A portable stroboscope which has a good colour rendition has been constructed. Two fluorescent lamps using Mg-tungstate (Argon gas 3.0mmHg and Mercury one drop) and a Neon-Argon lamp (total pressure 3.3mmHg, Argon percentage 20%) are operated synchroni-cally. Chief advantages of this stroboscope are considered as follows:- (1) a good colour rendition is obtained. (2) stable stroboscopic operation is available at the frequency range of 100c/m-15, 000c/m for a long time. (3) only about 300 V d.c. source obtained by an ordinary eliminator is sufficient for the operating circuit. (4) the apparatus is small enough to be portable (total weight 17Kg), but the light intensity is strong enough to take photographs in darkness (50 lux at the point 50cm distant when operated at 3, 000c/m). (5) the life of the light source tubes is long.
A theoretical calculation is made of the back-diffusion coefficient, b, of diffusion pump, giving the formula: b=exp(-4[ƒ(+)-ƒ(-)]qL/λON_??_), where ƒ(+)-ƒ(-) represents the fraction of gas molecules travelling towards the fore vacuum side after the collisions with pumping fluid molecules, q the rate of flow of the fluid vapor stream, L the effective length of the stream, N the molecular density at 1μHg pressure, λ0 the mean free path of a fluid molecule in the gas at N concentration and v the mean molecular velocity of gas. This formula explains satisfactorily Dayton's experiments with octoil and air. The difference from the earlier theories lies in the free-molecule treatment of the pumping action whereby thorough consideration is given to the mechanism of intermolecular collisions.
If a specimen is a perfect crystal, X-ray beam divergent from a point is reflected only at a region which is nearly a straight line approximately parallel to the edge at which the plane of the crystal face and that of the photographic plate would meet. A slight change in orient-ation of the crystal causes a marked shift of reflection pattern. This can be applied to study sub-structure orientation. If the X-ray source is of finite dimension, its breadth perpendicular to the said edge broadens the region of reflection and lowers the sensibility for detecting orientation difference while its length parallel to the edge intensifies the pattern but lowers the resoloving power. Dimensions of the X-ray source should therefore be chosen in due consideration of these facts.
Geometrical conditions of low angle X-ray camera are examined. Both the resolving power and the brightness of pattern are much increased with the use of fine focusing X-ray tube. Good results are obtained in measuring large crystal periods of protein and in deter-mining particle size of carbon black in a relatively short time of exposure.
As reported previously by the authors, A. C. excited C-shaped electric sheet steel with a movable coil placed between the poles can be made as a directional positioning unit. Further developement has been made to facilitate it as an automatic positioning controller by adding another winding to the cone, the induced constant voltage lagging 180° in phase behind that in the moving coil. With a mechanism to keep up the resultant voltage to zero, a simple automatic positioning controller is made. A three channel electronic switch has been devised for simultaneous observation of the wave forms of excited voltages in the moving coil and the added winding and their resultant voltage.
Previous paper by the author and E. Fukushima confirmed the possibility of electrical capacitance being applied to measurement of roughness of metal surface. This led to the developement of capacitance-type roughness tester designed for measuring directly the rough-ness of casting and sand-blasted surfaces and the like within a few minutes on the spot. It consists of two parts, an indicator and a pick-up. Owing to special structure of the pick-up head, waviness of surface does not affect the accuracy of measurements which is a charac-teristic of the tester. The measurable range is 3_??_200 micron of roughness height.