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finding an object or 'a particular spot in it becomes 

 more difficult with the increase in power and even 

 in experienced hands becomes quite vexatious. 

 Recourse may be had to two methods : 



First.- - By using- a low power eyepiece. 



Second.- -By using a low power objective as a 

 finder. 



The object is thus found and after moving to 

 the center of the field the objective is removed 

 and the high power attached, or in case a revolv- 

 ing nose-piece istised, swing the high power objec- 

 tive in position, care being taken not to touch the 

 slide, and focus in the manner to be described. A 

 low power eyepiece in this connection is also very 

 useful. The object may not be in the field, due to 

 a slight variation in the centers of the objectives, 

 but it will certainly be very close and ought to be 

 easily found. 



The Mechanical Stage in either the fixed or 

 .attachable form will be found to greatly facilitate 

 work in this direction, particularly if the object is 

 minute and if in an important investigation one 

 desires to be absoluely convinced that the whole 

 field of the object has been covered, as for instance 

 in the search for bacilli. 



To Illuminate the Object.- -This is an ex- 

 tremely important feature and should always be 

 carefully done, as one may easily fail to obtain the 



