Fig. 95. Second wind vane
In the meantime, Harry had found out to his own satisfaction that his water-wheel windmill would not work.
"What have you curved those ends out for?" he exclaimed on catching a sight of Ralph's vane.
"Why, to make it more sensitive to the slightest breeze. Those curves catch the wind quicker than flat surfaces; have you never noticed that on the weather bureau vanes they are always curved out like that?"
"No," said Harry. "By the way, do you know why my mill doesn't work?"
"I have told you about six times that a water-wheel receives the water on one side only, while your mill receives the same pressure on both sides of the centre. The two forces balance, so your mill can't very well turn. If you could cut off the wind from one side, it would go all right."
"Well, why can't I box in one side?"
"You can, but then you will have to shift it every time the wind changes. You could construct a combination mill and vane, and arrange it so that the box would be shifted by the vane, but honestly, I don't think it worth the trouble. It would be clumsy, top-heavy, and hard to balance. I have a scheme for a horizontal mill, but we will take it up later. In the meantime, let's make a happy jack windmill!"
"Happy jack?"