In existographies, Guillaume Amontons (1663-1705) (IQ:175|#250) (GPE:55) (CR:14) was a French physicist and engineer, noted for []

Overview
In 1699, Amontons, building on Galileo, Robert Boyle, and Edme Mariotte, built a constant-volume air thermometer with which he used to develop the first verbal formulation of the ideal gas law and to argue that there was a zero point of temperature characterized by the absence of heat, which he calculated to be −239.5° C (or 33.65° K), the modern values being: −273.15° C (or 0° K).

Fire wheel
See main: Fire wheel
In 1699, Amontons published his experimental work in thermometry and on the development of the ideal gas laws and research into the nature of cold, which were said to have been repercussions of his failed attempt to create a ‘fire wheel’ that used the heat of a fire to expand air and make it move a wheel. The device was described as a very ingenious mill wheel, moved by the action of fire, based on a large number of experiments, and on arguments, which he called a moulin à feu (mill of fire). Some of his fire wheel research was used to create better thermometers. [1]

It is also said that Amontons had designed a “steam wheel” (a name which may be a synonym for his fire mill wheel), a sort of prototype steam engine, and that he tried to evaluate its performance in terms of the number of men or horses it could replace. [3]

Cannon engine
In 1699, Amontons, in his “Method of Substituting the Force of Fire for Horse and Man Power to Move Machines”, supposedly, pointed out that the “cannon” was a type of heat engine, or “fire engine”, that could be used to move machinery. [5]
 A picture of Amontons' 1699 constant-volume air thermometer. [7]

Temperature | Boiling water
In 1699, Amontons, built his so-called "constant volume air thermometer", shown adjacent, consisting U-shaped tube ending in a bulb, filled with mercury, the long end of the tube being 45 inches, the height of the long arm being the measure of the "spring" which the air, in the region above the mercury in the big bulb, had obtained.

In one of his first experiments, Amontons submerged the bulb into boiling water, and observed that the mercury always stood at the same level, no matter how long or how vigorously he boiled the water. Herein, as Halley had done, he arrived at the idea of "constancy of the boiling point".

In 1702, Amontons did another experiment with different volumes of air, under same initial pressure, at room temperature, namely he heated three unequal masses of air and water in glass bulbs, submerged in boiling water; commenting:

“Uneven masses of air loaded with equal or equal weights also increased the force of their spring by equal degrees of heat.”
— Guillaume Amontons (1702), Publication [7]

In 1702, Amontons did an experiment with different initial pressures, finding that at the same temperature of boiling water, the air could always sustain a column of mercury 1/3 longer than it could at room temperature; commenting:

“The same degree of heat, however small it may be, can always increase the spring force of the air more and more, if this air is always loaded with a greater and greater weight.”
— Guillaume Amontons (1702), Publication [7]

In 1702, Amontons, in his “Discourse on a Few properties of Air, and the Means to know the Temperature in all Climates of the Earth”, stated, supposedly, that the product of the pressure times volume equals the product of temperature times an unknown constant. [4] In modern formulation, thus would be an equation of the form:

$P V = k T \,$

which is the first prototype of the ideal gas law. The details of this, however, are a bit wanting; people, supposedly, in the 18th century were referring to Amontons law, as follows:

“The law connecting pressure and temperature at constant volume has been referred to as ‘Amontons law’.”
W.S. James (1929), “The Discovery of the Gas Laws. II. Gay-Lussac’s Law” [7]

Said another way, Amontons work, according to James (1929), amounted to an experimental proof of what would later be known as "Gay-Lussac's law" (1802) as formulated by Joseph Gay-Lussac.

Absolute zero
In 1703, Amontons mathematically derived the idea of an “absolute zero”. [1] Specifically, Amontons calculated “extreme cold”, as he referred to it, to −239.5° C (or 33.65° K), the modern values being: −273.15° C (or 0° K) (or −459.67° F). In commentary on this, he said the following:

“It appears that the ‘extreme cold’ [absolute zero] of this thermometer is that which would reduce the air by its ‘spring’, to sustain no load at all.”
— Guillaume Amontons (1703), Publication [7]

Amontons also calculated the coefficient of expansion to be 1/239.5 per degree ° C. This, supposedly, was a value more accurate than most of the values obtained over the next hundred years. [7]

Using his gas equation, he showed that a total absence of heat was theoretically possible, in the sense that if the product of the pressure times volume became zero, the temperature would go to zero; although, to note, Amontons supposedly did not come right out and say that there was an ‘absolute zero’.

Friction | Laws
Amontons, in engineering mechanics (Ѻ), not to get his “Amontons law” of gases confused, also has two “Amontons laws” of friction named after him, in respect to laws of dry (unlubricated) friction, when blocks are pushed on a surface, as shown below:

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Influences
Amontons was influenced by Galileo, Robert Boyle, and Edme Mariotte.
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Influenced
In c.1724, Daniel Fahrenheit used Amontons' "fixed point" of the constant temperature of boiling water in the construction of his now-commonly used Fahrenheit thermometer.

In 1738, Daniel Bernoulli, in his Hydrodynamica, credited Amontons as having been the first to derive the gas law equation; which according to Bernoulli was published in the Society memoirs of 1702.

Education
Amontons was born deaf and was largely self-taught in the sciences.

