Temperature is measured using thermometers. There is a rich history behind thermometers [local]. Celsius [local] developed a temperature scale.

The word thermometer usually brings to the chemist's mind a device that has a liquid which expands in a narrow tube when heated. Control Engineering OnLine offers an interesting discussion of thermometers [local] in industry. Omega Engineering has a page comparing thermometer properties [local].

Bimetallic strip thermometers are likely to be a part of student experience. Thermocouples [local] are used to measure temperatures. Thermistors [local] are temperature-sensitive electrical resistors. Ear thermometers detect infrared radiation emitted from the ear drum.

The Galileo thermometer depends up the decreasing density of a liquid with increasing temperature. The Florentine thermoscope, a gas thermometer, depends up the expansion of a heated gas.