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To avoid this, some weather services require that all mercury-in-glass thermometers be brought indoors when the temperature falls to −37 °C (−35 °F). To measure lower meteorological temperatures, a thermometer containing a mercury-thallium alloy which does not solidify until the temperature drops to −61.1 °C (−78.0 °F) may be used.
A thermometer has two important elements: (1) a temperature sensor (e.g. the bulb of a mercury-in-glass thermometer or the pyrometric sensor in an infrared thermometer) in which some change occurs with a change in temperature; and (2) some means of converting this change into a numerical value (e.g. the visible scale that is marked on a mercury ...
The first sealed thermometer was constructed in 1654 by the Grand Duke of Tuscany, Ferdinand II. [1]: 19 The development of today's thermometers and temperature scales began in the early 18th century, when Daniel Gabriel Fahrenheit produced a mercury thermometer and scale, both developed by Ole Christensen Rømer.
1709 — Daniel Gabriel Fahrenheit constructed alcohol thermometers which were reproducible (i.e. two would give the same temperature) 1714 — Daniel Gabriel Fahrenheit invents the mercury-in-glass thermometer giving much greater precision (4 x that of Rømer). Using Rømer's zero point and an upper point of blood temperature, he adjusted the ...
Instant-read thermometers provide quick, accurate readings, probe thermometers are best for oven-roasting, digital thermometers offer precise results and alarms, and traditional dial thermometers ...
It is simultaneously dynamically connected to an external pressure reservoir, from which it is materially and thermally insulated. Other thermometers (e.g. mercury thermometers, which display the volume of mercury to the observer), may now be constructed, and calibrated against the ideal gas thermometer.
A medical thermometer or clinical thermometer is a device used for measuring the body temperature of a human or other animal. The tip of the thermometer is inserted into the mouth under the tongue (oral or sub-lingual temperature), under the armpit (axillary temperature), into the rectum via the anus (rectal temperature), into the ear (tympanic temperature), or on the forehead (temporal ...
Early technologies included mercury thermometers with electrodes inserted directly through the glass, so that when a certain (fixed) temperature was reached the contacts would be closed by the mercury. These were accurate to within a degree of temperature. Common sensor technologies in use today include: Bimetallic mechanical or electrical sensors.