The Gulf was as smooth as a pond, as it often is in summer, and every minute Frank could see fish darting through the transparent water, and great turtles and sea-fans and brain-stones on the bottom. He was as much excited over it as if he had been starting for China.
"There's something ahead," he exclaimed, about the middle of the afternoon, "that I should say was a city growing right out of the water if I didn't know that it must be the great fort. But there can hardly be any fort as big as that. Is that really it, doctor?"
"That is really the fort," the doctor answered, "and I think we will be there now inside of an hour."
"But it seems to stand right in the water!" Frank exclaimed. "I don't see any land around it at all!"
"It would take good eyes to see any land around it," the doctor replied, with a twinkle in his own eyes. "You see, the island was only five acres in extent, and they built a fort covering seven acres, so the foundations were laid right out in the water."
When they were near enough to see plainly, Frank did not try to conceal his delight.
"What an immense building!" he exclaimed. "I never imagined there was such a big building in the world. No wonder it cost thirty millions! And there are roofs and chimneys inside the walls, and palm-trees waving over the top. I didn't know they had chimneys on a fort, doctor, and palm-trees?"
"They do in this one," the doctor laughed. "The roofs and chimneys belong to the officers' quarters and barracks, and the palm-trees have been growing ever since the fort was dismantled, thirty years ago."
Once inside the great walls, they were in a large yard grown up with palms and bushes; and crossing this, they entered the officers' quarters, where Dr. Murray had his office and living-rooms. Such big rooms, too, with great open fireplaces, and broad halls with iron staircases.