These hinges are for the drop-leaf on a sewing machine. Since these have the flashed copper finish, we will date this pair from 1900 to 1920.
The base of the hinge, that is mortised into the wood and fastened with screws, measures 1 1/8 inches round. The pen is 1 1/8 inches long. Screws will be provided.
In the fifteen years we have handled old hardware, this is the only pair of sewing-machine hinges we have had. I guess they must be scarce.