THE SUCCESSORS OF GALILEO 



previously excited by rubbing, can exercise likewise its 

 virtue through a linen thread an ell or more long, and 

 there attract something." But this discovery, and 

 his equally important one that the sulphur ball be- 

 comes luminous when rubbed, were practically for- 

 gotten until again brought to notice by the discoveries 

 of Francis Hauksbee and Stephen Gray early in the 

 eighteenth century. From this we may gather that 

 Von Guericke himself did not realize the import of his 

 discoveries, for otherwise he would certainly have car- 

 ried his investigations still further. But as it was he 

 turned his attention to other fields of research. 



ROBERT HOOKE 



A slender, crooked, shri veiled-limbed, cantankerous 

 little man, with dishevelled hair and haggard coun- 

 tenance, bad-tempered and irritable, penurious and 

 dishonest, at least in his claims for priority in dis- 

 coveries this is the picture usually drawn, alike by 

 friends and enemies, of Robert Hooke (1635-1703), a 

 man with an almost unparalleled genius for scientific 

 discoveries in almost all branches of science. History 

 gives few examples so striking of a man whose really 

 great achievements in science would alone have made 

 his name immortal, and yet who had the pusillanimous 

 spirit of a charlatan an almost insane mania, as it 

 seems for claiming the credit of discoveries made by 

 others. This attitude of mind can hardly be explained 

 except as a mania: it is certainly more charitable 

 so to regard it. For his own discoveries and inven- 

 tions were so numerous that a few more or less would 

 hardly have added to his fame, as his reputation as a 



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