198 HAWATIAN ISLANDS. 
area influenced by these changes is about twice the extent of Kilauea 
itself, or nearly eight square miles. 
V. Frequency of eruptions.—TVhe last three eruptions of Kilauea 
have taken place in a period of nineteen years, or with intervals of 
eight or nine years. Between the years 1789 and 1823, there may 
have been a season of comparative quiet, as we learn from the natives 
of no great eruption. ‘This evidence, however, is by no means deci- 
sive. They say, in general terms, that eruptions have taken place 
during all their kings, and assert that the crater has been in action 
from time immemorial. It is quite possible that in the above-men- 
tioned interval, there were submarine eruptions, if not subaérial ; 
and very probably, the latter also may have taken place. ‘The state- 
ment of the native to Mr. Bishop that the lavas, after reaching a cer- 
tain height, would flow out as they had formerly done under the sea, 
is evidence that they were aware of this mode of emptying Kilauea 
of its lavas. 
VI. Isolation of forces—We simply allude to the fact here, that 
eruptions take place from the walls of Kilauea, while the boiling pools 
are open many hundred feet below, and that these pools rise and fall 
independently, intending to recur to the subject in our general re- 
marks on Mount Loa. 
VIL. Rocks and minerals of Kilauea—The rocks of the walls of 
Kilauea, are remarkable for the distinctness and seeming regularity of 
their stratification. In a distant view, it was difficult to distinguish 
any variation from horizontality. Many minor irregularities were 
however apparent. In texture they were nowhere scoriaceous, though 
often vesicular, ‘The larger part contained few cellules, and many of 
the Jayers were quite compact. As far as observed, in the rapid sur- 
vey made, they appeared to vary in character between a ferruginous, 
compact basaltic rock, and graystone; and while some layers con- 
tained grains of chrysolite, in others none could be detected. The 
same facts, as we have stated, both as regards stratification, texture, 
and the absence of scoria, were presented by the walls of the lower pit. 
We have described the recent lavas of the crater and their scori- 
aceous crust, and have mentioned also that while the crust covers the 
overflowings of the pools, the lavas from other openings are generally 
destitute of this crust, and have an obsidian-like exterior, not at all or 
but slightly cellular. The part of the layer below the crust is gene- 
rally so solid that to the inexperienced eye it bears scarcely more evi- 
dence of having been through the fires than a piece of limestone ; and 
yet but a few hours before it was liquid. 
