[ SI ] 
ferences in the circumffances of our experiments, fre- 
quently caufmg very material differences in their re- 
fults. And perhaps no one, who has not applied his 
mind clofely to enquiries of this kind, could con- 
ceive how the pointing a piece of metal, or not , fhould 
make any material difference in the experiment. 
The electrician has it always in his power to con- 
vince any one of the faCt, who, through inexperience, 
may be inclined to entertain the lead: fcruple about 
it : for even from thofe experiments to which it was 
thought proper to appeal at the committee, it ap- 
peared, that the difference in the effects upon this 
fluid, between pointed and blunted metal, is as 
12 to r. 
A thunder-cloud therefore, according to that rea- 
foning, (the circumflances of it being fuppofed to be 
nearly fimilar with what is called the prime-conduCtor 
in thofe experiments), if it aCted at 1200 yards di- 
flance upon a point, would require a blunted end to 
be brought within the diflance of 100 yards j and 
beyond thofe limits, would pafs over it, without af- 
fecting it at all. On this occafion permit me to 
obferve, that the longer the conductors are above any 
building, the more danger is to be apprehended from 
them ; as they will in that cafe approximate nearer in 
their effects to thofe that are pointed. And that is 
one reafon why I was not for adviling the propofed 
conductors at Purfeet , to be fo high as ten feet above 
the maga 2 ines, and more particularly upon that 
building called the Board-houfe , which (lands con- 
fiderably higher than the magazines themfelves. 
But, before we advance farther into this fubjeCt, it 
may be proper to fhew the reafons for introducing a 
