His wife went to the back yard, where she had noticed some, and while she was gone the boys looked at the apparatus.

It consisted of a big wheel, with spokes made in zig-zag fashion. The spokes were shaped like a trough and contained a number of metal balls, which were prevented from falling out, as the wheel turned, by some strips of wood.

There were other smaller wheels connected with the big one, and a tall chute, with a sort of endless chain, to which were attached hooks and buckets. There were also several heavy springs.

"Ye see th' way it works," explained Mr. Kendall, "is by them balls. They roll down the spokes of th' wheel, toward the tire, so t' speak, an', of course, their weight makes th' wheel go 'round. Then, when they git t' th' end of th' spokes they drop out an' roll toward th' high chute. Soon as th' balls git thar th' endless chain an' th' hooks an' buckets on it catches hold of th' balls an' lifts 'em t' th' top. Then they drop inter th' hollow spokes agin an' th' same process goes on over agin. It goes on forever, like th' brook that poetry feller writ about—I forgit his name. It's perpetual motion as sure as ye're a foot high. Ah, here comes Mandy with th' clothes pole. Now I'll jest give th' big wheel a start, 'count of it gittin' stuck, an' you'll see suthin' worth watchin'."

With the long clothes pole Silas gave the big wheel a cautious poke. It began to move slowly, and he released a big spring.

"Stand back, everybody!" he called. "She vibrates suthin' terrible when she gits goin', an' I don't want nobody t' git hurt!"

At first the wheel barely turned. Silas gave it another prod with the clothes pole and it moved more quickly. Then it released another spring and began to gather speed. Faster and faster it went, the iron balls rolling along the hollow spokes and dropping out with a noise like distant thunder.

"There she goes!" cried the old man, his chin whiskers vibrating in the intensity of his excitement. "There she goes!"

Faster and faster the wheel whizzed around. The balls began dropping with such a continuous noise that one had to shout to be heard.

"How do you stop it?" called Dick.