and the effects of UgJitning on H.M.S, Rodney^ ^-c. 127 



action; thus we find the points of ingress and egress of an 

 artificial charge, when caused to fall on a slip of gold leaf or 

 other matter, are always those in which the most powerful 

 effect arises ; and when we desire to fire inflammable matter 

 by electricity we place it directly between detached metallic 

 points. 



21. The circumstance of the lightning striking over portions 

 of the wet mast without damage, is precisely the same effect as 

 observed in certain cases of artificial electrical discharges. Thus 

 a very slight film of moisture will allow a jar intensely charged 

 to discharge a luminous ball over a long strip of glass. Dr. 

 Franklin found he could destroy a dry rat by an electrical 

 shock when he failed to hurt a wet one. If we continue to 

 follow the discharge we find similar expansive and destructive 

 effects; such as the bursting of the hoops on the mast, &c., 

 &c., which will sometimes occur and sometimes not. 



22. There is really nothing in all this to call for especial 

 remark, except we may observe, as shown by the experiments 

 already described, that if a good capacious conductor had been 

 incorporated with the mast from the truck to the metallic masses 

 in the hull and to the sea, then these expansive and destructive 

 effects could not possibly have occurred; since the interrupted 

 circuit would have been avoided, and the intense electrical action 

 have vanished, or nearly so, at the mast-head, for it would 

 have no longer been driven to force its way in a dense explo- 

 sive form to the hull and sea: of this we have the most com- 

 plete evidence from experience, particularly in the cases of 

 the ships struck by lightning having such conductors as those 

 just alluded to, curiously enough quoted by Mr. Sturgeon as 

 evidence to the contrary. It seems a strange way of disproving 

 a fact to quote those who, having been eye witnesses, insist 

 upon its truth. That the electric matter finally distributed 

 itself upon the hull as *weU as on the sea, is evident from the 

 circumstance of the casing of Hearle's pump at /, which 

 led through the side under water being shivered ; from the 

 vivid electrical sparks below, and from the usual smell of sul- 

 phur in the well, and appearance of smoke in the orlop-deck. 



23. The interrupted circuit thei'efore to be traced here, is 

 first from the vase-spindle to the copper funnel of top-gallant 

 rigging ; 2nd, from this to the conducting bodies at the heel 

 of the top-gallant mast; 3rd, thence to the metallic masses 

 about the parrel of topsail-yard; 4th, between this and the 

 metallic bodies about the head of lower mast ; 5th, from this 

 over the detached metallic bodies on lower mast ; finally, from 

 lower mast to the hull and sea. The effect of this shock of light- 

 ning appears to have been somewhat palliated by heavy rain. 



