Pa ee 
4 
Volcanic Eruptions on Hawaii. 363 
raises the bottom of the crater; the lavas continue to boil over, 
and go on accumulating, and elevating the area of action ; the 
pressure is consequently gradually increasing ; the action becomes 
after a while more intense, perhaps in part from the ‘increasing 
pressure, and the increasing height to which vapors ascend be- 
fore escaping ; new centres of ebullition add to the effect ; finally, 
after the bottom is raised 400 or 500 feet above its lower level, 
these centres are numerous, the ebullition is violent, the overflow- 
ings almost incessant ;—at last the increased pressure, in addition 
to the force of rising vapors proceeding from the increased ac- 
tion, cause a rupture through the mountain’s sides and the lavas 
flow out. 
This is the history from a period of quiet to one of greatest 
activity. If the larger pool, after an eruption, should become 
a 
consequence of it. With this principle in view, we may trans- 
late the language of Kilauea into that of Vesuvius or Etna. The 
of the greater or less viscidity of the lavas. 
same seontiion of effects with the same results ; and periods of 
quiet and violent action may have the same mutual relations and 
dependence. We need look to no extraordinary influx of waters 
to occasion an eruption, as the eruption is a result of a progres- 
Sive state of things, perhaps long in action. I do not here itd 
that such a paroxysmal influx of waters may at times take p ace, 
and has produced results. I urge only that they are exceptions’; 
and that phases of quiet and violent activity would necessarily 
Succeed one another without such intervention. 
