“You mean—” Johnny stared.
But just then someone called to Bex from outside the mill and Donald said once more to Johnny:
“You want to go down?”
At once Johnny’s mind was all awhirl with thoughts of mysterious whispers and wheezes from those lower regions of the mill, and with the strange wealth that came from those depths. “Sure,” he said once again. “Sure I would.” So the other boy turned the key in the lock and they went down.
“I’ve helped my grandfather at this sort of thing quite a lot,” Donald said as he switched on a light—the place below had no windows. “He used to have a shop just outside of the city. That was where I worked with him most. But the air there was too impure, too much dust. Lot of smoke from chimneys and factories.
“So he came down here.” The boy seemed to be talking to himself quite as much as to Johnny. “Air down here in the mountains is about as pure as you can hope to find anywhere. No cars shooting along kicking up dust and coughing out gas. If any smoke passes over, it crosses at the mountain tops, not down here.
“Another thing,” he pushed a lever. There came the sound of rushing water and slowly revolving wheels. “Another thing,” he repeated, “this power down here is cheap. Don’t cost you anything. All you have to do is to keep up the dam and see that the mill is in good repair. You’ve really got to have cheap power. Costs only about half as much down here.”
“What costs half as much?” Johnny thought this question but did not ask it. Johnny could wait.
From one corner came a sucking sound. This increased until the room seemed full of the sucking and hissing of a steam engine, yet there was no steam. It was strange.
Donald dragged a canvas-covered something from a corner. This proved to be a large jug. It was not made of clay however, nor of glass.