Pascal’s’ experiments with barometers
Torricelli died a few years after the barometer experiment had been performed, an did not live to see his explanation of it, in terms of atmospheric pressure, generally accepted among scientists. After Torricelli’s death Pascal repeated the experiment in France and set up two barometers. The first of these was placed at the foot of a mountain in Aubergine called the Puy-de-
Dome, while the other was carried up the mountainside and the height of the column read at intervals on the way up. Owing to the decreasing height of the atmosphere above this barometer, its mercury column showed a progressive fall due to the reduced atmospheric pressure. The barometer at the foot of the mountain showed practically no change. It was this final experiment which brought about the downfall of the theory that nature abhors a vacuum and established the principle that the atmosphere exerts a pressure.