170 ELECTRICAL PROPERTIES OF SILK. 



of the silk is not merely to prevent the return of 

 electricity from the cylinder to the cushion, but that 

 it is the chief agent in the excitation,, while th%-i 

 cushion serves only to supply the electricity, and,: | 

 perhaps increase the pressure at the entering partf! 

 There likewise seems to be little reason to doubti 

 but that the disposition of the electricity to escapfl 

 from the surface of the cylinder, is not prevented 

 by the interposition of the silk, but by a compeiu j 

 sation after the manner of a charge ; the silk being | 

 then as strongly negative as the cylinder is positive 3 

 and lastly, that the line of light between the silk : 

 and cushion in weak excitations, does not consiaH 

 of returning electricity, but of electricity which ' 

 passes to the cylinder, in consequence of it 

 having been sufficiently supplied during its contaqw 

 with the rubbing surface. 



