96 THE HISTORY OF SCIENCE 



Torricelli in the space at the top of his barometer 

 (pressure-gauge) had produced what is called a Tor- 

 ricellian vacuum. Otto von Guericke, a burgomaster 

 of Magdeburg, who had traveled in France and Italy, 

 succeeded in constructing an air-pump by means of 

 which air might be exhausted from a vessel. Some of 

 his results became widely known in 1657, though his 

 works were not published till 1673. 



Robert Boyle (1626-1691), born at Castle Lismore 

 in Ireland, was the seventh son and fourteenth child 

 of the distinguished first Earl of Cork. He was early 

 acquainted with these various experiments in refer- 

 ence to the air, as well as with Descartes' theory that 

 air is nothing but a congeries or heap of small, and, 

 for the most part, flexible particles. In 1659 he wrote 

 his New Experiments Physico-Mechanical touching 

 the Spring of the Air. Instead of spring, he at times 

 used the word elater (eXar^o). In this treatise he 

 describes experiments with the improved air-pump 

 constructed at his suggestion by his assistant, Robert 

 Hooke. 



One of Boyle's critics, a professor at Louvain, 

 while admitting that air had weight and elasticity, 

 denied that these were sufficient to account for the 

 results ascribed to them. Boyle thereupon published 

 a Defence of the Doctrine touching the Spring and 

 Weight of the Air. He felt able to prove that the 

 elasticity of the air could under circumstances do far 

 more than sustain twenty-nine or thirty inches of 

 mercury. In support of his view he cited a recent 

 experiment. 



He had taken a piece of strong glass tubing fully 

 twelve feet in length. (The experiment was made 



