38 EEPOET — 1881. 



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 electric 

 conductor, by mechanism that imposes through its extreme simplicity. 

 In this connection the names of Reiss, 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 jjroduction 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 efiects 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 electric light, gas-lighting has found a formidable 

 competitor, 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 

 comparative 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 of energy as the Falls of 

 Niagara, and to work our cranes, lifts, and machinery of every descrip- 

 tion by means of sources of power arranged at convenient centres. To 

 these applications the brothers Siemens have more recently added the 

 propulsion of trains by currents passing through the rails, the fusion 

 in considerable quantities of highly refractory substances, and the use of 

 electric centres of light in horticulture as proposed by Werner and William 

 Siemens. By an essential impi'ovement by Faure of the Plante Secondary 

 Batteiy, the problem of storing electrical energy appears to have received 

 a practical solution, the real importance of which is clearly proved by Sir 

 Wilham Thomson's recent investigation of the subject. 



It would be difficult to assign the limits to which this development of 

 electrical energy may not be rendered serviceable for the purposes of man. 



As regards mathematics I have felt that it would be impossible for 

 me, even with the kindest help, to write anything myself. Mr. Spottis- 

 woode, however, has been so good as to supply me with the following 

 memorandum. 



In a complete survey of the progress of science during the half-century 

 which has intervened between our first and our present meeting, the part 

 played by mathematics would form no insigniflcant feature. To those 

 indeed who are outside its enchanted circle it is difficult to realise the 

 intense intellectual energy which actuates its devotees, or the wide 

 expanse over which that enei"gy ranges. Some measure, however, of its 



