MAGNIFYING GLASSES. 
tion. The most simple method of effecting this would be to 
hold the lens to the eye with one hand, and to present the object 
before it at the proper distance with the other. But even in 
this case it would be necessary that the lens should be attached 
to a convenient handle, and unless the magnifying power were 
very low, the steadiness necessary to retain the object in the focus 
could not be imparted to it, and while the observation would be 
unsatisfactory the fatigue of the observer would be considerable. 
When high powers are 
Fig. 14. 
taste 
used, every motion of 
the object is as much 
magnified as the object 
itself, and consequently 
in such cases the most 
extreme steadiness is 
indispensable. 
Whatever be the form 
of the mounting, there¬ 
fore, it is necessary 
that the object should 
be supported by some 
piece attached to that 
by which the doublet 
itself is supported, so 
that it may be steadily 
held in the axis of the 
lenses, and that its dis¬ 
tance from them may be 
varied at pleasure, by 
some smooth and easy 
motion, by which the 
observer can bring the 
object to the proper 
focus. 
The means by which 
these ends have been at¬ 
tained vary according 
to the use to which the 
microscope is to be ap¬ 
plied, to its cost, the 
and the skill and address of 
and fancy of the observer, 
the maker. 
One of the most convenient forms of mounting, for a common 
hand microscope is shown in fig. 14. 
The doublet is inserted in a socket c made to fit it; the screen 
110 
