[ i68 ] 
as has been already mentioned, communicates with 
the leaden pipes, and thefe with the ground. 
Thefe towers, from their near fituation to the cu- 
pola, which is a building fo much higher, may pof- 
fibly be Ids liable to milchiefs from lightning than if 
they were erefled at a more confiderable diifance. 
As the diredlion of the lightning is, however, uncer- 
tain, from a variety of caufes, as alfo to what extent 
one building will protect another, the Committee are 
of ojdnion, that this apparatus to the towers will be 
expedient. 
It is to be remarked, that wherever iron is em- 
ployed as a condudlor of lightning, efpecial care muft 
be taken to prevent its becoming rufty ; as, from be- 
ing long expofed to the moift atmofphere, it will be 
corroded to a confiderable depth : and fo much of the 
iron as is corroded ceafes to be of ufe as a condudlor ; 
the Committee therefore have, in direding the fize of 
thefe iron bars, made fome allowance for the wafte of 
the iron by ruft. 
The fize, as well as number, of the iron bars re- 
commended here by the Committee, are only to be 
confidered as applicable to St. Paul’s, and not as a 
flandard for any church or building of lefs dimen- 
lions ; as in thefe laH, condudfors of a fmaller fize, 
and fewer in number, may anfwer the purpofe as fe- 
curdy as the larger. But St. Paul’s church is parti- 
cularly circumflanced : it is an edifice not only of 
great height, but its cupola, to fay nothing of the lead 
on the body of the church, prefents a large furface of 
metal to the clouds j on .which account it is very li- 
able to receive greater cpiantities of the eleCtric fluid ; 
and, from large quantities of fuch an elahic power. 
