Lord Kelvin (1824-1907), British engineer and physicist William Thomson, 1st Baron Kelvin, better known as Lord Kelvin. Co-discoverer in 1852 of the Joule-Thomson effect, Kelvin proposed the existence of absolute zero in 1848 and the use of an absolute temperature scale (the Kelvin scale). Knighted (1866) for his work on Atlantic telegraph cable signals and galvanometers, he was made Baron Kelvin (1892), President of the Royal Society (1890-95), President of the Institution of Electrical Engineers (1874, 1889, 1907) and appointed to the Order of Merit (1902). Engraving by Charles Henry Jeens for subscribers of the journal Nature in 1876.