- John Herapath
John Herapath (
May 30 ,1790 -February 24 ,1868 ) was an Englishphysicist who gave a partial account of thekinetic theory of gases in 1820 though it was neglected by the scientific community at the time.Herapath's scientific interests started with an attempt to provide a mechanistic explanation for
gravity . Motivated by his search for a mechanical explanation of gravitation, he started to consider how a system of colliding particles could give rise to "action at a distance". In considering the effect of the hightemperature s near theSun on his "gravific particles" he was led to a relationship between temperature and particlevelocity .Herapath postulated that the
momentum of a particle in agas is a measure of theabsolute temperature of the gas. He used momentum, rather than thekinetic energy on which the later established theory is based, as it seemed to him to avoid some difficulties around whetherelastic collision s were possible between indivisibleatom s. Apparently ignorant ofDaniel Bernoulli 's work, he was led to the incorrect, but suggestive, relationship that expresses the product ofpressure "P" andvolume "V" as proportional to the square of his "true temperature". The correct relationship is proportional to the absolute temperature, not its square, the error arising from his identification of momentum, rather thanenergy , with temperature.He submitted his ideas in a paper to the
Royal Society in 1820 where it waspeer review ed by SirHumphry Davy . Davy had already sympathised with the view that heat was associated withmolecular motion rather than withJoseph Black 'scaloric theory ofheat but he rejected Herapath's paper with some coolness, uncomfortable with the implication that there was anabsolute zero of temperature at which all motion ceased. Davy may also have had some distaste for the mechanistic Newtonian picture, influenced as he was by the moreholistic philosophy of theRomantic movement .In 1821, Herapath managed to have his paper published in the "
Annals of Philosophy ", a well-read journal that countedMichael Faraday among its regular contributors. However, the paper seems to have attracted little attention other than fromJames Prescott Joule who presented a short account of the work in 1848, again to little reaction. Meanwhile, Herapath maintained a campaign against Davy and the Royal Society in the correspondence pages of "The Times " newspaper.He discovered the Great Comet of 1831 on
January 7 ,1831 .In 1835 Herapath became editor of "The Railway Magazine" (which became " Railway Gazette", and is not to be confused with "The
Railway Magazine " which commenced publication in 1897 - see notes in discussion page), which gave him some limited opportunity to publish his scientific ideas. In 1836, he published a calculation of themean molecularspeed in a gas based on his kinetic theory and hence thespeed of sound . Joule reproduced his results but is usually incorrectly credited as the originator.He revised his theories in the 1840s, largely based on the experimental work of Thomas Graham and
Henri Victor Regnault , and published it in his two-volume "Mathematical Physics" (1847).References
Further reading
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*External links
* [http://www.math.umd.edu/~lvrmr/History/Neglected.html Neglected Pioneers: John Herapath]
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