It is generally accepted that one of the secondary causes of earthquakes and volcanic eruption is the variation of atmospheric pressure. The author of the present paper thought that a certain tectonic line or volcano has a special mode of dislocation or eruption, and consequently it is necessary to take a special condition of atmospheric pressure gradient proper to them when a fault or an eruption occurs there. In this paper this working hypothesis is accertained using seismometrical and volcanic data of semidestructive earthquakes and strong eruptions observed at our meteorological stations. The following conclusions are drawn:- (1) Dislocation may occur when the direction of atmospheric pressure gradient becomes perpendicular to the existing fault line and the amount of pressure gradient changes spontaneously from lowest or highest value. Moreover, when a pressure tends to increase in this case there occurs a destructive one, and when it is decreasing, a moderate shock may occur. Following few examples may support this theory; (2) When an extraordinary intense anticyclone covers the region surrounding a certain volcano even a slight variation of pressure may cause in many instances volcanic earthquakes and eruption. The examples of this case are found in the eruptions of Mt. Asama, Mt. Sakurazima, Mt, Bandai and others. All of these eruptions occurred, without exception, in the day of anticyclonic weather.
The author puts his finger on the point that there are more than 30 species of cicada in Japan so that the Phenological reports in cicada must be prepared for each of the species. The mean dates of the first chirping of cicadas observed at Kagosima Meteorological Observatory are as follows Species Average date Terpnosia pryeri, Distant Last ten days of March Leptopsaltria japonica, How. July (Cryptotympana pustulata, Fab.?) First ten days of July
The velocity of motion of the center of each cyclone is measured in a unit of 2° Latitudes or Longitudes of displacement per 6 hours. Following results show mean velocities of cyclones in various situation of cyclones and anticyclones, which appeared in the weather charts for seven years 1919-1925 issued from the Central Meteorological Observatory, Tokyo. From the above statistics we can draw conclusion that Okada's law is true so far as For Eastern cyclones are concerned.