"They tried to, but the charge blew out; there are the holes."
"Perhaps their powder gave out."
"I guess I know how this went."
"How?"
"This stone ran on its edge round the other; there was an upright shaft in the middle; and that hole in the centre was made to receive a pintle, to hold the foot of it, and it was turned by a horse, or by hand, just like a cider mill."
Walter began to hunt in the long grass around the stone, and soon exclaimed,—
"Here it is! here is the track worn into the ground, where somebody or something travelled."
"It was a horse or mule," said Ned, holding up a rusty shoe.
"That is too big for the foot of an ass."
"What is the stone trough underneath for, Wal?"