Mercury-in-glass thermometer Mercury-in-glass thermometer The mercury-in-glass or mercury thermometer was invented by physicist Daniel Gabriel Fahrenheit in Amsterdam (1714). It consists of a bulb containing mercury attached to a glass tube of narrow diameter; the volume of mercury in the tube is much less than the volume in the bulb. The volume of mercury changes slightly with temperature; the small change in volume drives the narrow mercury column a relatively long way up the tube. The space above the mercury may be filled with nitrogen gas or it may be at less than atmospheric pressure, a partial vacuum. In order to calibrate
Beckmann thermometer then be set for readings between the required temperatures. Beckmann thermometer A Beckmann thermometer is a device used to measure small differences of temperature, but not absolute temperature values. It was invented by Ernst Otto Beckmann (1853 – 1923), a German chemist, for his measurements of colligative properties in 1905. Today its use has largely been superseded by electronic thermometers. A Beckmann thermometer's length is usually 40 – 50 cm. The temperature scale typically covers about 5 °C and it is divided into hundredths of a degree. With a magnifier it is possible to estimate temperature changes to 0.001 °C.