Dynamo with steel magnet and brass and ebony terminals in a polished wood case. Designed for use on patients. Michael Faraday (1791-1867) discovered the principles of the electric motor and dynamo in 1831. He was followed fairly quickly by the adoption of electricity for medical purposes. These machines were made in large numbers and were thought to be effective in a wide variety of physical and nervous disorders. Faraday's great life work was the series 'Experimental Researches on Electricity', published over 40 years in 'Philosophical Transactions'. In it he described his many discoveries including electromagnetic induction (1831), the laws of electrolysis (1833) and the rotation of polarised light by magnetism (1845).