LIGHTNING AND LIGHTNING CONDUCTORS. 9 



the transit of the lightning from the mast-head to the sea, 

 some of which, to an electrician of the present day, would 

 l to be sufficiently alarming to discountenance in toto 

 particular plan of conductors, notwithstanding that 

 they were originally projected by Mr. Henley, one of the 

 ablest practical electricians of the last century,* who, no 

 doubt, was led into the error from a want of more expe- 

 rience than could possibly be afforded at the time he pro- 

 posed them. In a paper, by this excellent electrician, 

 which appears in the Transactions of the Royal Society, 

 the author states that if instead of chain conductors " plates 

 of copper rVin. thick and 2in. broad, with the edges neatly 

 rounded off, were inserted in a groove and continued down 

 the main-topgallant-mast, the main-topmast, and part of the 

 main-mast, into the well-hole; a communication from the 

 mast to the underside of one of the decks might be made 

 with a plate of metal flattened at each end, and from that 

 rod the conductor might be continued by plates of lead or 

 copper on the underside of the deck and down both outer 

 sides of the ship as low as the keel, if it be thought neces- 

 sary; and this method, I should apprehend, would be pre- 

 ferable to the chains, now in use. Particular care should be 

 taken to have all the plates which form the conductor as 

 nearly as possible in contact with each other, and to fix a 

 sharp pointed slender rod of copper at its summit. And, for 

 the purpose of connecting the plates inserted in the main- 

 topgallant-mast, the main-topmast, and main-mast, if a hoop 

 of copper were fixed in a groove of its own thickness at the 

 top of the main-mast, and another such hoop at the upper 

 end of the main-topmast, perhaps they might answer this 

 end very conveniently." 



71. It seems pretty clear, from Captain Duntze's official 

 report alone, that explosions took place below deck as well 



• See Mr. Henley's paper on this subject, in the Philosophical Transactions 

 of the Royal Society for 1774. 

 C 



