Otf THE HICSOSCOPB. 35 



ties, they are sold very cheaply, when the quality of the lenses 

 is taken into consideration. Therefore, until some manufacturer 

 concentrates his efforts upon the production of the more con- 

 venient forms, and turns them out in very large numbers, the 

 vertical microscope will probably maintain its place in the 

 market, and many beginners will be led into buying an instru- 

 ment which, even in its most complete and perfect form, will 

 almost certainly be a source of dissatisfaction. Whenever a 

 sum greater than three or four dollars is to be expended, some 

 form other than the vertical should be chosen. 



Occasionally microscopes of this kind are furnished with 

 achromatic objectives of pretty fair quality. In such cases the 

 objectives and eye-pieces, if they could be applied to a better 

 stand, would be worth more than the whole microscope in its 

 original form. 



The Continental Form. Most of the stands made by 

 the better class of French, German and Austrian microscope 

 makers are characterized by a low, compact form, and great 

 simplicity and solidity of construction. Our engraving, Plate 

 I, shows a very serviceable instrument, manufactured by Mr. 

 George Wale, formerly of the Stevens' Institute, now of Pater- 

 son, New Jersey. The general form of this stand is very similar 

 to that of the large model of Nachet, of Paris, but the details of 

 construction have been changed considerably, and we think for 

 the better in many respects. The coarse movement is effected 

 by means of a pinion and chain, the latter "being kept tight by 

 means of a spring instead of by a screw, as is the common 

 method, and as the pinion round which the chain is wound is 

 milled so that the links fit into it, all slip is avoided, and there is 

 positively no "lost motion " whatever the movement respond- 

 ing promptly in either direction even when suddenly reversed. 

 The fine movement consists of a lever which carries the entire 

 body (coarse movement included) downward by means of a 

 spring, and upward by means of a screw, the milled head of 

 which is placed below the arm which carries the body. This 

 brings both movements so close together that the hand may be 

 kept on both at the same time the thumb and fore finger 

 operating the coarse movement, while the third and fourth 

 fingers make the fine adjustment. 



