“I don’t know what I do think—yet,” was the reply. He held the keg aloft, and aside from the water that dripped from the outside none came from it. “There’s no leak there,” half growled Abe. “Some one has emptied that water butt!” He looked to where Mr. Skeel stood at the helm.

“Do you think——” began Tom in a whisper.

“Wait. Don’t say anything yet,” cautioned Abe. “But we’ll keep our eyes open.”

But if Mr. Skeel knew he was suspected he did not show it. He accepted his small share of food and water with the others, and he did not complain, as he usually did.

For three more days they sailed on, each hour adding to their sufferings, for it was very hot. And they scarcely seemed to cool off in the night before it was daylight again.

The water got lower, and to Tom’s horror, one day, as he went to serve out the food, he saw that the supply was much lower than he had thought.

“I’m sure there was more than this,” he said to the sailors when the professor was at the helm.

“There’s something wrong going on here,” decided Joe, “and I’m going to see what it is. There’s got to be a search made.”

One was soon under way, but it revealed nothing. Mr. Skeel had been in the habit of sleeping on a pile of the canvas and this was looked over. The man was evidently aware of the suspicion in which he was held, but he said nothing, and quietly moved away when the sailors looked under his canvas bed.