C 457 ] _ - 
at 20 of the electrometer ; fometimes the pieces will 
he driven near ten feet from the machine* 
Experiment III. 
A fmall fquare piece of Portland done, with holes 
drilled at each end fo as to admit the wires, was in 
like manner bur ft in pieces, when a fecond coated 
phial was added to increafe the ftroke* 
The iron cramps in ftone buildings are fimilar to 
the wires, and when a building is ftruck by light- 
ning produces a fimilar effect. I obferved, that when 
the tobacco pipe, or ftone, was damp, the experi- 
ment fucceeded better than when dry ; and 1 fre- 
quently found, that either of them, after being firft 
dipped in water, would be broken with a lefs explo- 
fion than before. 
This obfervation is different from the received 
opinion of many, not well acquainted with elec- 
tricity, that lightning is lefs likely to do mifehief af- 
ter a fhower of rain than before : fo far may be true, 
that the rain will bring down fome of the lightning* 
and alfo render thatched houfes, &c. lefs likely to 
take fire, but will not affift buildings that have me- 
tallic ornaments near their tops, as the weather- 
cocks of churches, &c. 
As a metallic conductor from the tops of build- 
ings to the earth will prevent the effedts of light- 
ninp' on them, fo will the fmalleft wire prevent the 
effects of electricity on the ftone, or tobacco-pipe, 
when in contadt with the two wires, c c, fig. 2. 
Vol.LVII. Nnn 
If 
