Everything about James Joule totally explained
James Prescott Joule FRS (;
December 24,
1818 –
October 11,
1889) was an
English physicist (and
brewer), born in
Salford,
Lancashire. Joule studied the nature of
heat, and discovered its relationship to
mechanical work (see
energy). This led to the theory of
conservation of energy, which led to the development of the
first law of thermodynamics. The
SI derived unit of energy, the
joule, is named after him. He worked with
Lord Kelvin to develop the absolute scale of
temperature, made observations on
magnetostriction, and found the relationship between the flow of
current through a
resistance and the heat dissipated, now called
Joule's law.
Early years
The son of Benjamin Joule (
1784–
1858), who was a wealthy brewer, Joule was tutored at home until 1834 when he was sent, with his elder brother Benjamin, to study with
John Dalton at the
Manchester Literary and Philosophical Society. The pair only received two years' education in
arithmetic and
geometry before Dalton was forced to retire owing to a
stroke. However, Dalton's influence made a lasting impression as did that of his associates,
chemist William Henry and Manchester engineers
Peter Ewart and
Eaton Hodgkinson. Joule was subsequently tutored by
John Davies. Joule was fascinated by
electricity. He and his brother experimented by giving electric shocks to each other and to the family's servants.
Joule became a manager of the brewery and took an active role until the sale of the business in
1854. Science was a hobby but he soon started to investigate the feasibility of replacing the brewery's
steam engines with the newly-invented
electric motor. In
1838, his first
scientific papers on electricity were contributed to
Annals of Electricity, the
scientific journal founded and operated by Davies's colleague
William Sturgeon. He discovered
Joule's law in 1840 and hoped to impress the
Royal Society but found, not for the last time, that he was perceived as a mere provincial dilettante. When Sturgeon moved to Manchester in
1840, Joule and he became the nucleus of a circle of the city's intellectuals. The pair shared similar sympathies that science and theology could and should be integrated. Joule went on to lecture at Sturgeon's
Royal Victoria Gallery of Practical Science. an early electric
battery. Joule's common standard of 'economical duty' was the ability to raise one pound, a height of one
foot, the
foot-pound.. This was a direct challenge to the
caloric theory which held that heat could neither be created or destroyed. Caloric theory had dominated thinking in the science of heat since it was introduced by
Antoine Lavoisier in 1783. Lavoisier's prestige and the practical success of
Sadi Carnot's caloric theory of the
heat engine since 1824 ensured that the young Joule, working outside either
academia or the engineering profession, had a difficult road ahead. Supporters of the caloric theory readily pointed to the symmetry of the
Peltier-Seebeck effect to claim that heat and current were convertible, at least approximately, by a
reversible process.}}
Joule here adopts the language of
vis viva (energy), possibly because Hodgkinson had read a review of Ewart's
On the measure of moving force to the Literary and Philosophical Society in April 1844.
Further experiments and measurements by Joule led him to estimate the
mechanical equivalent of heat as 838 ft·lbf of work to raise the temperature of a pound of
water by one degree
Fahrenheit. He announced his results at a meeting of the chemical section of the
British Association for the Advancement of Science in
Cork in 1843 and was met by silence.
Joule was undaunted and started to seek a purely mechanical demonstration of the conversion of work into heat. By forcing water through a perforated cylinder, he was able to measure the slight
viscous heating of the fluid. He obtained a mechanical equivalent of 770 ft·lbf/
Btu (4.14
J/
cal). The fact that the values obtained both by electrical and purely mechanical means were in agreement to at least one
order of magnitude was, to Joule, compelling evidence of the reality of the convertibility of work into heat.
Joule now tried a third route. He measured the heat generated against the work done in compressing a gas. He obtained a mechanical equivalent of 823 ft·lbf/Btu (4.43 J/cal). In many ways, this experiment offered the easiest target for Joule's critics but Joule disposed of the anticipated objections by clever experimentation. However, his paper was rejected by the
Royal Society and he'd to be content with publishing in the
Philosophical Magazine. In the paper he was forthright in his rejection of the caloric reasoning of Carnot and
Émile Clapeyron, but his
theological motivations also became evident:
I conceive that this theory ... is opposed to the recognised principles of philosophy because it leads to the conclusion that vis viva may be destroyed by an improper disposition of the apparatus: Thus Mr Clapeyron draws the inference that 'the temperature of the fire being 1000°C to 2000°C higher than that of the boiler there's an enormous loss of vis viva in the passage of the heat from the furnace to the boiler.' Believing that the power to destroy belongs to the Creator alone I affirm ... that any theory which, when carried out, demands the annihilation of force, is necessarily erroneous. |
In 1845, Joule read his paper
On the mechanical equivalent of heat to the British Association meeting in
Cambridge. In this work, he reported his best-known experiment, involving the use of a falling weight to spin a paddle-wheel in an insulated barrel of water, whose increased temperature he measured. He now estimated a mechanical equivalent of 819 ft·lbf/Btu (4.41 J/cal).
