I have shown, differs from that
of the Great Geyser, may be accounted for on the same general
principle. The foreign substances thrown in on top of the boiling
water stops the escape of steam, which, under ordinary circumstances,
is sufficiently great not to require the periodical relief of an
eruption. An accumulation of compressed steam takes place in the
reservoir below, and this continues until the obstruction is ejected.

[Illustration: GREAT GEYSER AND RECEIVER.]

[Illustration: STROKHR AND RECEIVER.]

This, I believe, is substantially Lyell's theory; though, having no
books by me at present, I quote entirely from memory, and it is
possible I may be mistaken in some of the details. The preceding
diagrams will enable the reader to understand more clearly the whole
process by which these eruptions are produced.

Six long hours remained till ordinary breakfast-time. What was to be
done? It was getting terribly lonesome. I felt like one who had been
to a theatre and seen all the performances. Zoega had promised to be
back by eight o'clock; but eight o'clock in Iceland, on the 21st of
June, is a late hour of the day. A treatise on trigonometry might be
written between sunrise and that unapproachable hour. The only thing I
could do was to make some more tea and eat a preliminary breakfast.
When that was done nothing remained but to go to work in front of my
little tent and finish up my rough sketches. This is a very absorbing
business, as every body knows who has tried it, and I was deeply into
it when Zoega made his appearance.

"Well, sir," said he, "what success? Did he erupt?"

"Of course he erupted, Zoega. You didn't suppose a Great Geyser would
keep a gentleman all the way from California waiting here an entire
night without showing him what he could do?"

"No, sir; but he sometimes disappoints travelers. How do you like it?
Does he compare with your California Geysers?"

"Well, Zoega, he throws up more hot water, to be sure, because our
Geysers don't erupt at all; but here is the grand difference. We
Californians are a moral people; we don't live so near to (I pointed
down below) as you do in Iceland."

"I don't understand you, sir," said Zoega, with a puzzled expression.

I called him over and whispered in his ear, "Zoega, I hope you're a
good man. Do you say your prayers regularly?"

"Yes, sir."

"Then you are all right. Let us be going. I don't like this
neighborhood."

"Whenever you wish,