Galileo Galilei was a famous Italian mathematician, astronomer, and physicist who (among many other things) invented and improved several instruments that made measurements more accurate. I have always admired Galileo’s work, because he has contributed so much to the advancements of telescopes, microscopes, balances, compasses, and thermometers.

I bought my boyfriend this Galileo Thermometer for Valentine’s Day, because he mentioned a while back that he always wanted one as a kid (he’s a nerd too):

This thermometer is 24″ tall, and it’s based on Galileo’s discovery that a liquid’s buoyancy decreases as its temperature increases. This sealed glass cylinder contains 11 multi-colored floating spheres, each having different weights that rise and fall at different temperatures. The current temperature is indicated by the tag attached to the lowest of the floating spheres. When I took these pictures, the current temperature was 70 degrees and the sphere representing 68 degrees was floating downwards:

I think Galileo thermometers are beautiful, interesting to look at, and an accurate way of measuring indoor ambient temperature. This particular thermometer has a range of 62 to 82 degrees, with each sphere separated by 2 degrees. I bought the biggest one I could find, but there are smaller ones (that have less spheres and a smaller temperature range). Another good fact is that if this thermometer does happen to fall and break, the liquid in the cylinder is free of CF2 gasses, almost inflammable, and non-poisonous.