1841] WRITINGS OF JOSEPH HENRY. 197 



The principal facts here detailed, although perhaps not 

 unusual occurrences, afford interesting illustrations of the 

 action of electrical induction. First, the horizontal gutter 

 and the vertical tin pipe, both filled with water, formed a 

 long continuous electrical conductor, extending from the 

 point where the lightning first struck to the lower farther 

 corner of the front of the house ; and this conductor, on ac- 

 count of its length, would be intensely affected by the in- 

 duction of the distant cloud, or rather by that of the ap- 

 proaching discharge. If the electricity of the cloud, were 

 positive, then that of the water in the nearest end of the gut- 

 ter would be negative, and consequently a powerful attrac- 

 tion would determine the lightning on the point where it 

 struck. The house, under these circumstances, might have 

 been damaged even had the rod been much higher than it 

 was, and its connection with the earth much more perfect. 



Again, the phenomena exhibited to the women in the 

 upper chamber were also most probably due to inductive 

 action. After a proper allowance for imperfect observation, 

 occasioned by the fright and confusion of the moment, it is 

 still evident that the one on the floor was in some degree 

 affected by the discharge, although none of the electricity of 

 the cloud actually entered the room, since no traces of it were 

 to be found on the walls or other parts. The effects may 

 therefore be referred to the inductive action of the lightning 

 at a distance and through the wall as it passed along the 

 gutter across the front of the house. When a shock of elec- 

 tricity from a Ley den jar is passed through a slip of tinfoil 

 pasted on one side of a pane of glass, the hand on the other 

 side will receive a slight sensation from the lateral induction 

 through the glass. In the same way, it may be supposed 

 that the effects perceived by these persons were due to the dis- 

 turbance for an instant of the natural electricity of the cham- 

 ber by the passage of a large charge along the outside of the 

 house. 



The discharge, as has before been stated, came from the 

 southwest, and in its passage it crossed obliquely some houses 

 on the opposite side of the street. In one of these, two persons 



