36 KEPOET— 1891. 



system and of the alternating-current-trausformer system has 

 done much to reduce the exj)ense of distribution. 



In dynamo construction electric engineering may be said to 

 have reached such a point of excellence that the study of 

 minor points is all that remains to be done. This was due 

 principally to the application of Kapp's theory of the magnetic 

 circuit to their construction, and to the almost perfect know- 

 ledge we now have of the magnetic behaviour of iron. 



Though electric railway and tram traction has already 

 reached a high standard of efficiency, many difficult problems 

 in connection with it still remain unsolved. Practical experi- 

 ence gained from systems working under the various conditions 

 to which they may be subjected will do much to clear the 

 ground in this branch of electric industry, in which it is ex- 

 tremely likely that we shall see great developments in the 

 course of the next few years. 



Many examples of the applications of electricity I might 

 give ; but, as I fear I have already occupied too much of your 

 time, I will bring my address to a close with a short description 

 of two of these which at the same time are both simple and 

 interesting. 



Great interest has lately been executed by some experi- 

 ments made by a Eussian, Specnew, on the application of 

 electricity to agriculture. He conducted all his experiments, 

 extending over a period of five years, in a thoroughly scientific 

 way. He first investigated the effect of the electric current on 

 different seeds, and then submitted growing plants to two kinds 

 of electric action. In one case, he placed large plates of copper 

 and zinc — 3ft. square — in the ground, and connected them 

 above ground with a wire, thus forming a zinc-earth-copper 

 element. Between the plates he sowed the various seeds. In 

 the other case, he set up a number of iiisulating-rods having 

 comb collectors mounted on them, and planted his seeds 

 about. In all cases he found that the electric action helped 

 the growth of the plants, and in some cases as much as 200 

 per cent. 



The other application of electricity to which I wish to direct 

 your attention — namely, welding by electricity — is one of great 

 commercial importance. It is the invention of Elihu Thom- 

 son, an American professor ; and is remarkable, like very many 

 great inventions, for its simplicity. 



It has long been known that when the ends of any two 

 conductors are brought together, and a strong electric current 

 passed, the junction becomes very hot (as in the case of the 

 electric arc), due to the resistance at the loose junction being 

 much greater than that of the solid conductors. The applica- 

 tion of this simple fact is all that is involved in the invention. 

 The apparatus required for the process is particularly simple — 



