Institute and Museum of History of Science, Florence, ITALY

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Creditis The syphon experiment Torricelli's barometric experiment

Experiments on the vacuum.
Otto von Guericke, Experimenta Nova (ut vocantur) Magdeburgica De Vacuo Spatio, Amsterdam 1672


In a letter dated 1630, Giovan Battista Baliani a patrician from Genoa, asked Galileo for the reason why water did not rise through the syphon he had made to carry water over a hill about 21 metres high.
In his reply, Galileo claimed that nature's abhorrence of the void did not entail a repugnance, and was not invincible - on the contrary, it could be overcome with adequate force. Galileo had in fact ascertained that the force of the vacuum was enough to lift a column of water with a pump up to a maximum height of 18 'braccia' (around 11 metres) Beyond this limit, the force of the vacuum was insufficient, and the column of water disintegrated. This, according to Galileo, was why Baliani's syphon couldn't work.
Even if he was unaware of the determining function of the weight of air, the galileian interpretation of the void helped to get experimentation going on the subject, and, above all, dispelled the conviction in the absolute impossibility of generating a vacuum in nature.



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