He continued carr y ing out experiments at home with the intention of finding out if it would be more efficient to power the brewery using an electric battery than the steam power that was traditionally used. In he discovered what became known as Joule ' s First Law. This defined the relationship between the amount of heat produced and the current flowing through a conductor.
At this time, things seemed to be going well for Joule; he was still an amateur scientist but had been accepted as a member of the London Electrical Society.
However, following the acceptance of Joule's First Law, he decided to look into the wider question of how much work can be extracted from a given source and soon found that the scientific establishment was strongly opposed to his ideas.
Joule's experiments showed that heat could be generated by an electric current; however, this went against the prevailing theory of the time, known as the caloric theory. In Joule presented his results to a meeting of the British Association for the Advancement of Science, in Cambridge, but contemporary anecdotes claim that he was met by a stony silence.
Undeterred, he continued his experiments. In , believing he had compelling evidence, he submitted his paper to the most prestigious scientific group of all, the Royal Society… who refused to publish his work. The accepted theory of the time, caloric theory, considered heat to be a material—a type of fluid that flowed from warmer to cooler bodies—while Joule's ideas posited that heat was a form of molecular motion and that it would continue without dying out.
However, the very existence of atoms and molecules was not widely accepted until much later in the century. The atomic theory pioneered by John Dalton may seem inarguable to us now, but at the time that it was first suggested it was deeply controversial.
Joule's theory was a huge step for the scientists of the day to take; simply too huge for many of them. It was later found that Joule's rejection of caloric theory went too far, and later scientific theories, including those put forward by Lord Kelvin, sought to find ways to unify the two seemingly contradictory theories. Another reason many of Joule's contemporaries were quick to reject his theories was because they simply didn't believe that he could carry out his experiments with the level of accuracy that he claimed.
However, Joule had two secret weapons. One was his background as a brewer, which meant he had ways to measure much more precisely, as the finely tuned measurement of temperatures is critical to the brewing process.
The other was John Benjamin Dancer, an exceptionally talented instrument-maker who created custom equipment for him featured in more detail below. Some of Joule's belongings are currently on display in our exhibition Electricity: The spark of life , while others are held in the wider Science Museum Group collection:. In Joule successfully published his paper in a less prestigious publication, the Philosophical Magazine.
Despite the establishment's indifference to his ideas, it was enough to bring him to the attention of scientists including Michael Faraday and William Thompson—later Lord Kelvin—and Joule's fortunes began to turn.
John Dalton was a true polymath who at the age of 15 was helping run a Quaker boarding school in Kendal where he taught everything from ancient Greek to hydraulics, alongside his brother Jonathan. An enthusiastic experimenter, he later turned his full attention to science and in put forward a new and deeply controversial idea: that chemical elements were made up of something called atoms and that the same atoms could be rearranged differently to form new substances.
Dalton was one of Joule's earliest tutors in Manchester. Born to a poor family and originally apprenticed to a bookbinder, Michael Faraday went on to become one of the foremost scientists of his generation. In the late s, Joule wed Amelia Grimes.
Yet he was also concerned with their apparent conflict with the then widely accepted caloric theory originally proposed by Antoine Lavoisier, which stated that heat existed as a type of fluid that flowed from warmer to cooler bodies. Their association with one another also resulted in the discovery of the Joule-Thomson effect , a phenomenon in which a gas allowed to expand freely experiences a change in temperature. The Joule-Thomson effect laid the foundation for the emergence of the refrigeration business.
During the latter part of his career, Joule received much of the attention and accolades withheld from him in his earlier years. In , following his publication of one of his most consistent calculations of the mechanical equivalent of heat, Joule became a fellow of the Royal Society, from which he received the Royal Medal in and the Copley Medal in Various institutions of higher learning, including Trinity College Dublin, University of Oxford and University of Edinburgh, also awarded him with honorary degrees, and the Royal Society of Arts bestowed to him the Albert Medal Joule remained an isolated amateur scientist for most of his life.
After the death of his wife and young daughter in , he lived in relative seclusion. Beginning about his health deteriorated. He died at his home in Sale, Cheshire, on Oct. James G. Crowther gives an excellent treatment of Joule in his British Scientists of the Nineteenth Century Alexander Wood, Joule and the Study of Energy , merits reading. Cardwell, D.
Martin's Press,
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