Description

Offered for sale a rare find – an Andrew Ross Large First Class Exhibition model, serial number 1966 of immense size.
The foot engraved “Ross, London 1966” with:

– Bar-limb design with large rectangular section slider
– Monocular optics with graduated manual draw-tube
– RMS objective
– Straight-cut coarse focus
– Vernier screw/lever fine focus
– Rotating fully mechanical stage with non-concentric x/y controls to right hand side
– Technical sub-stage with condenser featuring, mechanical rotation and centering
– Newly added plano-concave mirror on sliding mount with good silvering
– Good bright lacquer finish

Background to Andrew Ross & Co.

Andrew Ross founded his business in 1830 and, like James Smith, later of Smith & Beck, he collaborated with J.J. Lister, the manufacturing optician who invented a mathematical method of producing objectives which were both achromatic and aplanatic. Ross’s early instruments were constructed initially in a fashion similar to other contemporary makers, including a construction style similar to that of the Lister-limb design.  He continued this practice until 1840 when he developed the “bar-limb”, a very stable design and from then on also supported his stands on the classic Y-shaped foot with two upright supports. Early examples of the Ross bar-limb construction used a triangular bar, which was later replaced by a square one and finally on the largest and heaviest version (like this example) a rectangular one. The Ross bar-limb design became the standard for many British microscope makers throughout the second half of the 19th century. Some conservative companies such as Powell and Lealand continued the manufacture of bar-limb microscopes into the 20th century, long after improved continental designs appeared in the market. Andrew Ross died in 1859 and his son Thomas Ross carried on the business. Thomas Ross died about 1870 and the management of the firm was taken over by famous inventor Francis Wenham who was responsible for the development of the Ross-Zentmayer models in the 1880s and these remained in production into the 1890s until replaced by continental designs. The Ross company went on to produce optical products well into the twentieth century, although large high-quality microscopes became less important to the firm as the years went by. The firm was called Ross & Co between 1837 and 1841, then Andrew Ross & Co and finally Ross Limited from 1897 onwards. The firm discontinued the production of microscopes in 1906. (Source: ‘Antique Microscopes’ website)

This example of a Ross monocular bar-limb microscope presents really well with some lovely gleaming brass-work details and some age-appropriate patination here and there, although nothing detracts from the visual appeal, which is what you’d hope for with an antique instrument of this age.  The instrument’s look and feel is of a quality not found in modern microscopes in that’s it’s fashioned from solid brass, giving it a really weighty feel and it’s also quite a large instrument at around 22 inches in height  when inclined for use, rising to over 24 inches when positioned vertically with full extension.

Technical details – the construction is a brass Y-shaped foot measuring 8 inches wide by 9 inches in length, with large twin 8 inch high uprights with bolsters.  The uprights supporting a pivot with tension lever and inclination restrictor plate, which in turn supports a bar-limb configuration for the upper part of the instrument  The coarse focus is by rack and pinion with the older-style straight cut rack and there’s plenty of travel, so I reckon even a 3 or 4 inch objective would achieve sharp focus.  The slider for the coarse focus is Ross’s largest being rectangular in section set in a massive brass pinion box and is very stable in operation.  The coarse focus has a nice smooth action and holds in position as it should in its working range.  Fine focus is operated via a graduated brass thumb-wheel located at the rear of the main tube on the bar, being a vernier screw acting on a lever against sprung resistance moving the nose-piece only, also working well. 

In terms of its optics, this microscope has a single optical tube with manually operated graduated draw-tube with nice smooth action.  It’s supplied with an approx 8x magnification top-hat B eyepiece that with correct illumination produces bright age-appropriate images.  It’s fitted with a 2 inch Watson objective and also an unbranded 1/4 inch brass objective, as shown in the listing photos on a brass double turret.  As such this instrument is essentially currently set up for low-medium power entomology work and the like with a magnification range of around 24x to 200x.  With the objective fitting being RMS, there are plenty of other objectives by Ross and other makers that will also fit.

The instrument tilts for inclined viewing and holds in position as it should on inclination.  It can be tightened in position via a limb-tension lever to the right hand side of the pivot, which is also fitted with a restrictor plate allowing the instrument to be tilted to the horizontal position with stability.  The all-brass specimen stage is fully mechanical with in addition a mechanically operated rotation feature.  The x/y adjustment thumb-wheels are on the right-hand side, giving about 1 inch of travel in the x/y planes, with the rotation control below stage.  All the mechanical controls work very well and hold position on inclination, with rotation well damped.  The oxidised brass stage top-plate has a pair of slide clips which work well for holding slides in position. 

Turning to the sub-stage, both stage and sub-stage are attached to the massive brass pinion box and there’s a condenser lens fitted to a mounting assembly with height control via a rack and pinion mechanism with single-sided control.  In addition there are further controls for condenser position, with mechanical rotation and centering via brass thumb-screws.  There’s a lengthy brass tailpiece on which the plano-concave illumination mirror is mounted, with height and gimbal adjustability. 

The instrument has been very gently dusted and also lightly lubricated with non-hardening grease where appropriate, so that the controls operate smoothly.  This example displays exceptionally well having a substantial presence and some lovely lacquered brass-work with rich gold and copper tones which catch the light beautifully.  This antique microscope is very much a usable proposition and would naturally benefit from additional Ross RMS objectives and further sub-stage accessories could also be added to assist with higher-power or more specialised work.  It will make a stunning antique display piece as is, perhaps in a library or home office type of setting, especially when set up with an appropriate antique slide. There’s no case with this instrument at the present time.

Owing to the very heavy weight and delicacy of this antique microscope, it will be partially dismantled, carefully wrapped for shipping and dispatched by insured courier upon receipt of cleared funds. 

Thanks for looking – please also check out my other listings if you get the chance.