DESCRIPTION
This
compound microscope arises from a Continental Horseshoe foot of
the form used by Watson and similar to those used by most European
microscope makers of the time. The oxidized brass finished horseshoe
gives rise to a lacquered brass round pillar. It is signed on the rear
top of the horseshoe foot: 'W. WATSON & SONS, 313 HIGH HOLBORN,
'LONDON'. The serial number 3102 is engraved on the back edge of the
horseshoe foot.
The plane and concave mirrors are housed in a lacquered
brass
casing attached to an oxidized brass gimbal. The mirror support slides
inside a slot of the oxidized brass swinging tailpiece.
The substage support, separate from the mirror tailpiece, is attached
to the underside of the stage and the entire substage assembly can
pivot out of the optical axis on a hinge. When in normal position a
brass screw on the opposite side of the stage bottom accepts the catch
that holds the substage assembly in position. In contrast to the 'H'
model, the substage is a simple sleeve and the condenser must be
focused by sliding it manually up or down in that sleeve. There is no
mechanism for centering the condenser. With the instrument is a single
condenser housing with condenser with an iris diaphragm and a
filter/stop holder (stops missing). This condenser is unsigned.
The Stage of this model is a plain flat stage with brass
stage clips.
Coarse focus is by diagonal rack and spiral pinion whilst the fine
focus is via a long lever controlled from the top edge of the rear part
of the arm. The knurled lacquered brass fine focus knob is calibrated
and numbered from 0-9.
The outermost main optical tube is 1.2 inches outside diameter and is
about 5 inches (130 m.m.)long. There is one brass calibrated
drawtube with an outer diameter of about 1 inch with calibration lines
every 1 cm. The inner draw tube accepts the narrower 23 mm eyepieces.
The maximum mechanical tube length is about 9 5/8
inches (245 m.m.) There is one eyepiece with the instrument labeled 'B'.
All the rack and pinion fittings have the capacity for
adjustment in
the event of wear, as do the the slides in which the tubes and substage
travel. Every part of this microscope works like it did 100 years ago.
ACCESSORIES
FOR THE 1892 WATSON EDINBURGH B MICROSCOPE
Accessories currently with this microscope include the single eyepiece
mentioned above, the condenser, and the objectives noted below.
Objectives with this microscope at this time include:
- 2 inch Watson with 0.17 n.a. which makes it a holoscopic,
though not labeled as such.
- 2/3 inch,
n.a. 0.28 which makes it a parachromatic, though not labeled as such
- 1/6 inch
Parachromatic
Options for this microscope at the time of its manufacture
included
a finer grade of graduations to the fine adjustment but major upgrades
to the stand otherwise would have changed it to a 'C' or 'D' stand.
The stand is in excellent condtion, though it lacks the small
registration piece for the fine adjustment. Although it came to me with
many parts quite loose, the built-in adjusting screws allowed me to
tighten everything up perfectly so the microscope now works as well as
it did 112 years ago.
HISTORY OF THE
EDINBURGH STUDENT MICROSCOPES
The Edinburgh stand, is a model apparently devised in 1887
with the advice of
an Edinburgh professor, Dr Alexander Edington, a lecturer on
bacteriology at the University of Edinburgh. The first entry
in the Watson Delivary Books for an Edinburgh Student Microscope was on
November 29 1887. The first with compound substage was listed on
January 20, 1888. In the Watson delivery books, the Edinburgh Student microscopes were often abbreviated as 'E.S.'
The Edinburgh microscopes
preceded the Van Heurck and later Royal models, and indeed were the
inspiration and basic stand on which both were based. The Edinburgh
stand went through several iterations and improvements over the years.
The various Edinburgh stands were at first indicated in the Delivery
Books only by description (e.g. Edinburgh Student Microscope with Rack), then during 1889 by the numbers 1,2,3, and
4, but by 1889 the catalog referred to them by letters and these were
used in the delivery books from early 1890 onward. The letters A,B,C,
and D replaced the 1,2,3,and 4. In 1892, came the E,F,G, and
H, which were identical to the first
four except for having a tripod foot instead of the (initially
standard) horseshoe foot.
The Edinburgh A,B,C and D models were reported in the 'English Mechanic and World
of
Science' in August of 1889 and were also listed in the
'Ninth' edition
of Watson microscope catalogs which has an introduction dated
1889. For a summary of the chronology of these events, please
see below.
The A and E had a push-pull coarse focus and the standard Watson long
lever fine focus. The condenser sleeve was built into the bottom of the
stage. There was a swinging tailpiece with mirror riding in a slot,
just as the example of the B in this collection.
The
B and F were identical to the A and E but featured the addition of
diagonal rack and spiral pinion coarse focus instead of the push-pull
coarse focus.
C and G then featured the
addition of a separate 'compound' substage
with diagonal rack and pinion focusing and controls for centering the
condenser sleeve.
Finally, on the D and H, was added the rack and pinion mechanical
stage, which became standard on the Royal much later.
In 1893, an option was to add a second draw tube which was controlled
by rack and pinion. The Royal
introduced later, was actually an Edinburgh D or H, with the mechanical
draw tube standard and the option of a substage fine focus as supplied
on the Van Heurk models. Other options, including Nelson's
unidirectional mechanical stage can be seen on the Edinburgh accessory catalog page.
