CHAP. II.] 



LIGHTNING-COND UCTORS. 



541 



inflammable particles, from which the current of electricity must be 

 kept as far as possible. 



Ships at sea, from their form and the height of their masts, are 



FIG. 347. Lightning-conductor with multiple points. 



much exposed to the strokes of lightning. It is therefore very import- 

 ant to provide them with one or more lightning-conductors, whose 

 vertical rods are fixed to the summits of the masts. The conductors 

 may be either rods or metallic ropes, which join the copper covering 

 of the keel. The constant communication with the immense mass of 

 the sea, renders the protection of this apparatus always effectual. 

 Harris has invented for the protection of ships a system of 



