ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
649 
method consists in shortening the distance between the object-glass and 
eye-piece, thereby obtaining a diminution of magnification with a corre- 
sponding increase of field ; the Microscope being made to act somewhat 
after the fashion of a telescope. A very great depth of focus is thus 
obtained. It is possible that this form of Microscope might be very 
serviceable in the study of circulating systems when high magnification 
is not desired. 
It should, however, be pointed out that the great shortening of the 
tube-length will put the objective out of correction ; but this would not 
make any important difference with the very low powers which only 
would be used in this manner. 
Berger’s New Microscope. — In the account of Messrs. Zeiss’ new 
Microscope (Berger’s model) * a description of the mechanical stage was 
unfortunately omitted. On referring to fig. 98, p. 584, it will be seen 
that the heads of the pinions are on Turrell’s plan, but the outer head 
gives transverse movement to the stage-plate instead of vertical move- 
ment. The pitch of the screw on this pinion is fine, so that the motion 
is slow. The vertical movement, which is actuated by the inner pinion 
head, is on altogether a novel plan. The motion is one in arc ; this stage- 
plate being pivoted on the left-hand side, has rack teeth cut in it, into 
which a pinion is geared. This pinion has a toothed wheel fixed to it, 
in which engages an endless screw attached to the pinion that carries 
the inner pinion head. The speed of the object at the centre of the 
stage is about half that of the rack, because the object is placed about 
half-way between the rack on the right and the pivot on the left-hand 
side of the stage. 
The stage is concentric with simple non-mechanicalj rotation ; it can 
be clamped in any desired position by a small screw at a the side of the 
stage (not shown in the figure). 
Watson and Sons’ “School” Microscope. — This Microscope (fig. 
154) is of plain but substantial construction, and has been designed spe- 
cially for the use of schools, and for the teaching of animal and vegetable 
histology. The makers have adopted a suggestion that has been made 
on many occasions, viz. that a Microscope possessing a thoroughly good 
coarse adjustment without any fine adjustment should be supplied in 
place of the ordinary cheap student’s Microscope, which is provided 
with an indifferent fine adjustment and plain sliding body. 
The power needed for ordinary student’s work can be quite well and 
precisely focussed by means of this rackwork and pinion. The Micro- 
scope takes the Continental size of eye-piece, and has a draw-tube. The 
universal fitting for substage apparatus screws into the under side of 
the stage ; an inclining joint and adjustable double mirror are also fitted. 
The total height of the instrument is 10 in. 
Bausoh, E. — Manipulation of the Microscope. A Manual for [the work-table, and 
a Text-book for the Beginners in the use of the Microscope. 
Rochester, N.Y., 1899, 8vo, 200 pp. 
* See this_ Journal, 1898, p. 583. 
