VOL. LXIV.] PHILOSOPHICAL TRANSACTIONS- 56l 



might be made with a plate, or rod 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 the outersides of the ship, as low as the 

 keel, if it be thought necessary: and this method I should apprehend would be 

 preferable to the chains, which are 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 maintop-gallant- 

 mast, the maintop-mast, and the 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 maintop-mast; perhaps they might answer this 

 end very conveniently. Dr. Watson has collected from ancient history, the ac- 

 counts of electrical appearances, on pointed bodies; as the spears of soldiers, 

 &c. &c. which have been very judiciously introduced by Dr. Priestley into his 

 History of Electricity; and I cannot but think those accounts furnish a very 

 strong argument in favour of pointed conductors ; for had the bodies here spoken 

 of been terminated by blunted ends, or round knobs, it is probable that many 

 of them, instead of drawing off the lightning silently, would have been struck 

 with it; and this, being deemed a common occurrence, would have passed unno- 

 ticed, and consequently never have been recorded in history. 



If pointed bodies had really the property of drawing down strokes of lightning 

 on themselves, I think the pillar on Fish-street Hill, commonly called the Mo- 

 nument, could not long have escaped. This pillar is terminated by a basin of 

 metal, 4-J- feet in diameter. The basin is surrounded by a great number of 

 bended plates of metal, sharply pointed, to represent flames of fire. From the 

 basin, to the floor of the gallery, are fixed perpendicularly in a circular order 4 

 thick bars of iron ; and in these bars are inserted 28 strong hoops, and 4 seg- 

 ments of circles, of the same metal, which serve as steps from the gallery to 

 the basin. One of these bars, being 1 inch thick and 5 inches broad, is con- 

 nected with the iron rails of the stair-case, which reaches to the bottom of the 

 building, and forms a substantial, regular conductor of metal the whole length. 

 The monument was erected by Sir Christopher Wren in remembrance of the 

 fire of London, which happened in the year l666. It was completed by that 

 great architect in the year }677; is, including the blazing urn at its summit, 

 about 202 feet in height, from the pavement; and has never, as far as I have 

 been able to learn, been struck by lightning. The antennae and legs of the-- 

 grashopper on the Royal Exchange in Cornhill; and the tongue and tail of the 

 dragon on the spire of Bow church in Cheapside, London, are also remarkable 

 instances: indeed I have often thought it rather a favourable circumstance, that 

 most of the lofty public buildings in this metropolis which have metallic tenni- 



VOL. XIII. 4 C 



