MICRO-OBJECTIVES AND COMPENSATING OCULARS. 



161 



double the price that our best English opticians 

 charge for theirs, whilst the prices of apochromatic 

 homogeneous immersion lenses are, considering their 

 great aperture, probably the same as those of our 

 first English makers. Meanwhile many microscopists, 

 especially students, have to content themselves 

 with a microscope stand and objectives of 1 in. 

 and a \ in. focus, costing altogether not more than 

 one of the new apochromatic 1 in. objectives, and 

 a good working instrument can be had nowadays 

 at a very small cost. In conclusion, I express the 

 hope that other optical apparatus besides the 

 microscope will derive important benefits from the 

 invention of these new optical glasses. 



Magnifications of the Apochromatic Objectives and 

 Compensation Oculars for 250 mm. Screen Distance. 



