Trials of charges in plates of air 219 



Diameter of the globe = 12-1, therefore quantity of electricity in globe is 

 to D in circle of same diameter as 1-56 to i*. 



457] Two trial plates were made on a piece of the large bit of ground glass, 

 one 2-37 inches diameter on place where the thickness = 1-80, computed 

 power =31-2; the other 2-57 inches diameter where thickness = 1-90, com- 

 puted power = 34-8. 



The first is called S the other L. 



fThe plates of ground glass E and F were each coated on one side with a 

 circle 7-95 inches diameter communicating with coating on the other side. 

 These plates were kept from touching by three bits of sealing-wax. When the 

 coatings were kept at distance -39 from each other this is called plate of air 

 39 thick, &c. 



A piece of wire of the same thickness as the other was made to slide thereon. 



When the plate of air was tried against trial-plate S with wire drawn out 

 12 inches it is expressed 



plate air S + 12 &c. 



Double plates A and B S + 29^ sep. a little pos. 

 L + 17 sep. a little neg. 



plate air -343 S + o did not sep. 



[L] + 3 a little pos. 



plate air -39 S + 18 sep. a little pos. 



L + 3 sep. a little neg. 



same plate air L + 38 sep. pos.^f 



S + 18 did same. 



Tried again in afternoon of the same day. 



A and B 8 + 27 sep. a little pos. 



plate air -39 S + 19 do. 



A and B 8 + 29 do. 



A and B L + 15 sep. a little neg. 



plate air -39 L + 4 do. 



458] The wire not drawn out is about 40 inches, and may therefore contain 

 about 10 cyl. } inc. of electricity, id est, as much electricity as is contained in 

 circle of 10 inches diameter. Quantity of electricity in additional wire is sup- 

 posed to be equal to its length [divided] by 4-4. 



Both the trial plates together, whose computed power = 66, is equi- 

 valent to 2A + 26 + 80 inches of wire + 45 of additional wire, id est, to 

 73-4 + 20 + io- 1 = 103-5 inches of electricity, therefore i inch of computed 

 power in the glass of which trial plates are made should be equivalent to 

 1-41 inches of electricity. 



By the experiment marked ^f in [457], a difference of computed power in 

 the trial plates = 3-6, which is equivalent to 5-08 inches of electricity, was 



* [See Art. 653 and Preface.] t [See Art. 341.] 



J [Probably "circ." See Art. 648.] 



