110 



How they 

 ought to be 

 made and 

 applied. 



Instance of 

 «ecuri;y. 



Another. 



i»llEVENTION OF DAMAGE BY LICHTNINCf. 



rod down any way that is most convenient, without consi- 

 dering wiiethci' it passes near or even touches any conduct'^' 

 in<; substance in the building; in which case the rod, in- 

 stead of protecting, is calculated to bring on the building 

 the mischief it was iuleuded to prevent. 



Electric rods should be three quarters of an inch in ^ 

 diameter, according to ray opinion ; should not touch the 

 building in any part by three inches; and all their fasten- 

 ings to it should be by nonconductors. They should end 

 in a single point of brass, and this point be elevated six 

 feet at least, but ten feet if possible, above the highest 

 chimney of the house. If the rod is not of brass, or b.tube 

 of brass, a strong brass wire ought to be wound round it, ' 

 connected with the point, and passing once round the rod 

 in the space of 12 or 18 inches, sufBcient to keep the brass 

 wire close to the iron, all down to the earth. I have no 

 doubt upon my mind, from all the observation I have 

 made, that electric rods of this nature will never fail to give , 

 perfect safety. Even on board vessels an iron chain, the 

 worst of all conductors that can be called a conductor, has 

 been known to preserve the. vessel and crew. As a proof, I 

 will quote a passage from Captain Cook's Journal of his 

 Second Voyage Round the World. " April 25, 1774» 

 *• Otaheite — This day we had a very violent tempest. We. 

 *' were obliged to get our electrical chain up to the top- 

 *' gallantmast head, td secure the masts. Removed all 

 ** the iron off the decks, and secured down all the hatches. 

 *' — As the seaman, who carried the chain up, was 

 *' coming down, he got foul of the chain, and it lightning 

 *' at the same time, he received a slight blow on the leg, 

 *' which, though it did him no harm, shook every bone 

 ** within him." Captain Cook had seen an instance of the 

 great utility of the electrical chain in his former voyage, 

 while at Batavia, which, being of a singular nature, I shall 

 relate in his own words, or as they are given by Dr. Hawkes- 

 worth. " About 9 o'clock we had a dreadful storm of 

 " thunder, lightning, and rain, October 10, 1770, du- 

 " ring which the mainmast of one of the Dutch East 

 " Indiamen was split, and carried away by the deck . 

 ** The main topmast and topgallautmast were shivered 



all 



