64 THE MICROSCOPE. 



microscope-tube, is moved by the larger milled-heads ; a,nd 

 a more delicate adjustment of this optical part is effected 

 by the small milled-head above the bar. The other 

 milled-head fixes the arm to the triangular bar. The 

 mirror slides up or down the tube to which it is attached. 

 A smaller compound achromatic microscope, fig. 37, is 

 particularly adapted for students : this is packed into a 

 neat mahogany case, with excellent object-glasses, for the 

 small sum of 51. 15s., by Mr. Baker, 244, Holborn, who 

 likewise furnishes all the requisites for microscopical pur- 

 poses, and well-selected specimens of mounted objects, 

 very cheap. 



Fig. 38. Powell and Lealand's Microscope, with Amid prism, arranged 

 for the oblique illumination of test-objects. 



Messrs. Powell and Lealand's improved microscope is 

 represented in fig. 38. The three legs are considerably 

 stouter and more inclined than in their former instrument, 



