114 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
III. The horse-shoe foot. The author considers that in the Con- 
tinental stands now made the horse-shoe foot is far too small. This 
defect is especially noticeable in the smaller models, which are very 
liable to be overturned by a comparatively slight shock. The space 
between the two arms of the horse-shoe is also 
not sufficiently wide for stable equilibrium. As 
a model for the correct shape of the foot, he 
points out the instrument which was constructed 
thirty-five years ago by Merz in Munich. The 
requirement that the boundary of the supporting 
surface shall be as far as possible from the 
vertical line from the centre of gravity, is suf- 
ficiently satisfied by the curvature of the horse- 
shoe being here replaced by an almost straight 
bar b (fig. 6), which, at a comparatively great 
distance from the column of the stand, throws out in front, on right 
and left, with a sudden turn, the two parallel three-sided prismatic 
arms x x. 
The foot is broader than long in about the proportion of 7 : 6. The 
width between the arms is nearly equal to the diameter of the object- 
stage. Five circular leather discs e of a half-inch diameter, distributed 
as shown in the figure, support the foot. These discs are screwed on to 
the foot, as seen in fig. 7. 
Zeiss’ Hand-Microscope.* — This instrument, shown in half full size 
in fig. 8, is intended for class demonstration. The sliding-tube, after 
Fjg. 7. 
adjustment, can be securely fixed by a clamping ring. Fine-adjustment 
can be effected by altering the position of the eye-piece. In use it is 
directed towards the window or lamp. 
Zeiss’ Stand IX. j - — This stand (fig. 9) is intended as a simple 
auxiliary stand for laboratory and technical purposes. It has a plain 
large stage of 100 mm. diameter, with large aperture, which can be 
decreased by dropping in a diaphragm. The adjustment is by rack and 
pinion, the construction of which admits of the use of medium powers. 
* Zeiss’ Catalogue, No. 30, 1895, p. 56. f Op. cit., pp. 56-7. 
