“Did you look thoroughly on the floor, Edwards?”

“Yes, sir; hunted thoroughly.”

“Wait; I’ll go down with you,” proposed the principal.

Both principal and student searched thoroughly in the locker.  Dick, as in duty bound, was still there, on guard at the door.

“Mr. Prescott,” asked puzzled Dr. Thornton, did any student have admittance to the locker after recess today?”

“None, sir,” answered Dick promptly.

“Hm!  And you’re absolutely sure, Mr. Edwards, that you left the little package in your overcoat pocket?”

“Positive of it, Dr. Thornton.”

“It’s so strange that it startles me,” admitted the good principal.

“It startles me a good deal,” confessed Edwards, grimly, “to think what explanation I am to offer my mother.”

“Oh, well, it must turn up,” replied Dr. Thornton, though vaguely.  “Anyway, Edwards, there has been no theft.  The door is locked, and the only two keys to it are the one carried by the monitor and a duplicate which is kept locked in my own desk.  You’ll probably find it in one of your pockets.”

“I have been through every pocket in my clothes at least seven times, sir,” insisted the dismayed Edwards.  “And that is a rather valuable pin,” he added; “worth, I believe, something, like fifty dollars.”

“Rest assured that we’ll have some good explanation of the mystery before long,” replied the principal as soothingly as he could.

Edwards went away, sore and disheartened, but there was nothing more to be said or done.

Thursday morning Dr. Thornton carried the investigation further, but absolutely no light could be shed on the missing pin.

But at recess it was Frank Thompson who came upstairs breathless.

“Dr. Thornton,” he cried, excitedly, “it’s my own fault, of course, but I’m afraid I’ve seen the last of my watch.  It’s one that father carried for a good many years, and at last gave me.  The works are not very expensive, but the case was a gold one.”

“How did you lose it?” inquired the principal, looking up over the gold rims of his spectacles.

“Why, I had to hurry to make school this morning, sir, and, as you know, it’s a rather long walk.  So I carried my watch in the little change pocket in my reefer in order to be able to look at it frequently.  I reached the locker just in time not to be late, and forgot and left my watch in the reefer.  When I went down just now I found the watch gone.”

“Oh, but this is serious!” gasped Dr. Thornton, in dismay.  “It begins to look like an assured fact that there is some thief at work.  Yet Prescott alone has a key to that locker.”

“Prescott is all right.  He’s no thief,” put in Thompson, quickly.

“I agree with you, Mr. Thompson.  I consider Mr. Prescott too manly a fellow to be mixed up in anything dishonest.  Yet something is wrong—–­very wrong.  For the safety and good name of us all we must go to the bottom of this mystery.”