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In the Soviet Union
The fiftieth anniversary of Hertz’s discovery of waves was marked in Moscow by two ceremonial meetings.
On March 25 a meeting was held, organized by the Technical Section and the Section for Scientific Propaganda of the Academy of Sciences of the USSR. The introductory address was delivered by Academician V. F. Mitkevich. A report on “Hertz’s Waves in Lines of Communication and Energy Transmission” was delivered by Academician A. A. Chernyshev. The report by Corresponding Member of the Academy of Sciences B. F. Arkad’ev was devoted to Hertz’s work and to the electromagnetic theory of light. Academician M. V. Shuleikin read a report, “The Fundamental Principles of Radio Engineering in Hertz’s Works.” Prof. Arenberg spoke to those assembled about Hertz’s experiments.
On April 3 a ceremonial meeting was held of the general colloquium of the Physics Faculty of Moscow State University and of the Maxwell Laboratory of Electromagnetism. At the meeting the following reports were read: Corresponding Member of the Academy of Sciences V. K. Arkad’ev, “Hertz’s Discovery, the Significance of His Works, and Their Further Development”; Prof. A. A. Glagoleva-Arkad’eva, “Fusion of the Boundaries of Hertzian and Infrared Waves on the Micron Scale”; Prof. A. G. Arenberg, “Hertz’s Experiments”; Prof. S. E. Khaikin, “Hertz and Modern Radio Engineering.”
Experiments were demonstrated at both meetings.
A method for sensitometry of X-ray films. At the Central Institute of Roentgenology and Radiology, G. A. Zhegal’kin has developed a method for the sensitometry of X-ray films.
The X-ray sensitometer consists of a system comprising an X-ray source, a stationary lead screen with a stepped cutout giving a ratio of the amount of light falling on two adjacent fields of the sensitogram of \(1:\sqrt{2}\), a rotating cassette \(40 \times 40\ \mathrm{cm}^2\), and an ionization chamber (of the universal dosimeter type). Exposure is measured not by time, but by the reading of the dosimeter. The design of the instrument makes it possible to expose 15 samples of film in 3 minutes.
Sensitometers of this type are being manufactured by the institute’s experimental workshop for factories producing X-ray film. The significance of this work is especially great if one considers that, until now, factories have been issuing X-ray film while orienting themselves according to its sensitivity to normal “daylight,” which has little in common with X-ray sensitivity.
A new X-ray film. At the Scientific Research Institute of Cinema and Photography, under the direction of K. S. Bogomolov, a new method has been developed for obtaining X-ray film. The method consists in the following:
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In selecting, for the X-ray emulsion, gelatin that does not contain specific X-ray desensitizers that destroy the latent image in the presence of X-rays.
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In establishing a procedure for synthesizing emulsions with a high content of silver bromide.
The film is suitable for industrial and medical defectoscopy both with intensifying screens and without screens, and for X-ray
structural analysis. It is three times more sensitive than the film currently produced by the factories when photographing with screens at 80 kV, and 7–8 times more sensitive when photographing without screens at any voltage. The film has very high contrast. The grain size is normal.
X-ray film of the new type will be introduced into production in the first quarter of 1939, with the aim of completely replacing the existing grade.
FROM FOREIGN JOURNALS
A new thermostat is proposed by Laby and Hopper of the natural-science laboratory of the University of Melbourne.
A resistance thermometer is made from copper wire (a single-layer spiral), which is brought into good thermal contact with the microscope condenser. The latter is the part of the apparatus whose temperature must be kept constant. The copper spiral serves as one arm of a Wheatstone bridge; the other arm is made of manganin resistance. Any change in the temperature of the apparatus, and consequently of the copper wire, causes the light spot coming from a galvanometer connected to the Wheatstone bridge to be deflected. At a specified angle of deflection the light spot falls on a photoelectric cell. A controlled relay element then switches the heating device on or off (all or nothing). This principle of thermostat design was used by the authors for experiments on measuring the charge of the electron. After an hour of operation, such a thermostat maintained the temperature of the apparatus with complete precision (the thermocouple gave unchanged readings).
The authors do not give a more detailed description of the device.
