“All right. Then in some public place, where there are a number of people present, we must make sure Puss has the cards with him; after which we will accuse him, and make him show whether this one card is missing from his pack.”

“Gee! you know how to show up these things all right, Frank!” exclaimed, the delighted Andy. “Suppose you get that brain-box of yours busy on another little mystery we know of now. Honestly, I have a hunch that if you would only try you could discover what became of my darling little monkey wrench. I’m like the baby and the soap you see advertised—I’ll never be happy till I get it.”

“I don’t believe you’ll give me any rest till you do remember where you put that plagued little tool,” declared the other, laughing.

“Hold on, don’t you go to calling it names,” said Andy, aggressively; “because it’s no fault of the wrench that it’s missing. I’m the one to blame, I reckon. But I’ll never give up trying to recollect where I put the thing away so safe that I’ve even forgotten the combination.”

“Yes,” smiled his cousin, “I’ve known people to do that before. Perhaps I may have done it myself. But if it comes to the worst, I suppose you can have a duplicate made that will answer just as well?”

“Oh! I reckon so,” replied Andy. “But think of the time and worry that thing cost me, not to mention the expense. Besides, I just don’t know how we’re ever going to make that first ascent minus that invaluable tool.”

“Well, forget it just now. We’ve sure got all the trouble we want to install this important part of our machine. I’ll drop in at Spencer’s place the first time I’m in town today, and see if the bolt of stuff has arrived. It would be great good luck if I found it had, Andy.”

Throwing off their coats, the two boys got to work. And presently they were as busy as beavers, crawling about the apparently clumsy object which occupied so much of the shed’s interior.

Colonel Whympers had had the place constructed especially for the purpose of furthering their plan. There never was a guardian more indulgent than this old traveler, now reduced to hobbling around with a crutch and cane. And Andy never tired of letting the old chap know how much he appreciated his generous heart.

Of course the structure was flimsily built, as most hangars are, being intended merely as temporary resting places for air craft. Many times Frank and his cousin knew that the town boys had come out of their way to peer through the crack in order to gratify their natural curiosity. But up to now no one had ever attempted to injure anything connected with the monoplane, or its shelter.