THE MICROSCOPE. 105 



First (and principally). Perfection of action: the upper 

 plate carrying the object, must respond instantly to the move- 

 ment of the screw, upward by positive action, downward by 

 the spring of the plate; and without any lateral or side motion; 

 these, of course, are the essential features of a fine' adjustment. 



Second (and important). This perfect action will continue as 

 at first; as there are no joints to wear loose or become strained, 

 there can be developed no lost motion nor lateral motion, by 

 wear or rough handling, all excepting the screw being made 

 practically one piece. Third. It is inexpensive in construction. 



(An objection is sometimes made that one side of the stage- 

 plate is moved, while the other is not, thus elevating one side 

 more than the other. We only ask those to whom this may ap- 

 pear an objection to make a practical and careful test. They 

 will find that this objection is utterly invalid in practice, as 

 the range of motion required is very slight ; at mid-range the 

 stage-plate is strictly horizontal.) 



We can well recommend this microscope to medical students, 

 and to physicians who may not desire to purchase a more ex- 

 pensive intruments, as efficient for histological v:orh and urinary 

 analysis. It has society-screw, and is furnished withl-inch and 

 1-5 inch objectives, and one Huyghenian eye-piece, in upright 

 case with handle. Powers range from 40 to 350 diameters ; the 

 1-5 inch is a lens of such good definition (and sufficient aperture) 

 that it will resolve P. angulatum. Price, complete, in neat imi- 

 tation mahogany case, $28.00. 



Clips and Ledge. — Nearly all microscopes are provided with 

 a pair of spring clips to hold the slide. Convenient as these 

 generally are, they often prove a positive nuisance, especially 

 when examining temporary mounts, by " whisking " off the 

 cover glass at the most inopportune moment. A mere ledge, 

 to rest the slide against, is more convenient. This can be im- 

 provised by bending a strip of thick sheet lead so as to grip the 

 stage sufficiently firmly to prevent the sliding down of the slide 

 when the stage is inclined, and still capable of being easily 

 pushed up and down. (This applies only to the rectangular 

 stages; not to the round ones). — H. M. Wilder, in Druggist's 

 Circular. 



