The sponge crawls of which the old man spoke are square pens make of stakes driven into the sand side by side, and as close as possible together. In some of them at Key West Mark and Ruth saw little negro boys diving to bring up stray sponges that the rakes had missed. They did not seem to enjoy this half as much as Mark and his boy friends used to enjoy diving in the river at Norton, and they shivered as though they were cold, in spite of the heat of the day. When the children told Mr. Elmer about these little, unhappy-looking divers that night, he said, "That shows how what some persons regard as play, may become hard and unpleasant work to those who are compelled to do it." Several days after this Mr. Elmer engaged a carriage, and took his wife and the children on a long drive over the island. During this drive the most interesting things they saw were old Fort Taylor, which stands just outside the city, and commands the harbor, the abandoned salt-works, about five miles from the city, and the Martello towers, built along the southern coast of the island. These are small but very strong forts, built by the government, but as yet never occupied by soldiers. In one of them the Elmers were shown a large, jagged hole, broken through the brick floor of one of the upper stories. This, the sergeant in charge told them, had been made by a party of sailors who deserted from a man-of-war lying in the harbor, and hid themselves in this Martello tower. They made it so that through it they could point their muskets and shoot anybody sent to capture them as soon as he entered the lower rooms. They did not have a chance to use it for this purpose, however, for the officer sent after them just camped outside the tower and waited patiently until hunger compelled the runaways to surrender, when he quietly marched them back to the ship. In all of the forts, as well as in all the houses of Key West, are great cisterns for storing rain-water, for there are no wells on the island, and the only fresh-water to be had is what can be caught and stored during the rainy season. It was a week after the orange auction that Mr. Elmer came into the cabin of the schooner one afternoon and announced that the court had given its decision, and that they would sail the next day.