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I think, a condudor of metal lefs than fix or eight 
inches in breadth, and a quarter of an inch in thick- 
nel's (or an equal-quantity of metal in any other form 
that may be found more convenient) cannot with 
faicty be depended on, where buildings are expofed 
to the reception of fo great a quantity of lightning. 
Thefe are the only points in which 1 have ventured 
to differ from Dr. Franklyn. 
I fhall not think my time ill employed, if thefe 
obfervations contribute to our fecurity againff the 
effeds of lightning. Certainly an inquiry into the 
properties of the eledric fluid, as it furnifhes us with 
the means of preventing fuch accidents, is far from 
being an ufelefs ipeculation. I am. 
your mod humble fervant. 
Old Palace Yard, 
June 28, 1764. 
Edward Delaval. 
XLII. A 
