32 



Stands and Holders. There is a great variety 

 of mechanical contrivances for holding magnifiers, 

 to give steadiness as well as to leave the hands 

 free for moving and working on the object and 

 adjusting for focus. When provision is made to 

 hold and adjust the lens the apparatus may be 

 called a lens holder or stand, but when a platform 

 called a stage is added, upon which the object can 

 be placed, and a mirror for illuminating the object 

 properly, it is called a dissecting microscope. 



There are two forms of magnifiers which contain 

 within themselves some properties of stands, one a 

 Tripod Magnifier, Fig. 16, rests upon three legs 



Fig. 16. 



and has a screw for adjustment of focus. Its 

 optical parts are two convex lenses, usually having 

 a power of 10 diameters, and which are separated 



