Lightning-Conductors in Ships. 311 



to the table already given, (page 179): admitting that quantity 

 of metal is the great requisite for a conducting rod, it must be 

 equally efficient in any form. For the conducting power of the 

 mass must consist of the conducting power of all its parts ; now 

 it would be absurd to suppose that a mass of metal, expanded 

 into any extent of surface, would not conduct in all its parts ; 

 indeed, our experience is positively conclusive as to this point, 

 since it is quite impossible to destroy one portion of a perfectly 

 homogeneous metallic surface by artificial electricity, without 

 destroying the whole ; nor is there any instance of the kind on 

 record in cases of damage by lightning. The case of his Ma- 

 jesty's ship Badger, struck by lightning at Chatham in August 

 1822, is in point here; the electric matter, which shattered the 

 mast, &c. finally precipitated itself upon the copper lining of 

 the galley, and was immediately lost. We do not take into the 

 account any immediate edge or single point, upon which the 

 whole force of the explosion is at first concentrated, or the occa- 

 sional fusion of some points in metallic surfaces not perfectly 

 homogeneous ; since we know, for example, that a given elec- 

 tric explosion may be equivalent to fuse some metals and not 

 others. 



33. A further confirmation of this principle will be found in 

 the following experiments : — 



Let an accumulation of artificial electricity be passed upon a 

 single wire, just powerful enough to fuse it ; after which, let a 

 similar charge be passed upon two such wires as the former ; in 

 this case neither of them will be fused. If a charge be now ac- 

 cumulated equivalent to fuse both the wires, then, by adding a 

 third, the three will remain. 



84. Let any number of wires be taken, and let a charge be 

 transmitted through them sufficiently powerful to fuse the 

 whole ; if but one more be added in a similar arrangement, 

 they will all remain perfect : the charge, therefore, is equally 

 diffused upon them all. Suppose the wires infinitely near to 

 each other, and divide them infinitely so as to make up a sur- 

 face, and the result must be the same, — for this is but another 

 term for a surface. Now, a wire may be divided into any lesser 

 number of smaller wires, and still transmit a charge, without 

 being heated more than the original wire from whence they are 



