718 



Experiments on the communication of 



[Sept. 



In the diagram the connexion is made with No. 2, and the dotted 

 line shews the deflection of the needle — and this deflection may be 

 reversed by crossing the course of the battery wires, as shewn at R. 

 The five parallel lines at D shew the conductors, which may be in- 

 definitely prolonged. 



Thus by a move of the radius wire to any of the cisterns we can 

 deflect the needle at the corresponding galvanometer ; and by a move of 

 the cross wires we can reverse the deflection at our pleasure. 



We have here a combination which affords sufficient numbers for 

 spelling, numbering, dictionary and cypher signals. Even four gal- 

 vanometers which can be worked by five wires, will afford the 

 necessary combinations for every description of signals.* 



* This telegraph has been actually laid down between London and Drayton, and r 

 to be carried on to Bristol. Though extremely ingenious, I shall presently prove that 

 the railway itself without any special conductors, or at most with one wire, is a perfect 

 telegraphic line. 



