f 6 34 ] 
not afingle inftance of mifchief from lightninghad hap- 
pened in that city. He informs me further, that at 
Philadelphia in a thunder fiorm, the lightning was 
feen to firike the ridge of a houfe, upon which an ap- 
paratus of this fort was eredted. The lightning, like a 
ball of fire, ran from the ridge of the houfe to the 
apparatus p^nd in running down, it melted the con- 
dudling-wire, without doing any damage to the houfe. 
This (hews the expediency of applying either large 
wires, or fmall rods, in which the melting will molt 
probably be prevented ; notwithstanding it has been re- 
peatedly found, that, though the wire has been melted, 
it has never failed of firft anfwering the purpofe of a 
conductor, and preventing the mifchiefs threatened 
by the lightning. 
Though the mifchiefs arifing from lightning are 
not very frequent in Great Britain, yet at times they 
are fevere enough to be very alarming. The damage 
occafioned by a thunder ftorm in July 1759 in Lon- 
don, and in various other places at no great difiance 
from it, are very frefh in our memories. I fubmit 
it therefore to your Lordfhip, how far it would be at- 
tention mifapplied to think of an apparatus of this 
fort in his Majefiy’s powder magazine, eredting at 
Purfleet. The expence would be trifling j and 
every argument, which is produced of their expedi- 
ency in preventing mifchiefs arifing from lightning 
on board of fifips, will have more force in this in- 
ftance; where frequently an immenfe quantity of gun- 
powder muft be colledted within a comparatively very 
lmall fpace. 
As motives of humanity, and the hopes of public 
utility, are the caufe of my troubling your 
