PHYSICS OF NINETEENTH CENT. ELECTRICITY. 571 



Morse apparatus, which prints the despatch at the receiving station, is 

 shown in Fig. 287. At M' the reader will not fail to recognize a pair 

 of electro-magnets, above the poles of which he will see a bar of soft 

 iron, B, attached to one end of a lever, A, turning on a pivot c. The 

 other end of the lever has a projecting pin with a blunt point. This 

 point, when B is depressed by the attraction of the electro-magnets, 

 applies itself to a groove traced in the cylinder w; but when the current 

 is not circulating it is drawn away by the action of the spring/ A 



FIG. 286. THE NEEDLE TELEGRAPH. 



continuous strip of paper,/, half an inch wide, is drawn from the roll 

 R, by the action of clockwork, during the reception of the message, 

 so that the pressure of the pin indents it with a longer or shorter line, 

 according to the time during which the electro-magnet is in action. 

 Different combinations of two signals, a very short line or dot, and a 

 longer line, indicate the several letters. When a message has to be 

 received, the clerk at the receiving station is warned ; he sets the 

 clockwork of his instrument in motion, and the message is automa- 

 tically wound off printed in the conventional signals of dot and dash, 

 and capable of being read off at leisure, and preserved for reference 



