This is a timeline of temperature and pressure measurement technology or the history of temperature measurement and pressure measurement technology.
Daniel Gabriel Fahrenheit FRS was a physicist, inventor, and scientific instrument maker. Born in Poland to a family of German extraction, he later moved to the Dutch Republic at age 15, where he spent the rest of his life (1701–1736). A pioneer of exact thermometry, he helped lay the foundations for the era of precision thermometry by inventing the mercury-in-glass thermometer and Fahrenheit scale.
The Fahrenheit scale is a temperature scale based on one proposed in 1724 by the European physicist Daniel Gabriel Fahrenheit (1686–1736). It uses the degree Fahrenheit as the unit. Several accounts of how he originally defined his scale exist, but the original paper suggests the lower defining point, 0 °F, was established as the freezing temperature of a solution of brine made from a mixture of water, ice, and ammonium chloride. The other limit established was his best estimate of the average human body temperature, originally set at 90 °F, then 96 °F.
A thermometer is a device that measures temperature or temperature gradient. A thermometer has two important elements: (1) a temperature sensor in which some change occurs with a change in temperature; and (2) some means of converting this change into a numerical value. Thermometers are widely used in technology and industry to monitor processes, in meteorology, in medicine, and in scientific research.
The melting point of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at a standard pressure such as 1 atmosphere or 100 kPa.
Thermodynamic temperature is a quantity defined in thermodynamics as distinct from kinetic theory or statistical mechanics.
The mercury-in-glass or mercury thermometer is a type of thermometer that 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.
The Réaumur scale, also known as the "octogesimal division", is a temperature scale for which the melting and boiling points of water are defined as 0 and 80 degrees respectively. The scale is named for René Antoine Ferchault de Réaumur, who first proposed a similar scale in 1730.
The Rømer scale, also known as Romer or Roemer, is a temperature scale named after the Danish astronomer Ole Christensen Rømer, who proposed it in 1701. It is based on the freezing point of pure water being 7.5 degrees and the boiling point of water as 60 degrees.
The Delisle scale is a temperature scale invented in 1732 by the French astronomer Joseph-Nicolas Delisle (1688–1768). Delisle was the author of Mémoires pour servir à l'histoire et aux progrès de l'Astronomie, de la Géographie et de la Physique (1738). The Delisle scale is notable as one of the few temperature scales that is inverted from the amount of thermal energy it measures; unlike most other temperature scales, higher measurements in degrees Delisle are colder, while lower measurements are warmer.
The Newton scale is a temperature scale devised by Isaac Newton in 1701. He called his device a "thermometer", but he did not use the term "temperature", speaking of "degrees of heat" instead. Newton's publication represents the first attempt to introduce an objective way of measuring temperature . Newton likely developed his scale for practical use rather than for a theoretical interest in thermodynamics; he had been appointed Warden of the Mint in 1695, and Master of the Mint in 1699, and his interest in the melting points of metals are likely inspired by his duties in connection with the Royal Mint.
The International Temperature Scale of 1990 (ITS-90) is an equipment calibration standard specified by the International Committee of Weights and Measures (CIPM) for making measurements on the Kelvin and Celsius temperature scales. It is an approximation of thermodynamic temperature that facilitates the comparability and compatibility of temperature measurements internationally. It defines fourteen calibration points ranging from 0.65 K to 1357.77 K and is subdivided into multiple temperature ranges which overlap in some instances. ITS-90 is the most recent of a series of International Temperature Scales adopted by the CIPM since 1927. Adopted at the 1989 General Conference on Weights and Measures, it supersedes the International Practical Temperature Scale of 1968 and the 1976 "Provisional 0.5 K to 30 K Temperature Scale". The CCT has also published several online guidebooks to aid realisations of the ITS-90. The lowest temperature covered by the ITS-90 is 0.65 K. In 2000, the temperature scale was extended further, to 0.9 mK, by the adoption of a supplemental scale, known as the Provisional Low Temperature Scale of 2000 (PLTS-2000).
Temperature measurement describes the process of measuring a current local temperature for immediate or later evaluation. Datasets consisting of repeated standardized measurements can be used to assess temperature trends.
A medical thermometer or clinical thermometer is a device used for measuring a human's or animal's body temperature. The tip of the thermometer is inserted into the mouth under the tongue, under the armpit, into the rectum via the anus, into the ear, or on the forehead.
A thermoscope is a device that shows changes in temperature. A typical design is a tube in which a liquid rises and falls as the temperature changes. The modern thermometer gradually evolved from it with the addition of a scale in the early 17th century and standardisation throughout the 17th and 18th centuries.
The degree Celsius is the unit of temperature on the Celsius scale, one of two temperature scales used in the International System of Units (SI), the other being the Kelvin scale. The degree Celsius can refer to a specific temperature on the Celsius scale or a unit to indicate a difference or range between two temperatures. It is named after the Swedish astronomer Anders Celsius (1701–1744), who developed a variant of it in 1742. The unit was called centigrade in several languages for many years. In 1948, the International Committee for Weights and Measures renamed it to honor Celsius and also to remove confusion with the term for one hundredth of a gradian in some languages. Most countries use this scale; the other major scale, Fahrenheit, is still used in the United States, some island territories, and Liberia. The Kelvin scale is of use in the sciences, with 0 K (−273.15 °C) representing absolute zero.
The kelvin, symbol K, is a unit of measurement for temperature. The Kelvin scale is an absolute scale, which is defined such that 0 K is absolute zero and a change of thermodynamic temperature T by 1 kelvin corresponds to a change of thermal energy kT by 1.380649×10−23 J. The Boltzmann constant k = 1.380649×10−23 J⋅K−1 was exactly defined in the 2019 redefinition of the SI base units such that the triple point of water is 273.16±0.0001 K. The kelvin is the base unit of temperature in the International System of Units (SI), used alongside its prefixed forms. It is named after the Belfast-born and University of Glasgow-based engineer and physicist William Thomson, 1st Baron Kelvin (1824–1907).
Temperature is a physical quantity that expresses quantitatively the attribute of hotness or coldness. Temperature is measured with a thermometer. It reflects the kinetic energy of the vibrating and colliding atoms making up a substance.
Scale of temperature is a methodology of calibrating the physical quantity temperature in metrology. Empirical scales measure temperature in relation to convenient and stable parameters or reference points, such as the freezing and boiling point of water. Absolute temperature is based on thermodynamic principles: using the lowest possible temperature as the zero point, and selecting a convenient incremental unit.
The Wedgwood scale (°W) is an obsolete temperature scale, which was used to measure temperatures above the boiling point of mercury of 356 °C (673 °F). The scale and associated measurement technique were proposed by the English potter Josiah Wedgwood in the 18th century. The measurement was based on the shrinking of clay when heated above red heat, and the shrinking was evaluated by comparing heated and unheated clay cylinders. The scale started at 1,077.5 °F (580.8 °C) being 0 °W and had 240 steps of 130 °F (72 °C). Both the origin and the step were later found inaccurate.
Jean-Pierre Christin was a French physicist, mathematician, astronomer, and musician. His proposal in 1743 to reverse the Celsius thermometer scale was widely accepted and is still in use today.