306 HOUGH WAYS MADE SMOOTH. 



advocated for street illumination, that there is a difference 

 between the problems which the photographer and the 

 street-lighter have to solve. The Jablochkoff candle, for 

 instance, must be screened on all sides, and even above, 

 when used to illuminate the streets. If its direct light is 

 allowed to escape in any direction, there will be a mis- 

 chievous and unsightly beam, and from every point along 

 the path of the beam, the intensely bright light of the candle 

 will be directly visible. Again : it is essential that whatever 

 substance is used to screen the light should be dense enough 

 to cause the whole globe to seem uniformly bright or nearly 

 so. The only modification which seems available (when 

 these essential points have been secured) is that the tint of 

 the globe should be such as to correct any colour which 

 the light may be found to have in injurious excess. We 

 may, however, remark that the objection which has been 

 often raised against the colour of the electric light can 

 hardly be just the injury to the eyes in certain cases 

 arising probably from the strong contrast between the light 

 and the background on which it is projected. For, as to 

 colour, the electric light derived either from the glowing car- 

 bon or from incandescent metal is appreciably the same as 

 sunlight. 



The Rapieff burner, employed in the ' Times ' office, 

 consists of four carbon pencils, arranged thus )( (except that 

 the two v's are not in the same plane, but in planes at right 

 angles to each other). The spark crosses the space between 

 the points of the v's, and arrangements are made for keeping 

 the two points at the right distance from each other, and 

 also for keeping the ends of the two pencils which form each 

 point in their proper position. If the current is from any 

 cause interrupted, an automatic arrangement is adopted to 

 allow the current to pass to the other lamps in the same 

 circuit. There are six lamps in circuit at the * Times ' 

 office ; and M. Rapieff has exhibited as many as ten. The 

 advantages claimed for this light are the following : ' First, 

 its production by any description of dynamo-electric machine 



