“Bob is out of his mind again,” replied the scientist. “He seems much worse. Did you bring a list of medicines? I find I shall need several kinds.”

“The houseboat is gone,” said Jerry.

“Gone?” and the professor’s face looked blank.

“And poor, dear papa is gone with her,” put in Rose.

Jerry quickly explained what had happened and Ned spoke of his theory.

“I believe you’re right,” agreed Uriah Snodgrass. “We are in strange waters and things have happened that I never would dream of. But, girls, don’t worry. I’m sure your father is all right. I wish I could find him, as I am worried about Bob, and I’m sure he would have the very medicine I need to make the boy well.”

“Let me assist in nursing him,” said Olivia. “It will help to take my mind off our troubles.”

“We’ll aid you,” added Rose and Nellie, and the three young ladies went into the tent where Bob was tossing in the delirium of fever. The professor was glad enough of their help and they at once bathed Bob’s head, face and arms in witch hazel which gave him some relief. They also kept wet cloths on his brow to reduce the fever.

“Now, boys, we’ve got a serious problem ahead of us,” said Mr. Snodgrass as he beckoned Ned and Jerry to follow him out of earshot of the tent. “It seems that we are caught in a sort of trap. We’re on a lake from which there appears to be no outlet, and it is constantly falling. In a little while there’ll be no water in it and if we want to get back home we’ll have to walk.”