The discoveries of Galileo, Pascal, and Torricelli incited him to solve the problem 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 instead an open field, to which were invited Emperor Ferdinand III., and all the princes of the Diet at Ratisbon.
When they were assembled he produced two hollow brass hemispheres about two feet in diameter, and placing their exactly fitting surfaces together, proceeded to pump out the air from their hollow interior, thus causing them to stick together firmly in a most remarkable way, apparently without anything holding them.