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conclusion must be reached in so far as it effects 

 the height of the instrument. 



Base. The base is an important feature and 

 while not over heavy should insure steadiness by 

 the proper form and disposition of metal ; it 

 should not rest on more than three points, with the 

 rear one fairly distant from the pillar. 



The Joint for Inclination of Arm. This, 

 without question is an advantage and while it is 

 an inexpensive addition it will add considerably to 

 the comfort of working and should invariably be 

 present, if pecuniary means do not absolutely 

 prohibit it. 



Coarse Adjustment. Almost all instruments 

 for reliable work are provided with both fine and 

 coarse adjustments. The choice of the latter lies 

 between the sliding tube or rack and pinion. The 

 former has only the advantage of economy and is 

 a decided disadvantage in the hands of students in . 

 injuring objectives and preparations. Further 

 than this, it is almost impossible for the maker to 

 center the nosepiece with the tube, so that a change 

 of objective usually throws an object out of the 

 field and requires that it be looked for anew with 

 each change. With the rack and pinion the nose- 

 piece has an unvarying relation to the tube and is 

 not liable to this difficulty and offers a steady and 

 agreeable adjustment. The advantages of the rack 



