THE MICROSCOPE, ETC. 25 



CHAPTER III. 



THE MICKOSCOPE, ILLUMINATION, ETC. 



Before beginning a detailed description of the 

 microscope, a few hints to the uninitiated are neces- 

 sary. 



Avoid purchasing instruments adorned with in- 

 numerable screws and mechanical arrangements for 

 performing the various movements. All superfluous 

 apparatus, is not only useless, but a decided hindrance 

 to accurate investigation, in fact the various additions 

 generally made to the first class instruments of the 

 present day, are both an insult to the skilled micro - 

 scopist and a means of perpetuating clumsy manipu- 

 lations. On the other hand many excellent instru- 

 ments are made, which owing to some peculiarity of 

 shape, are useless for photography. 



The first essential of a microscope is a firm heavy 

 stand, so arranged that the body may be inclined at 

 any angle between horizontal and perpendicular and 

 clamped in that position. The stand should be high 

 enough to allow space beneath the stage for sub-stage 

 apparatus, and the points on which it rests should be 

 sufficiently distant from each other to prevent the 

 instrument being easily overturned. 



The coarse adjustment is best accomplished by 

 rack and pinion movement, (not by one tube sliding 



