THE SUCCESSORS OF GALILEO 



a ml Mariotte). He also ascertained that air existed 

 in a state of mechanical mixture with liquids, "existing 

 between their particles in a state of condensation." He 

 made many other experiments, especially on the colli- 

 sion of bodies, but his most important work was upon 

 the atmosphere. 



But meanwhile another contemporary of Boyle and 

 Mariotte was interesting himself in the study of the 

 atmosphere, and had made a wonderful invention and 

 a most striking demonstration. This was Otto von 

 Guericke (1602-1686), Burgomaster of Magdeburg, and 

 councillor to his "most serene and potent Highness" 

 the elector of that place. When not engrossed with the 

 duties of public office, he devoted his time to the study 

 of the sciences, particularly pneumatics and electricity, 

 both then in their infancy. The discoveries of Galileo, 

 Pascal, and Torricelli incited him to solve the prob- 

 lem of the creation of a vacuum a desideratum since 

 before the days of Aristotle. His first experiments 

 were with a wooden pump and a barrel of water, but 

 he soon found that with such porous material as wood 

 a vacuum could not be created or maintained. He 

 therefore made use of a globe of copper, with pump 

 and stop-cock ; and with this he was able to pump out 

 air almost as easily as water. Thus, in 1650, the air- 

 pump was invented. Continuing his experiments upon 

 vacuums and atmospheric pressure with his newly 

 discovered pump, he made some startling discoveries 

 as to the enormous pressure exerted by the air. 



It was not his intention, however, to demonstrate his 

 newly acquired knowledge by words or theories alone, 

 nor by mere laboratory experiments; but he chose 



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