Date context
1818–1889
Research around Manchester
Born into a brewing family in Salford, Joule received instruction from Dalton. He pursued experiments while working in the family business, drawing on laboratory equipment, precise thermometers and local scientific societies rather than beginning with a university appointment.
Heating produced by current
He investigated the heating of conductors by electric current and established quantitative relations involving current and resistance. The experiments connected circuit behaviour with measured temperature changes and helped make the conversion between different forms of energy experimentally comparable.
Mechanical work and heat
In paddle-wheel experiments, falling weights drove paddles that slightly warmed water. Joule compared mechanical work with the measured heating and corrected for unwanted heat exchange. Repeated experiments during the 1840s and his 1849 report progressively strengthened the measurements.
Experimental support for energy conservation
Joule’s results supported treating heat as energy transfer rather than a conserved material fluid. He later collaborated with William Thomson on temperature changes in flowing gases. The establishment of energy conservation involved several researchers and cannot be assigned to a single experiment.