ANIMAL-TRAP
The jaws cross and interlock so they cannot be sprung apart.
Two spring arms are joined at one end and tensioned to spread apart at the other, each carrying a curved jaw. A pivoted detent engages a catch plate to hold the jaws open, and a wire trigger extends across the opening between them. The animal enters between the jaws and presses the trigger; the detent releases and the jaws snap shut. Because the jaws are curved in opposite directions, they cross and interlock upon closing, preventing the animal from springing them apart laterally.
“In other words, I have sought to produce a trap of this character which is light, strong and durable and capable of being manufactured at a comparatively small cost.”— Ferrand F. Ellis, from the specification
And the world did not beat a path to his door.