Daniel Gabriel Fahrenheit FRS was a physicist, inventor, and scientific instrument maker, born in Poland to a family of German extraction. Fahrenheit invented thermometers accurate and consistent enough to allow the comparison of temperature measurements between different observers using different instruments. Fahrenheit is also credited with inventing mercury-in-glass thermometers more accurate and superior to spirit-filled thermometers at the time. The popularity of his thermometers led to the widespread adoption of his Fahrenheit scale attached to his instruments.
In thermodynamics, the triple point of a substance is the temperature and pressure at which the three phases of that substance coexist in thermodynamic equilibrium. It is that temperature and pressure at which the sublimation, fusion, and vaporisation curves meet. For example, the triple point of mercury occurs at a temperature of −38.8 °C (−37.8 °F) and a pressure of 0.165 mPa.
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.
This is a timeline of temperature and pressure measurement technology or the history of temperature measurement and pressure measurement technology.
The following is a timeline of low-temperature technology and cryogenic technology. It also lists important milestones in thermometry, thermodynamics, statistical physics and calorimetry, that were crucial in development of low temperature systems.
Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible. Surface tension is what allows objects with a higher density than water such as razor blades and insects to float on a water surface without becoming even partly submerged.
The mercury-in-glass or mercury thermometer is a thermometer that uses the thermal expansion and contraction of liquid mercury to indicate the temperature.
A hydrometer or lactometer is an instrument used for measuring density or relative density of liquids based on the concept of buoyancy. They are typically calibrated and graduated with one or more scales such as specific gravity.
In physics, the meniscus is the curve in the upper surface of a liquid close to the surface of the container or another object, produced by surface tension.
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.
A hygrometer is an instrument which measures the humidity of air or some other gas: that is, how much water vapor it contains. Humidity measurement instruments usually rely on measurements of some other quantities such as temperature, pressure, mass and mechanical or electrical changes in a substance as moisture is absorbed. By calibration and calculation, these measured quantities can lead to a measurement of humidity. Modern electronic devices use the temperature of condensation, or they sense changes in electrical capacitance or resistance to measure humidity differences. A prototype hygrometer was invented by Leonardo da Vinci in 1480. Major leaps came forward during the 1600s; Francesco Folli invented a more practical version of the device, while Robert Hooke improved a number of meteorological devices including the hygrometer. A more modern version was created by Swiss polymath Johann Heinrich Lambert in 1755. Later, in the year 1783, Swiss physicist and Geologist Horace Bénédict de Saussure invented the first hygrometer using human hair to measure humidity.
Psychrometrics is the field of engineering concerned with the physical and thermodynamic properties of gas-vapor mixtures.
A Galileo thermometer is a thermometer made of a sealed glass cylinder containing a clear liquid and several glass vessels of varying density. The individual floats rise or fall in proportion to their respective density and the density of the surrounding liquid as the temperature changes. It is named after Galileo Galilei because he discovered the principle on which this thermometer is based—that the density of a liquid changes in proportion to its temperature.
Drinking birds, also known as dunking birds, drinky birds, water birds, or dipping birds are toy heat engines that mimic the motions of a bird drinking from a water source. They are sometimes incorrectly considered examples of a perpetual motion device.
Temperature measurement describes the process of measuring a current temperature for immediate or later evaluation. Datasets consisting of repeated standardized measurements can be used to assess temperature trends.
A reversing thermometer is a mercury-in-glass thermometer which, unlike most conventional mercury thermometers, has the unique ability to record a temperature for later viewing. When inverted, these thermometers capture and display the current temperature until they are returned to their upright position. From around 1900 to 1970, reversing thermometers were the primary instruments oceanographers relied on to measure water temperatures beneath the ocean's surface.
Six's maximum and minimum thermometer is a registering thermometer that can record the maximum and minimum temperatures reached over a period of time, for example 24 hours. It is used to record the extremes of temperature at a location, for instance in meteorology and horticulture. It was invented by the British scientist James Six, in 1780; the same basic design remains in use.
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, under the armpit, into the rectum via the anus, into the ear, or on the forehead.
An indoor–outdoor thermometer is a thermometer that simultaneously provides a measurement of the indoor and outdoor temperatures. The outdoor part of the thermometer requires some kind of remote temperature sensing device. Conventionally, this was done by extending the bulb of the thermometer to the remote site. Modern instruments are more likely to use some form of electronic transducer.
A cryometer is a thermometer used to measure very low temperatures of objects. Ethanol-filled thermometers are used in preference to mercury for meteorological measurements and can measure temperatures in the range of −38 to 70 °C. Their main physical limitation is the freezing and boiling point of the liquid used.
