ROBERT BOYLE 63 



journeys, particularly through Italy and France, and then 

 lived as a man of means at his birthplace. In his later days he 

 was one of the founders of the Royal Society, which became 

 of great importance for the development of science in 

 England. He was filled with a tireless passion for the observ- 

 ation of nature. The number of experiments of all kinds, 

 which he describes in his extensive works, is immense; he 

 was the wanderer who takes pleasure in everything there is 

 to be seen, and also spares no trouble to see as much as 

 possible, but has no great interest in plumbing hidden 

 depths. 



He experimented with mercury in glass tubes, like 

 Toricelli or Pascal; he devised the plan of trapping a quantity 

 of air over mercury in the closed limb of a U-tube, the other 

 limb of which was open. Mercury columns of various 

 heights could then be formed in the open limb, and the 

 pressure of the enclosed air varied at will. He then recorded 

 the height of the mercury column corresponding to each 

 volume of air. It then appeared that, when the already 

 known atmospheric pressure acting on the mercury in the 

 open limb, was taken into account, the volume of the 

 enclosed air was inversely proportional to the total pressure 

 under which it stood. Thus the important law was discovered 

 which connects gas volume and gas pressure with one 

 another at constant temperature, and this is the most impor- 

 tant result for posterity of Boyle's work. It was later 

 verified by Mariotte. Boyle himself did not attach great 

 importance to it.^ As a matter of fact, when Guericke had 

 determined that air fills uniformly all space accessible to it, 

 and that the volume it occupies is the smaller, the greater the 

 pressure upon it, Boyle's law was practically given as the 

 simplest possibility. It is hardly a matter for surprise that 



^ In many editions of his works it is not even given, for example in 

 Nova expervnenta de vi aeris elastica, translated from the EngUsh original 

 in 1659, Hagecommicum, 1661. 