An English journal on Bernal’s book “The Social Function of Science.” In the English journal Nature, in the bibliography section, the contents of the 1939 book by the well-known physicist J. D. Bernal, The Social Function of Science, are considered in detail. The review particularly notes that throughout all his work the author emphasizes the dependence of the future of science on the development of society, as well as the necessity for the scientific worker to take an interest in politics. Bernal indicates in his book that science brings the greatest benefit in the Soviet Union.
Gustav Tammann has died. At the age of 78, the well-known physicist Gustav Tammann died, having worked in the field of the study of the crystalline and amorphous states of bodies. G. Tammann began his principal scientific activity after the appearance of the works of Gibbs and Roozeboom on equilibrium in heterogeneous systems, setting himself the task of collecting experimental material confirming Gibbs’s idea. Investigating ice bodies over a wide interval of temperatures and pressures, Tammann showed the existence of several modifications of ice.
Tammann became widely known for his studies of supercooled liquids (measurements of the rate of crystallization, the number of crystallization centers, etc.). These works of Tammann played a large role, in particular, in clarifying the nature of glass.
Tammann’s metallographic works are of exceptionally great importance. He studied, by the most varied means, the structure and physical properties of metals and alloys. Tammann was the first to point out that the chemical properties of solid solutions are connected with the arrangement of atoms in the lattice.
Tammann is the author of a number of books, most of which have been translated into Russian (Metallography, The Aggregative State).
Introduction of physics into industry. American journals note the most interesting physical investigations introduced into industry in 1938.
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Use of hydrogen in engines to reduce friction. The friction of rotating parts of large generators in hydrogen is reduced tenfold in comparison with friction in air.
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New uses of the “electric eye”:
a) for automating control in paper cutting: a negligible deviation of the paper tape from the required direction sets the corresponding photo-relay into operation;
b) for detecting defects (holes and small cracks) in sheet steel. A photoelement detects holes as small as \(1/100\) mm and marks them. -
Production of single crystals of various salts for the needs of the optical industry. For the first time, crystals of rock salt, KBr, LiF, and other compounds, weighing approximately 13–14 kg, have been obtained. The process of obtaining the crystal lasts 7–10 days. Throughout this entire time, the constancy of the temperature is maintained, with the aid of special devices, to an accuracy of up to \(0.1^\circ\). Extremely extensive and careful work is carried out on the preliminary purification of the salt. The crystals are obtained from the melt.
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A new type of insulation. For a number of purposes, gaskets made of glass fiber have been employed with great success.
Exhibition of the Physical Society of England. The annual exhibition of the Physical Society has opened. The catalogue of items appearing at the exhibition runs to more than two hundred pages—this gives an idea of the number of exhibits. The exhibition is divided into 2 sections: the first showing industrial samples of physical instruments, the second devoted to research work in the field of physics.
In the first section of the exhibition, attention is drawn to the enormous spread that electronic instruments have now attained—the overwhelming majority of the new exhibits contain photoelements as a structural component. Among such instruments, for example, thermoregulators figure.
At the exhibition one could see an industrial model of a high-vacuum pump operating not on mercury or oil, but using a special organic substance with a very low vapor pressure. In the course of operation this liquid continuously purifies itself.
In the second section of the exhibition there figured very special experimental installations, such as calorimetric ones and those for determining the dielectric constant.
Alongside this, a number of experiments were demonstrated especially for the general public. These may include: an installation for the quantitative estimation of noise, an X-ray installation, etc. The same purpose was served by the demonstration of glass with sputtered molecular films. Such a step grating produced beautiful interference colors.
At the exhibition, instruments for schools were also demonstrated. An instrument for determining Planck’s constant attracted attention. In view of the ease with which this apparatus can be compared with a photometer. A number of well-known scientists gave illustrative demonstrations of certain physical experiments.
Conferences. On April 28–29 of this year, the annual conference devoted to questions of radio was held in Washington (USA). The conference was attended by the Institute of Radio Engineers, the International Union of Research Workers in the Field of Radio, the U.S. National Academy of Sciences, and the American Societies of Physicists and Geophysicists.
★ On March 8–9, the annual conference of the Institute of Metals was held in London. Half of the time at the conference was devoted to the question of the industrial application of spectroscopy in nonferrous metallurgy.