Tuesday, May 22, 2007

The Better Mouse Trap

When I recall my youth, I remember a number of activities that foretold my career as an engineer, including the time that I tried to make a better mouse trap.

We sometimes had mice (I remember Mom catching one with a broom and a dustpan), so we also had mousetraps. I noticed that mice could sometimes nibble the cheese gently enough to avoid getting caught, so I concluded that the triggering lever wasn’t sensitive enough. The big strong lever for catching the mouse was held by a second lever, which in turn was held by a third triggering lever that held the cheese.

I figured out that the purpose of the second lever was to reduce the force at the triggering lever. But the problem was that the triggering force was not reduced enough. So I built a mouse trap with more levers. As best as I can recall, the improved design was something like this:

A triggering lever made of a length of horse-hair held a stouter lever made of a broom-straw, which held a lever made of a tooth-pick, which held a lever made of a Popsicle stick, which held the strong capturing lever. The horse-hair didn’t need to hold the cheese, because the mouse’s whiskers would spring the trap if he just got close enough to sniff the cheese.

To test the trap, I set it up on the stairs that went from the kitchen up to the boys’ bedroom. (My three brothers and I shared one big bedroom.)

Now you must understand that one could not tip-toe up these stairs without most of the steps creaking. (This was advantageous to us boys when our parents could hear mischievous noise coming from the bedroom, and one of them tried to sneak up the stairs to find out who was doing what. But that’s another story.) But actually you could sneak up the stairs noiselessly if you knew the secret sequence: step over the first three steps, landing on the far left side of the fourth step, then go to the far right of the sixth step. etc.

Because the trap was essentially a vibration sensor, I thought that by setting it up near the top of the stairs, one of my brothers would walk up the stairs, would creak a step near the trap, and then be surprised by the trap snapping.

So I set up the mouse trap on the stairs – easy to say, but tedious to do. First, pull back the big spring lever, then get the Popsicle stick to hold it down, then set the tooth-pick to hold the Popsicle stick, then set the broom-straw to hold the tooth-pick, then set the horse-hair to hold the broom-straw. The process got more and more delicate.

That done, I next had to retreat, navigating the secret sequence in reverse. I tip-toed down nearly to the bottom when I miscalculated, a step creaked, and ten steps above me, the trap snapped shut.

That was the end of the experiment. I concluded that the trap was a bit too sensitive.

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