CHAP, viii.] THK ELECTRIC LIGHT. 689 



brillancy is unsupportable. On dark nights it has the same effect 

 as lightning. Another great disadvantage arises from the circum- 

 stance of one single blaze replacing a multitude of luminous points, 

 which results in a startling contrast between the strong light on 

 illuminated objects and the dark and hard shadows thrown on the 

 unilluminated parts. In a word, the light by this system is not 

 diffused on all sides, and the attempted substitution of several lights 

 for a single qne only diminished these inconveniences without 

 destroying them. 1 



Although, however, the electric light does not appear to be 

 applicable to public illumination under ordinary circumstances, it 

 may, on the contrary, be advantageously employed at fetes. 



But a more important and useful application was that made 

 of the electric light during the siege of Paris for reconnoitring the 

 works and operations of the enemy at night. Apparatus was fixed 

 for this purpose on Mont Valerien and on the barrier of Mqnt- 

 martre. At this latter station the light was produced by an Alliance 

 magneto-electric machine. A parabolic reflector, having its focus 

 at the point where the carbon points produced the light, threw the 

 beam of light to a distance, in a direction which might be .changed 

 at pleasure, according to the orders of the officers charged with these 

 reconnoitrings. 



Plate XXII. shows the Siemen's dynamo-electric light apparatus 

 as arranged for Field Service, an employment which is certain to be 

 found for it in future campaigns. 



We shall conclude what we have to say upon the electric light 

 and its applications by recalling what we have already said on its 

 advantageous employment for microscopic projections, as well as its 

 use in photography. In both these cases the electric light makes 

 up for the absence of the sun. We shall also say a word on the 

 electric lamps that have been invented for illuminating mines, and 

 are at the same time safety lamps ; the light produced in this apparatus 

 is not the voltaic arc leaping between two carbon cones there is no 

 necessity in this case for so considerable an intensity. 



1 Does not this enervating action of the rays of the most refrangible part of the 

 spectrum depend in some way on the extreme rapidity of the undulations of the 

 ether which they produce, which agitate the retiDa and optic nerve with excessive 

 energy I 



Y V 