Quotes | On
The following are quotes on Amontons:

“I read that the celebrated Amontons, using a thermometer of his own invention, had discovered that water boils at a fixed degree of heat. I was at once inflamed with a great desire to make for myself a thermometer of the same sort, so that I might with my own eyes perceive this beautiful phenomenon of nature.”
Daniel Fahrenheit (1724), “Experiments and Observations Concerning the Congealment of Water in a Vacuum” [6]

“The question whether there is a limit to the degree of cold possible, and, if so, where the zero must be placed, was first attacked by the French physicist, G. Amontons, in 1702–1703, in connexon with his improvements in the air-thermometer. In his instrument temperatures were indicated by the height at which a column of mercury was sustained by a certain mass of air, the volume or “spring” of which of course varied with the heat to which it was exposed. Amontons therefore argued that the zero of his thermometer would be that temperature at which the spring of the air in it was reduced to nothing. On the scale he used the boiling-point of water was marked at 73 and the melting-point of ice at 51½, so that the zero of his scale was equivalent to about –240° on the centigrade scale. This remarkably close approximation to the modern value of –273° for the zero of the air-thermometer was further improved on by Johann Lambert (Pyrometrie, 1779), who gave the value –270° and observed that this temperature might be regarded as absolute cold.”
— Anon (1911), Encyclopedia Britannica (§:Cold)

Amontons seems to have been the first to realize the importance of actually measuring the thermal expansion of elastic fluids, and the first to have studied the increase of pressure with temperature. Amontons also noticed, as Halley had done, that when water boils the temperature remains constant. Unlike Halley, he seems to have recognized the importance of this: boiling water provides an eminently suitable datum or fixed point for a thermometric scale.”
Donald Cardwell (1971), From Watt to Clausius (pgs. 18-19)

Amontons, who had been deaf since childhood, invented and perfected various scientific instruments. In 1687 he made a hygrometer (an instrument for measuring moisture in the air), in 1695 he produced an improved barometer, and in 1702-03 a constant-volume air thermometer. In 1699 he published the results of his studies on the effects of change in temperature on the volume and pressure of air. He noticed that equal drops in temperature resulted in equal drops in pressure and realized that at a low enough temperature the volume and pressure of the air would become zero -an early recognition of the idea of absolute zero. These results lay largely unnoticed and the relationship between temperature and pressure of gases was not reexamined until the next century (by scientists such as Jacques Charles). Amontons also published in 1699 the results of his studies on friction, which he considered to be proportional to load.”
— John Daintith (1994), Biographical Encyclopedia of Scientists (pg. 18)

“The macroscopic laws of friction (Ѻ) found in textbooks were first published by the French engineer Amontons about 300 years ago, albeit the first recorded studies go back even further to the Italian genius da Vinci. Both found that the friction F between two solid bodies, firstly is independent of the apparent area of contact, and secondly is proportional to the force normal L or load that pushes the two objects together.”
— Martin Muser (2003), “Statistical Mechanics of Static and Low-Velocity Kinetic Friction” (pg. 190)

“Although Guillaume Amontons, the son of a lawyer from Normandy, had no format scientific education, he nevertheless studied geometry and the sciences and made important contributions in physics and meteorology. Amontons became deaf at an early age white in a Paris Latin school but was not deterred by this handicap. He went on to design many scientific instruments, such as a hygrometer (1687), an improved barometer (1688), an optical telegraph (1688-95), a conical nautical barometer (1695), a thermometer (1699), and various air and liquid thermometers including a constant-volume air thermometer (1702). As a career, however, he worked in government on various public works projects as an engineer.”
— Don Rittner (2014), A to Z of Scientists in Weather and Climate [8]

References
1. Shachtman, Tom. (1999). Absolute Zero and the Quest for Absolute Cold (pgs. ix-x, 45-48). Mariner Books
2. (a) Bernoulli, Daniel. (1738). “On the Properties and Motions of Elastic Fluids, Especially Air” (Hydrodynamica, Section 10) in: The Kinetic Theory of Gases of Gases (pgs. 57-65), 2003, by Stephen G. Brush, Nancy S. Hall. Imperial College Press.
(b) Bernoulli, Daniel. (1738). Hydrodynamica, Sive Vivibus et Motimus Fluidorum Commentarii. Sectio Decima: “De affectionibus atque botimus fluidorum elasticorum, praecipue autem aeris.” (pgs. 200-204). Argentorati, Sumptibus Johannes Reinholdi Dulseckeri.
3. Reynolds, Terry S. (2003). Stronger Than a Hundred Men: A History of the Vertical Water Wheel (pg. 204). JHU Press.
4. Amontons, Guillaume. (1702). "Discours sur Quelques proprietes de l’Air, et le moyen d'en connaitre temperature dans tous les climats de la Terre," (Discourse on a Few properties of Air, and the Means to know the Temperature in all Climates of the Earth) Memoires de I'Academie Royale des Sciences, pgs. 161-80. Paris.
5. (a) Amontons, Guillaume. (1699). “Method of Substituting the Force of Fire for Horse and Man Power to Move Machines”, Historie et Memoires de l’Academie Royale des Sciences (pg. 112).
(b) Cardwell, Donald S.L. (1971). From Watt to Clausius: the Rise of Thermodynamics in the Early Industrial Age (pg. 20). Cornell University Press.
6. Fahrenheit, Daniel G. (1724). “Experiments and Observations Concerning the Congealment of Water in a Vacuum” (“Experimenta et Observationes de Congelatione aquae in vacuo factae a D. G. Fahrenheit” (Ѻ), Philosophical Transactions, London, Vol. 33, pg. 78.
7. James, W.S. (1929). “The Discovery of the Gas Laws. II. Gay-Lussac’s Law” (abs), Science Progress in the Twentieth Century (1919-1933), 24(93):57-71.
8. Rittner, Don. (2014). A to Z of Scientists in Weather and Climate (pg. 5). InfoBase.