"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 book, in front of the camp. It had been a
great nuisance to keep our filter barrel full. Every few days we would
have to form a bucket brigade, passing pails of water up the line until
the barrel was filled. Now Bill proposed to do away with all this bother
and let the river do the work for us.
Surveying for the Water Wheel.
[Illustration: Fig. 250. Surveying for the Water Wheel.]
We first determined the height of the upper filter barrel above the level
of the river. This was done with our surveying instrument, which was set
level with the top of the barrel. We sighted with the instrument to a long
pole that was held upright at the edge of the water.
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