222 HAWAIIAN ISLANDS. 
mediate vicinity. How then, with so limited a protecting influence, 
can it relieve from danger a neighbouring island? Nothing can be 
farther from the truth, however popular the opinion, or however sup- 
ported by authority. Volcanoes are in fact indexes of danger, and 
the absence of them is the best security. They point out those por- 
tions of the globe which are most subject to earthquakes, and are 
results of the same causes that render a country liable to such con- 
vulsions. 
We also understand, from this study of volcanic action, why it is 
that earthquakes in volcanic regions are so seldom attended by pulsa- 
tions or any increased action in the active vents. 
VI. Phases of Volcanic Action.—Moreover there can be no truth, 
at least as regards Mount Loa, in the principle reasoned out at length, 
in an able article on volcanoes, by Bischof,* that the phases of vol- 
canic action depend on water gaining access to the central fires of the 
globe; for the evidence is certainly conclusive that the main action 
of waters is comparatively near the surface. 
The phases of volcanic action at Kilauea are simply as follows :— 
1. The centres of action, when most quiet, are reduced to a single 
one, which occasionally overflows. ‘This overflowing 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 gra- 
dually increasing; the action becomes after a while more intense, 
from the increasing pressure, and increasing height to which vapours 
ascend before escaping ; new centres of ebullition add to the effect ; 
finally, after the bottom is raised 400 feet above its lower level, these 
centres are numerous, the ebullition is violent, the overflowings almost 
incessant ;—at last the increased pressure, in addition to the force of 
rising vapours proceeding from the increased action, cause a rupture 
through the mountain’s sides and the liquid rock flows out. 
This is the history from a period of quiet to one of greatest activity. 
If the larger pool, after an eruption, should become crusted over, as 
happens with the smaller pools, the lavas sinking far below the 
surface, there would seem to be a state of inactivity. But the same 
process going on, the surface would be gradually reached, and the 
work would be continued as above explained. ‘This is all a simple 
result of the passage of vapours from below, inflating the lavas as they 
ascend, producing the appearance of ebullition, and occasioning thus 
* Natural History of Volcanoes by G. Bischof, Jameson’s Edinburgh Journal, xxvi., 
1839; American Journal of Science, xxxvi., 249, 250. 
