FRANKLIN ON LIGHTNING. 575 



Franklin began his immortal work. Yet it has been con- 

 tended, over and over again, that there was really nothing 

 left for Franklin to do; that if Gray and Wall had not sub- 

 stantially discovered the identity of electricity and light- 

 ning, Nollet (for Freke and Winkler seem to have been 

 generally overlooked) certainly did so. So easy is it thus 

 to argue, when stimulated by pride of opinion and inter- 

 national rivalries. 



Of the rise and progress of the idea in Europe Franklin 

 probably had no knowledge. In I737 1 he quotes with ap- 

 proval the theory of Dr. Lister, that "the material cause 

 of thunder, lightning and earthquakes is one and the 

 same, namely, 'the inflammable breath of the pyrites, 

 which is a subtle sulphur and takes fire of itself.' " Lister 

 regarded thunder and lightning as due to sulphur fired in 

 the air, and earthquakes to the same substance ignited 

 underground. "Why there may not be thunder and light- 

 ning underground in some vast repositories," comments 

 Franklin, "I see no reason, especially if we reflect that 

 the matter which composes the noisy vapor above us exists 

 in much larger quantities underground." The conception 

 of the electrical nature of lightning seems to have come to 

 him at the very outset of his electrical studies, and then 

 to have been formulated in writing; but he refrained from 

 communicating it to Collinson until experiment brought 

 him assurance. Then, in the early summer of 1749, he 

 despatched the first of the two famous papers in which his 

 discovery is made known to the world. 



The theory developed in this essay is interesting, not 

 because of its inherent truth for Franklin himself aban- 

 doned it not long afterwards but as showing the path 

 over which his mind moved. It furnishes, moreover, a 

 striking instance of the deductive, as distinguished from 

 the inductive, method of reasoning. The ocean is assumed 



1 Pennsylvania Gazette. 



