70 ADDRESS TO THE BRITISH ASSOCIATION, 1881. 



through one and the same wire connecting two distant 

 places. 



Another more recent and perhaps still more won- 

 derful achievement in modern telegraphy is the inven- 

 tion of the telephone and microphone, by means of 

 which the human voice is transmitted through the 

 electric conductor, by mechanism that imposes through 

 its extreme simplicity. In this connection the names 

 of Keiss, Graham Bell, Edison, and Hughes are those 

 chiefly deserving to be recorded. 



Whilst electricity has thus furnished us with the 

 means of flashing our thoughts by record or by voice 

 from place to place, its use is now gradually extending 

 for the achievement of such quantitative effects as the 

 production of light, the transmission of mechanical 

 power, and the precipitation of metals. The principle 

 involved in the magneto-electric and dynamo -electric 

 machines, by which these effects are accomplished, may 

 be traced to Faraday's discovery in 1831 of the induced 

 current, but their realisation to the labours of Holmes, 

 Siemens, Pacinotti, Gramme, and others. In the elec- 

 tric light, gas-lighting has found a formidable com- 

 petitor, which appears destined to take its place in public 

 illumination, and in lighting large halls, works, &c., for 

 which purposes it combines brilliancy and freedom 

 from obnoxious products of combustion, with com- 

 parative cheapness. The electric light seems also to 

 threaten, when sub- divided in the manner recently 

 devised by Edison, Swan, and others, to make inroads 

 into our dwelling-houses. 



By the electric transmission of power, we may hope 

 some day to utilise at a distance such natural sources 



