In order to assure the safe operation of trains, the Imperial Government Railways equipped all cars in service with the latest automatic couplers in July, 1925, and again, proposed a plan of adopting the air-brakes instead of the vacuum-brakes on trains.
Since April, 1927, the air-brakes have been used on a part of the freight trains operated on the government railroads as well as other companies' lines connected to it. Nearly all of the train-cars and suburban electric trains have long been equipped with the air-brakes. The Anther gives in this paper the outline which will be read before the Tokai meeting of the I.E.E. of Japan.

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When Carrier current is superposed on an aerial telephone circuit, the effo ctive transposition forms between that circuit and any neibhbouring one sho uld be so selected that, in the expression κ=∫ι 0 e^-rxdx=1/y(1^-e-rl).δ Where 8 is less than unity.If all transpositions in the length l occur at regular interval, the distance between two transposing points should be less than One-fourth Of the wave length Of carrier current.The Writer shows the ValUes 0f δ for all kinds.of transposition forms for the telephone circuits used 2.90m.m.copper wires assuming that l is 12.8 KM.(8miles)an.carrierfrequency is 30, 000 cycle/sec., and points out which forms should be avoided in suchcase.
As anappendix, formulae to calculate the amnount of energy induced in electromagne ic and electrostatic fields between two circuits and energy discipated in neighbouring circuit by induction are given to show that these vaiues of energy proportional to k or k².

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The present paper is the description about a new type vacuum tube voltmeter, designed by the authors for the purpose of measuring very small alternating voltages.
It consists of a balanced high resistance bridge, two symmetrically placed triode rectifiers, and a D'Arsonval type galvanometer.
If a small voltage is applied to one corner, and an auxiliary voltage of the same frequency to another corner of the bridge as seen in Fig. 1, the galvanometer gives the deflection proportional to the scalar product of these two voltages.
The voltage sensitivity of this voltmeter arrangement can be varied by choosing the auxiliary voltage in a wide range, the maximum sensitivity obtained by our experiment was 2.4mm for one millivolt with the auxiliary voltage of 8volts.
The advantages of this arrangement are, the portability, the easy handling and the high sensitivity, and the inconvenience lies in the slight instability of the zero position of the galvanometer.
This apparatus can be used conveniently, also for the very precise comparison of frequencies of high frequency current, the difference of even one tenth of a cycle may be detected by our method.

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In the previous report, the writer stated that, when the humidity is relatively high, the impulse ratio of the sphere gap is nearly equal to that of the needle gap so adjusted as to discharge at equal value of continuously applied voltage.
In th's short-note, the writer has investigated the same phenomena, in the most dry season of the year, and the following facts have been observed.
I. Under the low humidity, the impulse ratio of the sphere gap may tend to unity.
II. When the impulse is repeated, the irregularity of the sparking voltage is greater in the case of the brass sphere gap, compared with that in the case of platinum needle gap.
Finally, it has been remarked that, for the impulse test of such a short-gap as the form of the cathode electrode plays an important role on the sparking potential, the surface. condition of electrodes should be taken carefully into consideration.

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The authors describe in some details the merits of Electromobiles and discuss the necessity of Electromobiles, specially in this country where the natural resource of oil is exceedingly small.

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In the previous report (JI.E.E. of Japan No. 467), the author proposed a new electric wave projector which can produce the sharpest beam of radio waves. In that case, the sending antenna, reflectors, and directors were all vertically erected above the ground, and experiments were made with respect to vertically polarized waves.
In the present paper, the horizont I antenna is used, and same experimental studies are made with horizontally polarized waves. Of course, in this case, each of wave reflector and director rods is placed horizontally along the earth. This wave projecting system is now called 'horizontally polarized wave projector."
The action of horizontal wave directors, which form a horizontal wave canal, is studied in detail and compared with that of vertical wave directors. It is pointed out that the length of wave directors is the most important factor to improve the directivity and consequently to increase the received energy. Some results of field measurements are also given and obtained polar diagrams prove the realization of the sharp beam of horizontally porarized electric waves. (see Fig. 18, Fig. 19.)
In our experiments, the wave length was 441 ems. and the length of each director being 200 cms. and their interval 150 cms. The field was measured by means of a horizontal receiving antenna comprising a thermo-couple and a micro-ammeter. (June, 1927)

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The present paper is the report of experimental studs on the higher natural electrical oscillations of solenoidal coils of a finite length.
Coil specimens under experiment, all wound on octagonal frames made of ebonte bars of one centimeter square section with double cotton covered copper wires, included fourteen different coils of single layer type, as shown in Table (I).
The higher natural wave lengths were measured when both ends of the coil were free and also when one end of the coil was earthed, and it was concluded from the experimental results that the ratio of the fundamental natural wave length λ1 to the higher natural wave length of the m th order λm could be represented practically by a linear equation λ1/λm=1+α(m-1) as seen in Curves (2) and (3), the coefficient a plotted in Curve(4)being the function of the dimension ratio h/2r of the Coil.
These experimental results were explained qualitatively, taking into account the mean propagation velocity of electrical disturbance along the length of coil.
The writer observed by a very simple method, the wave form of the potential standing was appeared along the length of coil when the coil was in resonance with the applied frequency. Curves(5)and(6)are the typical examples in which it is clearly shown that the positions of loop and node differ widely from the normal ones which would be resalted if the solenoidal coil were infenitely long.
The influences of shield wire and also of shield cylinder upon the natural wave lengths were studied, and it was found that the effects of the variation of the length and position of the shield conductors differ for respective natural wave length, as seen in Curves from (7) to (20).
The various experimental results obtained with shielding conductors were explained, considering the increase of effective distributed capacity of the coil due to the presence of sbielding conductors.

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The necessary conditons for the occurrence of spark-over in air through any spark gap are;
(1) the existence of potential gradient high enough to cause a partial break-down of air at any point in the spark gap.
(2) The existence of such circumstances under which, the partial breakdown can develop into the complete breakdown of the whole path.
The second condition is determined by the stability of the system, either partial or as a whole, which consists of the spark gap, the power source and other circuits connected with hem.
With a view to analyse the factors affecting the second condition, the authors studied the flash-over phenomenon in alternating electric field, especially for unsymmetrical arrangements of electrodes having comparatively long spark lengths.
First the stability of the spark-over phenomenon in the gap between a sphere with a diameter of 1cm. and a plane electrode was studied, and notwithstanding its apparent irregularity in flash-over values for a certain range of gap length, the instantaneous values of the voltage at which the flash-over began to proceed, were found to be in accord with the classical results given by Prof. Max Toepler for unidirectional voltage in the same arrangement of electrodes.
Next the effect of air current on the flash-over value was studied. One of the electrodes used for this purpose was a syringe tube, which was placed with its end against a plane or a spherical electrode with a diameter of 12.5 cm. It was found that the sparkover i oltage was raised to a considerable extent by the suction of air through the end of the tubular electrode. In ordinary condition, the flash-over was found to start at the end of the tube during its positive potential, while the suction of air seemed to have an effec t to stabilize the positive discharge from the tube end, with the results that the flash-over started from the negative discharge appeared for a certain range of gap lengths and at the same time, the ihigher flash-over values were observed.
On the other hand, the rotation of the electrode was found to lower the flash-over value, probably owing to its effect of impairing the stability of the spark discharge system.

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