7o 
PRACTICAL PHOTO-MICROGRAPHY. 
may be removed, and the remaining part forms an 
excellent condenser for the lower power objectives. 
This is the condenser most frequently used by the 
writer and by several of his friends. 
This condenser is shown in fig. 17. 
Higher in the scale of excellence and of expense is 
0®• 
Fig. 18. 
Fig. 18. Fig 19. 
