592 Whether Lightning Rods attract Lightning. 



The notion that a lightning rod is a positive evil, appears to have 

 arisen entirely out of assumptions, and a partial consideration of 

 facts. Thus in consequence of the track of a discharge of lightning 

 being always determined through a certain line or lines, which upon 

 the whole least resist its progress (48), it has often been found to fall 

 in the direction of pointed metallic bodies, such as vanes, vane 

 spindles, iron bars, knives, &c. The instances in which these 

 bodies seem to have determined the course of lightning have 

 been carefully recorded, the phenomena being peculiarly striking 

 and remarkable (54) ; but on the other hand, no attention has been 

 given to those instances in which lightning has altogether avoided 

 such bodies, and passed in other directions (46). Now it will be 

 found, as we shall presently show that the action of a pointed con- 

 ductor is purely passive. It is rather the patient than the agent ; 

 and such conductors can no more be said to attract or invite a dis- 

 charge of lightning, than a water-course can be said to attract the 

 water which flows through it at the time of heavy rain. 



We have shown, in a former section (71), what quantity of me- 

 tal is really sufficient for the perfect conduction of any quantity of 

 lightning liable to be discharged in the most severe thunderstorms : 

 therefore, to assume that any conductor which may be applied is not 

 sufficiently capacious, is to reason against experience, and to 

 resort to a species of argument quite foreign to the conditions of 

 the case. It would be, as if we were to insist upon the danger of 

 applying water-pipes to buildings, under the assumption that we do 

 not really know what quantity of rain may possibly fall from the 

 clouds, and that hence the pipe may after all be too small to con- 

 vey it. 



In all these reasonings we should recollect, as already explained 

 (10), that the forces in operation are distributed over a great ex- 

 tent of surface, and that the point or points upon which lightning 

 strikes is dependent on some peculiar condition of the intervening 

 air, and the amount of force in operation, — not in the mere pre- 

 sence of a metallic body projecting for a comparatively short dis- 

 tance into the atmosphere, — " that such bodies provoke the shaft 

 of heaven is the suggestion of superstition, rather than of science."* 

 * Leslie, Edin. Phil. Magazine. 



