416 THE. ADDRESSES, LECTURES, ETC., OF 



added to the general interest of this most complete and successful 

 exhibition. 



But apart from the interest afforded to the general observer in 

 bringing before him a great variety of practical applications of 

 electric energy, apparently under complete control, the Vienna 

 Exhibition is chiefly remarkable, in my opinion, for its display of 

 measuring instruments, and for the great attention given both by 

 exhibitors and the examining judges to accurate information, 

 rather than to mere visual effects. The directing council, in 

 justly appreciating this tendency, have substituted for the usual 

 international jury a scientific commission, charged with a careful 

 investigation of the scientific bearings of such exhibits as were 

 submitted to them, and it is intended to reward meritorious 

 exhibitors by a publication of these reports, instead of by mere 

 medals and certificates, expressive only of undefined merit. It is 

 one of the greatest charms connected with electrical effects, that 

 they are susceptible of very accurate measurement, and it would 

 be difficult, indeed, to apply this form of energy either to the 

 purposes of telegraphy, or of lighting, or for the transmission of 

 mechanical power, unless at every step accurate measurement and 

 calculation was resorted to, in order to weigh against each other 

 the influence of electrical resistance, of magnetic and voltaic 

 induction, of Foucault currents, and of heat produced by mis- 

 directed electrical energy, in order to arrive at practically useful 

 results. For these purposes, accurate and simple instruments for the 

 measurement of electrical quantities are of the utmost interest, and 

 engage, at the present moment, the attention of leading physicists 

 and engineers in this and other countries. 



The International Electrical Congress, which met at Paris in 

 1881, has done excellent service in laying down what is now com- 

 monly called the practical system of electric units, based, in the 

 main, upon the British Association, or C.Gr.S. system. It is to be 

 regretted that the fundamental unit, that of electrical resistance, 

 has not yet been definitely determined upon by the International 

 Committee charged with that duty ; but it is more than probable 

 that the values resulting from the recent careful investigations by 

 Lord Kayleigh and Mrs. Sidgwick, supported by those of Mr. 

 Glazebrook, will prove so perfectly accurate, that standards based 

 upon these determinations may be accepted provisionally by prac- 



