78 PRACTICAL TREATISE ON THE MICROSCOPE. 



oostly as the first described ; and, although much lighter and 

 more portable than it, is nevertheless exceedingly steady, 

 from all the parts being accurately balanced. 



MESSES. POWELL AND LEALAND'S PORTABLE MICROSCOPE. 



One of the most portable and convenient forms of compound 

 microscope is that made by Messrs. Powell and Lealand, and 

 represented by fig. 44, about one-third of its actual size. It 

 is supported on three legs, ABC, capable of being folded one 

 upon the other, and when so folded can be brought in a line 

 with the tube D E, supporting the stage, G, and the mirror, 



F, and through which slides the triangular bar, H, having at- 

 tached to it the arm, I, carrying the compound body, L K ; 

 this last, for convenience of package, is made to unscrew at 

 K, and the eye-piece, L, being removed, the folded legs can be 

 passed through the tubular part of the body, and both together 

 laid parallel with the tube D E. The legs are connected with the 

 tube D E by a strong ciirved piece of brass, M, which winds 

 round to the opposite side of the tube ; a stout pin, with a 

 screw nut, serves as an axis upon which the tube, D E, and all 

 that is attached to it, can be turned from a vertical to a hori- 

 zontal position. The stage, G, presenting a box-like appear- 

 ance, is also capable of being turned into a position parallel 

 with the folded legs, by drawing back the sliding-piece, P, 

 which, when in use, keeps it in a horizontal position. The 

 apparatus for moving the stage is contained within the box, 



G, and is similar to that employed by Messrs. Powell and 

 Lealand in their larger instruments, the up and down move- 

 ment being performed by turning the milled head, N, and 

 that from side to side by the larger milled head, O. The 

 slide, Q, is for the purpose of supporting the object when the 

 microscope is inclined, and in it are two sockets for receiving 

 the forceps for holding opaque objects. To the under-side of 

 the stage are attached a diaphragm and a small arm for carry- 

 ing the dark stops or wells ; and, should it be required, an 

 achromatic condenser, or polarizing prism, may be fitted into 

 the place occupied by the diaphragm. The coarse adjustment 



