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Top 10 Facts about James Prescott Joule

James Prescott Joule was born in Salford, Lancashire on December 24, 1818. He was an English physicist, mathematician, and brewer. James studied the nature of heat and discovered its relationship to mechanical work which led to the law of energy conservation. This in turn led to the development of the first law of thermodynamics. The SI-derived unit of energy, the joule is named after him.

Jamed worked with Lord Kelvin to develop an absolute thermodynamic temperature scale which came to be called the Kelvin scale. James made observations of magnetostriction and found the relationship between the current through a resistor and the heat dissipated. His experiments’ transformation was first published in 1843.

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1. His Early Life

When James was young, he was tutored by the famous scientist John Dalton and was strongly influenced by chemist William Henry and the Manchester engineers Peter Ewart and Eaton Hodgkinson. James has always been fascinated by electric shocks to each other and to the family’s servants.

As an adult, James managed his father’s brewery and treated science as a mere hobby. When 1840 came around, James started to investigate the feasibility of replacing the brewery’s steam engines with the newly invented electric motor. James’ first scientific papers on the subject were contributed to William Sturgeon’s Annals of Electricity.

James was a member of the London Electrical Society which Sturgeon and others established.

2. James’ Innventions in 1841 & 1843

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When he discovered Joule’s first law in 1841, he went on to realize that burning a pound of coal in a steam engine was more economical than a costly pound of zinc consumed in an electric battery. James captured the output of the alternative methods in terms of a common standard, the ability to raise a mass weighing one pound to a height of one foot, the foot-pound.

In 1843, James published results of experiments that showed that the heating effect he had quantified in 1841 was due to the generation of heat in the conductor and not its transfer from another part of the equipment. This was a challenge to the caloric theory which held that heat could neither be created nor destroyed.

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3. His Breakthrough in August 1843

During his further experiments and measurements with his electric motor, he was led to estimate the mechanical equivalent of heat as 4.1868 joules per calorie of work to raise the temperature of one gram of water by one Kelvin. He later announced his results at a meeting of the chemical section of the British Association for the Advancement of Science in Cork in August 1843.

Due to the fact that he was met with silence after his discovery, James started to seek a purely mechanical demonstration of the conversion of work into heat. He figured out that by forcing water through a perforated cylinder, he could measure the slight viscous heating of the fluid. The fact that the values obtained were both electrical and purely mechanical means were in agreement was fascinating to James.

4. His Best-Known Experiment

Later in June 1845, James read his paper On the Mechanical Equivalent of Heat to the British Association meeting in Cambridge. This work involves the use of a falling weight, in which gravity does the mechanical work, to spin a paddle wheel in an insulated barrel of water which increases the temperature. He later estimated a mechanical equivalent of 819 foot-pounds force per British thermal unit.

James wrote a letter to the Philosophical Magzine published in September 1845 describing his experiment. In 1850, James published a refined measurement of 772.692 foot-pounds force per British thermal unit. 

5. James’ Recognition From Hermann 

Hermann Helmholtz became aware of both James’ work and the similar 1842 work of Julius Robert von Mayer. Even though both men had been neglected since their respective publications, Hermann’s definitive 1847 declaration of the conservation of energy credited them both. In the same year, another of his presentations at the British Association in Oxford was attended by George Gabriel Stokes, Michael Faraday, and the precocious and maverick William Thomson.

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6. His Collaboration with William

Later, James and William 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. Even though William felt that James’ results demanded a theoretical explanation, he retreated into a spirited defense of the Carrot-Clapeyron school. 

Their collaboration lasted from 1852 to 1856, the discoveries included the Joule-Thomson effect. The published results did much to bring about general acceptance of James’ work and the kinetic theory.

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7. His Memorable Work on Kinetic Theory

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James was a pupil of Dalton and it was not shocking that he had learned a firm belief in the atomic theory. Even though many scientists of his time 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. James perceived the relationship between his discoveries and the kinetic theory of heat. Most of his laboratory notebooks reveal that he believed heat to be a form of rotational rather than translational motion.

James had been attributed with explaining the sunset green flash phenomenon in a letter to the Manchester Literary and Philosophical Society in 1869. He merely noted the last glimpse as bluish-green without attempting to explain the cause of the phenomenon.

8. His Unique Legacy

Over the years, James has been remembered for his experiments with engines, electricity, and heat. His findings resulted in the development of the mechanical theory of heat and Joule’s law. This describes the rate at which heat energy is produced from electric energy by the resistance in a circuit. 

James is vastly known for his discovery in 1841 which is known as Joule’s First Law. It defined the relationship between the amount of heat produced and the current flowing through a conductor.

9. His Statue at Manchester Town Hall

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His remarkable work was honored through the establishment of his statue at the Manchester Town Hall. It is a fitting memory of his legacy and the impact he had on the scientific community. The statue was put up because of his work on the mechanical equivalent of heat and the first law of thermodynamics. The discoveries he made laid the foundation for future generations of scientists.

10. His Personal Life

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In 1847, James settled down with Amelia Grimes. The couple had two sons and a daughter. However, Amelia and his second son died in 1854. Following a long illness, James died on October 11, 1889, in Sale, Greater Manchester, England at the age of 70 years old.