306 Mr Harris on the Utility of fixing 



never depart in inquiries of this kind, will illustrate very satis- 

 factorily the operation of lightning-rods as a successful means 

 of defence in thunder storms — the cases (e) (y), p. 158, already 

 alluded to, is a striking illustration : indeed, if a great natural 

 experiment could have been instituted for the purpose of deter- 

 mining the utility of a lightning-rod, such should have been the 

 conditions under which it should have been placed. In a me- 

 moir presented to the Royal Academy of Sciences at Paris, in 

 the year 1790, by the celebrated French philosopher Le Roy, 

 we find two French frigates successfully protected by lightning- 

 conductors, which completely disarmed the fury of the vivid 

 flashes that assailed them, and transmitted the electric matter 

 securely to the sea. In Mr Kinnersly's account of the stroke 

 of lightning which assailed Mr Wesfs house in Philadelphia *, 

 we find that the lightning-conductor effectually performed its 

 office. Charles'' church and steeple, at Plymouth, struck by 

 lightning a few years since, were protected in a similar way ; 

 the electric matter passed down in a dense stream over the con- 

 ductor, into the ground, tearing up the ground in its course. 

 It is worthy of remark, that, of six church-towers in Devon- 

 shire, struck by lightning within a few years, the only one 

 which escaped damage was the church at Plymouth, which last 

 was also the only one defended by a lightning-conductor. The 

 cases of the Warrior and Norge, already mentioned, are also 

 striking Instances. In the fifty-second volume of the Transac- 

 tions of the Royal Society, there is an instance mentioned, of a 

 ship, called the Generous Friends, twice preserved by a light- 

 ning-conductor. Captain Winn observed, that his chain-con- 

 ductor was broken for a short distance above the ship's side, 

 leaving an interval of about three-fourths of an inch ; over this 

 space the electric matter was observed to pass in the form of 

 sparks, during two hours and a half, at the time of a thunder- 

 storm -f-. 



28. It is therefore by no means unreasonable to consider the 

 conducting power of a lightning-rod as arising, not out of any 

 attractive property inherent in it, but from an action purely 



* Priestley's History of Electricity. 

 f Transactions of the Royal Society. 



