The authors of thesis are now carrying on series of experiments on the needle and sphere gap discharge and also on insulation break down of several fibrous iusnlating materials with induced impulse voltage in the secondary caused by sudden connection of the primary of a trausformer to the direct current source.
In the experiments, while wave form of impulse voltage is examined by means of a static oseillograph, maximum voltage Value is constantly meas-ured by kenotron, condensor and quadrant electrometer. The results of the experiments lead to discover that in spark gap there occurs irregularity of discharge, and that the spark gap as only means of crest voltage indicator of impulse voltage is not reliable.
The arrangement of the paper is in the following order. The first article, references of the paper already published on the subject.
The second article, description of impulse circuit set up and a l'st of some of instruments employed by the authors.
The third article, magnetization curves of transformer and energy of impulse circnit.
The fourth article, wave form of current and electro motive force.
The fifth article, calibration of static crest voltmeter.
The sixth article, discharge in needle gap.
The seventh article, discharge in sphere gap.
The eighth article, influence of the surface of electrodes.
The ninth article, characteristics of some of insulation materials under impuse voltage.
1. Press-Pahn, 2. Red rope paper. 3. Vulcanized fibre, 4. Horn fibre. 5. Empire cloth.
The tenth article, cummulative effect. The eleventh, conclusion.

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To measure telephone frequency, the simplest arrangement is that devised by Campbell. But this arrangement is not suitable to measure lower frequ-ency in most cases. It is shown how the original arrangement can be modified to adapt the measurement of frequency which changes over wide range. The generalized frequency bridge is thus obtained and its principle explained. Some special cases of this generalized bridge are found very simple and satisfactory for the purpose. A frequency bridge devised by Edy Valender (A. I. E. E. Nov. 1921) is also one of them.

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This article gives in details the description of the Rochling-Rodenhauser furnace of one ton capacity installed in Miike Works, Ohmnta.
In the first chapter short remarks are given on the theory, history and advantages of this type of furnace. From the second to the fourth chapter, it is spent on the question of design furnishing actual data covering the constrnction, electrical calculation and accessory machincries, and pointing out a few phases on which special care must be paid. It shows no general procedure for design, but an example of a furnace which is operating suc-cessfully with cold scrap. The fifth chapter briefly describes the practical operating method of the furnace. In the sixth chapter the anthor speaks from experience upon those problems, particular to this type of furnace, such as hearth lining, circulation of molten iron and pyroelectric characte-risthes of refractory material.
At final conclusion, it is stated this type of furnace is superior to arc furnace in many respects and is recommended for producing high grade steel from cold scrap at small scale, although the difficulty of obtaihing good hearth lining may hardly give favorable results at first to those who are non-expert with basic lining.

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