joined here by Sam Robinson's father and mother and two sisters who thought that they would share some of Sam's fun.
This place was almost a mile and a half above sea level and so cool in the early morning that when the boys looked out it seemed that the whole valley was on fire, for every spring and stream and geyser was sending up a column of steam. Dr. Curtis called to his party just before sunrise to get up and see Old Faithful, the greatest geyser of them all, throw its stream of water into the air as high as a fourteen-story skyscraper while the morning sunrise on the enormous clouds of steam made reds and greens and all the colors of the rainbow, and the rainbow itself.
"How did you know when to call us, Dr. Curtis?"
"Old Faithful works on schedule time, every sixty-three minutes, night and day, summer and winter. It's very handy for travellers."
"But what makes geysers go off anyway?" asked the always curious Sam Robinson.
"Oh, wait until the Giantess goes off and we will see how it is done." They were fortunate enough to see this irregularly working geyser before they left this basin.
It had a crater 30 feet wide filled with sapphire colored water. Suddenly the water began to flow out and there was an explosion down in the ground that shook everything for a mile around and then water and steam flew out a hundred feet in the air.
"What made the explosion?" asked Sam.
"Way down deep in the rocks where they are very hot the water in the crevices turns to steam just as it does in a boiler when the boiler bursts. The steam then blows out all the water anywhere near it. After this the water runs in again as in any other spring."
"But what makes the rocks hot, Dr. Curtis?"
"This used to be a volcanic region and it hasn't cooled off yet."
There isn't space to tell the fortieth part of the things that the boys did and saw in their three weeks in the Park. We can only refer to a few.
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