210 MICROSCOPIC ILLUSTRATIONS. 



other respects like those for some operations on the eyes, 

 (i. e. without bows), having one arm inserted in a long 

 handle, and the other left short, playing against a feeble 

 spring to keep it open, is the sort of tool required. It is 

 held like a pin, and cuts by the pressure of the index 

 finger on the short arm. You may, of course, dissect 

 with simple microscopes of loiv powers as well as with the 

 engiscope, but the present stand is not so well adapted 

 for them as a separate one would be. 



9th. Mounting the Diamond and Sapphire Microscopes 

 for opaque objects. — It is one of the vices of simple mi- 

 croscopes that they can only shew opaque objects with 

 cups — at least if their powers exceed one quarter of an 

 inch. The lower foci shew opaque objects admirably 

 with day- light, the stand being in the vertical position. 

 When used for plain day-light in a horizontal one, all 

 that is necessary is to assume such an attitude relative to 

 the window that the head shall not intercept its light. 

 For example, if you sit with the bar horizontal and pa- 

 rallel with the window, the light will naturally fall be- 

 tween the stage and the magnifier upon the object. When 

 cups are employed, they act precisely like those attached 

 to the engiscope, and magnifiers thus mounted are 

 managed in the same way. 



10th. The Amician Catadioptric Engiscope is attached 

 to the present stand by means of the arm, fig. 20, and is 

 managed precisely on the same principle as the refracting 



