Thursday, September 22, 2011

Humid Hairs

Last night we made a hygrometer for extra credit in our science class.  A hygrometer is a tool used to measure humidity.  The best kind of hair to use is horse hair, so I called up our sweet friend who owns a horse and asked her if she would kindly perform a plucking.  Or two.  A true friend is one who will actually deliver a horse hairball to your house for you.

Anyway, we googled directions for construction.  They cost ten cents to make.  Oh, and it's best, as Hayden pointed out, to use the tails side with your tail hairs.

You attach a plastic pointer, weighted with the dime, to the horse hair and mount it on a board.

When the hair gets moist it should expand and lengthen and cause the pointer to aim downward.

Each boy made a hygrometer and we mounted them to opposite sides of a cardboard box.  We then set the box in the guest bath with the shower running.  When we went in to check our status, both pointers were facing straight up!  Vertical!  There was lots of give and slack in the horse hair.

Hmmm...the hair was supposed to elongate, but it curled up instead and caused significant movement on our primitive tool.  I'm not sure if we get extra credit for an experiment gone awry, but I found the outcome very interesting.  We tested a second time and got the same result.

We left it sitting on the counter overnight and it was back to the horizontal position this morning.

So there you have it.  An interesting tale.