Who were Gabriel Fahrenheit and Anders Celsius?

Today’s thermometers are calibrated in standard temperature units of Fahrenheit or Celsius, both named for early researchers. In the early 1700s, the German scientist and engineer Gabriel Fahrenheit developed the alcohol and mercury thermometers and in 1724 invented the first temperature scale. The zero-degrees point was based on the lowest point to which the mercury fell during Germany’s cold winters. The freezing point of water was 32 degrees Fahrenheit, the boiling point of water was 212 degrees Fahrenheit, and the human body temperature was defined as 96 degrees Fahrenheit. The Fahrenheit scale was widely used in the Europe, until Alders Celsius, a Swedish astronomer, developed the Celsius temperature scale in 1742. His thermometer labeled 0 degrees for the freezing point of water, and 100 degrees for water’s boiling point. The Celsius temperature scale is also called the “centigrade” scale; centigrade means “consisting of or divided into 100 degrees.”