The following was extracted from The Microscope by Hogg 1898:
Of Messrs. Baker's
larger stands, the Improved " Nelson Model," No. 2
(Fig. 88) stand is selected in preference to their
more elaborate No. 1, and their simpler form, No.
3, as a high-class instrument, and one well
suited for fine critical work ; the former
being somewhat better, only from having extra
adjustments; the latter possessing no
superior advantage over the " Advanced
Students' " Microscope. This microscope is mounted
on a solid tripod foot, which insures stability,
whether placed in a vertical, horizontal, or
inclined position; the front toes are slotted, so
that they may be clamped to the base plate of a
photo-micro- graphic apparatus, first introduced
for photo-micrographic work, and will also be found
convenient in ordinary work; as the fine adjustment
milled head is placed at the bottom of the pillar,
instead of at the top, the more usual place. For
photo-micrographic work the advantage is that the
strain of the pulley in such apparatus actuates the
fine adjustment, and is less liable to cause
vibration of the instrument. The advantage when the
instrument is used for ordinary work lies in the
fact that the weight of the hand is rested on the
top of the tripod, thus admitting of steadier
movement of the milled head. The fine adjustment is
obtained by a "Campbell" differential screw, each
revolution of which is equal to 1/200 m.m. The
draw-tubes being graduated in m.m., allow of either
short or long tube objectives being used, closing
up to 150 m.m. and extending to 280 m.m., the rack
and pinion adjustment to the lower tube affording a
ready means of correction for cover-glass
thickness. The eye-piece gauge, as will be seen
from its dimensions is of large size, being the
same as that adopted by Zeiss for his long tube
compensating oculars; smaller eye-pieces can,
however, be adapted at any time.
The mechanical
rotating stage is divided on brass to 1/100-inch,
with clamping bars and stop, by which a specimen
can always be brought back to a certain position
for registration. The sub-stage has rack-work
focusing adjustment, and centering screws; a fine
adjustment is added, if desired.