THE COMPOUND MICROSCOPE. 109 



T^ rr^i^^ substituted, which wiU be subsequently described, 

 xne black glass for the stage, and the mirror, together with all 

 the motions of the tube, F, upon the foot, and that of the stage, 

 and with It the compound body upon the tube, are all simUar 

 to those of M. Oberhauser, but the mode of applying the 

 polarizing apparatus, achromatic condenser, &c,, beneath 

 the stage, are so very ingenious, as to require a separate 

 description. 



In fig. 55 are shown the stage and a portion of the tube sup- 



Fig. 55. 



porting the same, but in order to render the use of the slide, 

 T, more plain, it has been represented as drawn out to its 

 fullest extent. In the centre of the slide is seen the tube, V, 

 which is capable of being raised or depressed by the lever, L ; 

 into this tube, the polarizing apparatus, the achromatic con- 

 denser, the oblique prism, &c., are placed; the slide, T, 

 being pushed in as far as it will go, the tube, V, is then im- 

 mediately under the hole in the stage, O ; in this position the 

 tube can be raised or depressed as accurately as by a screw or 

 rack-work. The knobs, E, are for the purpose of drawing 

 out the slide, T, the hole in the tube, O, is to allow of the 

 movements of the lever. By this arrangement, any kind of 

 condenser or the polarizing apparatus may be placed under 

 an object on the stage, without its being in the least disturbed. 

 To this microscope M. Nachet adds a moveable stage, composed 

 of a sliding-plate, which is made to move by two screws, placed 



