To focus low power objectives : 



Attach objective to the nose-piece. Lower the head 

 to the level of the stage and, watching the front of the 

 objective, lower the tube by the coarse adjustment until 

 the front of the objective is within one quarter inch of 

 the object ; look through the eyepiece and slowly elevate 

 by the coarse adjustment until the image is distinct. 

 Use fine adjustment. 



The upward movement should be slow so that if 

 the object be faint it is not missed and the adjustment 

 not run beyond its focal distance ; or it is possible that 

 in the case of a very minute object it may be out of 

 the center and thus out of the field of vision, in which 

 case the surface of the cover glass or the minute 

 particles of dust upon it should be distinguishable. 



The object will first appear with faint outlines and 

 indistinct, then gradually more distinct and finally 

 sharply defined, and if the adjustment goes beyond 

 this point it will gradually become more dim, in which 

 case return to the point of greatest distinctness. 



To focus high power objectives : 



Attach objective to nose-piece. Lower the head to 

 the level of the stage and look between objective and cover 

 glass toward a window or flame. Slowly lower the 

 objective with the coarse adjustment until the front of 

 the objective is nearly in contact with the cover glass ; 

 look into the eyepiece and slowly elevate the tube vuith 



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