On the Earth-current Observations at Kakioka and Toyo-hara (Second Report)

[摘要] Angenheister investigated the time of occurrence of the pulsatory oscillation of terrestrial magnetism recorded at several observatories over the world but he could not decide whether it is progressive or stationary owing to instrumental difficulties. In this country, three, quick running magnetographs of the same type were installed at Kakioka, Tsingtau and Toyohara during the Second Polar Year, S. Imamiti investigated the magnetogram and found that each pulsatory oscillation occurs within the limit of a fraction of second at the three places.On the other hand it was investigated by M. Hirayama and authors that the phase difference between the pulsation of terrestrial magnetism and of earth current was less than one second. So it was concluded indirectly if the pulsation of terrestrial magnetism was stationary the pulsation of earth-current should also be stationary. But it is worthy of comparing directly the shape and the time of occurrence of pulsation of earth-current at both places.The proper period (no damping) of the galvanometer was 4.5 sec at Toyohara and 3.4 sec at Kakioka, and the record was taken in critical damping state at respective places. The time scale is 13.5mm per minute at Toyohara and 22mm per minute at Kakioka: Every minute was marked on the sensitised paper in turning off the light source by the electric current through the standard clock, which was regulated by the time signals of llh and 21h of 135°E meridian time.Some examples of the pulsation of earth-current are shown in figures. (Fig. 1-Fig. 5)The difference of the time of occurrence of the pulsation of earth-current(The time of occurrence at Toyohara)-(that at Kakioka)is -0.s858±2.s12. The number of waves compared is 160, which were all of the available. Nextly they were divided into groups according to the hour of the day, to period of oscillation and to the type of oscillation. The difference of the time of occurrence of the pulsation was calculated for every groups.

[学科分类] 大气科学