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How did Blaise Pascal investigate atmospheric pressure in Paris and near Clermont-Ferrand?
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Blaise Pascal
Blaise Pascal, oil painting by an anonymous artist, c. 1650; in the Musée Carnavalet–Histoire de Paris, Paris. Pascal laid the foundation for probability theory.
To investigate atmospheric pressure, Blaise Pascal constructed mercury barometers and added a graduated scale to the tubes to allow for precise measurements.12
His investigation involved two primary locations:
- Paris: Pascal conducted initial experiments in Paris to reproduce and amplify the work of Evangelista Torricelli regarding atmospheric pressure.12
- Clermont-Ferrand: To test the effect of altitude, Pascal enlisted his brother-in-law, Florin Perier, to carry a mercury barometer up the Puy de Dôme mountain near Clermont-Ferrand in September 1648. By measuring the height of the mercury column at different elevations along the ascent, they provided empirical proof that air pressure decreases at higher altitudes.12
These experiments were fundamental to his later work in hydrostatics and his treatises on the weight and density of air.2