1 2 HEROES OF INVENTION AND DISCO VERY. 



the vessel employed being a round globe, without any other 

 mouth or opening than the narrow one in which the pump was 

 inserted, things could not be conveyed into it, nor, consequently, 

 any experiments made in that vacuum which had been obtained. 

 Boyle, who says that he had himself thought of something like 

 an air-pump before he heard of Guericke's invention, applied 

 himself, in the first place, to the remedying of these defects in 

 the original instrument, and succeeded in rendering it con- 

 siderably more convenient ana useful. At the time when he 

 began to give his attention to this subject, he had Robert 

 Hooke, who afterwards attained a distinguished name in 

 science, residing with him as an assistant in his experiments ; 

 and it was Hooke, he says, who suggested to him the first 

 improvements in Guericke's machine. These, which could not 

 easily be made intelligible by any mere description, and which, 

 besides, have long since given way to still more commodious 

 modifications of the apparatus, so that they possess now but 

 little interest, enabled Boyle and his friends to carry their 

 experiments with the new instrument much farther than had 

 been done by the Consul of Magdeburg. But, indeed, Boyle 

 himself did not long continue to use the air-pump which he 

 describes in this first publication. In the second part of his 

 Physico-Mechanical Experiments he describes one of a new 

 construction ; and, in the third part of the same work, one still 

 farther improved. This last, which is supposed to have been 

 also of Hooke's contrivance, had two barrels moved by the same 

 pinion-wheel, which depressed the one while it elevated the 

 other, and thus did twice as much work as before in the same 

 time. The air-pump has been greatly improved since the time 

 of Boyle by the Abbe Nollet, Gravesande, Smeaton, Prince, 

 Cuthbertson^ and others. 



