812 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
advantages derived from the slides resting on five supports are still secured. 
Under previous constructions it was impossible to cut an object more 
than 1 cm. high without moving either the knife or the preparation. 
The new arrangement allows continuous sections to be made from objects 
3 cm. high. The object slide is now vertical, and the holder movable 
about two horizontal axes. In consequence of all these changes the 
instrument is considerably larger and heavier. 
Apparatus for preparing Sections of Crystals cut in definite 
directions.* — Dr. E. A. Wiilfing gives a description of this apparatus. 
It consists of three entirely separate parts : — (1) a “grinding tripod,” 
with adjustable screw-feet and a carrier for the crystal ; (2) a “levelling 
tripod,” with micrometer screw-feet; (3) a levelled glass plate. 
(1) Grinding tripod. — A brass plate a (figs. 95 and 96), 2/5 in. 
thick, and in the form of an equilateral triangle of 4 in. side, is provided 
at each corner with an adjustable steel screw b. These screws have 
square heads, on which the key E fits, and they permit of the plate being 
inclined about 15° in any direction. In the centre of the plate is a tube 
Fig. 95. Fig. 96. Fig. 97. Fig. 98. 
c, provided with a lug d (fig. 96) internally, which fits into a corre- 
sponding groove in a steel cylinder capable of free motion up and down, 
but not of rotation on its axis. The steel cylinder (fig. 97) is flanged at r, 
and the flange bears a projection v, the object of which will appear sub- 
sequently. The cylinder bears two lateral slots g , and its internal cavity 
is slightly conical. The brass cone (fig. 98) fits inside it, and is furnished 
at h with a flange and a broad disc-like base, whilst at top it bears a 
* Zeitschr. f. Krystallographie, xvii. (1890) pp. 445-59. 
