John Herapath
Encyclopedia
John Herapath was an English
physicist
who gave a partial account of the kinetic 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 high temperature
s near the Sun
on his gravific particles he was led to a relationship between temperature and particle velocity
.
Herapath postulated that the momentum
of a particle in a gas
is a measure of the absolute temperature of the gas. He used momentum, rather than the kinetic energy
on which the later established theory is based, as it seemed to him to avoid some difficulties around whether elastic collision
s were possible between indivisible atom
s. Apparently ignorant of Daniel Bernoulli
's work, he was led to the incorrect, but suggestive, relationship that expresses the product of pressure
P and volume
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 than energy
, with temperature.
in 1820 where it was peer review
ed by Sir Humphry Davy
. Davy had already sympathised with the view that heat was associated with molecular motion rather than with Joseph Black
's caloric theory
of heat
but he rejected Herapath's paper with some coolness, uncomfortable with the implication that there was an absolute 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 more holistic philosophy
of the Romantic movement.
In 1821, Herapath managed to have his paper published in the Annals of Philosophy, a well-read journal that counted Michael Faraday
among its regular contributors. However, the paper seems to have attracted little attention other than from James 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.
, and is not to be confused with the current Railway Magazine which commenced publication in 1897. This gave him some limited opportunity to publish his scientific ideas. In 1836, he published a calculation of the mean
molecular speed
in a gas based on his kinetic theory and hence the speed of sound
. Joule reproduced his results but is usually incorrectly credited as the originator.
and Henri Victor Regnault
, and published it in his two-volume Mathematical Physics (1847).
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
physicist
Physicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...
who gave a partial account of the kinetic 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
Mechanical explanations of gravitation
Mechanical explanations of gravitation are attempts to explain the action of gravity by aid of basic mechanical processes, such as pressure forces caused by pushes, and without the use of any action at a distance. These theories were developed from the 16th until the 19th century in connection...
, he started to consider how a system of colliding particles could give rise to action at a distance
Action at a distance (physics)
In physics, action at a distance is the interaction of two objects which are separated in space with no known mediator of the interaction. This term was used most often in the context of early theories of gravity and electromagnetism to describe how an object responds to the influence of distant...
. In considering the effect of the high temperature
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
s near the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
on his gravific particles he was led to a relationship between temperature and particle velocity
Velocity
In physics, velocity is speed in a given direction. Speed describes only how fast an object is moving, whereas velocity gives both the speed and direction of the object's motion. To have a constant velocity, an object must have a constant speed and motion in a constant direction. Constant ...
.
Herapath postulated that the momentum
Momentum
In classical mechanics, linear momentum or translational momentum is the product of the mass and velocity of an object...
of a particle in a gas
Gas
Gas is one of the three classical states of matter . Near absolute zero, a substance exists as a solid. As heat is added to this substance it melts into a liquid at its melting point , boils into a gas at its boiling point, and if heated high enough would enter a plasma state in which the electrons...
is a measure of the absolute temperature of the gas. He used momentum, rather than the kinetic energy
Kinetic energy
The kinetic energy of an object is the energy which it possesses due to its motion.It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes...
on which the later established theory is based, as it seemed to him to avoid some difficulties around whether elastic collision
Elastic collision
An elastic collision is an encounter between two bodies in which the total kinetic energy of the two bodies after the encounter is equal to their total kinetic energy before the encounter...
s were possible between indivisible atom
Atom
The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...
s. Apparently ignorant of Daniel Bernoulli
Daniel Bernoulli
Daniel Bernoulli was a Dutch-Swiss mathematician and was one of the many prominent mathematicians in the Bernoulli family. He is particularly remembered for his applications of mathematics to mechanics, especially fluid mechanics, and for his pioneering work in probability and statistics...
's work, he was led to the incorrect, but suggestive, relationship that expresses the product of pressure
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...
P and volume
Volume
Volume is the quantity of three-dimensional space enclosed by some closed boundary, for example, the space that a substance or shape occupies or contains....
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 than energy
Energy
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...
, with temperature.
Papers published
He submitted his ideas in a paper to the Royal SocietyRoyal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...
in 1820 where it was peer review
Peer review
Peer review is a process of self-regulation by a profession or a process of evaluation involving qualified individuals within the relevant field. Peer review methods are employed to maintain standards, improve performance and provide credibility...
ed by Sir Humphry Davy
Humphry Davy
Sir Humphry Davy, 1st Baronet FRS MRIA was a British chemist and inventor. He is probably best remembered today for his discoveries of several alkali and alkaline earth metals, as well as contributions to the discoveries of the elemental nature of chlorine and iodine...
