FRANKLIN ON POINTED CONDUCTORS. 541 



come satisfied that his colleagues and himself had made 

 some really new discoveries, wrote, under date of the 28th 

 instant, to Collinson, so advising him and expressing the 

 intention of soon sending him an account of them ; adding 

 that he "never was before engaged in any study that so 

 totally engrossed my attention and my time as this has 

 lately done," and that, during some months past, he has 

 had " little leisure for anything else." 



On July n, 1747, Franklin fulfills his promise, and the 

 story is told to Collinson of the first electrical discoveries 

 made in America. Immediately at the very threshold 

 is foreshadowed the great achievement which left Frank- 

 lin's name immortal. The initial announcement refers to 

 u the wonderful effect of pointed bodies both in drawing 

 off and throwing off the electrical fire." 



It was no novelty to electrify pointed conductors. Von 

 Guericke had done so, and Gray and Dufay and the Ger- 

 mans. Hauksbee had seen the glow at his finger-tips. 

 The fire hissing from the ends of iron rods is abundantly 

 pictured in the old engravings of the apparatus ofWinkler 

 and Nollet and Watson. But that was not the achieve- 

 ment which Franklin relates. 



He electrified a small cannon ball, and suspended a bit 

 of cork near to it by a silk string. The cork, after touch- 

 ing the ball, was repelled to a few inches' distance and 

 maintained in that position. When he brought the point 

 of a steel bodkin, held in his hand, in the vicinity of the 

 ball, however, the cork fell back against the ball and was 

 co longer repelled by it. The little metal rod thus seemed 

 to conduct the electric atmosphere away from the iron: to 

 draw it off, as Franklin says. 



There is no doubt in Franklin's mind as to the part 

 taken by the sharpened end of the rod. In the dark, a 

 light gathers around it like that of a fire-fly or glow-worm; 



America, by Benjamin Franklin, LL. D., and F. R. S. The fifth ed., 

 London, 1774. A list of the various editions of Franklin's electrical 

 papers will be found in Mr. P. L. Ford's Bibliography of Franklin. 



