BECK'S ECONOMIC MICROSCOPE. 77 



" For ordinary pathological, physiological, and botan- 

 ical investigations, many of the delicate adjuncts applied 

 to the higher-priced instruments are unnecessary, and 

 tend rather to contuse than to assist the beginner." 



To this let these pages say again, Amen. 



" A firm stand and well-corrected object-glasses are,, 

 however, indispensable." 



In response to this we not only say amen, but shall, 

 in the proper place, have something further to add. 



6 'The stand of the "Economic" is made in two 

 forms : the one with a sliding adjustment for focussing 

 the object, and the other where the quick movement is 

 produced by rack and pinion. On both stands the fine 

 adjustment is given by means of a milled head at the 

 top of the stem. The stand is fitted with the society 

 screw. 



The foundation of the stand is a heavy horseshoe 

 base A, at the head of which is a firm pillar B, having 

 at its top a hinge joint C, which allows the body D to 

 be inclined to any angle, and is sufficiently firm to per- 

 mit of its being;* placed horizontal for use with the 

 camera lucida. 



The body tube is short, but by means of the length- 

 ening draw tube V can be made of the standard length. 



In the more expensive stand the coarse adjustment is 

 by rack and pinion; in the cheaper instruments the 

 quick movement is produced by sliding the body D up 

 and down the tube H, sliding over the inner stem with 

 a spring inside, the fine adjustment being accomplished 

 by the milled head I. 



