which are notched to the
right length to stretch the cloth taut. A cleat is nailed over each
notch, as shown in Fig. 248, forming forks to hold the corner pieces.
The long spreaders are now forced down until they meet the short
spreaders, to which they are tied with waxed string. The long spreaders
may be nailed to the corner sticks by driving brads right through the
cloth into the cleats and the sticks. The belly band may be fastened to
any one of the corner sticks at the spreaders, and from the points where
it is tied it should measure about 45 inches in length. The point where
the main string should be attached to the belly band may be best
determined by experiment."

[Illustration: Fig. 249. The Diamond Box Kite.]

CHAPTER XXI.

THE WATER WHEEL.

Summer found us again on Willow Clump Island with heads full of new
ideas. Bill had come across an old copy of Ewbanks' "Hydraulics" in the
school library. It was a book describing machines of the
ancients--principally devices for raising water. Rather dry reading, I
thought, even though it was a wet subject; but Bill seemed to find it
absorbingly interesting. I came in late one afternoon, after a glorious
game of baseball, only to find Bill poring over the yellowed leaves of
the "Hydraulics" as fascinated as most fellows would be over a detective
story. It exasperated me to note that he thought more of this old book
than he did of our baseball team.

"Bill," I exclaimed, "what's got into you? I can't for the life of me
see what is so entertaining in that prehistoric book."

"Oh, go way. Don't bother me," was the surly reply.

But I wouldn't be put off that way. Quickly I snatched the book from his
grasp and threw it out the window.

"Now, sir," I cried, "maybe you will kindly explain to me why you
persist in studying that old volume, to the neglect of our baseball
team."

"Don't get so excited, old chap," he replied. "That book is all right.
I'm studying up some new schemes for next year's expedition to Willow
Clump Island. Why, there are lots of things in that old book that we can
make." And he proceeded to unfold his plans, sketching out some curious
designs of water wheels and pumps.

By the time school closed for the summer Bill had thoroughly digested
that volume, and was ready to reconstruct many of the ancient machines.

THE WATER WHEEL.

Our first work on reaching the island was to erect a water wheel, or
"noria," as it was called in the b