566 THE POPULAR SCIENCE MONTHLY. 



know that he is engaged on a machine which, when complete, will place 

 him in the other class also. Instead of two single carbon rods, M. 

 RapieflF employs two pairs of rods, each pair forming a V. The light 

 is produced at the common junction of the four carbons. The device 

 for regulating the light is of the simplest character. At the bottom of 

 the stand which supports the carbons are two small electro-magnets. 

 One of them, when the current passes, draws the carbons together, and 

 in so doing throws itself out of circuit, leaving the control of the light 

 to the other. The carbons are caused to approach each other by a de- 

 scending weight, which acts in conjunction with the electro-magtiet. 

 Through the liberality of the proprietors of the " Times " every facility 

 has been given to M. Rapieff to develop and simplify his invention at 

 Printing House Square. The illumination of the press-room, which I 

 had the pleasure of witnessing, under the guidance of M. RapiefF him- 

 self, is extremely effectual and agreeable to the eye. There are, I be- 

 lieve, 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 disk, and as posi- 

 tive carbon a rod, he has, I am assured, obtained very satisfactory re- 

 sults. 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 carbon 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 im- 

 provement of regulators is this : The positive carbon wastes more pro- 

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

 heat of the former. It occurred to Mr. William Siemens 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 of copper is thus caused 

 to remain fixed in space, for it is not dissipated, the positive carbon only 

 needing control. I have seen this lamp in action, and can bear witness 

 to its success. 



I might go on to other inventions, achieved or projected. Indeed, 

 there is something bewildering in the recent rush of constructive talent 

 into this domain of applied electricity. The question and its prospects 

 are modified from day to day, a steady advance being made toward the 

 improvement both of machines and regulators. With regard to our 

 public lighting, I strongly lean to the opinion that the electric light 



