From Sakurajima I went to Bandaisan, or Kobandai, a famous volcano in central Japan northwest of Tokyo and on the shore of a beautiful lake. It looks like an ordinary rocky peak, but its fame was made by a steam explosion from its flank which blew out the side of the mountain and left avast sulfurous quarry with numerous solfataras and hot springs. Bandai was known by geologists to be one of a chain of volcanoes, but prior to 1885 its activity was in question. One morning the sky was darkened by the overwhelming explosion, and vast volumes of rock from the outbreak poured down as a landslide and completely dammed a river system. It left extraordinary little heaps in the new dammed up lake. These appeared to be individual blocks of rock against which heaps of debris were piled so as to leave pyramidal humps scattered over the surface of the impounded water near the volcano. An excellent report in English on this eruption was published at the time, and the eruption became the type of what geologists call a phreatic explosion, meaning pure steam. There was doubt as to whether any fragments of new lava were thrown up. I took with me to Bandaisan a photographer-guide. We camped in a mountain inn with thatched roof, visited a hot spring resort, and hiked to the crater where we measured temperatures and took photographs. It was a vast flat-floored shelf, dug out of the side of the mountain, with steam jets and puddles of boiling water at the back. Looking out at the new water-filled valley with its many islands at the base of the slope below the crater, we could see shoreline levels higher than the present beach, where the damming had produced the highest stand of the water. The eruption and landslide overwhelmed villages and killed many people, though it lasted only a few days. It was on the side of the mountain remote from the older lake. In clambering over the broken debris, which looked more like glacial deposits than volcanic agglomerate, I picked up some pieces of vesicular basalt that were definitely lava. Wada, a Japanese geologist, had found the same thing, and we both concluded that these were an internal live basalt blown to fragments in the Bandaisan eruption, but that most of the material was from the shattered old mountain. My interpretation of Bandaisan is that it is an old volcano in the line of Asama and other volcanoes of central Japan, and that the line is a deep crack always full of lava in the depths, which is selective of outlet, depending upon what part of the crack opens as the path of least resistance. Eruption may be occasioned by lava wedging upward at one volcano, or by lava sinking downward at another volcano, according to the way the medial rift of continental Honshu is warped and stressed by the earthquake forces. One part of a volcano chain is always sinking, with lava withdrawn. Another part is always swelling up, with lava penetrating the cracks under active crater pits, like that of Asama.