ANIMAL TRAP
A snap trap whose bait pan holds the jaw with one ear.
A wire base has an upturned end that passes through an aperture in the bait pan, on which the pan pivots loosely. A single tongue on the pan is wedged between a notch and a shoulder on the upturned end, holding it approximately level, while an extension contacts one jaw to keep the trap set. The mouse disturbs the pan; the tongue slips from the notch and releases the jaw; the coiled spring snaps both jaws closed.
“By virtue of this arrangement in which the bait pan has a single ear or extension contacting with one of the jaws, an extremely sensitive setting can be obtained with the minimum of manipulation.”— John U. Lehn and Mary A. Huebener, from the specification
And the world did not beat a path to their door.