††††The more accurate alcohol-filled thermometers were first used in about 1650. The Fahrenheit thermometer was invented by Gabriel Fahrenheit, a German physicist living in Amsterdam, in about 1720. Anders Celsius, a professor of astronomy from Sweden, invented the Celsius scale, with 100 degrees between the freezing and boiling points of water, in 1742. The medical or clinical thermometer first appeared in 1626, the invention of Santorio of Italy.
Modern electrical thermometers contain parts that vary in electrical resistance or voltage with the temperature. A digital thermometer is an electrical thermometer that displays the temperature directly as a number.
