A device for calibrating thermometers at the boiling point of water. As the boiling point depends on the atmospheric pressure, which in turn depends on the height above sea level, the apparatus can be used to measure height above sea level.
Chemical Engineering
An instrument used to determine elevation above sea level by measuring the change in the boiling point of water. Water and liquids generally boil at progressively lower temperatures as pressure decreases. Since atmospheric pressure decreases with altitude, the decrease in boiling point temperature is therefore an indicator of the atmospheric pressure and therefore elevation. It can also be used to calibrate thermometers.