REVIEW?. 



31 



Fig. 2. 



In the compound microscope the mechanical parts may be divided into 

 two parts the stand and the body. " The stand is usually composed of a 

 tripod, with two upright 

 pillars ; between these 

 pillars is a bent bar, 

 which works in a joint; 

 the bar carries at one 

 end the compound body, 

 to which the object- 

 glass and eye-piece are 

 attached, and at the 

 other end the stage and 

 mirror. The body con- 

 sists of a long brass 

 tube, which carries the 

 object-glass at one end 

 and the eye-piece at 

 the other ; the object- 

 glasses are screwed on 

 to the body, but the 

 eye-pieces are attached 

 by their own tubes, 

 which slide into the 

 tube of the body, " 



" The stage consists of 

 a plate of brass, hav- 

 ing another plate of 

 brass, called the object- 

 plate, fitted to it, and 

 made so as to slide up 

 and down upon it ; the 

 object-plate has a raised 

 edge, at the lower end, 

 for supporting the object when the instrument is inclined." In|the^more 

 expensive instruments the object-plate is made to move in different direc- 

 tions by screws with milled heads. Quekett's dissecting microscope is 

 occasionally arranged as a travelling compound body. (See next page, 

 fig. 4.) 



The accuracy with which observations can be made depends on the skill 

 of the observer and the quality of his object-glasses. The ease with which 



