ANNUAL ADDRESS. 181 



pleted the series of fundamental discoveries, and since that time 

 everything has been elaboration. 



Oersted's discovery respecting the influence of an electric cur- 

 rent closely followed by that of Arago in the same direction 

 opened the way for Faraday's complete discovery of induction, 

 which underlies the construction of the dynamo. This ascer- 

 tained, the province of the inventor was well defined, to con- 

 jure some mechanical appliance whereby the principle might be 

 utilized. But here, as elsewhere, the work of discovery and that 

 of invention went on almost pari passic ; the results of each in- 

 creased those of the other. The distance from the Clark and 

 Page machines of the middle '30's, with their cumbrous horse- 

 shoe magnets and disproportionate expenditure of power, to the 

 Siemens machine of the '50's was long, but it was no leap. In 

 like manner, slow steps marked progress thence to the Gramme 

 machine, in which one finds the outgrowth of many years of labor 

 by many men, both investigators and inventors. In 1870, forty 

 years after Faraday's announcement of the basal principle, the 

 stage was reached whence progress could be rapid. Since that 

 time the dynamo has been brought to such stage of efficiency that 

 the electro-motor seems likely to displace not merely the steam 

 engine, but also other agencies in direct application of force. 

 The horse is passing away and the trolley road runs along the 

 country highway ; the longer railways are considering the wis- 

 dom of changing their power ; cities are lighted brilliantly where 

 formerly the gloom invited highwaymen to ply their trade ; and 

 even the kitchen is invaded by new methods of heating. 



Long ago it was known that if the refining of pig iron be 

 stopped just before the tendency to solidify became pronounced 

 the wrought iron is more durable than that obtained in the com- 

 pleted process. This imperfectly refined metal was made 

 frequently, though unintentionally and ignorantly. A short 

 railroad in southwest Pennsylvania was laid in the middle 60' s 

 with iron rails of light weight. A rail's life in those days rarely 

 exceeded five years ; yet some of those light rails were in ex- 

 cellent condition almost fifteen years afterwards, though they had 

 carried a heavy coke traffic for several years. But this process 

 Annals N. Y. Acad. Sci., XI, July 29, 1898 — 13. 



