No. 8. 



Lightning Rods, JVo. 1. 



249 



electrified body, as seen in fig. 3, it will re- 

 Fig. 3. 



^ 



ceive a spark when brought within striking 

 distance, accompanied by an explosion ; and 

 the body so approached, will be found to 

 have parted with its electricity. This is 

 called the explosive discharge. 



21. But if a pointed wire be presented 

 in like manner as sliown in fig. 4, no spark 



Fig. 4. 



or explosion will ensue, but the charge will 

 be removed even more completely than in 

 the former case, before it has been brought 

 within several times the .striking distance 

 of the body. This is called the silent dis- 

 charge. 



22. Again, if both the ball and point be 

 presented at once, as seen in fig. 5, only 

 with the latter at three or four times the 

 distance of tiie former — still the discharge 

 will take place silently, and the ball will 

 not receive a spark. 



23. If, however, the point be presented 

 along side of, and close to a larger obtuse 

 body, without actual contact, as seen in 



Fig. 5. 



fig. 6, it will be found that the discharging 

 Fig. 6. 



power of the point is greatly diminished, if 

 not entirely destroyed. 



24. The same effect will be still better 

 observed, if the point be passed through a 

 broad moveable ring, as seen in fig. 7. The 



Fiff.l. 



discharging power of the rod will increase 

 or diminish, as the ring is made to recede 

 from, or approach the point. 



