1 68 THE ADDRESSES, LECTURES, ETC., OF 



quite successful ia some of the applications made at that time in 

 Germany, in Holland (between Amsterdam and Eotterdam), and 

 in this country under my own superintendence between Manchester 

 and Bowden, telegraphy itself had not advanced sufficiently to call 

 for an application of this invention upon a more extended scale, 

 and it has only met with favour on the part of telegraph adminis- 

 trations since its re-introduction to public notice by Mr. Steam, of 

 Boston, in 1872, who improved however upon the original arrange- 

 ment by balancing the discharge from the line by the discharge 

 from an arrangement of condensers. Another important advance 

 in duplex telegraphy has been made by Mr. Louis Schwendler, 

 who by the application of an improved "Wheatstone Bridge 

 arrangement has produced the means of readily adjusting the effect 

 of the neutralizing current during the working of the instrument, 

 and has carried duplex telegraphy into effect with great 

 advantage upon the long lines of India, with which he is 

 connected. 



The quadruplex telegraph, which may be considered to have been 

 theoretically introduced by Dr. Stark, of Vienna, in 1855, and 

 contemporaneously by Dr. Boscha of Leyden, has been developed 

 by Mr. Edison of New Jersey, U.S., and has been for some time 

 established upon the line between New York and Boston, under the 

 superintendence of Mr. Prescott, the engineer of the Western 

 Union Line. In this system the principle of duplex telegraphy is 

 combined with the equally well-known system of producing different 

 effects by currents differing in strength, and it is, indeed, not diffi- 

 cult to conceive that by further combinations of the same nature 

 six or eight pairs of instruments may be worked simultaneously 

 and independently through one and the same conductor. The 

 success of these improved methods of transmission depends almost 

 entirely upon the perfect insulation and undisturbed condition of 

 the line-wire, a subject which has yet to receive much attention on 

 the part of the Telegraph Engineer. 



Our attention is next arrested by the great novelty of the day, the 

 Telephone. 



This remarkable instrument owes its origin to the labours of 

 several inventors. 



In the year 1859 the late Sir Charles Wheatstone devised an 

 arrangement by which the sounds of a reed or tuning-fork, or 



