MICROSCOPE-ANTIQUES.COM © 2013-19.

COMPOUND MICROSCOPE

MAKER: ANDREW ROSS

c. 1836-7

SIGNED: 'ROSS, LONDON'

COLLECTION OF: Dr Jurriaan De Groot

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Ross Lister limb Microscope understage

fine focus Ross Lister limb Microscope

An Early Andrew Ross Lister limb microscope circa 1836-1837

DESCRIPTION:
This is a very early example of a Lister-limb type microscope made by Andrew Ross and is signed on the foot: “Ross London”. It pre-dates the model illustrated in the 1839 Penny Cyclopaedia article and stems from the time that the early makers of achromatic microscopes were still experimenting with the basic layout of the limb as well as the placement of the coarse and fine adjustment controls before the most satisfactory arrangement was finalized.

This microscope stands on a heavy tripod brass foot, the ends of which are curved upward, roughly in an S-shaped curve. From this arises a large round pillar 160 mm in height terminating in a compass joint and clamping screw at its upper end. This supports the Lister limb, which is cast in one piece. The stage and tailpiece carrying the mirror are attached to the bottom end of the casting. The stage fits into a slot in the limb and is secured to the limb by two rivets.

To the top of the limb is attached a fixed external brass body tube with an external dimension of 41 mm. An internal optical body tube slides in this external tube, and has a length of 210 mm and external diameter of 38.6 mm. This inner tube is moved up and down by means of a rack which is screwed into its inner surface with its teeth protruding along a longitudinal slot in this tube, and moved by a pinion attached to a single knurled knob on the right side of the outer stationary tube. According to Paul Ferraglio, who examined one, this arrangement is exactly the same as at least one example of the Powell & Lealand 'Iron Microscope' of almost a decade later.

The Ross short lever fine focusing mechanism is positioned at the lower end of the body tube and is adjusted by a knurled knob protruding on the right in the 3 o’ clock position. A longitudinal recess is cut into both sides of the outer body tube at its lower end to clear the fine focus mechanism during coarse adjustment. This particular coarse-focus arrangement is reminiscent of earlier designs, such as on Martin drum microscopes and precedes the later designs by Ross (as in the so-called 'Penny Cyclopaedia model') where the body tube is fixed to a cradle which moves up and down on a triangular extension of the limb into which the rack is attached. Hugh Powell also utilized the latter arrangement.

In comparing the limbs of this model, to the later 'Penny Cyclopaedia' (PC) model, the limb of this model has a more 'sculptural' shape, gradually changing shape to a triangular profile, with the apex of the triangular part of the limb pointing back towards the user, while the PC model has a squared off or rectangular profile which abruptly changes to a triangle with its apex facing forward and thef rack directly attached to it. In the earlier microscope shown on this page, the rack is part of the inner optical tube, the brackets supporting the outer tube being on a fixed position on the limb. In this case the pinion, on the outer tube, acts on the rack on the inner tube, rather than the limb which has no rack.

The oxidized mechanical stage is operated by twin inverted screws for X- and Y movement. Its under surface carries a disc of aperture stops. There is an extra bracket affixed to the stage in the 9 o’ clock position to carry stage accessories, such as the side-reflector and stage forceps.

Since Andrew Ross did not start numbering his instruments until 1841, other methods have to be used to date this early, unnumbered microscope. An obvious feature of this microscope is the ornamental, curved shape of the tips of the toes of the foot. This feature disappeared from Ross microscopes sometime in 1837, which would date this microscope to 1837 at the latest.

The microscope is stored in a large high-quality mahogany case with external dimensions 475 mm (h), 280 mm (w) and 235 mm (d). There are 8 small drawers and one large central drawer to house accessories and slides. For storage, the upper 50 mm portion of the body tube is unscrewed and stored in a recess at the back of the case.

ACCESSORIES:
In addition to the original case, accessories with this microscope include 4 objectives (one a later addition), two eyepieces, a stage forceps, a Ross silver side reflector, and a large brass hand forceps. There is also a free-standing bench condenser.

Early Ross 1 inch objective in a can signed ‘1 In And^w Rofs, Optician, London’.

Two early Ross ½ inch objectives, one of these in a can signed ‘ ½ In And^w Rofs, Optician, London’ and one of these in another can signed ‘ ½ In And^w Rofs & C^o., Opticians, 33 Regent St, Picadilly'

A ¼ inch Ross objective, itself signed 'A. Rofs, London'and also engraved 'Covered' and 'Uncovered' above and below the setting lines, in a can signed: And^w Rofs, Optician, London’ (later addition) .

NOTE: All objectives have the internal(female) early Ross thread.

Two eyepieces are included. One is an ordinary 'top-hat' Huygenian type with a power of approximately 8X, and has an outer diameter of 37.4 mm. The second is a Ramsden type, originally a micrometer eyepiece, but lacks its micrometer; this eyepiece allows focusing on the micrometer disc by sliding the top of the eyepiece up and down. As shown here, it was pictured and described by Quekett in the first edition of his Treatise of 1848.

Stage forceps.

A 'Ross-type' silver side-reflector (probably one of the first ever made – see history section) .

A large pair of brass hand forceps.

Free-standing bench condenser on heavy brass foot. The rod can be unscrewed into two halves for storage in the larger center drawer.

