“Is it marked in any way?” questioned our hero. “Perhaps it has his name or initials on it.”

“Oh, I don’t think so,” returned Nat. “Let us hurry up and get back to the school. If we are late, old Haskers will be after us.”

“Go on and run the boat as fast as you please, Nat,” answered Dave. “But I want to look at that handkerchief.”

Rather unwillingly, the money-lender’s son passed the bandanna over. It was now growing so dark that Dave could see but little.

“Wait, I’ll light a match,” suggested Gus, and did so, and by the protected but flickering flare our hero looked the handkerchief over. In one corner there was a faint stamping.

“Looks like ‘Rossmore Sanitarium’ to me,” said Dave, slowly. “Or it may be ‘Bossmore’ or ‘Crossmore.’ The beginning is too faded to be sure.”

“Bossmore Sanitarium?” queried Nat, and then he became silent and thoughtful. A little later he asked for the bandanna and placed it in his pocket.

The run in the motor-boat to the school dock did not take long. As soon as Nat’s craft was properly housed, Dave and Gus assisted the 136 money-lender’s son up the walk and across the campus.

“I suppose I’ve got to report the loss of the rowboat,” said Gus, ruefully.

“It wasn’t your fault, Gus,” answered Dave. “I’ll go with you to Doctor Clay.”