FRANKLIN'S EXPERIMENTS. . ,s8i 



it definite instructions how to make the actual trial itself, 

 and to leave the performance to others, whose facilities for 

 carrying it out might be better than his own. This self- 

 abnegation shows itself every where throughout Franklin's 

 scientific career. No one could have been more destitute 

 of pride of opinion than he, no one more totally free from the 

 desire of profit in any form to himself, no one more purely 

 single-hearted in the devotion of his genius to the good of 

 all men. 



The little experiment, as usual, was made with homely 

 apparatus. He hung up an old-fashioned pair of brass 

 scales by a twisted cord attached to the middle of the beam 

 so that the pans, as the cord untwisted, would move round 

 in a horizontal circle. He suspended the pans from the 

 beam by silk threads instead of the usual chains, so as to 

 insulate them. On the floor, and in such position that the 

 scale-pans would move over it in their path, he set up an 

 old metal punch, on end. Then he electrified one scale- 

 pan. 



Now, as this pan came over the punch, it was attracted 

 and moved down to the iron, and when near enough the 

 charge would pass from pan to punch with a snap and 

 crack. But if a sewing-needle were u stuck on the end of 

 the punch, its point upwards, the scale, instead of drawing 

 nigh to the punch and snapping, discharges its fire silently 

 through the point and rises higher than the punch. Nay, 

 even if the needle be placed upon the floor near the punch, 

 its point upward, the end of the punch, though so much 

 higher than the needle, will not attract the scale and re- 

 ceive its fire, for the needle will get it and convey it away 

 before it comes nigh enough for the punch to act." Of 

 course, the scale pan here represented the electrified 

 cloud, and the punch the building or mountain which 

 might be struck by the spark, did not the needle draw it 

 harmlessly off. 



This description is the preface to the two famous para- 

 graphs which were destined to place Franklin first among 

 living philosophers. 



