216 or 1 60, in line with the upper end of the main 

 tube, in accordance with the tube length for which the 

 objectives are corrected. 



Attach low power eyepiece. 

 Attach low power objective. 

 Place object on stage. 

 Illuminate object. 

 Focus on object. 



To Attach Eyepiece. The exterior surfaces of 

 the eye lens and field lens being exposed are apt to 

 become dusty and should always be carefully cleaned 

 before using. If there are two or more eyepieces, 

 always use the lowest power first. Eyepieces should 

 be so loosely fitted that they will drop into the tube as 

 far as the collar by their own weight. They do this 

 slowly when the objective is attached, as an airtight 

 compartment is formed and air to the extent of the 

 dimensions of the eyepiece must first be expelled from 

 the tube. This displacement of air may, however, be 

 hastened by gently pushing the eyepiece downward, 

 but not to such an extent as to push in the draw-tube, 

 or force down the coarse adjustment. In fact, care 

 must be used in applying the eyepiece, or sliding the 

 draw-tube, as the focus may be disturbed, or the 

 objective forced against the object and thus destroy it. 



116 



