AND LIGHTNING CONDUCTORS. 79 



what has already been stated, and from other well-attested 

 facts that will appear in the sequel, there is no reason to 

 suppose that such a fashion of conductors has ever been con- 

 ducive to lessen either the violence of thunder-storms, or of 

 an individual flash of lightning. 



51. Franklin's limited experience in atmospheric electri- 

 city could not be expected to afford very profound ideas 

 respecting the electric condition of thunder-clouds, on 

 which account he wisely hesitated in giving a decided 

 opinion, although he was led to suppose that, although they 

 are occasionally positive, they are more frequently in a 

 negative state.* With respect to his pointed conductors, 

 however, it appeared to him to be a matter of no conse- 

 quence in what direction the lightning traversed them, as 

 they would be ecjually efficient whether it proceeded frona 

 the clouds or from the ground. Had these views been 

 correct, we should never have heard of lightning explosions 

 taking place upon those conductors below their highest 

 points; because, as they are exposed on every side to the 

 non-conducting air, or to bodies of very inferior conduction 

 to themselves, electrical discharges from the ground would 

 traverse their whole length, and invariably quit them at their 

 highest points. Moreover, as the electric element would 

 select the best conductors, and escape most freely from 

 those with sharp terminations, comparatively low objects, 

 situated close to tall-pointed conductors, would not be liable 

 to suifer from upward discharges of lightning. But since 

 it is well known that lightning frequently strikes pointed 

 conductors much below their upper extremities, as well as 

 comparatively low objects vicinal to them, it is obvious 

 that in those cases the discharges proceeded from the clouds, 

 and that the efficiency of pointed conductors in guiding 

 strokes of lightning, and preventing damage, is much less 

 perfect for dovmward than tor upward discharges. 

 * Pbilosop'uical Letters and Papers. 



