MAGNETIC TELEGRAPH. 125 



be here given. It has already been stated, that a piece 

 of soft iron becomes a magnet, when a current of elec- 

 tricity circulates in a coil surrounding it. Now, sup- 

 pose the two ends of such a coil, situated in a distant 

 city, to be made long enough to reach a battery in 

 the place where the reader resides, and to be stretched 

 along over posts, and connected with the poles of the 

 battery. The current occupies no perceptible time in 

 its passage. Therefore, as soon as the battery is set 

 in operation, it circulates through the whole extent 

 of the wire, and, of course, through the coil in the 

 distant city. The piece of iron which it incloses 

 is made a magnet, and will immdiately lift its arma- 

 ture. If the current is stopped, the piece of iron ceases 

 to be a magnet, and drops its armature. But the 

 operator at the battery can send or stop the current at 

 will, by simply disconnecting one of the wires, and 

 thereby lift or let fall the armature a hundred or a thou- 

 sand miles off, as often as he pleases. He can have 

 an understanding, also, with the person in the distant 

 city, who sees the motion of the armature, as to what 

 it shall mean. One lift may indicate the letter A ; two 

 lifts, the letter B ; and so on. So any thing may be 

 spelled out, and it thus becomes possible to commu- 

 nicate ideas by electricity. If these lifts of the arma- 

 ture can be made to record themselves on a slip of 

 paper, the further advantage of writing at the distant 

 station is gained. And this is precisely what is realized 

 in Morse's telegraph, and more particularly described in 

 all recent works on Natural Philosophy. 



