency of the vibration, n2: the second order natural frequency of the vibration. Actually the values of the constants n1, n2 and K were n1=160 cps, n2=500 cps and K=0.2μ. It is concluded that the human body can be represented by a fine vibrograph, its magnification coefficient being equal to the product of that of displacement vibrograph and that of accelerometer.
Discussions are made on the apparatus, procedure, and factors affecting the accuracy in the orientation determination with the back-reflection Laue method and with the light-figure method. It is shown that, although the accuray of orientation determination by the X-ray diffraction method has generally been highly appreciated, its proper high precision within . ±0.3° can be retained only when a great attention is paid for photographing a diffraction pattern and a special procedure is taken for the analysis of the diffraction pattern, and that the whole procedure of the X-ray diffraction method including the preparation and analysis of the diffraction pattern and calculation of the crystal orientation are considerably labourious and require a long time. On the other hand, the light-figure method can be applied for any metal crystals of any orientation with simple apparatus and procedure, and the orientation determination can always be made with an accuracy within ±0.1_??_0.2°. In fact, orientations of single crystal rods of iron, zinc, bismuth and tin determined by the light-figure method and by the back-reflection Laue method have been found to be in an excellent agreement with each other.