17 



When the machine is turned the "cloud" gradually becomes Charged with posi- 

 tive and tJie ''earth'' with negative electricity, and by bringing the cloud and earth 

 close enough together sparks, or flashes, occur which look exactly like the flashes 

 of lightning seen during thunderstorms. After each flash the plates again become 

 charged gradually. 



Rods on Toy Buildings Pkevent Flashes. 



Here is a T-shaped house with metal gutter to the eave-trough, whence two 

 conductor-pipes run down nearly to the ground. One conductor-pipe is connected 

 with the metal floor of the balcony. The house, which has a screen door, is placed 

 on the earth plate. (Fig. 20.) As the machine is turned a flash occurs to the 

 chimney, and thence the current follows the gutter and eave-trough, then flashes to 

 the screen door, which is so constructed that the current has air-gaps to jump. 



Fig. 21. — A woman stands under the 

 balcony and is struck. Note short flash 

 from balcony to woman's head. The gut- 

 ter, conductor-pipe, metal floor of balcony 

 and the woman form an easier path than 

 that by the screen door. 



Fig. 22. — The woman goes to the rain 

 barrel for a pail of " soft water " and is 



struck. This path is now the easiest for 

 the flash. 



making tiny sparks as it does so. From the door it flashes to the ground plate. 

 Note that flashes or sparks occur only where the current jumps air-gaps. 



A little metallic figure, representing a woman, is placed in front of the screen 

 door, and the flash strikes the woman instead of jumping the air-gap at the floor. 

 If the woman stands under the balcony the lightning takes a new path. (Fig. 21.) 

 Instead of going by the screen door it follows the eave-trough to the balcony floor, 

 thence strikes the woman and passes to the earth. Tlie new path offers lesa 

 resistance than the old. 



If the woman goes to the rain barrel for a pail of "soft water" the lightning- 

 takes another path still, following down the gutter, eave-trough, and conductor- 

 pipe, and thence striking the woman. (Fig. 22.) 



A copper wire without points is now put on the building, so it is in contact with 

 the chimney and leads down to the earth plate at each end. The flash now follows 

 the wire, and the woman is perfectly safe, standing at the eave-trough, under the 

 balcony, or at the scrcon floor. (Figs 23 A and 23E.) The copper wire ofl'ers les? 



