MICROSCOPES. 



the object-glass. The instrument, of course, is roughly adjusted by 

 the rack movement, and finished by the screw, or by such other means 

 as are chosen for the purpose. 



A more recent and more compact form of this instrument is 

 represented in the frontispiece ; but as the difference of construction 

 will be seen by a reference to the engraving, no more lengthened detail 

 is needed. It is the most 

 modern form of instru- 

 ment, and possesses the 

 advantage of a greater 

 compactness and steadi- 

 ness, from its being 

 supported on two pillars 

 in lieu of one. This in- 

 strument is perhaps the 

 best adapted for educa- 

 tional purposes, from its 

 not being so liable to get 

 out of order. 



GOULD'S MICROSCOPE. 

 A very convenient and 

 powerful form of instru- 

 ment is that which bears 

 the above name. Its 

 general form is as in the 

 annexed diagram, and the 

 whole fits into a mahogany 

 box. 



Tn the centre of the 

 lid of the box screws the 

 upright square stem A, 

 fig. 14. This has upon 

 one side of it a rack 

 movement, in which 

 works the screw B, in- 

 tended to raise or de- 



Figs. 13 and 14. 



