Apparatus for investigating temperature, 1772.
© Science Museum / Science & Society Picture Library
Engraved plate by C G Geissler from 'Recherches sur les Modifications de L'Atmosphere' (1772) by Jean Andre Deluc, after a drawing by the author. This apparatus is designed to investigate the temperature of boiling water. The temperature at which water boils varies with altitude due to the difference in atmospheric pressure. At sea level, water boils at 100 degrees Celsius, but at 10,000 feet, the boiling point is only 90.39 degrees. Deluc (1727-1817) was a Swiss geologist, meteorologist and physicist. He tried to prove that creation as described in the Bible was consistent with science. He investigated the atmosphere and the density of water, invented a hygrometer and was the first to record accurately the heights of mountains with the aid of a barometer.