MAGNIFYING GLASSES. 



Fig. 14. 



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 

 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 

 taste and fancy of the observer, and the skill and address of 

 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 



