HISTORY AND PROGRESS. 



29 



would be induced in the coil in one direction; and on 

 lowering it again, a current would traverse the coil in the 

 opposite direction. The ends -(- and were connected to 

 the commutator, and thence to the line wires. The coil a a 

 was called the inductor. 



The receiving instrument placed at the distant station is 

 represented in Fig. 13. It consists of a large coil or multi- 



N 



Fig. 13. 



plier, m m, of insulated copper wire, on a copper frame, the 

 ends -\- and being in connection with the line wires. 



A permanent steel magnet, MM, 18 inches long and 

 3"' X 5'" transverse section, was suspended in the middle 

 of the multiplier by a number of parallel silk fibres from the 

 ceiling of the room. 



To enable the observer to read off with care the small 

 deflections of the magnet, a mirror, N, was affixed to the 

 shaft K, carrying the magnet, in which was seen, through a 

 telescope, R, at a distance of 10 or 12 feet, the reflex of a 

 horizontal scale, s s. 



The commutator, introduced for directing the currents in 

 one direction or the other through the line, consisted of an 



