THE WORKS OF A WATCH. 



to cause that to revolve once. But as the former, 

 B, requires four hours for one revolution, it must 

 occupy twelve in making three : and consequently 

 the thirty-six toothed wheel will take twelve hours 

 to complete one. To its axle, therefore, the index 

 is attached, which we call the hour-hand of the 

 watch. The axle is a cylinder which incloses the 

 axle of the minute-hand, so that both revolve, in- 

 dicating the hours and minutes on the same circle 

 of the dial. 



It has taken some hundred years to perfect a 

 common time-piece, and the account of the suc- 

 cessive improvements is very curious. 



