RAT-TRAP
Spins rats off a ship's mooring cable into a hanging cone.
A sleeve clamps onto a ship's mooring cable and carries a freely revolving body fitted with a transverse plate and smooth tapered blades. A rat attempting to cross the cable climbs onto the revolving element; the element turns underfoot and the rat falls off. An inverted cone suspended below the sleeve receives the falling rat through a polished funnel entrance, where a spring-backed hinged door closes behind it. A slidable door at the bottom of the cone permits removal of the caught rats so that they may be destroyed.
“It will also be noticed that when a rat passes to the revoluble element and particularly when it attempts to climb over the plate or wall 7, the element will revolve and the rat will be precipitated therefrom.”— Willard Duplantis and Curtis Duplantis, from the specification
And the world did not beat a path to their door.