58 BELL. 



improve the color correction tlirough modification of these, under- 

 correcting the high powers and o\er-correcting the low ones. Inas- 

 much as the eye loses in acuity very rapidly at apertures beloAv 1 mm. 

 it Avould seem adA'isable to correct objectives for a rather lower power 

 than is now customarv. 



