1889 - 90 .] Mr C. Michle Smith on Volcanic Eruption. 67 
most part earthy, mixed with stones of all sizes ; hut at certain 
places, mostly near the crater, there were great piles of large blocks 
of stone almost free from earth. This was specially the case at the 
K.E. corner of the crater, where the crater- wall showed a magnifi- 
cent section of beds of lava intercalated with layers of scoriaceous 
material, lying unconformably on each other. 
The manner in which the fragments of Kobandai travelled out- 
wards resembled closely the rush of water from a reservoir on a hill 
when the embankment has burst. The stream followed, as a whole, 
the line of least resistance, but after descending a considerable way, 
and having acquired a very high speed, part of it flowed up hill 
again, and where, in descending the valley, any mountain spur met 
it at a sharp angle, it rushed up the hill side in some cases to a 
height of as much as 120 or 150 feet above the general level. In 
one place the torrent passed over a col about 200 feet high. The 
average velocity is given by Sekiya as 48 miles an hour. In one 
respect this earth-torrent behaved differently from a torrent of 
water, viz., in the way in which, owing to internal friction, it came 
suddenly to rest as if it had all at once been solidified. This is very 
marked in the case of the Mine stream, which ended in a bank with 
a nearly vertical face just above the village. 
In addition to the damage done by the earth-torrents, the forests 
all round, except where sheltered by hills, were almost entirely 
destroyed by the eruption. Most of the trees were uprooted or 
broken off, and the few that remained had not only every leaf and 
twig removed, but even the whole of the bark was stripped off from 
them on the side facing Kobandai. This destruction of the forests 
was ascribed to a gust of wind caused by the eruptiop. That the 
sudden liberation of a great volume of steam must have given rise to 
a strong air blast is undoubted, but that all the observed effects could 
have been produced by such a blast seems highly improbable. This 
was one of the points which I took up when I visited Bandaisan, 
in May last, in company with Dr C. G. Knott. We examined a 
number of the stumps left standing, and found that in every case the 
trunk on the side facing Kobandai was pitted with holes of all 
sizes, evidently caused by the impact of stones. In some cases 
stones of considerable size were found imbedded in the wood. This 
indicated pretty clearly that the damage to the trees had been 
