516 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



Fig. 118. 



Verick's Skin Microscope. — This (Fig. 118) is intended for the 

 examination of the skiu. The tube, with eye-piece and objective, is of 

 the usual form, but is attached to a lateral bar B, which is of brass, 

 with a piece of ivory at the lower end. This 

 bar serves for the adjustment of the Microscope 

 to the proper focus. It is graduated in accord- 

 ance with the objectives used, and when the 

 number corresponding to the particular objective 

 is brought to the point C, and the end of the bar 

 rested upon the object under observation, the 

 surface can be examined with facility. The 

 screw A serves to clamp the bar and tube 

 together. 



Watson's Microscope - Stand. — This new 

 stand (Fig. 119) presents several points of 

 novelty, the most notable of which is the in- 

 clining motion of the limb carrying the optical 

 body and stage on an axis in a line with the 

 object on the stage. By the simple inclination 

 of the limb, varying effects of oblique illumina- 

 tion can be obtained direct fi'om the mirror, 

 which can be attached for this purpose to the 

 centre of the base, and is then independent of 

 the inclination of the limb. 



The base of the stand is circular, with three 

 projecting claws; on this base a disk of metal 

 carrying the pillar-support (of the limb, stage, 

 &c.), is made to rotate on the perpendicular 

 optic axis (as in Nachet's Microscope, described 

 in vol. iii. p. 873), and a graduated zone shows the angle of rotation. 

 In the centre of the base a smaller disk (projecting slightly above the 

 general plane) is made to rotate ; this disk has a groove into which 

 the mirror-fitting slides, and a spring-notch shows the axial position. 

 The sliding fitting allows the mirror to be placed considerably out of 

 the axis radially, and then the rotation of the circular moving base- 

 plate gives a considerable range of obliquity of light in azimuth — 

 the light from the mirror remaining constantly directed upon the 

 object; this facility obtains with all inclinations of the limb and 

 stage because the object itself forms the centre both of the azimuthal 

 rotation and of the inclination in altitude. 



The limb is mounted in a " cradle " joint, at the top of the pillar, 

 permitting inclination from the perpendicular. The angle of incli- 

 nation is registered upon a graduated ring against the clamping 

 screw. 



The optical body is mounted not as usual on the front of the 

 " Jackson " limb, but on the side of it (the side of the limb is thus 

 converted into the front). 



The coarse adjustment is by the ordinary rack and pinion ; the 

 fine adjustment lifts the optical body in a separate slide-fitting by 

 means of a wedge-shaped block acted upon by the conical end of a 



