This paper gives the actual test data of the storage battery locomotives in Muke Colliery, one of the largest collieries in Japan. The locomotives under operation are those manufactured by the Jeffrey Mfg. Co., having the total weight of 3.32 ton and the batteries of 187.5 ampere hour capacity at 80 volts. One example of operation is such that:
capacity of transportation 88.0 ton-mile of net coal in 24 hour power consumption 0.677 K. W. H. per ton-mile of net coal
under the following temperature rises of the electrolyte, i.e.
maximum 20.5°C
mean 16.8°C.
A few examples are added under different conditions. For comparison, some data of trolley locomotives in the same mine are given. Finally the writer discusses [the _??_dvantages and disadvantages of the storage-battery locomotives from the practical point of view.

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It is stated in this paper that how behaves the discharger when it used as a lightning arrester and that the arrester, having series gap as in modern pratice, is undesirable. Next stated that though it is impossible to design a truly ideal arrester by the principle of a discharger, but it is possible to design a truly ideal lightning arrester by the combination of the principles of an ideal discharger and of an ideal high frequency energy absorber. At the end, it is explained the principle of a high frequency energy absorber which is designed by the author.

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The variation of residual charge and the ratio of conductivity to capacity for some crystalline dielectrics belonging to every crystallographic systems and some amorphous dielectrics were investigated experimentally by using a specially designed apparatus, and obtained the following results.
1. The accumulation time at which the residual charge is saturated, decreases as the temperature rises and the magnitude of residual charge increases with temperature; with further rise of temperature, the accumulation reaches a maximum with respect to time. The maximum accumulating time and the maximum value of residual charge decreases as the temperature rises.
2. The saturated value of residual charge increases with temperature and reaches a maximum, after which it decreases and tends to a certain stational value. The maximum tem erature and the maximum value of residual charge are characteristic for different materials and for different directions of crystal. As in the case of selenite, for a hydrite crystial, the saturated value of residual charge remains constant, though the temperature rises, till the whole water of crystallization is driven off. As in the case of barite, for some material, some different feature of variation of residual charge is taken place in the fresh heating.
3. The ratio of conductivity to capacity increases gradually with temperature at first, then it increases rapidly as the temperature of maximum residual charge being the middle point, and then gradually tends to a certain saturation value. The rate of increase of the ratio of conductivity to capacity is generally far greater than that of the saturated value of residual charge. As in the case of selenite, for a hydrite crystal, the ratio of conductivity to capacity remains constant till the whole water of crystallization is driven off, and afterwards it rapidly increases with temperature. As in the case of barite, for some material, the variation is quite different from other materials in the first heating.
4. The variation of residual charge with temperature seems to be mainly due to that of conductivity, since the variation of capacity due to temperature be very small when compared with that of conductivity. Thus we conclude that the mechanism of residual charge and of its variation due to temperature, may satisfactorily explain by a function of conductivity and the variation of its temperature coefficient.
5. Good insulating materials such as crystals belonging to monoclinic system (mica, selenite) and ambroid paper have generally a large maximum temperature (at which the residual charge becomes maximum) and comparatively a small residual charge. Amorphous dielectrics generally become greatly conductive above 100°C

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The creeping of induction type watthourmeter is discussed in each case of various types of its prevention devices. And the error caused by creeping is described to be taken account, when the load is intermittent service of short period or light load.

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With the development of high voltage and long distance transmission system, the line charging current is greatly increased. It is a well known fact that when charging such long transmission lines the generator will sometimes be self excited by armature reaction to an abnormally high voltage which threatens the insulation of the system.
This abnormal condition is usually explained by means of two curves; the line charging characteristic and saturation curve excited by armature leading current. This paper describes the precise nature of the two characteristics. Saturation curve excited by armature current can roughly be obtained by graphical method rom no load saturation curve and short circuit characteristic, and more accurately with further knowledge of armature leakage reactance.
The results of actual tests on machines coincide fairly with such curves obtained from the above graphical method. The same method can also be applicable to obtain the saturation curve excited by armature current with some field excitation.
The author compared the results obtained by the above graphical method with the actual test data at Yomikaki Power Station of Daido Electric Power Company, and at Ryushima Power Station of Keihin Electric Power Company and fairly coincidence is pointed out.
The above method holds for both balanced and unbalanced three phase problems.
The author further refers to miscellaneous problems concering the self-excitation.

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