ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
03 
The objective-board and objective , including the optical conditions 
for perfect projection, are described in detail, and arc followed by a dis- 
cussion of the ordinary method of projecting microscopic preparations 
by means of their photographs. But in fig. 14 the author explains how 
he projects from the microscopic preparation itself. The massive horse- 
shoe foot F is fastened on the objective-board by means of a groove and 
screw B (fig. 11), and can be moved forwards and backwards by the milled 
head II (fig. 10). On F (fig. 14) the short rectangular pillar A is firmly 
screwed, in which the cross-piece B is moved perpendicularly up and 
down by rack and pinion, operated by the screw a. The milled head b 
imparts a horizontal movement to the tube-holder. The short tube H has 
a clear diameter of 48 mm. ; it bears a projection Microscope objective at 
0, and can be focussed on the micro-preparation by means of the milled 
head c. When D is fully extended, an obje ctive of 12 cm. focus can 
be used. The object stage can be rotated, and has an iris of 25 mm. 
diameter. The stage, including E, is completely removable ; special 
holders for other objects, e.g. for bacteria cultures, can then be inserted. 
Abbe Camera Lucida. — Messrs. Bausch and Bomb bring out a sim- 
plified form of this accessory, in which, while the Abbe prism is used as 
in the large Abbe camera lucida, the mirror is reduced in size and is 
fixed. The prism and mirror are contained in a neat mounting which 
is attachable to the Microscope-tube by a clamping ring, and may be 
Fig. 15. 
A 
swung back out of the way of the eye-piece as shown in fig. 15. A beau- 
tifully clear image of the object and of the pencil point is said to be 
obtained. One feature of this camera lucida is that by means of the 
clamping ring the distance of the prism from the eye-lens can be varied, 
and thus the camera used with various oculars. 
