66 Proceedings of Boyal Society of Edinburgh. [sess. 
E. Before the eruption there were four peaks — Obandai, Kobandai, 
Kushiga-mine, and Akahani-yama. They are of volcanic origin and, 
according to tradition, formed at one time a single mass which was 
split into four by a great eruption early in the ninth century, at 
the time when Lake Inawashiro was formed. Bandaisan rises to a 
height of 6037 feet above sea-level, and Kobandai is believed to 
have reached almost exactly the same altitude. For about ten 
centuries the mountain had shown no signs of activity, except by 
the existence on it of a number of hot springs and solfataras. It 
was, however, included by Professor Milne in his list of the active 
volcanoes of Japan. 
The recent eruption took place on the 15th July 1888. There was 
no premonitory warning of the catastrophe except some rumblings 
heard at 7 a.m. of that day, which were followed by an earthquake 
of no great intensity. At 7.45 a great explosion took place, by 
which an immense cloud of steam and debris was shot up to a great 
height above the top of Obandai, and this explosion was quickly 
followed by fifteen or twenty minor explosions. The result of these 
explosions was that practically the whole mass of Kobandai was 
shattered, and the materials forming it were spread over an area of 
27 - 31 square miles. As calculated by Professor Sekiya, the volume 
of material moved by the explosion was 1587 x 10 6 cubic yards, or 
say a cone with a diameter of 1000 yards at the base and a height 
of 760 feet. 
The shattered fragments of the mountain travelled in two direc- 
tions. The main stream went northwards, spreading out as it 
advanced, overwhelming a number of villages and hamlets, and 
entirely damming up the Nagasegawa, the chief feeder of Lake Ina- 
washiro. The other stream took a south-south-easterly direction over 
the flank of Kushiga-mine and down the valley of the Biwasawa 
towards the village of Mine, part of which was swept away. This 
may be called the Mine stream. The eruption was due simply to 
an explosion of steam, no lava or pumice being ejected, and the 
so-called “mud” which spread over the country was simply the 
matter which had formed the mountain, more or less moistened by 
condensed steam and by water which had existed in the mountain, 
but most of it was certainly not wet enough to deserve the name of 
mud. The scattered materials may be described as being for the 
