DEVELOPMENT OF THE TELEGRAPH 



message. Such an arrangement necessitated the use of 

 at least twenty-five wires, one practically for each letter 

 and one extra for the return current, and was, of course, 

 impracticable. 



One of the most ingenious things about this chemical 

 telegraph was an arrangement whereby the attention of 

 the receiving operator could be attracted at any time. 

 The sending operator could ring a bell of the receiving 

 machine by simply pressing a button which closed one 

 of the circuits for a few seconds. It was so arranged that 

 the bubbles of gas produced at the metal point of this 

 particular circuit accumulated under an inverted cup 

 attached to a lever and immersed in the fluid of the re- 

 ceiving apparatus. The accumulation of gas naturally 

 caused the cup to rise toward the surface, and lifting at 

 the same time the lever, it released a small leaden ball 

 which fell upon the alarm bell and attracted the opera- 

 tor's attention. 



The objection to this form of telegraph, or at least 

 the most vital objection, lay in the fact that such a great 

 number of wires were required in its operation. These 

 wires were arranged by Sommerring in the form of a 

 cable, but this of course was very expensive and dif- 

 ficult to repair when injured. An improvement over 

 Sommerring's device was what is known as Schweigger's 

 telegraph, constructed on the same principle, but with 

 the number of wires reduced to two. In using this 

 telegraph a signal code was of course necessary, but 

 this requisite was also carefully worked out by Schweig- 

 ger. In actual practice, however, neither of these tele- 

 graphs was of sufficient value to make them of any 



