JOULE, JAMES PRESCOTT (181,8,89). An English physicist. He was horn at Salford, Eng land, and was the proprietor of a large brewery. but was at the same time an earnest student of science. His early education was secured at home. the chemist Walton being the young man's instructor, and at the age of nineteen he pub lished in the Annals of Electricity a description of an electro-magnetic engine which he had him self invented. 111 the course of researches on elec tricity he was able to show that in electrolysis the amount of heat absorbed was equivalent to the heat produced during the original combina tion of the elements. Joule was the first to as certain the mechanical equivalent of heat (we 11E.vr). and in an address delivered in 1847 at 31anehester he stated the doctrine of the conser vation of The paper was hardly noticed by press or scientists, and a similar paper pre sented to the British Association would also have been passed over had its merits not been seen by William Thomson, afterwards Lord Kelvin. Joule
worked for forty years to determine the mechani cal equivalent of heat, using both electric cur rents and the mechanical friction of water, and obtained a number of values for this quantity. Many researches on electricity and thermo-dyna mies are to be credited to him, and his name is given to the unit of work. while Joule's law for determining the amount of energy in an electric circuit has become fundamental in electrical sci ence. Dr. Joule received the Copley and other medals and numerous honors from the leading universities and scientific societies throughout the world. His .Scientilie Papers. in two volumes, were published in 1885 and 1887, and numerous valuable communications from him are to be found in the various English journals, and pro ceedings of societies.