26 
PRACTICAL PHOTO-MICROGRAPHY. 
movement without moving the hand from one place; 
and the pinion of one “ motion ” is carried through to 
the left side of the stage—an arrangement which is of 
great convenience sometimes. 
Below the stage we have the substage , which is in¬ 
tended to carry the substage condenser, and occa¬ 
sionally other appliances connected with illumination 
of the object. Except for the very simplest and lowest 
power work a condenser may be taken as necessary; 
and a condenser without a good focussing and centring 
substage to carry it is almost useless. The remarks 
made as to the necessity for a good coarse adjustment 
hold equally true for the substage; and in the highest 
class stands we have a fine adjustment also to the 
substage. A “swinging” substage is seldom used now¬ 
adays, but a centring arrangement there must be for 
the substage. So much attention has of late been 
given to the use of the condenser that the substage has 
also been much studied, and most stands of any pre¬ 
tension have a good substage. A mirror usually forms 