. Davy had already sympathised with the view that heat was associated with molecular motion rather than with Joseph Black
Joseph Black
Joseph Black FRSE FRCPE FPSG was a Scottish physician and chemist, known for his discoveries of latent heat, specific heat, and carbon dioxide. He was professor of Medicine at University of Glasgow . James Watt, who was appointed as philosophical instrument maker at the same university...
's caloric theory
Caloric theory
The caloric theory is an obsolete scientific theory that heat consists of a self-repellent fluid called caloric that flows from hotter bodies to colder bodies. Caloric was also thought of as a weightless gas that could pass in and out of pores in solids and liquids...
of heat
Heat
In physics and thermodynamics, heat is energy transferred from one body, region, or thermodynamic system to another due to thermal contact or thermal radiation when the systems are at different temperatures. It is often described as one of the fundamental processes of energy transfer between...
but he rejected Herapath's paper with some coolness, uncomfortable with the implication that there was an absolute zero
Absolute zero
Absolute zero is the theoretical temperature at which entropy reaches its minimum value. The laws of thermodynamics state that absolute zero cannot be reached using only thermodynamic means....
of temperature at which all motion
Motion (physics)
In physics, motion is a change in position of an object with respect to time. Change in action is the result of an unbalanced force. Motion is typically described in terms of velocity, acceleration, displacement and time . An object's velocity cannot change unless it is acted upon by a force, as...
ceased. Davy may also have had some distaste for the mechanistic Newtonian
Isaac Newton
Sir Isaac Newton PRS was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, who has been "considered by many to be the greatest and most influential scientist who ever lived."...
picture, influenced as he was by the more holistic philosophy
Philosophy
Philosophy is the study of general and fundamental problems, such as those connected with existence, knowledge, values, reason, mind, and language. Philosophy is distinguished from other ways of addressing such problems by its critical, generally systematic approach and its reliance on rational...
of the Romantic movement.
In 1821, Herapath managed to have his paper published in the Annals of Philosophy, a well-read journal that counted Michael Faraday
Michael Faraday
Michael Faraday, FRS was an English chemist and physicist who contributed to the fields of electromagnetism and electrochemistry....
among its regular contributors. However, the paper seems to have attracted little attention other than from James Prescott Joule
James Prescott Joule
James Prescott Joule FRS was an English physicist and brewer, born in Salford, Lancashire. Joule studied the nature of heat, and discovered its relationship to mechanical work . This led to the theory of conservation of energy, which led to the development of the first law of thermodynamics. The...
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
The Times
The Times is a British daily national newspaper, first published in London in 1785 under the title The Daily Universal Register . The Times and its sister paper The Sunday Times are published by Times Newspapers Limited, a subsidiary since 1981 of News International...
newspaper.
Railway journal
In 1835 Herapath became editor of The Railway Magazine, which underwent four changes of name during the boom years of railways to become Herapath's Railway Journal in January 1894. It is now called the Railway GazetteRailway Gazette International
Railway Gazette International is a monthly business journal covering the railway, metro, light rail and tram industries worldwide. Available by annual subscription, the magazine is read in over 140 countries by transport professionals and decision makers, railway managers, engineers, consultants...
, and is not to be confused with the current Railway Magazine which commenced publication in 1897. This gave him some limited opportunity to publish his scientific ideas. In 1836, he published a calculation of the mean
Mean
In statistics, mean has two related meanings:* the arithmetic mean .* the expected value of a random variable, which is also called the population mean....
molecular speed
Speed
In kinematics, the speed of an object is the magnitude of its velocity ; it is thus a scalar quantity. The average speed of an object in an interval of time is the distance traveled by the object divided by the duration of the interval; the instantaneous speed is the limit of the average speed as...
in a gas based on his kinetic theory and hence the speed of sound
Speed of sound
The speed of sound is the distance travelled during a unit of time by a sound wave propagating through an elastic medium. In dry air at , the speed of sound is . This is , or about one kilometer in three seconds or approximately one mile in five seconds....
. Joule reproduced his results but is usually incorrectly credited as the originator.
Revision of theories
He revised his theories in the 1840s, largely based on the experimental work of Thomas GrahamThomas Graham (chemist)
Thomas Graham FRS was a nineteenth-century Scottish chemist who is best-remembered today for his pioneering work in dialysis and the diffusion of gases.- Life and work :...
and Henri Victor Regnault
Henri Victor Regnault
Henri Victor Regnault was a French chemist and physicist best known for his careful measurements of the thermal properties of gases. He was an early thermodynamicist and was mentor to William Thomson in the late 1840s....
, and published it in his two-volume Mathematical Physics (1847).