MICROSCOPE-ANTIQUES.COM © 2013-15.
FRAM MICROSCOPE:
C. 1915
Maker: W. WATSON & SONS LTD.
Serial number: 13881
DESCRIPTION
This compound microscope arises from a tripod of the form used by
Watson in their more expensive instruments with slight differences.
The tripod is a single casting, and has round brass toes. At the top of the tripod are two
uprights accepting the trunnion joint with adjustments very similar if
not identical to many other Watson models like the Edinburgh and Royal. Unlike earlier models which had a different mechanism, there is a horizontal bar spaning the upright supports of the trunnion
joint which acts as a register for horizontal or vertical positions of
inclination. (For an example with a registration pin coming off the limb which registers to the top of the tripod, see the Holos Fram example on this web site.)
The plane and concave mirrors are housed in a lacquered
brass casing attached to an oxidized brass gimbal. The mirror fitting
slides up or down the swinging tubular brass tailpiece.
This example, instead of having the standard substage condenser
housing which can swing out of axis, but is not adjustable up or down, has the optional spiral screw focusing substage similar to American and German
models of the time.
The instrument is signed on the left side of the top of the tripod: 'W. Watson & Sons, 13881' and on the right side: '313 High Holborn, London'. The uprights also have additional signatures. On the right upright it is signed: 'Agent, Chas H....s, Cambridge' and the left upright signature has been obliterated. This may be Charles Higgins, but the letters are not readable even with oblique lighting and magnification.
The Stage of this model is a plain flat stage with vulcanite
applied to the top and two stage clips. It is the Nelson form, with
U-shape. This form of stage was standard on this model from 1898
through 1913, but a solid stage was an option as well.
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
not calibrated as was standard in 1912-13 for this model.
The outermost main optical tube is one and a half inch outside diameter and is
about 5 and one half inches long. There is one brass calibrated drawtube. The
inner draw tube is one inch in diameter and accepts the narrower 23 mm eyepieces. When fully extended, the mechanical tube length is about ten inches. There is one
eyepiece with the instrument.
All the rack and pinion fittings have the capacity for
adjustment in
the event of wear. Every part of this microscope works like it did 100 years ago, though the black finished parts are clearly repainted.
ACCESSORIES FOR THE WATSON
FRAM MICROSCOPE
Accessories currently with this microscope include a triple nosepiece, three objectives, a single eyepiece and a Abbe-type substage condenser. The eyepiece is labelled 'xxx' and the condenser is unsigned. The condenser has an iris diaphragm and a swing-out holder for a filter or stop.
Objectives with this microscope at this time include:
- Parachromatic 1 1/2
inch
- Parachromatic 2/3
inch
- Parachromatic 1/6 inch
HISTORY AND EVOLUTION OF THE
FRAM STUDENT MICROSCOPES
The Fram was an attempt at a slightly smaller and less expensive option than the earlier Edinburgh stand.
As noted above, it could eventually be equipped in a virtually identical way to the Edinburgh H stand. The Fram was first noted in the JRMS in 1898.
It was touted as a very good buy in many publications of the time, and truthfully, it is in my opinion an excellent microscope for the price. Changes in the Fram over time are mainly subtle changes in the construction of the tripod foot and an increasing number of options.
The tripod originally (my type I) was composed of three oxidized solid brass tubular rods extending down from the underside of a circular oxidized-brass cap. These rods apparently fit into holes bored into the top of the tripod and were then soldered in place; a round lacquered brass top-cap was screwed on top of the oxidized one. Two uprights from the brass top cap extended upwards to support the inclination joint captured by a screwed-on casing. This type of foot was in use from 1898 to about 1902. From 1902 to about 1912, the design changed (my type II)in that the tripod and its legs were all one casting. The three legs were now roughtly rectangular or heart shaped in cross-section. Some versions of this tripod were apparently made of a lightweight alloy, likely containing aluminum. A lacquered brass top-cap of the tripod was now roughly 'heart' shaped, and was screwed to the top of the tripod. The inclination joint was now of the same design as the Edinburgh. Starting about 1912, (my type III and the type of the instrument pictured on this web page), the tripod and uprights were all cast as a single solid piece of iron or steel, and the extra brass top cap was completely eliminated. It should be noted that the registration in the horizontal position of the inclination of the limb could be a pin projecting from the limb and resting on the top of the tripod, or, alternatively, the limb could rest on a small bar between the uprights, similar to the Edinburgh, Royal, and Van Heurcks. Both of these designs were used from 1898 through about 1912, after which only the bar type of limb rest was used.
By the time that my example was made, many options were available. Options included an attachable mechanical stage, the spiral screw focusing substage as on my instrument, or even a rack and pinion substage with provision for centering just like the Edinburgh H and Royal.
Noted for the first time in the JRMS in 1902, and also first
listed in the Watson 1902 catalog; the more deluxe 'Holos Fram'
came standard with the same mechanical stage and substage as the
Edinburgh H; it could even be ordered with a Males-Watson two speed fine asjustment and rack and pinion draw tube. In fact, as of 1902, any option offered for the Edinburgh H was available for the Fram or Holos Fram. A Holos Fram microscope, which was sold on Ebay in 2015, features the Males-Watson two speed find adjustment with two fine focus knobs and a mechanical draw tube, as well as the standard built-in mechanical stage, making it very much a miniature, and more portable version of the Royal!
The author would like to acknowledge the help of Dr Joe Zeligs in supplying some of the information on this page. I would also like to thank Richard Courtier, the former owner of the 'Holos Fram' shown here, for allowing me to reproduce his images. Finally I would like to thank Graham Marsh for his generous help in sorting out the construction of the Fram tripods, and other assistance and ideas he has given me since I first became interested in Watson microscopes.
