

714 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



safe screen to use (fig. 5). Plate XIV. also shows the spectrograph of 

 carbolfuchsin (fig. 1). This dye passes much more indigo than red 

 (as shown by the Edwards' plate — which was used for all these experi- 

 ments). Although a fair photograph may be obtained without any 

 screen, it is better to use the green pot-glass, which perfectly cuts^off the 

 light (fig. 2). 



Dowdy, S. E. — How to photograph crystals. 



Amateur Photographer, xl. (1904) pp. 93-5 (6 figs.). 



Hertzsprung, E. — Ueber Tiefenscharfe. 



[The article is mainly concerned with the " penetration " attainable in 

 ordinary photography ; but the author also deals with the subject as 

 affecting microstereoscopy.] 



Zeitschr.f. wiss. Photographic (Leipzig), ii. (1904) pp. 232-44 ; 



also as an extract in pamphlet form. 



Jones, C. — Developments of three-colour photographic processes. 



Nature, lxx. (1904) pp. 553-5, 578-80. 



Fig. 118. 

 (5) Microscopical Optics 1 and Manipulation. 



Photo grammetric Fccimeter for Microscopical Optics: an In- 

 strument for Verifying Microscopes.* — This instrument (fig. 118), due 



* Comptes_Kendus, exxxvii. (Aug. 3, 1903) pp. 314-6 (1 fig.). 



