– Most of us who have heard of James Prescott Joule have heard of him because of Joule’s law, his paddle experiment, and/or we know that energy is measured in joules in his honor, but who was James Joule?
Electricity, electricity, Electricity, electricity James Prescott Joule was born on Christmas Eve in 1818, in Salford, England, which is near Manchester. James was the grandson of William Joule, who had founded a popular brewery called Joule’s Beer, which James’ father ran after his grandfather’s death. James was prevented from going to school because he had a weak spine, but his spine problems didn’t stop him from enjoying rowing, riding horses, and playing electric tricks including recreating Benjamin Franklin’s electric kite experiment . In 1834, the Joule brothers were tutored by the now famous chemist, John Dalton, who popularized the idea of atoms in chemistry. By the time James Joule was 18 years old, Joule worked at the brewery seven days a week from nine a.m. to six p.m., but still found time to tinker with experiments in a spare room in his father’s house.
It was around this time that Joule learned about electric motors, and was inspired. See, a former shoemaker and soldier named William Sturgeon, who had invented the electromagnet in 1826, started to have trouble getting published, so he started his own. In Sturgeon’s first publication, in October of 1836, Sturgeon published a description of a motor he had made with electromagnets, which he claimed could be used for, quote, drawing water, wagons and carriages on a railway, and upon the same scale. It motivated Joule, and much of England, to try their hand at inventing their own electric motors. Secondly, the following year, Sturgeon published the account from a Russian/German man named Moritz Jacobi, who designed a better motor than Sturgeon, and published it first as well.
Joule then used those ideas to create his own motor, and published a description of it when he was only 19 years old in Sturgeon’s paper in February of 1838. Joule, therefore, designed system after system, but he quickly became frustrated that his motors weren’t very powerful, or very fast.
He then decided that he needed to have a machine to measure the current, something called a galvanometer, that was more precise, that had units that he could depend on because all of the systems before that were uncalibrated. It was these studies that led Joule to realize that he could use Faraday’s new law of electrolysis to quantitatively measure how much electricity was produced by how much hydrogen was decomposed.
By August of 1843, Joule was trying to convince anyone and everyone that, quote, wherever mechanical force is expended, an exact equivalent of heat is always obtained. As Joule was describing how heat transfers, this was eventually called a law of thermodynamics. Thermo is heat, dynamics is motion. However, Joule’s results were so precise that many scientists doubted him. Also, he was promoting the idea of atoms that heat was just the motion of molecules, and that was widely ridiculed, plus he was just a beer brewer, and they didn’t want to listen to him. Undeterred, Joule continued to give talks about conservation of energy to various uninterested parties.
By June of 1845, he created his most famous experiment, the paddle wheel. In this experiment he dropped a weight from a height, which then turns a paddle which would heat up the water. And then he could find the relationship between what we now call the potential energy of the weight, and the temperature change of the water. In this way, he found that 817 pounds at a height of one foot was equivalent to raising the temperature of one pound of water by one degree Fahrenheit. Side note, he made a more accurate experiment in 1849, and got a weight of 772.692 pounds, which corresponds with 4,160 jewels per calorie in modern units.
Anyway, on June 23rd, 1847, Joule gave a talk for the British Association of the Advancement of Science where a 23-year-old Scottish scientist named William Thomson heard him. However, as Thomson listened to the talk, he realized that at least some of what Joule said was, quote, a great truth and a great discovery. They met after the talk, and Thomson said that it quickly ripened into a life-long friendship.
This is why the temperature scale is measured in kelvins in his honor. He was knighted, and made Lord Kelvin in 1892. In this paper, Thomson said that the idea of an indestructible heat was a view, quote, nearly universally held except by Mr. Joule who had made, according to Thomson, some very remarkable discoveries on the subject. In Germany, a 27-year-old high school teacher named Rudolf Clausius read Thomson, and then Joule, and then others, and was inspired by everything except for the idea that heat was indestructible.
Instead, Clausius felt that heat is a form of energy. It is the energy that is conserved, partially because of what he called the careful experiments of Joule. Thomson really hated Clausius’s paper, and soon Thomson and Clausius published articles debating each other’s ideas. In addition, Thomson changed his mind about the calorific, and published a series of five papers on the dynamical theory of heat, which used Joule’s results to lay out new mathematics, and theories on the conservation of energy, and the laws of thermodynamics.
At first, this was a happy time in Joule’s life. His ideas were being accepted by scientists in the scientific community. His marriage to Amelia was strong with the birth of two children, Benjamin in 1850, and Alice in 1852. All of this changed in 1854, when Amelia had a very difficult time giving birth to their third child, who died 20 days later. By July of 1854, Joule wrote Thomson about the tragic news, and that he was, quote, very much alarmed about my dear wife who is not recovering well.
Joule was devastated, quit his scientific work, and moved with his children back to his father’s house. With love and support of his family, Joule started to recover, and regain interest in scientific work. By the next year, 1855, Thomson convinced Joule to continue his studies in electrodynamics as well as fluids, but he was never quite the same.
Joule started receiving awards for his work, and was awarded an honorary doctorate. In 1882, the president of the British Association for the Advancement of Science suggested that energy should be measured in joules in honor of James Joule, which we continue till date. James Joule died seven years later at the age of 70, and his grave has the number 772.55 for his final measurement for the weight in pounds to heat one pound of water by one degree Fahrenheit.
So that was a little background on James Prescott Joule. In addition, the committee included the scientists, Carl Siemens, and Cromwell Varley, whose brothers, Ernst Siemens, and Samuel Varley, along with Charles Wheatstone, all claim to have independently, and nearly simultaneously invented the self-exciting generator.