The Newton scale is a
temperature scale
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, such as the freezing and boiling point of water. Absolute ...
devised by
Isaac Newton
Sir Isaac Newton (25 December 1642 – 20 March 1726/27) was an English mathematician, physicist, astronomer, alchemist, Theology, theologian, and author (described in his time as a "natural philosophy, natural philosopher"), widely ...
in 1701.
He called his device a "
thermometer
A thermometer is a device that measures temperature or a temperature gradient (the degree of hotness or coldness of an object). A thermometer has two important elements: (1) a temperature sensor (e.g. the bulb of a mercury-in-glass thermometer ...
", but he did not use the term "temperature", speaking of "degrees of heat" (''gradus caloris'') instead.
Newton's publication represents the first attempt to introduce an objective way of measuring (what would come to be called) temperature (alongside the
Rømer scale
The Rømer scale (; notated as °Rø), 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 a ...
published at nearly the same time).
Newton likely developed his scale for practical use rather than for a theoretical interest in thermodynamics; he had been appointed
Warden of the Mint
Warden of the Mint was a high-ranking position at the Royal Mint in England from 1216 to 1829. The warden was responsible for a variety of minting procedures and acted as the immediate representative of the current monarch inside the mint. The role ...
in 1695, and
Master of the Mint
Master of the Mint is a title within the Royal Mint given to the most senior person responsible for its operation. It was an important office in the governments of Scotland and England, and later Great Britain and then the United Kingdom, between ...
in 1699, and his interest in the melting points of metals are likely inspired by his duties in connection with the
Royal Mint
The Royal Mint is the United Kingdom's oldest company and the official maker of British coins.
Operating under the legal name The Royal Mint Limited, it is a limited company that is wholly owned by HM Treasury, His Majesty's Treasury and is un ...
.
Newton used
linseed oil
Linseed oil, also known as flaxseed oil or flax oil (in its edible form), is a colourless to yellowish oil obtained from the dried, ripened seeds of the flax plant (''Linum usitatissimum''). The oil is obtained by pressing, sometimes followed by ...
as thermometric material and measured its
change of volume against his reference points. He set as 0 on his scale "the heat of air in winter at which water begins to freeze" (''Calor aeris hyberni ubi aqua incipit gelu rigescere''), reminiscent of the standard of the modern
Celsius scale
The degree Celsius is the unit of temperature on the Celsius scale (originally known as the centigrade scale outside Sweden), one of two temperature scales used in the International System of Units (SI), the other being the Kelvin scale. The d ...
(i.e. 0 °N = 0 °C), but he has no single second reference point; he does give the "heat at which water begins to boil" as 33, but this is not a defining reference; the values for body temperature and the freezing and boiling point of water suggest a conversion factor between the Newton and the Celsius scale of between about 3.08 (12 °N = 37 °C) and 3.03 (33 °N = 100 °C) but since the objectively verifiable reference points given result in irreconcilable data (especially for high temperatures), no unambiguous "conversion" between the scales is possible.
The linseed thermometer could be used up to the melting point of tin. For higher temperatures, Newton used a "sufficiently thick piece of iron" that was heated until red-hot and then exposed to the wind. On this piece of iron, samples of metals and alloys were placed, which melted and then again solidified on cooling. Newton then determined the "degrees of heat" of these samples based on the solidification times, and tied this scale to the linseed one by measuring the melting point of tin in both systems.
This second system of measurement led Newton to derive his law of
convective heat transfer
Convection (or convective heat transfer) is the transfer of heat from one place to another due to the movement of fluid. Although often discussed as a distinct method of heat transfer, convective heat transfer involves the combined processes o ...
, also known as
Newton's law of cooling
In the study of heat transfer, Newton's law of cooling is a physical law which states that
The rate of heat loss of a body is directly proportional to the difference in the temperatures between the body and its environment.
The law is frequently q ...
.
In his publication, Newton gives 18 reference points (in addition to a range of meteorological air temperatures), which he labels by two systems, one in arithmetic progression and the other in geometric progression, as follows:
See also
*
Comparison of temperature scales
This is a collection of temperature conversion formulas and comparisons among eight different temperature scales, several of which have long been obsolete.
Temperatures on scales that either do not share a numeric zero or are nonlinearly related c ...
*
List of obsolete units of measurement
This is a list of obsolete units of measurement, organized by type. These units of measurement are typically no longer used, though some may be in limited use in various regions. For units of measurement that are unusual but not necessarily obsolet ...
References
External links
Photo of an antique thermometer backing board c. 1758mdash;marked in four scales; the first is Newton's.
{{Portal bar, Energy
Obsolete units of measurement
Scales of temperature