In 1850, Joule published a refined measurement of 772.692 ft·lbf/Btu (4.159 J/cal), closer to
twentieth century estimates.
Reception and priority
» For the controversy over priority with Mayer, see Mechanical equivalent of heat: Priority
Much of the initial resistance to Joule's work stemmed from its dependence upon extremely
precise measurements. He claimed to be able to measure temperatures to within 1/200 of a
degree Fahrenheit. Such precision was certainly uncommon in contemporary experimental physics but his doubters may have neglected his experience in the art of brewing and his access to its practical technologies. He was also ably supported by
scientific instrument-maker
John Benjamin Dancer.
However, in Germany,
Hermann Helmholtz became aware both of Joule's work and the similar 1842 work of
Julius Robert von Mayer. Though both men had been neglected since their respective publications, Helmholtz's definitive 1847 declaration of the
conservation of energy credited them both.
Also in 1847, another of Joule's presentations at the British Association in
Oxford was attended by
George Gabriel Stokes,
Michael Faraday, and the precocious and maverick
William Thomson, later to become
Lord Kelvin, who had just been appointed professor of
natural philosophy at the
University of Glasgow. Stokes was "inclined to be a Joulite" and Faraday was "much struck with it" though he harboured doubts. Thomson was intrigued but skeptical.
Unanticipated, Thomson and Joule met later that year in
Chamonix. Joule married Amelia Grimes on
August 18 and the couple went on honeymoon. Marital enthusiasm notwithstanding, Joule and Thomson arranged to attempt an experiment a few days later to measure the temperature difference between the top and bottom of the
Cascade de Sallanches waterfall, though this subsequently proved impractical.
Though Thomson felt that Joule's results demanded theoretical explanation, he retreated into a spirited defense of the Carnot-Clapeyron school. In his 1848 account of
absolute temperature, Thomson wrote that "the conversion of heat (or caloric) into mechanical effect is probably impossible, certainly undiscovered" - but a footnote signaled his first doubts about the caloric theory, referring to Joule's "very remarkable discoveries". Surprisingly, Thomson didn't send Joule a copy of his paper but when Joule eventually read it he wrote to Thomson on
October 6, claiming that his studies had demonstrated conversion of heat into work but that he was planning further experiments. Thomson replied on the 27th, revealing that he was planning his own experiments and hoping for a reconciliation of their two views. Though Thomson conducted no new experiments, over the next two years he became increasingly dissatisfied with Carnot's theory and convinced of Joule's. In his 1851 paper, Thomson was willing to go no further than a compromise and declared "the whole theory of the motive power of heat is founded on ... two ... propositions, due respectively to Joule, and to Carnot and Clausius".
As soon as Joule read the paper he wrote to Thomson with his comments and questions. Thus began a fruitful, though largely epistolary, collaboration between the two men, Joule conducting experiments, Thomson analysing the results and suggesting further experiments. The collaboration lasted from 1852 to 1856, its discoveries including the
Joule-Thomson effect, and the published results did much to bring about general acceptance of Joule's work and the
kinetic theory.
Kinetic theory
Kinetic is the science of motion. Joule was a pupil of Dalton and it's no surprise that he'd learned a firm belief in the
atomic theory, even though there were many scientists of his time who were still skeptical. He had also been one of the few people receptive to the neglected work of
John Herapath on the
kinetic theory of gases. He was further profoundly influenced by
Peter Ewart's 1813 paper
On the measure of moving force.
Joule perceived the relationship between his discoveries and the kinetic theory of heat. His laboratory notebooks reveal that he believed heat to be a form of rotational, rather than translational motion.
Joule couldn't resist finding antecedents of his views in
Francis Bacon, Sir
Isaac Newton,
John Locke,
Benjamin Thompson (Count Rumford) and Sir
Humphry Davy. Though such views are justified, Joule went on to estimate a value for the mechanical equivalent of heat of 1034 foot-pound from Rumford's publications. Some modern writers have criticised this approach on the grounds that Rumford's experiments in no way represented systematic quantitative measurements. In one of his personal notes, Joule contends that Mayer's measurement was no more
accurate than Rumford's, perhaps in the hope that Mayer hadn't anticipated his own work.
Honours
Joule died at home in
Sale and is buried in
Brooklands cemetery there. The gravestone is inscribed with the number "772.55", his climacteric 1878 measurement of the mechanical equivalent of heat, and with a quotation from the
Gospel of John, "I must work the works of him that sent me, while it's day: the night cometh, when no man can work" (9:4).
Selected writings
Further Information
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