English physicist who established that the various forms of energy: mechanical, electrical, and heat - are basically the same and can be changed, one into another. Thus he formed the basis of the law of conservation of energy, the first law of thermodynamics. He also contributed electrochemistry developing electrowinning, or recovery by electrolysis, of precious metals. However, brewing was his true occupation.

The Age of Romanticism and the Industrial Revolution were in full swing when James Prescott Joule was born in Manchester, England to a prosperous brewery owner.

James Prescott Joule was the fourth born son to Benjamin and Alice Joule on Dec 24, 1818 in Salford , Great Britain. The first two boys the Joule’s had both died in infancy. The thirdborn child was James’ brother Benjamin (b. 1817) named after his father. James was followed by two sisters Alice (b. 1820) who died at the age of 14 and Mary (b. 1823). He also had a younger brother John (b. 1824). James’ father Benjamin, was a wealthy man who established a brewery in Manchester near a prison begun by John Howard (as in the John Howard Society). James spent much of his childhood (ages 5 - 12) in ill health due to a spinal weakness however through some unorthodox procedures by the brothers Taylor, who started their careers as horse doctors, James improved such that most of his youth he was fairly well. The illness had a greater impact on James psychologically, making him quite shy and unassertive when in the presence of others. James and his brother Benjamin were quite close though out their early lives. James did not receive a "normal" schooling, instead he and his brother Benjamin were tutored at home by a series of tutors. James was educated at home till he was 14 years old. At the age of 14, Joule attended Manchester University until he was 16 years old, then in 1835 he left for Cambridge to study with John Dalton, a well educated chemist who had formulated the theory that atoms are indivisible spheres. Indications are that much or James’ education was self administered.

EARLY INTERESTS

James’ early influences included an interest in trains (steam engines) as well as the steam powered devices of his father’s brewery. He had a boyhood interest in steam locomotives which may have sparked his interest in the field of thermodynamics. Ironically, Joule was involved in a train accident himself in which three people were killed. The brothers Joule took an interest in phenomena such as lightning and the aurora borealis which they discussed at length with their tutor John Dalton. The boys also "sounded" or measured the depth of Lake Windemere to be 198 feet (today known to be 220 feet). James lost his father’s cavalry pistol while investigating an echo in the mountains. This was not his only encounter with weapons, on another occasion he accidentally blew off his eyebrows. James also had a somewhat scary disregard for the servants’ health at the Joule residence. He carried out a series of tests on a servant girl giving her a series of shocks until ultimately she lost consciousness. James decided that this would be an appropriate point to conclude his experiment. (Lucky for the servant girl.) Although James did work at his father’s brewery his interest lied in experimentation which at first was spontaneous in nature. John Dalton who instilled in James the need to be a meticulous experimenter. Dalton did little more than teach the Joule boys arithmetic and geometry however he did introduce the boys to chemistry as was James’ father’s intention. Dalton insisted on following a careful procedure and becoming very skilled in the use of laboratory equipment. Having completed his education, James returned home. His independent means allowed him to begin independent researches in a laboratory built in his father's home. James went on to be a much more renowned experimenter than his mentor, combining skill, originality and ingenuity. For example, James constructed instruments of measurement of a precise degree of accuracy, for the time in which he lived. Even by today’s standards these instruments would be considered quite accurate. He was quite adept at balancing theoretical speculation and careful experimentation.

In 1847 Joule married Amelia Grimes, daughter of the Liverpool Comptroller of Customs. Joule spent much of his honeymoon in the Alps studying a waterfall. He found the temperature of the water at the base of the waterfall higher than the temperature of the water at the top. This proved that the energy of the falling water was being converted into heat. This was a major step in proving the theory of energy conservation. Taking time out of his own honeymoon to conduct an experiment shows his dedication to his hobby: physics. Joule had a son, Benjamin Arthur, in 1849 and a daughter, Alice Amelia, in 1852. Joule's wife and a second son died in 1854 and he remained a widower for the rest of his life.

JOULE’S SERIOUS WORK
 

Joule in his twenties

From 1837 to 1856 Joule worked in the family brewery. Hoping to replace steam engines by electric motors, his first research sought to improve electric motor efficiency. His investigations concerned themselves with the production of heat. One of Joule’s early interests was in the field of electricity. He was interested in improving the electric motor by making the electromagnet and batteries more efficient. He subscribed to a new journal The "Annals of Electricty" edited by William Sturgeon (1783 - 1850) and learned, from a paper written by Prof.M.H.Jacobi of the University of Dorpat, that electric motors offered the possibility of infinite power. His attempts to design a motor to generate infinite power failed and he gradually realised that his goal was not achievable. Instead he became interested in measuring the work done and the heat generated by electricity. As a result of his experimentation Joule discovered that the power of the engine was proportional to the product of the current and the emf (battery intensity). Joule eventually gave up on this line of experimentation since the steam engine of the day was much more economical. Joule still felt that the electric motor would someday replace the steam engine. It was after he reached this impasse with the motor that Joule turned his attention to the relationship between electricity and heat. Much of Joule’s work took place between 1837 and 1847. During this time Joule along with Hermann von Helmholtz, Julius von Mayer and William Thomson (later Lord Kelvin) established the principle of conservation of energy which states that energy used up in one form reappears in another form and is never lost.

