J88 ELECTRIC LIGHTING. 



the current is interrupted or weakened, the spring acts so as 

 to bring the carbons nearer together; when, on the contrary, 

 it increases, the inverse effect is produced and the carbons 

 are separated. Lacassagne and Thiers had, as will be pre- 

 sently seen, used a system of the same kind. 



On each face of the polyhedron, formed by the reflexion 

 cage, abut tubes which are arranged so as to carry the rays 

 projected by the lenses in certain directions ; and according 

 to the Scientific American, these tubes may be placed in the 

 streets, along buildings, or even under the floors, in order to 

 distribute the light in a house. For that purpose it would 

 suffice to fix a stout branch pipe with a properly inclined 

 mirror at each change of direction. 



By means of this system, says the American journal, each 

 street in a town may be provided with one or more pipes 

 carrying a certain quantity of light, which may always be 

 governed by simply changing the position of the reflectors. 

 The problem may thus be reduced to the conditions of a 

 water supply. 



Without stopping to discuss these rather fantastic dreams 

 of American inventors, we think we ought to give here 

 some figures they have published relative to the system of 

 lamp we have described. According to these, 195 lamps on 

 this system can be supplied by i-horse power, and a light 

 obtained equivalent to 1,958 candles, for which it follows that 

 this illumination would cost only one-twentieth the price of 

 gas. It is needless to say that we cannot accept such figures, 

 and if we give them, it is only to show to what length the 

 prolific imaginations of Americans will go. (See the Tele- 

 graphic Journal of i5th July, 1879, p. 231.) 



Lamps of various kinds. In order to complete our 

 monograph of the voltaic arc lamp, it remains only to speak 

 of various plans which, although they have not given very 

 important results in practice, nevertheless have an originality 

 of character which deserves attention. Of this number is 



