18 



The Use of a Simple Microscojoe. 



lias been effected by using a number of different pieces of glass of 

 different qualities combined together, so as to do away with imper- 

 fections natural to a lens formed of one single piece of glass only. 

 Lenses are mounted as common hand magnifiers, in tortoishell 

 frames, folding up for the pocket. These 

 contain from one to three glasses of different 

 powers, so arranged as to be used singly or 

 combined ; and a set. Fig 13, consisting of 

 one-and-a-half inch, one inch, and half-inch 

 focus, will be found very generally useful. 

 In addition to its use as a hand magnifier, 

 Messrs. Smith, Beck, and Beck provide a 

 stand, by which it can be made into a simple, 

 but very useful, single microscope, as shewn 

 in the accompanying illustration taken from 

 their catalosrue. 



Fig. 14. 



When a higher power is required in a single lens, the Stanhope 



and Coddington (so named 

 after their inventors) are 

 sometimes had recourse 

 to, they are mounted in 

 metal case for the waist- 

 coat-pocket or watch- 

 ffuard. 



