256 The Philippine Journal of Science 



or possibly two shocks felt were of such small magnitude as 

 not to be perceptible at the Gubat, Legaspi, or Manila stations. 

 I was informed by Mr. Chestnut that there had been a small 

 amount of steam given off for several years before the eruption, 

 which together with the existence of numerous hot springs in 

 that vicinity indicates conclusively that the rocks are hot. That 

 water poured from the crater and much steam was evolved 

 would seem to involve the fact that this rainy season was a long 

 and exceptionally heavy one. 



The explanation which appears the most plausible, and the one 

 that takes into consideration the observed facts, is that the large 

 amount of water from the heavy and long-continued rainy season 

 percolated through the beds of porous strata and encountered the 

 hot rocks, and more steam was generated than could be evolved 

 by the old vent, with the result that an explosion took place in 

 which the old vent was widened and volcanic ash derived from 

 the crater walls was thrown into the air and carried a distance 

 of about 25 kilometers by the strong southwest winds. Not 

 having seen the crater previous to the eruption, I cannot be 

 certain of an enlargement of the old vent, but observations 

 substantiate the belief. 



I do not believe that the ash was derived from molten lava 

 by the explosion of inclosed gases, because one would expect to 

 find coarser fragments of vesicular lava (bombs and lapilli) 

 scattered on the slope. 



The incandescence accompanying the eruption can very easily 

 be explained by static electricity, the particles of ash becoming 

 electrified by friction and discharging in the moist atmosphere. 



