This lecture was delivered in commemoration of the Golden Anuiversary of the telephone and was intended to give the interesting story of the telephone invention and its development during the past fifty years. In the year after Bell's invention was announced, that is in 1877, the telephone was introduced to our country and in 1890 the telephone exchanges were opened for tie first time with the subscribers of 179 in Tokyo and 45 in Yokohama. Many pioneers and experts have devoted themselves to the development of telephone business with the result that there are at present over 490, 000 subscribers and 90, 000 miles of toll lines. Moreover, every feature recently developed has also been adopted; for a instance the 500 miles long distance telephone cable is now under construction, the seven automatic exchanges were opened last year in Tokyo and Yokohama. In the latter pact of the lecture, the writer described the history of the tetephone industries in Japan.

View full abstract

It is a report about a simple portable testing set, deviced by the authors, for vacuum discharge type arresters, used in the weak current communication networks. This testing set consists mainly of a small variable transformer, a condenser and high resistances and is provided with a "glimm" lamp as a detector. The test current is taken from an ordinary lighting circuit and with simple manipula ion it is able to test the insulation and discharge characteristics of the arrester. The set may also be applied to test an ordinary carbon gap arresters, though designed for the vacuum discharge type ones. In the appendix, the authors treat the discontinuous discharge phenomena of a "glimm" lamp with D. C. and A. C. supply.

View full abstract

Observations on Atmospheric disturbances were made at Osaka Station at Osaka City by the personnel of the Station.
The report contains the general idea of atmospherics, the method and apparatus of measuring them, and the result of the observations.
The conclusions arrived at from the observations are as follows:
1. Atmospheric disturbances increase at the sunset of the receiving station, the high values prevailing at night, and after sunrise they decrease rather rapidly.
2. The atmospheric disturbances at Osaka come almost from the direction of the northeast to the southwest. This seems to warrant the fact that the atmospherics in general originate over land rather than over the ocean.
3. During the summer, they come from the northeastern direction and during the winter from the sonthwestern direction. This also warrants the fact that the sun has an important bearing upon the sources of atmospherics. It seems to me that the sources of atmospherics follows the sun in its changing path between the northern and southern hemispheres. Besides the local atmospheric disturbances of the mountain range of Japan called "Japan Alps predominate that of distant atmospherics. This fact is endorsed by the directional observation at Iwatuki near Tokio where the atmospherics came from the northern to northwestern direction.
4. The measurement at Peking during October and November combined witn the data obtained at Osaka indicates that the origin of atmospherics of this season is the tropical district of Dutch Indes.

View full abstract

The theory and experiments on the acoustic transformer and horns (conical and exponential) have been reported by the same author in some details in this journal. In most cases, the horn is used in connection with the acoustic transformer. It is pointed out in this paper that the frequency characteristic of the acoustic impedance at the sending side of such a combined system is simple in nature, and design procedure becomes much simpler by considering such an impedance. The criterion and design procedure of such a combined system are given, together with a chart which enables us to determine, under a certain criterion, the dimensions of an exponential horn of finite length.

View full abstract

Pulsation in d. c. voltage may be removed by using the transformer and battery. The method has some advantages in that:
1. it is independent of forms and frequencies of pulsating waves:
2. it is simple.
3. pulsations at no load is markedly depressed.

View full abstract

In large transmission systems the main lines are usually so arranged by means of parallel feeders that each substation on tie main system has two or more circuits over which power may flow from the generating station. Thus, when a fault develops on one of the circuits, it may be disconnected without entirely cutting the substation of the system.
In a system in which the neutral is connected to ground through a high resistance, fault current in case of one line ground is generally smaller than normal full load current, but symmetrical three phase short circuit current and line to line short circuit current are always greater than full load current. Ordinary relay systems which are used nowaday, i. e. current balance relay, over current relay, etc. give practically satisfactory protection for short circuits.
But the author has shown that for one line ground, any relay system which is used nowaday gives no satisfactory protection. Relay which has potential and current coils solves this problem. But potential transformer of such a high tension as 110, 000, 154, 000, 220, 000 volt is practically impossible to use.
The author has heard from Mr. Seto, the Engineer of Daido Electric Power Co., that a condenser bushing of oil circuit breaker would carry sufficient charging current for relay operation, and he has also shown that induced voltage in a "coupling wire" has sufficient values in amount and phase for relay operation.

View full abstract