ELECTRICITY. 349 



of a window,) is fixed into the hole, so that the 

 wire I K stands in the dotted representation L M, 

 then the metallic communication from H to N is 

 complete, and the instrument represents a house 

 furnished with a proper metallic conductor ; but if 

 the square piece of wood L M I K is fixed so that 

 the wire I K stands in the direction I K, as repre- 

 sented in the figure, then the metallic conductor 

 H N from the top of the house to its bottom is 

 interrupted at LM; in which case the house is 

 not properly secured. 



Fix the piece of wood L M I K, so that its wire 

 may be as represented in the figure, in which case 

 the metallic conductor H N is discontinued. Let 

 the ball G be fixed at about half an inch perpen- 

 dicular distance from the ball H; then, by turning 

 the glass pillar C, remove the former ball from the 

 latter; by a wire, or chain, connect the wire E F 

 with the wire Q of the jar P; and let another wire, 

 or chain, fastened to the hook O, touch the out- 

 side coating of the jar. Connect the wire Q with 

 the prime conductor, and charge the jar: then, 

 by turning the glass pillar D C, let the ball G 

 come gradually near the ball H, and when they 

 are arrived sufficiently near one another, you will 

 observe that the jar explodes, and the piece of wood 

 L M I K is pushed out of the hole to a considerable 

 distance from the thunder-house. Now the ball G 

 in this experiment represents an electrified cloud, 

 which, when it is arrived sufficiently near the top 

 of the house A, the electricity strikes it; and as 

 this house is not secured with a proper conductor, 

 the explosion breaks part of it, i. e. knocks off the 

 piece of wood I M.' 



Repeat the experiment with only this variation, 

 viz. that this piece of wood I M may be situated, 



