34 



THE POPULAR SCIENCE MONTHLY. 



In London the system has been in successful operation for about 

 five years, and has been used over a wire four hundred miles long. 

 The subscribers number about five hundred, among them many rail- 

 roads and public institutions. 



In connection with the synchronized clocks, Messrs. Barraud and 

 Lund have also established time-bells and flashing-signals, which afford 



Fig. 15 Barraud and Lund's Time-Bell. 



time-signals both to the ear and eye. These are shown in Figs. 15 and 

 16. The bell is an ordinary electric bell, and is rung by the regulat- 

 ing clock, which closes the circuit at the instant the signal is desired. 

 The flashing-signal consists of a red vertical disk on a vertical axis, 

 which normally shows only its edge, but is made to revolve once on 

 its axis in four sudden jumps, by simple mechanism in connection with 

 electro-magnets, when the regulator, by closing the circuit, sends the 

 current. The appearance is that of two flashes of red as the disk 

 revolves. 



In many places where noise prevents hearing a bell, the flashing- 

 signal becomes a necessity. It is in use at the London Stock Ex- 



