THE ERUPTIOX OF BANDAI-SÂ.N. 127 



roughly made pendulum tromometer, which had a magnifying power 

 of '27. We first set it near a fissure from which powerful jets of 

 steam were issuing with hissing sounds. Id that position the instru- 

 ment indicated very feehle vibrations of the ground, which were 

 doubtless caused by the issuing jets. We next set it in ISTakanoyu, 

 near our cam]), and made daily observations. As far, however, as the 

 magnifying power of the instrument enabled us to judge, there was 

 no evidence of lingering earth-tremors. And it would seem from 

 this that the forces which produced the explosion had been completely 

 expended in blowing away the mountain, and that the region had 

 already become seismically quiescent. 



Near the volcano the detonations in the earlier part of the erup- sound, 

 tion were described as deafening. Though rapidly lessening in inten- 

 sity, the thundering noises lasted for nearly an hour, and did not en- 

 tirely cease for several hours. The area over which the sound ex- 

 tended was very much smaller than might have been expected From 

 the tabulated reports at the end of this paper, and from other sources, 

 it appears that the sounds of the explosions were not heard distinctly 

 at a o-reater distance than 48 kilometres or 30 miles to windward of 

 Bandai-san, though to leeward they were audible at the Pacific coast, 

 a distance of 100 kilometres or 62 miles. How much farther they 

 reached, over the sea, we had no means of ascertaining. Mr. K. 

 Xakashima, of the Geological Survey, told us that, while he was as- 

 cending Kinboku-san in the island of S:ido, on the morning of July 

 15th, he heard did! rumblings which were supposed at the time 

 to proceed from the firing of heavy guns in the neighbouring 

 harbour (Report 21). Sado is in the Japan Sea, nearly 161 kilo- 

 metres or 100 miles west from Bandai-san. and therefore to windward 

 of it. Possibly, however, the sounds heard by Mr. JSTakashima came 

 from the volcano. It was also reported that peculiar detonating 



