THE USE OF THE MICROSCOPE 5 



of-the microscope by means of the mirror, and then place the 

 object on the stage. Twist down the body until the objective 

 is about a quarter of an inch from the cover-glass ; look down 

 the microscope, and gradually twist the body up until the 

 object becomes visible. Focus accurately by means of the fine 

 adjustment screw. 



2. When using a high power begin with the objective close to 

 the cover-glass, and then focus with the fine adjustment. It 

 will facilitate the process if, while focussing with the right 

 hand, you move the object about slightly with the left hand. 



3.~Take extreme care never to let the objective touch the 

 cover-glass ; and never to touch or allow any dirt to get on the 

 face of the objective. The face of an objective cannot be cleaned 

 without doing harm to it. 



4. Should by any chance a drop of glycerine get on the face 

 of the objective, wash it carefully with water from a wash- 

 bottle, and wipe it gently with a silk handkerchief or piece of 

 chamois leather. Should Canada balsam be allowed to get on 

 the objective, do not attempt to clean it yourself, but hand it 

 at once to the assistant. 



5. See that the body of the microscope slides smoothly in its 

 tube. If it does not, remove it, and clean it by rubbing with a 

 few drops of olive oil : wipe off the oil before replacing the body 

 in the tube. 



6. Keep both eyes open when looking through the micro- 

 scope : a very little practice will enable you to do this, and it 

 will save you much fatigue. Also get into the habit of using 

 either eye. 



7. With a high power, use a small diaphragm : the amount 

 of light will be somewhat diminished, but the clearness and 

 definition of the object much increased. 



8. When examining an object, keep one hand on the fine 

 adjustment, and keep screwing it up and down slightly the 

 whole time : in this way parts of the object at different depths 

 are brought into focus successively, and a clearer idea of the 

 object is obtained. 



9. If the object appears dim or dirty, find out where the 

 fault lies in this way : 



While looking down the microscope, turn round the eyepiece 

 with your right hand. If the dirt turns round too, remove and 

 clean the eyepiece. If the fault is not in the eyepiece, move 



