In the 16th century Galileo Galilei discovered the principle that drives this unique thermometer. As a liquid's temperature increases, its buoyancy decreases. These attractive thermometers are sealed, rugged, high-quality glass tubes. Each handmade floater is massed to within 0.002 g to allow an accuracy of ±0.1° F. Temperature is read by noting the tag on the lowest of the floating temperature floaters. These quality devices will spark your students' interest and demonstrate the concept of temperature in a whole new way.