560 PHILOSOPHICAL TRANSACTIONS. [aNNO 1774. 



the point of a lancet, or a wire 5 or 6 inches long, nicely tapered to a point, 

 tipped with steel, towards the conductor; though at the distance of 2 feet, or 

 somewhat more, this will draw off all its electricity silently; and not suffer a 

 spark to pass from it to the brass ball: it is also observable, that if the point of 

 the wire, or lancet, be brought nearly into contact with the prime conductor, 

 yet no sensation is felt in the arm, &c. of the operator. Hence appears clearly 

 the preference due to points, rather than round balls, or blunted ends, for the 

 termination of the conductors erected as a security to buildings, &c. from damage 

 by lightning; for it seems probable, that the sharp point of the conductor will 

 act on the electric atmosphere of the cloud, and perhaps gradually and silently 

 continue to diminish the contents, before the cloud can approach near enough to 

 strike; and thus contribute to lessen, if not actually prevent, a stroke. But 

 should the point be struck, the consequence I suppose will not be great, and a 

 curious instance I have now before me, which I shall beg leave to quote as fol- 

 lows. " About 9 o'clock we had a dreadful storm of thunder, lightning, and 

 rain, during which the main-mast of one of the Dutch East Indiamen was split, 

 and carried away by the deck; the maintop mast and top gallant-mast, were shi- 

 vered all to pieces; she had an iron spindle at the maintop gallant-mast head, 

 which probably directed the stroke. This ship lay not more than the distance of 

 2 cables length from ours, and in all probability we should have shared the same 

 fate, but for the electrical chain which we had but just got up, and which con- 

 ducted the lightning over the side of the ship ; but though we escaped the light- 

 ning, the explosion shook us like an earthquake, the chain at the same time 

 appearing like a line of fire; a centinel was in the action of charging his piece, 

 and the shock forced the musket out of his hand, and broke the ram rod. On 

 this occasion I cannot but earnestly recommend chains of the same kind to every 

 ship, whatever be her destination ; and I hope that the fate of the Dutchman 

 will be a warning to all who shall read this narrative, against having an iron spindle 

 at the mast head." See Capt. Cook's voyage. This conductor was of copper 

 wire, tV of an inch in diameter; which I am inclined to think is rather too small 

 for the purpose; I am of opinion it ought to be a quarter of an inch at least; 

 as I have l)een informed by Dr. Solander, that the point originally belonging to 

 the conductor, had been stolen; and that this, on which the lightning fell, was 

 of inferior workmanship, and not so sharp ; which was another great disadvantage : 

 perhaps if the wire of the chain had been larger, and the point more acute, the 

 stroke would have been much lessened, if not absolutely prevented. If, instead 

 of those chains, plates of copper, -'^ of an inch thick, and 2 inches broad, with 

 the edges neatly rounded off, were inserted in a groove, and continued down the 

 maintop-gallant-mast, the maintop-mast, and part of the main-mast, into the 

 well-hole: a communication from the mast, to the underside of one of the decks, 