HISTORY OF ANDREW ROSS LISTER LIMB MICROSCOPES:

Andrew Ross was born in 1798, the son of John Ross, a staymaker of Fleet street, London. He was apprenticed to John Corless, a member of the Joiners Company in 1813. In 1823 he went to work for W.T. Gilbert, a manufacturer of levels, theodolites and astronomical instruments, becoming their works manager in 1827/8. The company obtained a contract to manufacture a large lens to the orders of David Brewster, a well-known Scottish optical physicist, for use in a lighthouse. In 1828 W.T. Gilbert goes bankrupt, however.

Andrew Ross sets up his own business at 5 Albermarle street off St Johns Square, Clerkenwell in 1830. Meanwhile, Joseph J. Lister has read his paper to the Royal Society setting out the principles that were to be the foundation for constructing modern achromatic aplanatic objectives. In particular, he found that two or more achromatic doublets could be combined by placing them at such a distance apart, so that their aplanatic foci overlap resulting in a lens combination which is entirely free from both chromatic and spherical aberration. Not long after this, from 1832 onwards, Ross starts making microscope objectives using this formula, of which some are to J.J. Listers’ design. A full list of these early Ross objectives is given in E.M Nelson’s paper on the microscopes of Andrew Ross (JRMS 1900 pp.425-38). This work includes the design of the first 1/8 inch objective with correction for cover glass thickness (see the article about correction collars elsewhere on this site). E.M. Nelson also reported that Ross first developed the silver side-reflector in 1836, so the one with this microscope may be one of his first.

Ross apparently made his first signed microscope stand(left) in 1832 for William Valentine, a plant anatomist of Nottingham. It featured a micrometer fine focus control which was located under the base,or foot, and could be used as either a simple or compound instrument. This period of microscope design, also known as the 'transitional period', during which the first achromatic objectives were fitted to microscopes of an earlier pre-achromatic design, can be rightfully regarded as the crucible from which later more successful designs emanated. Not surprisingly, there was much experimentation by microscope makers who initially worked for the trade, and later started signing their own work. Hugh Powell, Andrew Ross, James Smith, and Andrew Pritchard were part of this environment. The pre-achromatic designs including the Jones most improved, Cary-Gould, Carpenters Improved Compound, and variations on these themes often provided the basis for these experiments aimed at improving both form and function. Many were not signed by their makers, but were signed by retailers such as Bate, Cary, Dollond and Carpenter & Westley. For an example of a transitional microscope of this period, signed by Cary, with features typical of both Andrew Ross and also Hugh Powell, see the Transitional Cary Achromatic Microscope on this site. Note that that instrument has a ball and socket joint at the top of the pillar, similar to many Ross microscopes of the time, and a one-sided gimbal for the mirror, characteristics of the work of Hugh Powell.

From extant examples of early Ross microscopes in museum collections, it is evident that Andrew Ross produced a number of early microscope stands which feature the ball-and-socket joints at the top of a pillar supported by tripod feet. These were later replaced by a compass-joint with screw clamp such as on the 'Aiken microscope' which can be dated to 1835 (MHS Oxford). The cylindrical limb of that instrument passes through the stage while the fine focus is still to be found at the bottom of the tailpiece below the mirror.

From 1837 Ross traded from 33 Regent Street, Piccadilly as “Andrew Ross & Co, Opticians”. Until recently, it was always thought that this was in partnership with J.J. Lister, but it has come to light that the partner was in fact one Alfred Aigner, architect and member of the Society of Arts. The dissolution of this partnership was announced in the London Gazette of November 1841 (see Bulletin of the Scientific Instrument Society No 124 March 2015). In Ross microscopes from this period the top of the tripod feet are flat, without the earlier curved ends, which now are simply bevelled downward at about a 45 degree angle. For the first time there is a full Lister limb cast in one piece, with a triangular upper extension into the rear portion of which the rack is recessed. Hugh Powell also used this type of Lister limb with a triangular profile. (For an example of an early triangular Lister limb microscope attributed to Hugh Powell, see the early microscope Ca 1840 elsewhere on this site). The optical tube is fixed to a cradle, which slides over this triangular bar, and containing the pinion for coarse focus. The short lever Ross nosepiece fine focus is retained on these 'Penny Cyclopaedia models' by Ross. Compare the earlier Ross design featured on this page, with that of the Penny Cyclopaedia model as shown in the images to the left.

By 1841 Ross had abandoned this cradle coarse focus arrangement and the rack was now directly attached to the body tube with a profile that matches the dovetail channel cut into the limb, while the tripod foot is replaced by a heavy circular base. After the dissolution of the partnership, Ross signed his microscopes 'Andrew Ross Optician, 33 Regent Street, Piccadilly' and started numbering them for the first time.

In 1843 Andrew Ross moved to 21 Featherstone buildings, Clerkenwell and the same year saw his announcement of a radical new microscope design as published in the London Physiological Journal of 1843. This would become known as his famous bar-limb model, and set the standard of microscope design for decades to come; it was copied by many other makers. The bar-limb design was also announced only months earlier by Hugh Powell. Powell's design used a different design for the foot however. Andrew Ross died in September 1859, when the firm passed to his son Thomas. It would not be until 1880 before we see a return of a Lister-limb design with the Ross-Zentmayer models.

We are very grateful to Dr Jurriaan De Groot for supplying the images and most of the information on this page. Thanks to Paul Ferraglio for his skill and suggestions while editing this page.