380 E. M. NELSON ON BINOCULAR MICROSCOPES. 



I never expected to live to see a critical image of a Podura 

 scale in a binocular, but that is now an accomplished fact, for I 

 have seen a most beautiful picture of a Podura scale with the 

 Leitz binocular and an apo 4 mm., and that, too, critical in all 

 azimuths. 



Dark-ground images are very suitable for the new binoculars 

 because the objective is working at full cone, so there is a larger 

 Ramsden disc than would be usually the case with transmitted 

 light. 



Messrs. Leitz sent with the microscope some of their new 

 Orthoskop-Kellner eye-pieces, the performance of which is very 

 satisfactory. I have had a cap, attachable to the eye-piece by a 

 small screw, made to prevent the eye lens being smeared by 

 contact with the eye-ball. This with a binocular happens 

 frequently, so that a process of continual wiping of the eye-lens 

 is necessary, which causes interruption and much interference 

 with one's work. 



Journ. Quekett Microscopical Club, Ser. 2, Vol. XII., No. 75, November 1914. 



