ELECTRICITY. TELEGRAPHY. 69 



Siemens in Germany, the last 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 submarine 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 Ger- 

 man Ocean, threading their way through the Mediter- 

 ranean, Black and Red Seas, until in 1866, after two 

 abortive attempts, telegraphic communication was suc- 

 cessfully established between the Old and New Worlds, 

 beneath the Atlantic Ocean. 



In connection with this great enterprise and with 

 many investigations and suggestions of a highly scien- 

 tific and important character, the name of Sir William 

 Thomson will ever be remembered. The ingenuity 

 displayed in perfecting the means of transmitting in- 

 telligence through metallic conductors, with the utmost 

 despatch and certainty as regards the record obtained, 

 between two points hundreds and even thousands of 

 miles apart is truly surprising. The instruments de- 

 vised by Morse, Siemens, and Hughes have also proved 

 most useful. 



Duplex and quadruplex telegraphy, one of the most 

 striking achievements of modern telegraphy, the result 

 of the labours of several inventors, should not be 

 passed over in silence. It not only serves for the 

 simultaneous communication of telegraphic intelligence 

 in both directions, but renders it possible for four 

 instruments to be worked irrespectively of one another, 



