'5' ] 



PART *. [{III.} EXPERIMENTS ON COATED {DIELECTRIC} 



PLATES.] 



Hitherto unpublished: see Table of Contents at the beginning of this volume.] 



295] This part consists chiefly of experiments made to determine the 

 charges of plates of glass and other electric substances coated in the manner 

 of Ley den vials. The method I used in doing this was nearly of the same 

 nature as that by which I determined the charges of the other sort of 

 bodies in the preceding part, but the apparatus was more compact and 



<& 



\ 



Fig. 20. 



portable and is represented in Fig. 20, where Hh is a horizontal board 

 lying on the ground, LI and LI are two upright pillars supporting the two 

 horizontal bars Nn and Pp, both at the same height above the ground, 

 and parallel to each other. 



* [Not numbered by Cavendish.] 



