Themometer

A thermometer is used to measure the temperature of an object. Galileo invented a rudimentary water thermometer in 1593. He called this device a thermoscope. However, this form was ineffective as water freezes at low temperatures. In 1714, Gabriel Fahrenheit invented the mercury thermometer, the modern thermometer. The long narrow uniform glass tube is called the stem of a thermometer. The scales in which the temperature is measured is marked on the scale. At the end of the stem there is a small bulb which contains mercury in it. A capillary tube is inside the glass stem in which mercury expands when the bulb is kept in contact with a hot body. Mercury is toxic, and it is very difficult to dispose it when the thermometer breaks. So, nowadays digital thermometers are used to measure the temperature, as they do not contain mercury.