machinery in operation, and the boat, propelled by a powerful dynamo, was soon speeding along beneath the surface of the sea.
Glass windows formed the sides and top of the vessel, and powerful search-lights illuminated the surrounding ocean, so that to Flora it was a veritable trip in fairy-land to pass through these wonderful regions inhabited by fish and other marine animals of the most curious shapes.
All too soon they reached the spot where the submarine houses were being erected, some already completed, others just begun. It was truly weird to see the workmen in their divingsuits engaged in the construction of these habitations, and Flora did not tire of watching them. Mr. Curtis, too, was interested, but he was puzzled as well.
"I must say, doctor," said he, in a tone of perplexity, "that I don't at all understand what you need these submarine houses for. Where do your workmen lodge at present?"
"Most of them return to Australia after their day's work is done," replied Dr. Giles, "but a number of them sleep in the caisson where the digging operations are carried on."
"Then, why is it they cannot continue to sleep
