HISTORY AND PROGRESS. 



13 



Too mucli credit cannot be given to all these men for their 

 energy in struggling, with the imperfect means and small 

 experience at their command, to realise an end which the 

 nature of the electricity they employed rendered impossible. 

 And if we can award to none of them the title of the in- 

 ventor of a practicable telegraph, we must, at least, give 

 them credit for having fully appreciated its importance, and 



Fig. 5. 



Fig. 6. 



for having dedicated their energies to the accomplishment of 

 the task they set themselves, and persevered in the face of 

 many sad difficulties and disappointments. 



III. TELEGRAPHS BY GALVANIC ELECTRICITY. 



19. A new discovery that of galvanic electricity had 

 for some years occupied the attention of the scientific world, 

 and at the beginning of the present century the thoughts 

 of students of electricity were directed to its application 

 for the purposes of Telegraphy instead of the unmanageable 

 frictional electricity with which they had hitherto had to 

 content themselves. 



The first mention we find of this species of electricity is in 

 the recital which Sulzer published, in 1767, of the follow- 

 ing experiment. On taking two pieces of different metals, 

 and placing one of them (zinc, for example) above, and the 

 other (perhaps copper) underneath his tongue, he found 



