THE ELECTRIC TELEGRAPH. 



its other appendages much greater power. So long, however, as 

 no more is required than to make it oscillate between the stops 

 t and tf, it may be constructed and mounted so as to be moved by 

 the most feeble degree of magnetism imparted to m m' by a 

 current of extremely low intensity. 



Now let us suppose the axis o of the lever g h to be in me- 

 tallic connection with a voltaic battery placed near to it at the 

 station s', and let the stop t' be in connection with the conducting 

 wire which extends to another more distant station s". When 

 the end g of the lever is brought into contact with the stop if, the 

 current produced by the battery at s' will flow along the con- 

 ducting wire to s" ; and when the lever deserts the stop V y and 

 is thrown upon t, the contact being broken, the current is 



Now it is evident that by this means the original current 

 flowing from the battery at the station s to the station s' is the 

 means of calling into action another current, which flows from the 

 relay battery at the station s' along the conducting wire to the 

 station s", and that the intensity of this current will not be affected 

 in any way by that of the original current from s to s', but will 

 depend solely on the power of the relay battery at s', and the 

 length of the conducting wire from s' to s". 



In the same manner another relay battery may be provided at 

 s", and so on. 



In this succession of independent currents, those only which 

 have signals to work need to have a greater intensity than that 

 which is sufficient to give motion to a light lever, such as we 

 have described above. 



It will be evident also by what has been stated that the pulsa- 

 tions given to the original current at s, and the succession of 

 intervals of transmission and suspension will be reproduced with 

 the most absolute precision in all the succeeding currents, so that 

 all signals which depend on these intervals of transmission and 

 suspension will be made at the final station as promptly and 

 exactly as if the original current from s to s' had been continued 

 throughout the entire line of communication with all the neces- 

 sary intensity. 



175. The lines of electric telegraph which have been constructed 

 and brought into operation in different parts of the world, like 

 the lines of railway, have been established in some by private 

 companies, and in others by the state. In the United Kingdom 

 and its dependencies and in the United States they have been in 

 all cases established by -the enterprise and capital of joint-stock 

 8 



