A cooper was someone that made or repaired wooden containers and barrels. This tool, the concave sun-plane, was used to smooth out the tops and bottoms of the staves after the container was put together.
Sun Plane, 19th Century, wood, metal, L:13 x H:3 x W:1.75, , ). The Farmers’ Museum, Cooperstown, New York, Gift of W.D. Ceas, F0236.1948(01).