Tests 'with various electrometers 



271 



With a quantity of additional wire = to gj inc. el. the balls sep. pos. when 

 the plates were at as great a distance as possible. When they were placed close 

 together they seemed to require rather more 

 additional wire, and as well as I could judge, 

 a quantity = about | inc. el. 



558] Excitation of electricity by separating 

 brass plate from glass one. 



Sat. afternoon. Th. 60. N. 9. 



The experiment of p. 71 [Art. 541] was 

 repeated. It was found that the brass plate 

 was electrified on lifting up as before, though 

 the plate was not electrified before. But if the 

 plate was first charged and discharged again 

 before the plate was lifted up, it was found to 

 be stronger electrified. 



I then took a piece of tinfoil of the same 

 size as the brass plate, with a silk string fast- 

 ened to it near the edge, and laid it on the glass 

 and lifted it up gently by the silk string. The 

 tinfoil was found to be electrified thereby. 



559] Comparison of Henly's, Lane's, and 

 straw electrometer. 



Th. about 58. N. 



Sun. Mar. 28 [1773]. 

 about 8. 



The two conductors of Nairne were placed 

 end to end, and Henly's electrometer placed 

 on that furthest from globe* parallel to con- 

 ductor and the cork pointing from globe. The 

 four jars were also joined to the usual wire with 

 the straw electrometer hung to it, the wire and 

 jars being placed at such a distance from the 

 conductors that the electricity was found not 

 to flow sensibly from them to the jars. 



The globe 3 f was then applied to that con- 

 ductor nearest the globe and electrified till 

 Henly's electrometer stood at 90. The globe 3 

 was then removed from the conductors and its 

 electricity communicated to the jars{. 



The straw electrometer separated to 2 + J. 



* [Of Nairne's electrical machine.] 



f [Globes 2 and 3 are glass globes coated as Leyden jars. See Art. 505 for their 

 charges.] 



J [For the charges of these jars see Art. 506.] 



[Henly's Electrometer, from 

 the original figure, Phil. Trans. 

 2 . P- 359-] 



