r 361 ] 



exactnefs, to the degree in which the body to which 

 it is connected is electrified ; but this inconvenience 

 is eafily remedied, by moiftening the ftem and the 

 index, for the femicircie cannot be too dry. 



I find by experience, that this electrometer an- 

 fwers all the purpofes I have mentioned, with the 

 greateft eafe and exactnefs. I am now fure of the 

 force of any expiofion before a difcharge of a jar or 

 battery, which I had no better method of gueffirig 

 at before, than by prefenting to them a pair of Mr. 

 Canton's balls, and obferving their divergency at a 

 given diftance ; but the degree of divergency was 

 itill to be guefTed at by the eye, and the balls can 

 only be applied occasionally ; whereas this in(lrument 9 

 being conftantly fixed to the prime conductor or the 

 battery, {hews, without any trouble, the whole £ro- 

 grefs of the charge 5 and, remaining in the fame fi- 

 tuation, the force of different explofions may be as- 

 certained with the utmoft exactnefs before the dif- 

 charge. 



If a jar be loaded with pofitive electricity, and I 

 want to know the exact time when, by attempting to 

 charge it negatively, it firft becomes difcharged, I fee 

 every ftep of its approach to this ftate by the falling 

 of the index - 3 and the moment I want to feize, is 

 the time when it has got into a perpendicular fitua- 

 tion, which may be obferved, without the leaft dan- 

 ger of a miftake. Accordingly I find that, in this 

 cafe, not the leaft fpark is left in the jar. If I con- 

 tinue the operation, the index, after having gained 

 its perpendicular pofition, begins to advance again, 

 and thereby mews me the exact quantity of the op- 

 polite electricity that it has acquired. 



Vol. LXIL A a a Confi- 



