The base of the previous trap will eventually get splintered where the hold-down bar isjammed into it. Using a staple to hold the end of the hold-down bar increases the usefullife of the mousetrap.
Imagine a gymnasium full of mousetraps. On each mousetrap is a ping pong ball. Now throw a single ping pong ball into the middle of the room. The ball lands on a trap, the trap triggers, and a second ball flies into the air. The first ball also bounces into the air again, so now there are two balls in the air. Each of those two balls triggers another trap, so there's four balls in the air. And so on...
This experiment is a well-known metaphor for nuclear fission. In nuclear fission, atoms of fissionable material such as uranium are the "mousetraps", and neutrons are the ping pong balls.
A recent article by Joachim Dagg () reviews the history of actual mousetraps, showing that they did indeed "evolve" from simple to more complex through time, including mousetraps that were similar to the modern snap mousetrap but had fewer parts.
|Wikimedia Commons has media related to Mousetraps.|