POSITION OF OBSERVER. 293 



have been laid down for his guidance, and these should 

 not be lost sight of. As his eyes become trained to this 

 kind of work, he will begin to pick up items of value 

 on his own account. Especially will he arrive nearer a 

 due appreciation of what we mean by tone of objective 

 and field. He will thus be able to recognize for him- 

 self, confidently, too, when things are just right. Ditto, 

 when they are not just right. Should the collar of his 

 objective need to be changed, he must be able to make 

 such change at once, and in the right direction. There 

 must be no indecision no guess work. He will have 

 learned, also, that when the adjustment is exactly cor- 

 rect, not only has the display of the striae become more 

 satisfactory, but that the general appearances of the 

 entire shells have improved. This effort at improve- 

 ment of the adjustment of the objective should become 

 a constant and never ending study ; in truth, after one 

 becomes tolerably advanced therein, it is no longer a 

 " study," but rather a pastime. 



We desire to insist with all the vigor we can com- 

 mand, that there is force attached to the reciprocal re- 

 lations above named, to wit: That when the student, 

 perforce of intelligent practice, shall be in position to 

 assert, dogmatically, that his manipulations are correct, 

 he will, conversely, be just as competent to reaffirm the 

 fact when things are not in proper adjustment. When 

 this obtains to an acceptable extent, he will be compe- 

 tent to use his glass for any field of investigation that 

 he may elect, and, as a matter of course, he will regard 

 those whom he is assured have not given proper atteu- 



