December 24, 1818 - Birth of James Prescott Joule, a law and a unit of measurement are named after him

Science was his passion and he was fascinated by electricity and magnetism, so he began to investigate the possibility of replacing the steam engine with a then newly invented electric motor. Joule found that burning one pound of coal in a steam engine produced five times the work of consuming one pound of zinc in a Grove Cell, one of the first electric batteries. Joule's standard unit of work was the ability to lift one pound to a height of one foot, the foot-pound.

Even so, Joule's interest shifted from purely financial about how much work could be extracted from a single source to speculating about energy transformation.

In 1840 he discovered the law that would bear his name and tried to impress the Royal Society but was unsuccessful, in 1843, he published the results of his experiments showing that the heating effect he had quantified was due to the generation of heat in the electrical conductor and not to its transmission from another part of the equipment. This was a direct challenge to the caloric theory that held that heat could neither be created nor destroyed and that had dominated the thinking of heat science since Antoine Lavoisier had introduced it in 1783. Lavoisier's prestige and the practical success of the caloric theory of Sadi Carnot's steam engine from 1824 meant that Joule, working outside academia and engineering, had a difficult road to travel.

In addition to discovering the relationship with mechanical work and leading to the theory of energy, he worked with Lord Kelvin to develop the absolute temperature scale, made observations on thermodynamic theory (Joule-Thomson effect), obtained the equivalent mechanical numerical value of heat, contributed to explaining the kinetic theory of gases, established the Joule effect and found a relationship between the electric current passing through a resistance and the heat dissipated, known today as Joule's law, etc.

If you want to know more about this scientist, click on the following link: James Prescott Joule