TIME-KEEPING IN LONDON. 



337 



error the hand of the time-piece must be set back five minutes. When 

 the setting is done, no further attention is required, all else being 

 automatic. 



The distributor (shown in Fig. 11) consists of twelve contact- 

 springs, each connected with a line of wire running through a district 

 of London, and twelve contact-screws, each connected with a battery. 



^M 



3] 



Fig. 11. Test-Box. 



The springs converging to the center press up against a small plate, 

 one inch in diameter, which is controlled by an electro-magnet in the 

 circuit of the current which the standard clock sends out hourly. 

 When the signal comes, the plate is pulled down and presses every 



vol. xxii. 22 



