CONSTRUCTION OF THE MICEOSCOPE 11 



2. The stage, a horizontal shelf upon which is placed the 

 preparation or slide to be examined. The stage is attached 

 to the column. 



3. The mirror, situated below the stage, by which the light is 

 reflected upward through the opening in the stage. 



4. The diaphragm of various forms, frequently accompanied 

 by light condensers, attached to the lower sidfe of the stage 

 and used to regulate the intensity of the light reflected by 

 the mirror. 



5. The tube, a cylinder which holds the lenses and moves 

 up and down perpendicularly above the opening in the 

 stage. The tube is raised or lowered either by sliding it 

 back and forth with a turning movement or by a rack 

 and pinion mechanism. This mechanism is called the 

 coarse adjustment. 



6. The fine adjustment, a milled head back of the tube, 

 which, on being turned, moves for a very short distance 

 the entire framework that holds the tube. 



7. The lenses, of two sorts, — eyepieces or oculars which slip 

 into the upper end of the tube, and objectives which screw 

 in at the bottom. An important accessory to the tube is 

 the nose piece, capable of carrying two or three objectives 

 which may be revolved into place at the lower end of the 

 tube. A student's microscope will generally be fitted with 

 two eyepieces, high and low, and with two objectives, high 

 and low, and these may be combined with one another to 

 give four grades of magnification ranging generally from 

 about 50 to more than 500 diameters. If the objectives are 

 respectively | inch and \. inch and the eyepieces 2 inches 

 and 1 inch, the lower objective with either eyepiece will 

 give a low power, the higher objective with the 2-inch eye- 

 piece a medium power, and the higher objective and 1-inch 

 eyepiece a high power. 



8. The stand consisting of the microscope without the 

 lenses. 



