CH. /] 



MICROSCOPE AND ACCESSORIES 



dry objectives t/iis is air and n=/,for water immersions n -.--/. y ( and for 

 homogeneous immersions 11=1.52. (For a table of natural sines, see third 

 page of coi't ;-. ) 



\ 40. Significance of Aperture. As to the real significance of aperture in 

 microscopic objectives, it is now an accepted doctrine that the corrections in 

 spherical and chromatic aberration being the same (i) Objectives vary 



