HOW TO WORK. 



To Attach Eyepiece.-- As the exterior sur- 

 faces of the eye lens and field lens are exposed, 

 they are apt to become dusty and should always 

 be carefully cleaned before use. 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. To fix in position however, it may be hast- 

 ened 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 objective may be 

 forced against the object and thus destroy it, or. 

 the focus may be disturbed. 



To Attach Objective.- Take a low power 

 objective first and after it has been removed from 

 the box, see that its front lens is clean ; elevate 

 the tube by means of the coarse adjustment so 



