114 Nichols: Franklin's 



revolved. This motor would make fifty revolutions a 

 minute and run half an hour from a single charge. 



In these devices we have a close approach to some 

 later forms of electrostatic apparatus, such as the influ- 

 ence machines of Toepler and Holtz. 



With the exception of the lightning rod, which came 

 later, these two machines represent Franklin's nearest 

 approach to practical electrical invention. In the con- 

 struction of apparatus to illsutrate the principles of the 

 science, to excite surprise or merely to amaze or amuse, 

 he was exceedingly ingenious and fertile. Such toys 

 failed, however, to satisfy the utilitarian spirit which 

 was always strong in him, and he expressed in an oft- 

 quoted passage his chagrin at being able " to produce 

 nothing in this way of use to mankind.^ What would 

 he say to the gigantic industrial growths from the seed 

 that he helped to sow? 



No scientific achievement of Franklin's made so pro- 

 found an impression upon the public of his day as his 

 demonstration that lightning is an electrical phenom- 

 enon and even now nothing is more generally associated 

 with his memory. He was not the first, as we have 

 seen, to compare the noise and spark of the artificial 

 electric discharge with thunder and lightning; but 

 neither Wall nor Grey nor yet NoUet appear to have 



^Franklin: Electricity, p. 37. 



