Editing Barometer (section)

=== Blaise Pascal ===
[[File:Portrait de Blaise Pascal (MARQ 999.3.1).jpg|left|thumb|178x178px|Blaise Pascal]]
In 1646, [[Blaise Pascal]] along with [[Pierre Petit (engineer)|Pierre Petit]], had repeated and perfected Torricelli's experiment after hearing about it from [[Marin Mersenne]], who himself had been shown the experiment by Torricelli toward the end of 1644. Pascal further devised an experiment to test the Aristotelian proposition that it was vapours from the liquid that filled the space in a barometer. His experiment compared water with wine, and since the latter was considered more "spiritous", the Aristotelians expected the wine to stand lower (since more vapours would mean more pushing down on the liquid column). Pascal performed the experiment publicly, inviting the Aristotelians to predict the outcome beforehand. The Aristotelians predicted the wine would stand lower. It did not.<ref name="History of the Barometer" />

==== First atmospheric pressure vs. altitude experiment ====
{{Main|Blaise Pascal#First atmospheric pressure vs. altitude experiment}}
[[File:Puy de dome, May 2012.jpg|thumb|Puy de Dôme]]
[[File:Florin Périer measuring the mercury level in a Torricelli barometer near the top of the Puy de Dôme.jpg|alt=Florin Périer measuring the mercury level in a Torricelli barometer near the top of the Puy de Dôme|thumb|Florin Périer on the Puy de Dôme]]
However, Pascal went even further to test the mechanical theory. If, as suspected by mechanical philosophers like Torricelli and Pascal, air had weight, the pressure would be less at higher altitudes. Therefore, Pascal wrote to his brother-in-law, Florin Perier, who lived near a mountain called the [[Puy de Dôme]], asking him to perform a crucial experiment. Perier was to take a barometer up the Puy de Dôme and make measurements along the way of the height of the column of mercury. He was then to compare it to measurements taken at the foot of the mountain to see if those measurements taken higher up were in fact smaller. In September 1648, Perier carefully and meticulously carried out the experiment, and found that Pascal's predictions had been correct. The column of mercury stood lower as the barometer was carried to a higher altitude.<ref name="History of the Barometer" />