The paper presents general equations of a transmission line grounded through a resistance at any point on the line for any treatment of the neutral points of the system with consideration of all line constants and thus the accurate compensating value of the earth coil is derived out and its most favorable numbers and situation on the system are determind.
According to the theoretical investigation, a n-phase n-line long distance transmission system of up-to-date can be very safely protected, for a grounding at any point of the system, by installation of two equal earth coils on the genarating and receiving ends of the line, specified by the following equation: _??_ which holds good for only the resultant imaginary components on both sides and where Y represents the required admittance of the coil, l the total line length and Y_s and k_s are the surge-admittance and attenuation constant of the line given by the following equations respectively: in which Y_{_??_} and Z_{_??_} represent the capacitive admittance and inductive impedance of the line to ground and Z₁₂ the mutual inductive reactance per unit length of the line. If the line is not very long, the transmission system may be protected also by installation of one earth coil specified by the following equation in the power station or substation without any dangerous pressure rise on the grounded system: Considered the short circuit impedance Z per phase of the transformer winding, to which neutral point the earth coil is to be hung, the reactive component of Z/n may be added to the compensating value of the inductive reactance on the earth coil to be obtained by the above equations.
For the case where the long distance transmission sytem thus compensated by the earth coils should supply on times to another network on the same line, the most reasonable technical solution is the separate compensation for the added line.

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In this paper, the studying results of behavours of the Aluminium cell and the Oxide film lightning arresters for the audio frequency E. M. F. are a Braun tube oscillograph is used for this studies.
It is stated in this paper that the Aluminium cell is superior, as a lightning arrester, to the Oxide film, because the former has no falling character in its discharging characteristic and large condenser action and moreover its discharge is not so suddenly as that of Oxide film, so that it produces no electric oscillation in the electric circuit by its discharging actions, while the latter has small condenser action and sudden discharging character, so that it has ability of bringing about the electric oscillation. The experimental result shows above facts.

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When a valve oscillator is so arranged as to produce sustained oscillations, it is often noticed that damped oscillations are unexpectedly obtained.
That damped oscillations may be produced in an oscillatory circuit connected to any rectifier is explained. Generally speaking, there are two chances for their coming into existence, one being at the start and the other at the end of the rectified half cycle of current. The former is namely an oscillatory charging of the condenser in the anode circuit and the other its oscillatory discharge.
If an alternating voltage of appreciable magnitude is impressed upon the grid of an amplifier, the plate current will pulsate and may even vanish during a certain part of its period. Thus owing to this rectifying character, damped oscillations may result in the oscillatory anode circuit.
The author has preliminarily studied this simple case using grid voltages of comparatively low frequency (50_??_) and a higher frequency (about 10, 000_??_). He has experimentally determined the critical frequency, the critical magnitude of the grid voltage and the critical filament current which are just necessary for the production of the damped oscillation.
In the next place, the production of damped oscillations in a triode oscillator as stated at the outset is of much interest and importance, and therefore the author has studied it experimentally as well as mathematically.
A certain inductance in the plate circuit is found necessary for its production, which forms an oscillation circuit with the internal static capacity of the triode.
This paper includes the following topics:
This paper includes the following topics: -
I. Introduction,
II. Damped oscillations produced by means of a rectifier,
III. Damped oscillations produced by means of a triode valve on account of its rectifying characteristic,
IV. Triode valve oscillator producing damped oscillations,
V Conclusions.

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