The "Popular Microscope.' 



67 



is obtained without the uncertainty that is inseparable from 

 the magnetic pattern. 



The mechanical stage is quite new and very simple. It 

 has the usual quick movements., and the slow ones are regu- 

 lated by two milled 

 heads working on con- 

 centric spindles, as in 

 Powell and Lealand's 

 pattern. One of these 

 spindles has a friction 

 hold upon a plate, which 

 it carries up or down, 

 while the second spin- 

 dle pulls the first back- 

 wards or forwards hori- 

 zontally, and the move- 

 able plate is so at- 

 tached as to go with 

 it. This again is an 

 arrangement that looks 

 likely to work well with 

 first-class instruments. 

 It is simpler than the 

 ordinary plan, and does 

 not add so much to the 

 thickness of the stage. 

 The " Popular Mi- 

 croscope " is fitted to 

 carry most of the ap- 

 paratus that advanced 

 students will require, 

 and a set of small an- 

 gled, Hbut fairly cor- 

 rected, objectives are 

 made expressly for it. 

 The makers observe 

 that " there are many 

 persons who would not 

 with ordinary objects, 

 and using only the first 

 and second eye-pieces, 

 see any difference between these powers and the very best." 

 They add that, " with very severe tests, and employing the 

 third or higher eye-pieces, the difference is very perceptible ; 

 but many who work with the microscope never require the 

 highest class of performance." Small angled glasses are well 



