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
Meat thermometer Meat thermometer A meat thermometer or cooking thermometer is a thermometer used to measure the internal temperature of meat, especially roasts and steaks, and other cooked foods. The degree of "doneness" of meat or bread correlates closely with the internal temperature, so that a thermometer reading indicates when it is cooked as desired. When cooking, food should always be cooked so that the interior reaches a temperature sufficient, that in the case of meat is enough to kill pathogens that may cause foodborne illness or, in the case of bread, that is done baking; the thermometer helps to ensure this.