Mr. brook’s Account, 6cc. 
greater or leffer charge or power, bv an arm being repelled to a 
greater or Idler diffance, or by ffriking differently at different 
diffances, yet the power of the charge was not in any manner 
afcertained ; we could lay, that the arm or index was repelled 
to iuch or fuch a number of degrees of a circle, or that it 
ft ruck to fuch or fuch a diffance ; but the repulfve power of a 
charge to repel the index fo much, or l'o many degrees of a 
circle, or the flrength of the charge to ffrike to fuch a dif- 
tance was not (that I know of) in any manner intelligibly 
aicertained. This fhews it by the weight that the repulfive 
power has to lilt up in grains, &c. ; which weight is to 
be proved by any tolerable pair of fcales and weights ; and I 
do not know any other method that has been yet tried to fhew 
the dilferent ftrength of charges fo good as that of repulfion. 
All the neceffary parts of the inffrument being made of 
metal and glafs that is pretty ffout, 1 think, the eledfncity 
is lefs liable to efcape than by wood, See. I have tried 
reeds on account of their being light, and covered them 
with tin-foil, or gilded them to make them good condudfors ; 
but fo frequently found inconveiiiencies from them by points 
riling up, the celerity of moving, and the different weight of 
them at dilferent times owing to moiffure, change of the wea- 
ther, and the like, that I have laid them all afide, and find my 
prefent inffrument as free from thefe inconveniencies as I could 
expedt ; nor is it liable to be out of order, if proper care is taken 
of it. 
