ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
351 
movements are graduated in millimetres for registration as a £C finder,” 
and the mechanical movement in each direction is 1 in. Although the 
transverse movement is 1 in,, the examination of a slip is not confined 
Fig. 44. 
to this amount, as is the case with most mechanical stages, because in 
this apparatus no limit is imposed as to the lateral position of the slip, 
neither is the length of the slip limited to the usual 3 in. The device, 
therefore, becomes eminently useful for the examination of serial 
sections. 
(2) Eye-pieces and Objectives. 
New Hartnack Homogeneous-Immersion Objective. — The Hart- 
nack firm have brought out a 1/10 in. homogeneous-immersion on the 
same model as their 1/12 in. (No. 1). Greater experience in the con- 
struction of immersion lenses allows the new objective to be issued at 
a much less price than the 1/12 in. (85 marks as against 125). The 
numerical aperture is 1*25-1 *30; the working distance 0*3-0*35 ; and 
magnification with suitable eye-pieces from 280 to 1050 diameters. 
(3) Illuminating- and other Apparatus. 
Zeiss’ Combined Horizontal and Vertical Camera. — This apparatus 
fully answers to its name, and secures, at the will of the operator, a hori- 
zontal, vertical, or 45° inclination of the camera. These three positions 
will be readily understood from figs. 45 and 46 ; the outlined portion of 
fig. 46 showing the 45° position. The massive triangular cast-iron sole 
plate F has recessed into it a revolving stage P, which is kept in position 
by a spring, and is adjustable by three setting screws i i, so as to give the 
Microscope its proper elevation and inclination. The Microscope is 
placed upon the rotating stage, and is adjusted in such a manner that 
in its vertical position its axis coincides with the axis of rotation of the 
revolving stage P. This adjustment need only be made once, as a stop 
1898 2 B 
