The Thermometer is probably the one weather instrument that just about everyone has used, at one time or another. Thermometers can be as basic as one hanging on a tree in the back yard, that you can read from the kitchen window, to a very sophisticated electronic thermometer that feeds hourly temperature data into your home computer. They all serve the same purpose of telling us what the temperature is outside and plays a major role in how we dress or prepare for each day.
Galileo invented the first thermometer in the late 1600's. The exact year is not known, but historians estimate that it was in 1593. He was a famous Italian Mathematician and Scientist whose inventions and mathematical theories are still in use today. The basic principle behind a thermometer, the expansion of air by heat and contraction by cold, was know many hundreds of years earlier. As far back as 300 B.C. experiments of Philo of Byzantium illustrated this principle. Along with Galileo, several other scientists developed better and more accurate thermometers. They were Marin Mersenne, Otto Von Guericke, Robert Boyle, Christian Huygens and Sir Isaac Newton.
