ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
693 
angles to the optic axis, so that a change in position of the light may 
be within certain limits compensated for without the necessity of altering 
the illumination. 
The achromatic centering condenser shown in fig. 100, which answers 
to these requirements, can be fitted into the socket of the illuminating 
apparatus in place of the ordinary condenser. 
(4) An illuminating apparatus (fig. 101) adjustable in the direction of 
the axis. 
Fig. 99. 
(5) For projection with very low magnifications (system of 70 mm. 
focal length without eye-piece) a body-tube of extra width. 
(6) Of especial importance is a good micrometer movement on the 
stand. 
(7) A Hooke’s key for the fine-adjustment if the operator prefers to 
be nearer the screen than the Microscope. In this case the base-plate 
of the Microscope is provided with an arrangement (a, fig. 99) for readily 
connecting the Hooke’s key with the micrometer screw of the stand. 
As answering to the above requirements the firm of Zeiss offer their 
stand for photomicrography which was described and figured in this 
Journal, 1889, p. 278. 
3 b 2 
