Back Button

MICROSCOPE-ANTIQUES.COM     2013-15.




EDINBURGH MODEL H MICROSCOPE:

c. 1918

Maker: W. WATSON & SONS LTD.

Serial number: 24203

DESCRIPTION HISTORY

 

DESCRIPTION

This compound microscope arises from an English tripod of the form used by Watson and similar to those used by Powell and Lealand and others. The tripod is painted a semi gloss black. The limb suspended by a trunnion joint. The spread of the toes is just slightly over 6 3/4 inches, despite the Watson catalog quoted spread of 7. Across the rear of the tripod is a bar, a protrusion on top of which is where the limb makes contact when the microscope is in the horizontal position. The protruding piece also projects forward to make contact with the limb in the vertical position. Thus there are stops for the horizontal and vertical positions of the limb. It is signed near the top of the rear toe with the serial number, and on th bridge connecting the rear to with the rest of the microscope: 'W. WATSON & SONS LTD, 313 HIGH HOLBORN, 'LONDON'.

The gimbaled plane and concave mirrors are housed in a lacquered brass casing. The mirror is supported by a black yoke attached to a stem, which is in turn, attached to a tubular fitting which slides over the fixed tailpiece descending from the stage.

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. The substage has coarse focus by diagonal rack and spiral pinion. There is a ring for a condenser which has controls for centering the condenser. There is a single condenser housing with condenser with an iris diaphragm and a filter/stop holder (stops missing).

The Stage of this model is virtually identical to the Royal model; square, non rotating* and with separate controls for the horizontal and vertical axes. Horizontal movement is by spiral screw and vertical by twin racks and pinions. There are two holes for the use of standard stage clips, which are screwed into the stage.

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. There is a steel pointer to register these calibrations. The instrument has a black triple nosepiece and it is unsigned.

The outermost main optical tube is of 1.5 inch outside diameter and is about 5 inches long. There is one chrome-plated calibrated drawtube. The inner draw tube accepts the narrower 23 mm eyepieces. There are two eyepieces with the instrument.

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.

*a few early examples have a rotating top plate on the top of the mechanical stage, but this should not be confused with the entire mechanical stage rotation found on the Van Heurck models. Rotation of the extra top plate introduced a movement independent of the main mechanical stage, yet in direct contact with the slide; this was a feature felt inferior to the usual standard stage and the Van Heurck stage type of rotation, where the top plate movement was controlled directly by the mechanical stage controls; it is an infrequently found feature.

ACCESSORIES FOR THE c. 1918 WATSON EDINBURGH H MICROSCOPE

edinburgh case

Accessories currently with this microscope include two eyepieces and three objectives and a Abbe condenser.

Eyepieces for this microscope and listed in the catalogs of the time are Huygenian.

Objectives (and matching cans) with this microscope at this time include:

  • Parachromatic 2/3 inch
  • Parachromatic 1/6 inch
  • Apochromatic 4 mm (1/6 inch)

There is also a can for a parachromatic 1/2 inch, but the objective itself is lacking; I hope to replace it some day. Watson apochromats were added to the Watson offerings around the time this instrument was made; Watson started to make their own apochromatics objectives sometime between 1914 and 1917.

Although there were many condensers to choose from at the time this microscope was made, it is equipped with the relatively cheap but standard Abbe condenser.

label The original case has spots for two eyepieces and three objective cans. There is no other case or drawer for other accessories. The door of the case has the classic Watson 'W' escutcheon. Inside the front door, rather than the usual magnification card, is the trade plaque for the optical retailer, Broadhurst, Clarkson & Co.

Options for this microscope at the time of its manufacture included fine adjustment to the substage, as the same option for the Royal model, and an option to increase the horizontal travel of the stage to 3 inches. The fine adjustment knob could also be ordered with divisions to hundredths instead of tenths of inches. Like the Royal, Van Heurck and others, the movements of the stage could be ordered with vernier calibrations.

 

HISTORY OF THE EDINBURGH MODEL MICROSCOPES

The Edinburgh stand, is a model devised in 1887 with the advice of an Edinburgh professor, Dr Alexander Edington, a lecturer on bacteriology  at the University of Edinburgh.  

It preceded the Van Heurck and later Royal models, and indeed was the inspiration and basic stand on which both were based. The Edinburgh stand went through several iterations and improvements over the years. Most of those changes are reflected in this 1918 model, but a slight change is noted in the 1928 catalog where the substage pinion box is enlarged compared to this model. Later, another change was to extend the limb below the stage to support the substage directly; on that model, as shown in the 36th edition of the Watson catalog, the condenser assembly independently swings out of the optical axis, like the Royal and Van Heurck of that era.


edinburgh According to Watson's delivery records, the first example of an Edinburgh microscope was sold on November 29, 1887. This stand was the inspiration for the Van Heurck stand, and like the Van Heurck, started out with a continental foot, but was soon  ordered more often with a tripod foot.  Like the Van Heurck, it was improved progressively over the years. This culminated in the Edinburgh 'D' model, shown to the left, and later the 'H' as shown on this page.  These  had most of the basic features of the (later) 'Royal' model. In fact, when the Royal was first introduced, it was actually slightly smaller than the Edinburgh H. The various Edinburgh stands were at first indicated by the numbers 1,2,3, and 4, but by 1890, letters were used A,B,C,D,E,F,G and  H.  For a more detailed review of the history of the various Edinburgh models, please see the Edinburgh 'B' page. This microscope continued to be manufactured as late as 1945, though by 1938 the microscope was all black with the controls chrome plated. As can be seen from the engravings, the original stand had the condenser assembly attached to a screw under the side of the stage. Later on, as seen on the 'H' pictured on this page, this attachment became more robust.

It is a common misconception that the 'Royal' is generally a larger stand than the 'Edinburgh H' and this is not true. The tripod heights, arm/limb size, foot spread and stage are of identical size in many examples; what makes the 'Royal' appear larger is the larger diameter optical tube and drawtubes including the rack and pinion draw tube. Even more interesting the substage fine adjustment was an option even for the Edinburgh H. A rack and pinion drawtube could also be ordered for the Edinburgh. Without the stand actually being engraved with the model name, the final version of the Edinburgh H and the Royal could not be differentiated from one another, as can be seen by a side-by-side comparison.