ZOOLOGY AND BOTANY, MICROSCOPY^ ETC. 
6G9 
on tlie table beside it, forming a rough scale by which its size may be 
estimated. The action of the various parts of this Microscope is so un- 
like that of any other instrument that they will hardly be understood from 
an inspection of the photograph ; a ‘detailed account is therefore necessary. 
To the flat tripod foot, which is about 18 X 12 in., are fixed two lateral 
flat upright posts, braced together at their upper end by a fixed hori- 
zontal rod ; to the centre of this rod one end of a quadrant is attached, 
its other end being fixed to the base. 
“ The quadrant and its lower point of fixture are clearly seen in the 
photograph ; but the fixed horizontal rod, which supports the upper end 
of the quadrant, is hidden by another horizontal bar ; its terminal screw, 
which passes through the right-hand vertical upright post, can however 
be seen. Through the bases of the upright posts is fixed a stout cylin- 
drical horizontal bar, its centre being the centre of the quadrant. A 
strong arm, forming a radius of the quadrant, turns on the middle of this 
bar ; its upper end, which embraces the quadrant, is produced a short 
distanco beyond the quadrant, and forms a rigid attachment for the 
lower end of the tail-piece. To the extremities of this lower horizontal 
bar is pivoted the lower end of a lattice bracing, the upper end of this 
bracing being attached to the lower fixed stage-plate, which in this 
Microscope is behind the tail-piece. The plan of this lattice-work is 
clearly seen in the photograph ; a more minute description is therefore 
unnecessary. Attention however may be drawn to the third horizontal 
rod, to which are attached the stays and struts of the lattice bracing, and 
which moves with the lattice bracing when the Microscope is inclined. 
The Microscope can be clamped in any inclined position by a screw, 
which, passing through the upper end of the radius, pinches the 
quadrant. Thus far we have an entirely original method of supporting 
a large Microscope, which ensures rigidity, apart from undue weight. 
Passing on to the Microscope itself, we see that it is constructed on 
the Ross model, with an unusually long (for that model) fine adjust- 
ment lever. The coarse adjustment is of the ordinary type, racking a 
prism bar out of the tail-piece. The body, which is binocular and 
12 in. long, is supported at the back by a strut. 
“ In this part we meet with little or no divergence from known forms ; 
but in the stage we find considerable novelty. The mechanism is as 
follows there are three plates, the upper one, which is identical with 
the actual stage of the Microscope, is attached by a pivot, seen a short 
distance from its lower end, to a middle plate, which carries a tangent 
screw. These two plates slide in a vertical dovetailed groove in the 
third or lowest plate, the vertical movement being actuated by rack and 
pinion in the usual way. The transverse movement is a transverse 
movement in arc ; this is performed by the tangent screw at the lower 
\ end of the middle plate causing the upper plate to revolve on the pivot 
seen a little above it. Special notice should be given to this stage with 
regard to its rigidity, which depends of course upon the rigidity of its 
lowest plate ; but this, as we have seen, is supported by no less than five 
struts of the lattice bracing and by the tail-piece. The result obtained 
by this design is an open, thin, and unhampered stage, and I know not 
where you will find its equal in this respect. 
“ From the stage we pass on to the substage, in which we shall find 
some more novel and interesting details. The substage itself has the 
usual rectangular movements for centering, and it is also fitted with a slow 
