COIL-SPRING TRAP.
The springs are also the legs, and the trap pursues the withdrawing foot.
A treadle is held raised by a latch above a base-plate carrying pivoted jaws. Each spring is a single wire bent into two stacked V-shapes joined by coils, and its lower halves extend outward to serve as the trap's supporting legs. When an animal depresses the treadle, the whole trap body sinks on these yielding legs and the jaws are released. If the animal lifts its foot, the springy legs push the trap body back up, so the closing jaws rise with the retreating leg and grip it.
“Moreover, when an animal steps on the treadle the entire body of the trap is depressed to release the jaws; but even though the weight of the animal should be removed immediately from the treadle in an effort to avoid the consequences of releasing the jaws, and no matter how quick this action on the part of the animal may be the yielding supports will cause the trap to rise, and thus follow the foot of the animal and grip the leg as high as though the foot had been allowed to remain on the treadle with the weight imposed thereon.”— James Dawkins, from the specification
And the world did not beat a path to his door.