167 



the ground, forming a series of conductors analagous to those 

 of Harris. 



But if lightning rods are useful to protect buildings, still 

 more useful are they for the protection of ships. In the 

 British navy, between the years 1810 and 1815, forty sail of 

 the line, twenty frigates, and twelve sloops, were damaged by 

 lightning. Between 1739 and 1793, seventy-three men sxere 

 killed, and several hundred dangerously wounded by the same 

 instrumentality. The amount of property destroyed cannot 

 be estimated. The main-mast alone of a seventy-four, costs 

 originally $5000. To this must be added the cost of its 

 removal, of ruined spars, rigging, hull and stores, and the daily 

 expenses of the ship, varying from $400 to $550 per day. 

 This estimate glances at the cost of repairing those not totally 

 destroyed by lightning. In the space of forty-six years the 

 average expense thus accruing amounted to $30,000 per 

 annum. Probably some of those ships that " sail from their 

 port and are never heard of more" are destroyed by lightning. 



To the foregoing estimate must be added the casualities 

 occurring to vessels weakened by the electric shock, and after- 

 wards lost in struggle with the wind or the foe. " The 

 Guerriere is an instance," says the Nautical Magazine, "of a 

 frigate fighting a superior force with her mainmast in a defec- 

 tive state, by a stroke of lightning, and which might have stood 

 but for this defect. The mainmast was carried away in battle, 

 by the fall of the foremast across the main stay, which cer- 

 tainly might not have led to this disaster, had the main-mast 

 been in an efficient state. The loss of all the masts was the 

 loss probably of the ship." 



The British government at length resolved to furnish the 

 national vessels with the most approved system of conductors, 

 that of Sir Wm. Snow Harris. This measure was fully justi- 

 fied by the result. For between the years 1828 and 1840, 

 upwards of sixty ships of the line had been exposed to light- 

 ning in all climates without sustaining any damage ; while for 

 the rest of the navy on different stations and not so protected, 

 there were damaged by lightning, 7 ships of the line, 7 

 frigates, 30 sloops, and 6 smaller vessels and steamers, in all 

 50 vessels, averaging more than one-fourth of the British navy 

 in commission. In a period of twenty- two years, of the ships 

 of the navy at sea, those without conductors, compared with 

 those with conductors, the number struck was in the proportion 

 of three of the former to two of the latter. 



