TIME-KEEPING IN LONDON. 



339 



each provided with a projecting pin. When the signal arrives, the 

 electro-magnet attracts its armature, and the two pins are brought 

 close together. The mechanical operation will be understood by ref- 

 erence to Fig. 12, where a side elevation, a plan, and a front elevation 

 are shown. This apparatus is fastened to ordinary clocks just back of 

 the dial-plate (Fig. 13). A curved slot is cut through the dial for a 

 short space on each side of XII, and through this the pins project. 

 When, at the end of the hour, the signal arrives, the two pins are 

 pushed together and bring the minute-hand exactly to XII. The posi- 

 tion of the pins before and just after the operation is shown in Fig. 

 14. Evidently the clock must not be in error more than two minutes 

 or so ; but, as the hand is set every hour, any ordinary clock can be 

 kept right by this device. 



Pig. 13. Face of Clock with Synchkonizer 

 attached. 



Fig. 14. 



Other ingenious arrangements have been added to guard against 

 danger, always present to long lines of wire, and for testing the 

 condition of the lines, but a description of them can not here be 

 given. 



The advantages claimed for the system are : 



1. That any number of clocks of any varying sizes can be syn- 

 chronized to any agreed standard time-keeper. 



2. That the mechanism is, when not in momentary use, entirely 

 detached from the works of the clock. 



3. That it can be applied to existing clocks. 



4. That any failure in the transmission of the time-current leaves 

 the clock going in the ordinary way, to be "set to time " by the next 

 completed current. 



5. That the clocks are kept to time whether having otherwise 

 either a gaining or losing rate, even if such rate amounts to many 

 minutes a day. 



