Furthering FP’s historical squirrel research:
Delaware Weekly Advertiser and Farmer’s Journal; January 31, 1828; Issue 20; col B

Mr. A.S. Bugbee, of Northampton, has contrived a method of turning to account the natural activity of the common grey squirrel. “He has,” says the Northampton Post, “a common cylindrical cage with wire bars, about three feet in diameter, to the axis of which, (four feet long) are connected some small brass wheels which move the machinery of a coffee and pepper mill. Three squirrels are usually employed in the labor of this novel tread-mill, though we have seen a single one turn the wheel with apparent ease. The power of each squirrel in the wheel is estimated by Mr. B. at sixty-five pounds, and in an hour they grind a pound of coffee, pepper, allspice, &c. The expense of the machine was about $300, and the cost of the subsistence of each of the little laborers is about two cents a week.”