DEVELOPMENT OF THE TELEGRAPH 



In this connection it is interesting to note that this 

 Doctor Jackson was the same man who contested 

 Doctor Morton's right to the discovery of etherization. 

 As with Robert Hooke, claiming other men's discoveries 

 seems to have been almost a mania with him. 



PRINCIPLE OF THE MORSE TELEGRAPH 



The principle involved in the Morse telegraph is the 

 same as that which was so graphically illustrated by 

 Professor Henry with his magnet and falling weight 

 referred to a moment ago. As illustrated by this experi- 

 ment, tapping sounds could be made at any desired 

 intervals by simply making and breaking a current 

 conducted along a wire. If a metal hammer, or arma- 

 ture, is so placed that it is held by a spring at a 

 short distance above a soft-iron core around which is 

 wound insulated wire connected with a galvanic battery, 

 it is obvious that when the current is passing along this 

 wire, making the soft iron a temporary magnet, the 

 metal hammer will be drawn against this core and held 

 there as long as the current is unbroken. On breaking 

 the current, however, the hammer will be released and 

 fly back to its original position. As this magnet can be 

 made to act instantaneously and with great force, a 

 sharp tapping sound will be made by the hammer as it 

 snaps against the magnet when the current is closed. 



If a key so arranged that by pressing a button the 

 circuit will be closed and broken when raised is placed 

 somewhere along the course of the wire, the hammer or 

 armature may be made to give a series of taps or blows 



[*3l 



