12 ELEMENTS OF APPLIED MICROSCOPY. 
piece forms an erect and virtual image, A®B’, of the real 
inverted image A'B'. 
9. Defects of the Compound Microscopes.—The com- 
Fic. 10.—Hooxe’s CompounpD Microscope (1665). 
(After Carpenter-Dallinger.) 
pound microscope was at first of little practical impor- 
tance, on account of the complications introduced by 
spherical and chromatic aberration. The former is due 
to the fact that the rays which pass through the outer 
