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A CHANGER FOR USE WITH SUB-STAGE 



CONDENSERS. 



By S. C. Akehurst, F.R.M.S. 

 Bead October 2Mb, 1913. 



Figs. 1 and 2. 



Petrological microscopes have been fitted in various ways to 

 arrange for a quick change of sub-stage condenser, and I have 

 frequently felt the need of a similar method applied to a 



Fig 1. 



biological microscope. I found the revolving nose-piece to carry 

 three condensers did not work satisfactorily, therefore adapted 

 the principle employed in the sliding objective changer to the 

 sub-stage fitting, and found this enabled me to get an easy and 

 rapid change of condensers. 



The scheme consists of a metal slide 2| x If, with bevelled 

 edges, on which the condenser is mounted, and, when necessary, 

 a throw-out arm for stops, and an iris diaphragm. Two D-shaped 



