356 



Lightning Conductors in Ships. 



pared with the copper links usually furnished to the British navy, to- 

 gether with the necessary equivalent in copper or iron bolt, in order 

 to obtain a conductor of the same mass. 



The resulting quantities in the last line at the bottom of the table, 

 represent, with the exception of the proposed conductors, the masses, 

 surfaces, and diameters of cylindrical metallic rods, supposed to ex- 

 tend the whole length of the mast. Thus in column 2, we have the 

 diameter and surface of a copper rod, containing 2423 cubic inches 

 of metal, being an equal quantity of matter to that in the proposed 

 conductors, and from which it is calculated. The sums, therefore, 

 are not the result of the addition of the successive masts. The same 

 may be observed in column 3; taking the equivalent in iron. In the 

 third and fourth columns, we have the mass and surface of a copper 

 rod of half an inch in diameter, generally allowed to be adequate to 

 any shock of lightning yet experienced : and, lastly, in column 4, 

 we have the mass and surface in the conductors now furnished to the 

 British navy ; which we find, as compared with the mass in the pro- 

 posed arrangement, is only as 94.4 ; 2423. 



TABLE. 



