THE SUCCESSORS OF GALILEO 



these experiments, devoting himself to researches in 

 all the fields of natural philosophy. He was associated 

 at Oxford with a company of scientists, including 

 Wallis and Wren, who held meetings and made ex- 

 periments together, these gatherings being the be- 

 ginning, as mentioned a moment ago, of what finally 

 became the Royal Society. It was during this resi- 

 dence at Oxford that many of his valuable researches 

 upon air were made, and during this time he invented 

 his air - pump, now exhibited in the Royal Society 

 rooms at Burlington House. 1 



His experiments to prove the atmospheric pressure 

 are most interesting and conclusive. "Having three 

 small, round glass bubbles, blown at the flame of a 

 lamp, about the size of hazel-nuts," he says, "each of 

 them with a short, slender stem, by means whereof 

 they were so exactly poised in water that a very small 

 change of weight would make them either emerge or 

 sink; at a time when the atmosphere was of conve- 

 nient weight, I put them into a wide-mouthed glass 

 of common water, and leaving them in a quiet place, 

 where they were frequently in my eye, I observed 

 that sometimes they would be at the top of the water, 

 and remain there for several days, or perhaps weeks, 

 together, and sometimes fall to the bottom, and after 

 having continued there for some time rise again. And 

 sometimes they would rise or fall as the air was hot or 

 cold." 2 



It was in the course of these experiments that the 

 observations made by Boyle led to the invention of his 

 "statical barometer," the mercurial barometer hav- 

 ing been invented, as we have seen, by Torricclli, in 



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