366 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



the utmost intensification of light ohtained, but none of the results 

 favoured the theory that crystals develop from a transitory liquid 

 phase. 



Stereo-Photomicrography.* — F. M. Duncan points out that as stereo- 

 photomicrography comes under the head of low-])ower work the Micro- 

 scope itself is notjrequired ; the Stephenson's prisms and objective being 

 attached directly on to the front of the camera. These prisms obviate 



X 



\":]W:' \.N££: 



S 



3° 



i&V.^^v,,^ 



a. 



1 



-•*■ ■*■■■"> . 



Fig. 81. 



the necessity of cutting and transposing the photographs as in the case 

 of ordinary stereoscopic work. The camera should be mounted on a 

 travelling stage of sufficient length and breadth to afford a firm support 

 to the camera when its bellows are racked out to their fullest extension. 

 To the base of this camera-stage two grooved blocks of wood should be 



r^y 



Fig. 82. 



firmly attached, the grooves corresponding in angle to the two V-shaped 

 rails which run the whole length of the baseboard. The baseboard to 

 carry the camera, object-holder, &c. should be made of well-seasoned 

 pine, 10 in. wide, 5 ft. long, and 1 in. thick. Fastened on the edge and 

 running the entire length of the baseboard, there should be two V-shaped 

 rails, on which the camera, &c. can be moved into the required position. 

 The object-holder must be so constructed as to bring the specimen 



* English Mech. and World of Science, lxxiv. (1901) pp. 354, 5 (2 figs.); and 

 Briliah Journal of Photography (loc. non cit.). 



