112 S. SEKIYA AND Y. KIKUCHI 



posing the conical heaps of débris above described, and that both 

 were derived from the andesitic rock which composed the mass of 

 Bandai-san. Hence it is apparent that this dust or ash is quite 

 different in character from the ashes that are usually ejected from 

 craters in other volcanic eruptions, e. g., that of Krakatoa in 1883. In 

 such cases, the ashes are chiefly derived from molten magma, expelled 

 by steam and mixed with fragments of the pre-existing rocks. They 

 contain, therefore, more or less glassy matter, and are in fact pumiceous. 



On the morning of the 15th, the wind blew from the W.N.W., 

 so that the dust was carried towards the E.S.E., gradually 

 spreading as it receded from the mountain. On the coast of the Pacific 

 Ocean, which is 100 kilometres or 62 miles from the volcano, the width 

 of the dust fall was 50 kilometres or 31 miles. In shape the dust-strewn 

 area resembled that of partly opened fan, as shown by the dotted 

 space on PL XXIV. On the land it covered a space of about 2,050 

 square kilometres or 790 square miles. How much farther it spread 

 over the ocean we had no means of ascertaining. 



At the immediate foot of the mountain, especially toward the 

 S.E., the dense cloud of dust produced pitchy darkness, which, how- 

 ever, did not last long; in the course of an hour the gloom had 

 diminished to about that of the twilight of a rainy evening. But it 

 was nearly 4 o'clock in the afternoon, or 8 hours afcer the eruption, be- 

 fore the dust wholly ceased to fall. The thickness of the deposite was 

 about 0*3 metre on the south and east flanks of Biwasawa. In part the 

 fall was in the form of a sticky, scalding mud-rain, produced by com- 

 n Lino-liner of the dust with condensing steam. It inflicted terrible 

 burns upon people exposed to it, and was the cause of many deaths. 

 The ground also became so hot from this rain and the later dust that 

 people had great diffculty in walking upon it. Every object was 

 covered with a thick grey coating. Foliage, especially, that of the 



