James Prescott Joule

James Prescott Joule (December 24, 1818–October 11, 1889) was an English physicist, born in Salford, near Manchester.

Life

Early years

The son of Benjamin Joule (1784?1858), 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 when Dalton was forced to retire owing to a stroke. However, Dalton's influence made a lasting impressions as did that of his associates chemist William Henry and Manchester engineers Peter Ewart and Eaton Hodgkinson. Joule was subsequently tutored by John Davis. Joule was fascinated by electricity, he and his brother experimenting by giving electric shocks to each other and to the family's servants.

Related Topics:
1784 - 1858 - Brewer - 1834 - John Dalton - Manchester Literary and Philosophical Society - Arithmetic - Geometry - Stroke - Chemist - William Henry - Manchester - Engineer - Peter Ewart - Eaton Hodgkinson - John Davis - Electricity

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Joule became a manager of the brewery and took an active rôle 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 Davis's colleague William Sturgeon. He discovered Joule's law in 1840{{ref|JPJ1}} and hoped to impress the Royal Society but found, not for the first time, the 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.

Related Topics:
1854 - Steam engine - Electric motor - 1838 - Scientific paper - Scientific journal - William Sturgeon - Joule's law - 1840 - Royal Society - Provincial - Dilettante - Science - Theology - Royal Victoria Gallery of Practical Science

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In his Manchester lecture, motivated in part by a business man's desire to quantify the economics of the decision, and in part by his scientific inquisitiveness, he set out to determine which prime mover had the greater 'economical duty'{{ref|unit1}}. He went on to realise that burning a pound of coal in a steam engine produced five times as much duty as a pound of zinc consumed in an electric battery. Joule's common standard of 'economical duty' was the ability to raise one pound, a height of one foot, the foot-pound{{ref|unit2}}.

Related Topics:
Economics - Pound - Zinc - Battery - Foot - Foot-pound

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Joule was influenced by the thinking of Franz Aepinus and tried to explain the phenomenona of electricity and magnetism in terms of atoms surrounded by a "calorific ether in a state of vibration".

Related Topics:
Franz Aepinus - Magnetism - Atom - Calorific - Ether

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However, Joule's interest diverted from the narrow financial question to that of how much work could be extracted from a given source, leading him to speculate about the convertibility of energy. In 1843 he published results of experiments showing that the heating effect he had quantified in 1841 was due to generation of heat in the conductor and not its transfer from another part of the equipment{{ref|JPJ2}}. 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 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 in an, at least approximately, reversible process.

Related Topics:
Energy - 1843 - Heat - Conductor - Caloric theory - Antoine Lavoisier - 1783 - Sadi Carnot - Heat engine - 1824 - Academia - Engineering - Profession - Peltier-Seebeck effect - Reversible process

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The mechanical equivalent of heat

Joule wrote in his 1843 paper:

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:"... the mechanical power exerted in turning a magneto-electric machine is converted into the heat evolved by the passage of the currents of induction through its coils; and, on the other hand, that the motive power of the electro-magnetic engine is obtained at the expense of the heat due to the chemical reactions of the battery by which it is worked."

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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 Philosphical Society in April 1844.

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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{{ref|unit3}}. 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.

Related Topics:
Mechanical equivalent of heat - Water - Fahrenheit - British Association for the Advancement of Science - Cork

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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 was at least in agreement to an order of magnitude that were, to Joule, compelling evidence of the reality of the convertibility of work into heat.

Related Topics:
Viscous - Btu - J - Cal - Order of magnitude

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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).{{ref|JPJ3}} 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 had 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 become evident:

Related Topics:
Gas - Royal Society - Philosophical Magazine - Émile Clapeyron - Theological

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:"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 that that of the boiler there is 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."

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In 1845, Joule read his paper On the mechanical equivalent of heat to the British Association meeting in Cambridgehttp://dbhs.wvusd.k12.ca.us/webdocs/Chem-History/Joule-Heat-1845.html. 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).

Related Topics:
1845 - Cambridge

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Reception and priority

:For the controversy over priority with Mayer, see

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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.{{ref|S1}} He was also ably supported by scientific instrument-maker John Benjamin Dancer.

Related Topics:
Precise - Measurement - Degree Fahrenheit - Scientific instrument - John Benjamin Dancer

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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.

Related Topics:
Germany - Hermann Helmholtz - 1842 - Julius Robert von Mayer - 1847 - Conservation of energy

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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 harboured doubts. Thomson was intrigued but skeptical.

Related Topics:
Oxford - George Gabriel Stokes - Michael Faraday - William Thomson - Lord Kelvin - Natural philosophy - University of Glasgow

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Unanticipated, Thomson and Joule met later that year in Chamonix. Joule married Amelia Grimes on August 18 and the couple was on honeymoon. Marital enthusiasm not withstanding, 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.

Related Topics:
Chamonix - August 18 - Honeymoon - Cascade de Sallanches

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Though Thomson felt that Joule's results demanded theoretical explanation, he retreated into a spirited defence of the Carnot-Clapeyron school. In his 1848 account of absolute temperature, Thomson wrote:

Related Topics:
1848 - Absolute temperature

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:"... the conversion of heat (or caloric) into mechanical effect is probably impossible, certainly undiscovered"

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