John Frederic Daniell
Daniell, John Frederic (1790-1845), an English scientist. He was born in London, and in 1831 was made professor of chemistry at King's College, London. He invented the dew-point hygrometer, which measures relative humidity; a pyrometer (a type of thermometer); and an electric cell called the Daniell cell. He wrote Meteorological Essays (1823) and other scientific works.