had got wind of Bill's discovery and meant to turn his find to
advantage.

"By jumping rat-tailed land-sharks, I never thought of that,"
exclaimed Bill. "Why, any one that knew our secret could sell it for a
large sum."

"That's so," agreed the boys; "but perhaps it was only a tramp and we
are scaring ourselves unnecessarily."

"I hope so, I'm sure," rejoined the old sailor, "but now, boys, you
drive on. You may manage to be of help at the fire."

"Won't you come, Bill?" asked Frank.

"No, thank you, lad, I'll stay here and guard my shanty. That feller
may hev been after some of my dried shark or stuffed land-crabs. I
wouldn't put it by him to steal that picture of the schooner, Boston
Girl, in a heavy blow off Hatteras. That's a real work of art, boys."

As the boys drove off they heard the old man grunting and grumbling
and poking about among the bushes in search for the intruder.

"I don't envy that fellow whoever he is, if Bill catches him,"
remarked Frank, as he urged the old sailor's little horse along.

"Nor I," laughed Billy; "but depend upon it he is a long way off by
this time."

As they drew near the aviation grounds, the boys saw that the fire was