Celsius scale is a temperature scale in which the fixed points are the temperatures at standard pressure of ice in equilibrium with water (o° C) and water in equilibrium with steam (100° C).
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The scale between these two temperatures is divided in 100°. The scale was formerly known as the Centigrade scale; the name was officially changed in 1948 to avoid confusion with a hundredth part of grade. Celsius scale is named after the Swedish astronomer Andres Celsius (1701-1744), who devised the inverted form of this scale (ice point 100° and steam point 0°) in 1742.