And that is just what had happened. That last great blast Tom Swift had set off had broken down the rock wall that hid the lost city from view. There it was, buried deep down under the mountain, where it had been covered from sight ages ago by some mighty earthquake or landslide; perhaps both. And the earth and rocks had fallen over the main portion of the city of Pelone in such a way—in such an arch formation—that the greater part of it was preserved from the pressure of the mountain above it.
The outlying portions were crushed into dust by the awful pressure of the mountain—millions of tons of stone—but where the natural arch had formed the weight was kept off the buildings, most of which were as perfect as they had been before the cataclysm came.
The buildings were of stone block construction, mostly only one story in height, though some were two. They were simply made, somewhat after the fashion of the Aztecs. A look into some of them by the light of portable electric lamps showed that the houses were furnished with some degree of taste and luxury. There were traces of an ancient civilization.
But of the inhabitants, there was not a trace: either they had fled before the earthquake or the volcanic eruption had engulfed the city, or the countless centuries had turned their very bones to dust.
"Oh, what a find! What a find!" murmured Professor Bumper. "I shall be famous! And so will you, Tom Swift. For it was your blast that revealed the lost city of Pelone. Your name will be honored by every archeological society in the world, and all will be eager to make you an honorary member."
"That's all very nice," said Tom, "but what pleases me better is that this tunnel is a success."
"Success!" cried Mr. Damon. "I should call it a failure, Tom Swift. Why, you've run smack into an old city, and you'll have either to curve the tunnel to one side, or start a new one."
"Nothing of the sort!" laughed Tom. "Don't you see? The tunnel comes right up to the main street of Pelone. And the street is as straight as a die, and just the width and height of the tunnel. All we will have to do will be to keep on blasting away, where the main street comes to an end, and our tunnel will be finished. The street is over half a mile long, I should judge, and we'll save all that blasting. The tunnel will be finished in time!"
"So it will!" cried Job Titus. "We can use the main street of the hidden city as part of the tunnel."
"Use the street all you like," said Mr. Bumper, "but leave the houses to me. They are a perfect mine of ancient lore and information. At last I have found it! The ancient, hidden city of Pelone, spoken of on the Peruvian tablets, of gold."