442 FRAGMENTS OF SCIENCE. 



has been given to M. Rapieff to develope and simplii 

 his invention at Printing House Square. The illuminj 

 tion of the press-room, which I had the pleasure of 

 witnessing, under the guidance of M. Rapieff himself, is 

 extremely effectual and agreeable to the eye. There 

 are, I believe, five lamps in the same circuit, and the 

 regulators are so devised that the extinction of any 

 lamp does not compromise the action of the others. 

 M. Rapieff has lately improved his regulator. 



Many other inventors might here be named, and 

 fresh ones are daily crowding in. Mr. Werdermann 

 has been long known in connection with this subject. 

 Employing as negative carbon a disc, and as positive 

 carbon a rod, he has, I am assured, obtained very satis- 

 factory results. The small resistances brought into 

 play by his minute arcs enable Mr. Werdermann to 

 introduce a number of lamps into a circuit traversed by 

 a current of only moderate electro-motive power. M. 

 Reynier is also the inventor of a very beautiful little 

 lamp, in which the point of a thin carbon rod, properly 

 adjusted, is caused to touch the circumference of a car- 

 bon wheel which rotates underneath the point. The 

 light is developed at the place of contact of rod and 

 wheel. One of the last steps, though I am informed not 

 quite the last, in the improvement of regulators is this : 

 The positive carbon wastes more profusely than the 

 negative, and this is alleged to be due to the greater 

 heat of the former. It occurred to Mr. William Sie- 

 mens to chill the negative artificially, with the view of 

 diminishing or wholly preventing its waste. This he 

 accomplishes by making the negative pole a hollow cone 

 of copper, and by ingeniously discharging a small jet 

 of cold water against the interior of the cone. His 

 negative copper is thus caused to remain fixed in 

 space, for it is not dissipated, the positive carbon only 



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