ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



99 



present instrument (fig. 5) in 1827, which was said to he very excel- 

 lent and superior in workmanship and definition to those made hy 

 Amici. 



In Cuthbert's reflecting Microscope the reflectors were supplied in 

 separate tubes, ranging from 2 in. to ^^ in. focus, and are screwed on 

 to the nose-piece like other object-glasses. For the illumination of 

 opaque objects Lieberkuhns wxre supplied. sprung on the tubes of the 

 lower powers. The triangular stem or bar carrying the stage is clamped 

 on the nose-piece at right angles to the optic axis, and has a rack, cut in 

 the angle of the bar, which gives coarse movement to the stage for 

 focusing. The stage carries a spring super-stage for holding object- 

 sliders and the live-box, but has no mechanical movement. The 



Fig. 5. 



double mirror and also a plano-convex condensing lens slide on the 

 triangular bar. A small bullseye, sprung on to the nose-piece for 

 illuminating opaque objects, is also provided. 



In another specimen in the Society's collection (fig. 6), the 

 triangular stem has no rack, but there is a fine-adjustment screw, which, 

 after being clamped on to the stem, moves the stage in the manner of 

 Cuff's fine-adjustment ; the coarse-adjustment is effected by sliding the 

 stage up and down the stem. The stage itself has mechanical move- 

 ments in two directions. A jointed arm carrying a spring forceps is pro- 

 vided, which takes the place of the stage when in use. 



The present instrument has three reflector-objectives, three eye- 

 pieces, Lieberkuhns and various other apparatus common to the Micro- 

 scopes of the period. 



From 1830 onwards, led by Charles Chevalier and Oberhaeuser in 

 Paris, and followed by Andrew Ross, Hugh Powell, and James Smith in 



H 2 



