Half-Round Can Opener: Push the Cutter In and Twist

Opening a sardine box or tin with a flat knife takes many strokes and leaves a ragged edge. Seth P. Chapin of Atlantic, New Jersey, received US 56,368, dated 17 July 1866, for an implement for opening sheet-metal cans and boxes: a cutter semicircular in section with sloping edges to a point, bevelled inside, on a handle; forced in nearly to the handle and twisted, it cuts a circle the size of its own curve, and a guard at its top keeps it in position and stops it going too deep. This rung works out how many twists a hole takes, then files the cutter from steel tube and opens a can.