166 LIVING LIGHTS. 



at the entrance-gates of drives ; insides of stables ; the base 

 of balustrades, or the entirety of balustrades ; for roads, as 

 luminous beacons of corners of dark country lanes, and at 

 the ends of bridges, ends of walls, and curbs of foot-paths; 

 for docks ; for edging of piers and wharves ; for water- 

 works ; for the safety and despatch of night-work by the 

 erection of luminous guides and beacons ; and for fire-plug 

 notices on walls ; in short, for any place where the light of 

 day will sufficiently excite the phosphorescent property as to 

 render the cement or concrete work luminous by night. 

 The difficulty of sighting rifles in the dark has been ingen- 

 iously overcome by the use of luminous paint, and it is 

 thought that the armies of various nations will adopt phos- 

 phorescent sights for general use'. 



I have before me as I write, through the courtesy of 

 M. Raphael Dubois of Paris, a fine photograph of a bust 

 of Claude Bernard, taken by the light of numbers of phos- 

 phorescent insects (elaters), which shows the possibility of 

 work in this direction. 



M. Ch. V. Zenger of Paris has made some interesting 

 experiments, and expressed the belief, some time in 1883, 

 that Mount Blanc could be photographed by phosphorescent 

 light emitted, and I understand this has been accomplished. 

 M. Zenger has pliotographed objects by the light of Balmain's 

 phosphoric plates. From a personal communication from this 

 scientist, I will quote some things which he has kindly sub- 

 mitted for the author's use in this volume, referring to this 

 work and the use of Balmain's liquid phosphorus. As a 

 light, he says, "• No doubt there may exist better and more 

 perfect phosphorescent bodies of green, greenish blue, and 

 violet hue, than are at my disposal ; and to avoid the use of 



