What did James Joule discover?

James Prescott Joule's main discovery was the relationship between heat and mechanical work. His discovery, known as Joule's Law, expresses the relationship between heat generation and currents flowing through electrical conductors.

His discovery was largely ignored until 1847, when it was noticed by Scottish physicist, William Thomson. Thomson, along with other scientists at the Royal Society, were instrumental in the publication of Joule's findings. Joule's Law became the basis for thermodynamics, a branch of physics that deals with heat and temperature inside mechanical systems. Thermodynamic principles are essential to the understanding of mechanical processes in the oil and gas industries.