The Delisle scale is a scale to measure temperature. It was introduced by French astronomer Joseph-Nicolas Delisle in 1732. Delisle used a thermometer that worked with Mercury. The unit is abbreviated "De" or "D". 0°De is equal to the boiling point of water under normal pressure. Delisle then measured the volume change of the mercury. At the start, the Delisle scale had 2400 degrees. Josias Weitbrecht recalibrated the theromometer in 1738, so that the melting point of ice was taken into account. Ice melts at 150°De.