40 THE ELECTRIC TELEGRAPH. 



with b f whilst the spring a was connected by a wire with 

 the negative pole of the element. 



39. On long lines of telegraph, Wheatstone found that 

 the current became much weakened by the resistance of the 

 wire, the coils of the apparatus, and by indifferent insulation, 

 so that he was obliged to employ a considerably augmented 

 battery power in order to effect the attraction of an arma- 

 ture, whereas, when he employed a magnetic needle, the 

 latter was always easily deflected. This suggested to him a 

 way to overcome the difficulty, which he succeeded in doing 

 by closing the circuit of a local battery, by the deflection of 

 a magnetic needle at the receiving station, by means of 

 which the electro-magnet of the alarm described above, or 

 an electro-magnet, whose armature formed a hammer and 

 struck directly on a bell, was put in action. The battery at 

 the receiving station was called the local battery, in con- 

 tradistinction to the line battery, which was placed at the 

 transmitting end. The local battery consisted of fewer 

 elements, as its circuit was short, and the resistance of the 

 coils of the electro-magnet not great. 



It was once a popular fallacy in England and elsewhere 

 that Messrs. Cooke and Wheatstone were the original in- 

 ventors of the electric telegraph. The electric telegraph 

 had, properly speaking, no inventor ; it grew up little by 

 little, each inventor adding his little to advance it towards 

 perfection. Messrs. Cooke and Wheatstone were, however, 

 the first who established a telegraph for practical purposes, 

 comparatively on a large scale, and in which the public were 

 more nearly concerned than in those experiments in which 

 the ends of the wires were brought into laboratories and 

 observatories. Therefore it was that the names of these 

 enterprising and talented inventors came to the public ear, 

 whilst those of Ampere and Steinheil remained comparatively 

 unknown. 



40. We read in Dr. TurnbulPs book, that in the latter part 

 of the year 1832, Mr. Morse, an American artist of some 

 notoriety, whilst on his homeward voyage from Europe, con- 

 ceived the idea of an electro-chemical telegraph ; and that in 



