202 Mr. Morgan's Ohfervatlons and Experltnenfs on 



flaaced fimilarly to the acids in the preceding experiment^ 

 were attended with fimilar, but not equal efFeds, becaufe, in 

 Gonfequence of the inferiority of their conducing power, it was 

 iieceflary to make the line through wiiich the charge pafled 

 confiderably (liorter. 



4. The brilliancy or fplendor of the ele6lric fluid in its- 

 paflage through any body is always increafed by leflening the 

 dimendons of that body. I would explain my meaning by lay- 

 ing, thatafpark, or the difcharge of a battery which we might: 

 fuppofe equal to a fphere one quarter of an inch in diameter, 

 would appear much more brilliant if the fame quantity of fluid. 

 is comprefled into a fphere one-eighth of an inch in diameter.. 

 This obfervation is the obvious confequenceof many known fa(fls. 

 If the machine be large enough to afford a fpark whofe length 

 is nine or ten inches, this fpark may be feen fometimes forming 

 itfelf into a brufh, in which ftate it occupies more room, but ap- 

 pears very faintly luminous. At other times the lame fpark may 

 be feen dividing itfelf into a variety of ramifications which (hoot 

 into the lurrounding air. In this cafe, likewife, the fluid is. 

 ditfufed over a large luiface, and in proportion to-the extent of^" 

 that furface, fo is the faintnefs of the appearance. A fpark, 

 which in the open air cannot exceed one quarter of an inch in 

 diameter, will appear to fill the whole of an exhaufted receiver 

 four inches v/ide and eight inches long. But in th.t former 

 cafe it is brilliant, and in the latter it grows fainter and fainter 

 asthefize of the receiver increafes. To prove the obfervation, 

 • which I think may be jufcified by the, preceding fa£ls, I made 

 t\\t follov*^ing experiments. 



EXP. VIII. To an infulated ball, four inches in diameter, I 



fixed a filver thread, about four yards long. This thread, at 



the end which was remotefl; from the ball, was fixed to another 



^ , infulated 



i 



