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Confideratiom to prevent Lightening from doing Mifchief 
to great IV orks , high Buildings , and large Magazines : 
jBy Mr. Wilfon, F.R.S. and Member of the Royal 
Academy oj Sciences at Upfal. 
TONG experience, fince the difcovery by Dr. 
Franklin, has now eftabbfhed a truth amongft 
philofophers, that lightening, like the eieCtric fluid, 
pa lies more freely through iron, copper, and other 
metals, than through dry wood, ilone, or marble. 
Inftances of this truth are innumerable : and to 
convince us thereof, we need only trace the late vio- 
lent effects of lightening on St. Bride’s Church, and 
the houfes in EfTex-ftreet, &c. 
For, upon examining thefe buildings, it appears, 
that there are certain thick bars of iron, through 
which the lightening has paft, without producing any 
vifible effects : and on the contrary, in certain parts 
where the junctions of thofe bars with the hone, or 
wood, are made, there the lightening, rufhing from 
the iron, has broke the ftone to pieces, and fhivered 
the wood. 
From the like experience we alfo learn, that if the 
iron is too {lender for conducting the lightening, it is 
either dafhed into pieces, or exploded like gunpow- 
der; juft in the fame manner as we are able, by the 
eieCtric power, to break and diffipate in vapour a very 
(lender wire. Bars of metal, of a proper thicknefs, 
and conveniently difpofed, feem therefore neceffary 
for the fecurity of inch buildings. 
It is to be noted, that the mifchiefs caufed by lighte- 
ning are not always owing to its direction from the 
clouds to the buildings or other eminences, and thence 
to 
