MICROPHOTOGRAPHIC APPARATUS. 



161 



Professor Draper employed the following form of 

 lantern for microphotography : a is a zirconia light 

 rendered incandescent by the mixed gases ; b b a very 

 short condensing lens ; c the stage or support carrying 

 the object to be photographed ; d the projecting lens, 

 formed of three sets of lenses, and giving a flat recti- 

 linear field ; a, c, d are mounted on a base board, e, f, 

 to the end of which the lantern box a b is attached, and 

 which is freely opened above and below for perfect 

 ventilation. The lateral grooves a, c, d slide and allow 

 of an adjusting movement by the screw r, and by 

 means of which the change of distance between a and 

 c admits of a correct focus being obtained. By means 

 of the hinge at Ji the whole can be adjusted at any 

 angle. 



FIG. 95a. Draper's Microphotographic Apparatus. 



