REVIEW OF VOLCANIC ACTION. 371 
In the observations on volcanoes which have here been made, the 
author has given his deductions from the facts observed, without 
mentioning that some of his conclusions have heen presented by 
others. This course has been followed because they give the effect 
of facts on a mind unbiassed by any theory, and they should, there- 
fore, have more interest as additional testimony on debated points in 
height, and in the rapidity of its slopes, to a state in which they produce an increase of 
breadth and diminution of the average angle of its slopes. It was once a crater of eleva- 
tion, through its eruptions ; it is now a crater of complanation, through the same means, 
—a distinction correctly recognised by Prevost. 
Hale-a-kala is a mountain of like slopes with Mount Loa (or a little more rapid), and 
answers the description of a crater of eruption in its broken summit. Yet the same facts, 
as regards structure, are to be accounted for as with Mount Loa. 
On page 367, von Buch says, ‘that if the vapours find an exit and escape, then no 
rock enters into fusion, and no lavas are formed.” Whether Kilauea, in the sense 
intended, gives exit to vapours or not, it may be difficult to say. Certain it is that 
vapours do escape on a grand scale, and lavas boil with unequalled activity, and over 
immense areas. The process instead of being paroxysmal, as von Buch’s remark im- 
plies, is gradual and incessant. Much of the error, with regard to the paroxysmal action 
of craters being an essential feature, has evidently arisen from the study of those vol- 
canoes only which have been long on the decline, the condition of igneous action gene- 
rally over the earth at the present time. 
On page 307, it is remarked that “if Lancerote had had a crater of eruption, there 
would probably have been none of its numerous cones of eruption,” implying that lateral 
eruptions would not have taken place. ‘The correctness of this opinion may be judged 
of from what has been already presented. ‘The fact that long after lateral eruptions have 
begun, the lavas may still ascend to the summit, is well shown in Mount Loa, in which 
eruptions take place at top while Kilauea is boiling ten thousand feet below. 
On page 323, von Buch says that there is only one volcano in the Canary Islands, 
the peak of Teyde or Teneriffe: “this is the grand outlet for vapours.” But we ask 
again, How much effect has the crater of Kilauea, with all its great breadth and extent, 
on the summit eruptions of Mount Loa, though situated on the flanks of this mountain ? 
These channels or internal conduits of heat and lava are probably as much isolated in 
voleanic regions generally, as in Hawaii. There is no reason to believe in the sympathy 
of adjoining islands except in some remarkable cases of action, as we have already sufhi- 
ciently explained. 
Judging from the descriptions of the Canaries, they have strong analogies in structure 
with the Hawaiian Islands. Teneriffe and Lancerote are double islands, resembling Maui 
and Molokai. M. von Buch suspects that Hualalai is the central volcano of Hawaii ; 
carrying out thus, his idea of a central vent of action, even at the expense of Mount Loa 
and Kea, far loftier than Hualalai, and not more steep in their slopes; and also, while 
Mount Loa is in eruption from top to bottom. 
The several considerations presented by M. Elie de Beaumont, in his able Memoirs, 
are sufficiently replied to in the preceding pages, as far as they relate to volcanic theory 
in general. 
