James Prescott Joule

James Prescott Joule was born on 24 December 1818. He spent years studying the nature of heat, running experiments that revealed its relationship to mechanical work. Those findings, first published in 1843, became the scaffold for the law of conservation of energy and ultimately the first law of thermodynamics. He also observed magnetostriction and established the relationship between current through a resistor and the heat it throws off - now known as Joule's first law. Working alongside Lord Kelvin, he helped develop an absolute thermodynamic temperature scale that became the Kelvin scale. He died on 11 October 1889, leaving physics a measurement and a framework it still uses every day.