Electricity 



205 



FIG. in. A wet battery of three cells connected to ring a bell. 



fasten another piece of wire from the carbon of the second 

 cell to the zinc of the third, as shown in Figure in. 



Fasten one end of a copper wire to the zinc of the first 

 cell and the other end of this wire to one binding post of an 

 electric bell. Fasten one end of another piece of copper 

 wire to the carbon of the third cell, if you have three, and 

 touch the other end of this wire to the free binding post of 

 the electric bell. If you have everything connected rightly, 

 the bell should ring. 



Different kinds of batteries. There are many dif- 

 ferent kinds of batteries. The one you have just made 

 is a simple one frequently used for doorbells. Other 

 batteries are more complicated. Some are made with 

 copper and zinc in a solution of copper sulfate ; some, 

 even, are made by letting electricity from a dynamo run 



