Imestigating Diatom Structure. By H. Hartridge. 369 



^.* ... ^ 



Ramsden Circle. 



S. 



Ramsden Eyepiece, 

 Micrometer, 



Ad^eteCble Apertiire. 

 Auxiliary Objective. 



S. 

 G. 

 S. 



S. 



Plane of Spectra. 



IiranerBlon Objective. 

 Slide Pleiirosiginao 



Gonrady Condenser. 



Images of Stops. 

 Auxiliary Condenser. 



Diaphragm A. 

 Auxiliary Lens. 



Micrometer Plates. 

 Slits. 



Field Lenses. 



S. 



Colour Filter. 



Condenser. 

 Mercury Lajnp, 



^IS ''c^'^Z^V'^'^^ ^° Grating, and Slits, are 

 iJiaricea G.and S, respectively. 



DIAGRAM OF OPTICAL SYSTEM 



Fig. 50, 



