1824.] Conductors of Lightning. 433 



these plates. But if we can rest against the brace C D, fig*. 8, 

 we should solder two ears to tke stem to embrace the upper 

 and lateral faces of the ridge, and descend to the brace, on which 

 they are fixed by means of the bolt, E. 



Lastly, if the paratonnerre be to be fixed on a vaulted roof, it 

 should be terminated by three or four feet, or spurs, which must 

 be soldered into the stone, with lead, in the usual manner. 



Of the Conductor of the Paratonnerre. 



The conductor, as has been stated, is an iron bar about three- 

 quarters of an inch square, B C D E F, fig. ] , or B' C D' E' F', 

 reaching from the foot of the stem to the ground. It is firmly 

 united to the stem, by being tightly jammed between the two 

 ears of the collar O, fig. 4, by means of a bolt; or it may be 

 terminated by a fork M, fig. G, which embraces the tail, N, of 

 the stirrup, and the two pieces bolted together. 



As the conductor cannot be formed of a single piece, several 

 bars are united end to end. The best method of doing this is 

 seen at fig. 10. The conductor is supported parallel to the roof, 

 at about six inches distance from it, by forked stanchions, which, 

 in order to prevent their letting the rain into the building, are 

 fashioned as follows : 



Instead of terminating in a point, they have a foot, figs. 11 

 and 12, formed of a thin plate about 10 inches long, and 1-J- inch 

 broad, at the extremity of which rises the stanchion, making 

 either a right angle with the foot, fig. 11, or an angle equal to 

 that which the roof forms with the zenith, fig. 12. The foot 

 slips in between the slates, but for greater firmness a plate of 

 lead is substituted for the lower slate, and the foot of the stan- 

 chion and the lead are nailed down to one of the rafters. The 

 conductor is kept in the forks by pins rivetted through them, 

 and the stanchions are placed at about 12 feet distance from 

 each other. 



The conductor, after turning over the cornice of the building, 

 fig. 1, without touching it, is brought into the walls, down 

 which it passes to the ground, and is fixed by means of cramps 

 let into the stone. When it has reached to D or D' in the 

 ground, about two feet below the surface, it is bent at right 

 angles to the walls in the line D E or D' E', and carried in that 

 direction about 12 or 15 feet, when it turns down into a well, 

 E F, or a hole, E' F', about 12 or 15 feet deep in the ground, it' 

 no water be met with, but a less depth is sufficient if there be 

 water. 



The iron buried in the ground in immediate contact with 

 moist earth becomes covered with rust, which, by degrees, 

 penetrates to its centre, and destroys it. This is prevented by 

 placing the conductor in a trough filled with charcoal, D E, or 



New Series, vol. vm. 2 r 



