THE ERUPTION OF BANDAI-SAX. 121 



metres (4,200 ft.) above the crater. If stones were thrown up to the 

 same height as the steam column, their initial velocity must have 

 been 158 metres per second, and this may be roughly taken as the 

 final velocity with which, on falling down, they would reach the ground. 

 But if we suppose that the steam and stones reached to double or 

 treble the above height, which is not improbable, the initial velocity be- 

 comes 224 and 274 metres per second respectively. The velocity need- 

 ed for penetrating a soft loamy soil to a depth of 2*5 metres would be 

 between 300 metres and 600 metres per second, according to the 

 values of coefficients we take, but in these calculations, as we are using 

 several more or less arbitrary assumptions we cannot take them as a 

 sound basis for discussion. 



It seems not strange, however, to find that the basin-like holes 

 wearing those appearances of having been blown out from below 

 have led to the theory of their formation by internal explosion. 

 Stones striking the ground with great force would make holes 

 of larger diameters than their own by throwing; the surrounding earth 

 outward. Again, if the fall of anv stone take place at a spot where 

 there are rocks on or near the surface of the ground, the concussion 

 will ."hatter the falling stone and at the same time blow up the ad- 

 joiningd soil, thus producing the appearance of an eruption. We have 

 witnessed great number of those cases on Obandai and Marumori-vama. 



The inhabitants at the base of the mountain noticed among the 

 rising steam small and large white objects ascending and descending 

 like shooting stars. At one time, they were so numerous that they 

 almost looked like white rain. It seems very probable that these ob- 

 jects were stones ejected from the crater. 



That, large fragments of rocks are hurled into the air during 

 volcanic eruptions is a matter of common experience. But that they 

 have left their traces upon mountain sides in the form of conical holes 



