274 Vefcrlption of an mproiJed EleBrovieter. 



ftrcngth of the repulfive power is pointed out by fourteen 



grains. 



If an eleftric power of twenty-five grains be required, the 

 ring S muft be removed to 27, and the weight of feventeeii 

 grains be put into the flicll H in order to produee a pre- 

 ponderance of four grains in regard to S. Thefe ieventeen 

 grains are added to the required power of twenty-five grains, 

 and the ring Q is puflied to 42, &c. In this manner the 

 repulfive power always a6ls before the attra6tive power 

 can. 



It may be readily perceived that the faults and inconve- 

 niences common to all the eleftrometcrs hitherto employed, 

 and which have been already mentioned, cannot take place 

 here; becaufe the difcharging is performed by immediate 

 connexion between the pofitive and negative eleftricity in 

 the inftrument itfelf, without any external means being 

 employed. 



One of the moft effential advantages of this inftrument is, 

 the certainty with which the fame refult may be expefted 

 when the experiment is repeated. For the fame degree of 

 ele£lric power, whatever be the temperature of the atmo- 

 fphere, will always be necefl'ary to commence the feparation 

 of the two balls B and E from each other, the quantity of 

 coated glais and the diftance of the ring Q from the axis L. 

 being the fame. 



Another no lefs important advantage of this inftrument 

 is, that in an experiment where the fame elc6tric power, 

 often repeated, is necefl'ary to afcertain the refult with accu- 

 racy ; fuch, for example, as the charging a battery through 

 acids, water, &c. ; the fame degree of precaution is not ne- 

 ceffary as is indifpenfibly fo in any other eleftrometer, as the 

 perfon who puts the machine in motion has nothing to do 

 but to count how often the eleftrometer difcharges itfelf ; and 

 the inftrument may be inclofed in a glafs cafe, or prevented 

 in any other manner from external eontaiSl, or any other cir- 

 cumltances which might render the experimtnt uncertain. 



Iflattef 



