Art. IV. — Electric Lighting. 

 By R. E. Joseph. 



[Read llth May, 1882.] 



A FEW months back, in a paper read before you, I briefly 

 reviewed the progress and improvements that had taken 

 place in electric lighting, and then promised to lay before 

 you, at a future time, further information on the subject. 

 In my former paper I gave you an account of the principal 

 machines used in generating currents, of the lamps in use, 

 and the adaptation of different systems for various require- 

 ments. Since then certain changes that have taken place, not 

 so much in the construction of the apparatus as in the 

 methods of using them, have necessitated a slight alteration 

 in my views on the matter. Commencing with generators 

 of the current, the battery appears to have remained in 

 exactly the same position as before, and I am not aware of 

 any improvements having been made in any of the numer- 

 ous forms, to render it a useful agent for electric lighting. 

 In dynamo-machines the principle of construction remains 

 the same ; very little, if anything, has been done to render 

 the machines more efficient. As a proof of this, the Siemens, 

 Gramme, and Brush, which were spoken of as giving the 

 best results, still hold the foremost position amongst the 

 now numerous descriptions of machines. The original 

 Siemens machine gives now, as before, a very high per cent- 

 age of useful work per horse-power, followed, however, very 

 closely by the Gramme. Since my former paper some twenty 

 or thirty new descriptions of dynamo-machines have been 

 introduced, but a very slight examination shows that they 

 are all constructed on either the Siemens or Gramme prin- 

 ciple, and that if they possess any advantage over them, 

 it is, in most cases, in mechanical details, such as simplify- 

 ing their manufacture, reducing the tendency to over-heat- 

 ing, and arrangements of certain parts to facilitate cleaning, 

 &c. There are, however, one or two exceptions in which 



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