A HALF-CENTURY OF SCIENCE. 205 



1834 our knowledge of the nature of the electric current had been 

 much advanced by the interesting experiment of Sir Charles Wheat- 

 stone, proving the velocity of the current in a metallic conductor to 

 approach that of the wave of light. 



Practical applications of these discoveries were not long in coming 

 to the fore, and the first telegraph-line on the Great Western Railway, 

 from Paddington to West Drayton, was set up in 1838. In America, 

 Morse is said to have commenced to develop his recording instrument 

 between the years 1832 and 1837, while Steinheil, in Germany, during 

 the same period, was engaged upon his somewhat super-refined ink- 

 recorder, using for the first time the earth for completing the return 

 circuit ; whereas in this country Cooke and Wheatstone, by adopting 

 the more simple device of the double-needle instrument, were the first 

 to make the electric telegraph a practical institution. Contempo- 

 raneously with, or immediately succeeding these pioneers, we find in 

 this country Alexander Bain, Breguet in France, Schilling in Russia, 

 and Werner Siemens in Germany, the latter having first, in 1847, 

 among others, made use of gutta-percha as an insulating medium for 

 electric conductors, and thus cleared the way for subterranean and sub- 

 marine telegraphy. Four years later, in 1851, submarine telegraphy 

 became an accomplished fact through the successful establishment of 

 telegraphic communication between Dover and Calais. Submarine 

 lines followed in rapid succession, crossing the English Channel and 

 the German Ocean, threading their way through the Mediterranean, 

 Black, and Red Seas, until in 1866, after two abortive attempts, tele- 

 graphic communication was successfully established between the Old 

 and New Worlds, beneath the Atlantic Ocean. 



In connection with this great enterprise, and with many investiga- 

 tions and suggestions of a highly scientific and important character, 

 the name of Sir William Thomson will ever be remembered. The in- 

 genuity displayed in perfecting the means of transmitting intelligence 

 through metallic conductors, with the utmost dispatch and certainty 

 as regards the record obtained, between two points hundreds and even 

 thousands of miles apart, is truly surprising. The instruments devised 

 by Morse, Siemens, and Hughes have also proved most useful. 



Duplex and quadruplex telegraphy, one of the most striking achieve- 

 ments of modern telegraphy, the result of the labors of several invent- 

 ors, should not be passed over in silence. It not only serves for the 

 simultaneous communication of telegraphic intelligence in both direc- 

 tions, but renders it possible for four instruments to be worked irre- 

 spectively of one another, through one and the same wire connecting 

 to distant places. 



Another more recent and perhaps still more wonderful achievement 

 in modern telegraphy is the invention of the telephone and microphone, 

 by means of which the human voice is transmitted through the elec- 

 tric conductor, by mechanism that imposes through its extreme sim- 