One of his more serious experiments led to the Joule's law. Describing "Joule's law" in a paper, "On the Production of Heat by Voltaic Electricity" (1840), he stated that the amount of heat produced in a wire by an electrical current is proportional to the product of the resistance of the wire and the square of the current. This was one of the first of many reports establishing the linkage between heat and other forms of energy.

Joule's Paddle-Wheel Apparatus, 1849, London Science Museum

This scheme shows the Joule's experiment illuminating the relationship between mechanical energy (in the falling weights and rotating shaft and paddles) and heat (in the water tank) and how the former is converted to the latter. In this well known experiment, a paddle wheel, driven by the mechanical energy of a falling weight, heated the water in a cup just enough to be measured by a sensitive thermometer. With more careful experimentation he refined his works until 1850 when he found that 772 foot-pounds of work always raised the water one Fahrenheit degree.

He also found that heat is not a fluid as was popularly belived in his time, but a form of energy. He showed that this energy is conserved during work. His careful experiments made it possible for general acceptance of the conservation of energy. Joule was not the first person to establish the mechanical equivalence of heat, but it was his demonstration that eventually came to be accepted. He did not claim, however, to have formulated a general Law of Conservation of Energy. Nevertheless, his experiments were certainly fundamental in bringing that formulation about. In addition, Joule's experiments showed that heat is produced by motion, contradicting the caloric theory.

Joule in his forties

Joule had a major association with William Thomson in which each helped the other refine their ideas. It appears from the readings that Joule was the better of the two experimenters in both the construction of lab equipment, execution of the experiment and in the theoretical side of the experiments. However the combination of minds led to greater accomplishments than had they not worked together. As a result of their collaborative efforts they determined that when a gas expands without performing work, it’s temperature falls. This became known as the "Joule-Thomson effect" and it was used to build a large refrigeration industry in the course of the 19th century. This collaboration of minds on research in a particular area was quite new and different to the research practices of the day.

 

Manometer with throttle (right) and thermometer Functional diagram

Thomson-Joule Effect Experiment on Throttle Cooling Air inside a flask of compressed air, under high pressure, flows through the fine opening in a throttle and expands in the process to the same pressure as the surrounding air. The throttle is isolated from heat exchange with its surroundings. The thermometers before and after the opening of the throttle show a large temperature difference. During expansion, the air has cooled. The amount of cooling increases in proportion to the pressure difference at the throttle, and increases substantially when the starting temperature of the air is reduced.

 

As is characteristic of many researchers, Joule's accomplishments were not limited to those things we today associate with the word "research". Much of what comes from experimental investigations results in practical devices and new technologies. In this respect one can note that James Joule was also an inventor. Amongst his many inventions are "arc" or electrical welding and the displacement pump. His greatest asset was the ability to think precisely. His work showed his inescapable logic. Early on in his career he was criticized for drawing conclusions based on his work that were not completely justified by his workings. Joule took these criticisms to heart and although he was noted for his experimental precision, he was also known to be cautious about making speculations about the meaning of his results. The last two years of Joule’s life were spent mainly in his house where he spent the majority of his time reading.

 

Joule was elected to the Royal Society in 1850, received its Copley medal in 1866 and was president of the British Association for the Advancement of Science in 1872 and in 1887. That he remained a brewer all his life and was never a professor did not seem to matter in the intellectual democracy of the world of science. He was a modest and unassuming man, a sincerely religious one, and toward the end of his life bitterly regretted the increasing application of scientific discoveries to the art of warfare.

 

Working individually Joule found many advantages and dissadvantages of not having an outside financial source. Some of the advantages included being able to choose his own hours, methods of study, and the subject of study. Some of the dissadvantages included not having the financial help that was needed, and not always having the equipment that he would have desired to have. Joule was very smart and was usually able to come up with some type of new invention to meet the equipment problem, and in some cases his models were much more practical for their uses. Most of his researches were funded from his own pockets. Unfortunately, this money ran out in 1875 and the following years were ones of continuous illness. On Oct. 11 1889 Joule succumbed to his illness, a form of degeneration of the brain. Portrait of James Prescott Joule by John Collier

As was the case of his life, he was honored for his achievements. His contributions in the field of thermodynamics were great and influential to the future developments in the field. In 1878 shortly before his death, after an appeal by the leading men of science of the day, Joule received pension of £ 200 per annum from the government as an honor for all his work. The SI unit of energy, the Joule, is named in his honor. 1 J is equal to the work done when the force of 1 Newton [N] is applied over the length of 1 m. (Newton-Meter) 1 J = 1 N m = 1 W s = 1 Kg m² s^-2.

James Prescott Joule died on the evening of Friday 11th October 1889 at 12 Wardle Road, Sale having lived all his life in the Manchester region. The grave of James Prescott Joule in Sale, a town in Manchester, UK

Important dates in Joule's life:
1818 - Born in Salford, Lanchashire
1840 - Joule's law
1843 - Determined the amount of work required to produce a given amount of heat
1848 - Paper on kinetic theory of gases
1889 - Died in Sale, Cheshire