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SERIAL No:5499


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DESCRIPTION:This is a fine example of a Ross Eclipse microscope, featuring the sliding-type coarse adjustment, as marketed for student use. It is signed in embossed letters on the circular base: Eclipse, Ross, London, and carries serial number 5499, dating its manufacture around 1885. The heavy circular ring base is 120 mm in diameter,and supports a circular limb with a hinged joint 45 mm above the base, allowing for the microscope body to be inclined. The ring foot has three areas that protrude downwards to form a tripod support. The stage plate encircles the limb and underneath carries a disc with 3 different apertures, in addition to a short brass sleeve for receiving understage accessories like a polarizer. The use of a condenser with the supplied concave mirror would be problematic. The gimbal for the single sided concave mirror is screwed to a swinging tail piece, which allows for oblique lighting of the specimen. The 166 mm tall brass pillar has a milled-head fine adjustment at the top, and an arm with a sprung casing, into which the 115 mm long tube slides. This is fitted with a drawtube, by which means the tube length can be increased from 155 to 210 mm. This tube admits eye pieces of continental diameter(23.2 mm).



The nosepiece is fitted with a double objective changer signed Ross, London and at one end is marked 1/4, this side being somewhat longer, so that the 1 inch and 1/4 inch objectives are always at a parfocal distance from the slide, which is held on the stage by two stage clips.

EYE PIECES: There are two Huygenian eye pieces with approximate magnifications of x5, and x8, with a diameter of 23.2 mm.

OBJECTIVES: There are two objectives marked respectively 21820,Ross,London, 1 In., and 21841,Ross, London, 1/4 In.. These have approximate numerical apertures of 0.20 and 0.56 respectively.

CASE: The microscope, eye pieces, and objectives pack away in a compact mahogany carry case with leather handle. This requires removal of the objective changer.

CONDITION: The microscope is in an excellent condition with all its lacquer intact. The fine adjustment operates smoothly and accurately.

PROVENANCE The present owner purchased this microscope in a rural antique shop in 1995, and was told that it previously belonged to a man who had served in Europe during World War I, bringing the microscope with him upon his return to New Zealand. It was accompanied by some 15 paper covered slides of various subjects.

The well-established firm of Ross had been producing microscopes since about 1830, and for decades continued to use their famous bar-limb design of 1843 in different sizes, and levels of complexity, mostly for wealthy amateur-scientists. In the 1870's they introduced their Jackson design, which was machined on optical bench principles, which automatically lined up the grooves in which the optical tube and substage run. The firm subsequently developed their Jackson model further in 1880, to feature a swinging substage, according to Zentmayer's patent, aimed at achieving oblique illumination at extreme angles, to maximise resolution. This feature became obsolete not long after, with the introduction of cheap large aperture condensers such as the Abbe. Towards the end of the 19th century, there was also an appreciable shift in those who used microscopes. The main customers were no longer amateurs, who observed pond life, or who sought to resolve the minute details of diatoms (the derisively named Diatom-dotters). Advances in science, however, resulted in a vast increase in the professional use of the microscope by medical students, scientists, and specialist workers in all fields of industry. Their needs proved to be quite different from the earlier amateurs; they were usually content with objectives of a lower aperture, with a stand which was more manageable, and most importantly with an instrument which was reasonably priced. It was this, in addition to the adoption to modern manufacturing methods which lead to the adoption of the Continental model of microscope. European manufacturers such as Leitz and Zeiss had built their success on this model, but the English microscope makers were slow to follow. Some firms such as Watson and Beck made a successful transition, and managed to stay in business, whereas for others, such as Powell & Lealand, this was the end of the road.

In their 1883 catalogue, Ross introduced a Continental style microscope, their No 4 student model, albeit still fitted with an English tripod foot, later to be followed by different Anglo-Continental designs. Some of these were designated their Eclipse models, of which examples are known with either a horse shoe- or large ring-shaped foot. The 15th edition (1898) of Hogg, The Microscope contains a description of this model: A further source of congratulation is that economy has all along been studied; so much so, that the instruments in question are within the reach of persons of moderate means. Messrs. Ross and Co. have taken a new departure in this respect, and their Eclipse Microscope is an entirely new form of stand with a ring foot. This microscope has been produced for the especial use of students, and can be purchased at a moderate sum. It will be seen at a glance how steady this form of stand must neccessarily be, since the level of gravity is secured in every direction and inclination. The body-tube carries eye-pieces, numbered, the Continental size and optical tube-length (160 mm), for which object-glasses are adjusted, and a draw-tube extending to eight inches. The fine adjustment is independent of set screws, and not subject to derangement. It is extremely sensitive and direct in action, and from its construction is equal in perfection of working to the best that can be made. Its fitting, by a new contrivance, is completely covered at all points, being thus preserved from disturbance or injury by dust. The Eclipse is furnished with two eye-pieces, 1" and 1/4" object glasses of highest excellence and large angular aperture, both adjusted to a double nose-piece, so that they focus in the same plane...and a swinging mirror and stage iris diaphragm. It appears, that different versions of this model were made; some have rack-and- pinion coarse adjustment, whereas more economical examples feature sliding tube coarse focusing, or a rigid limb, without the inclining joint. Ross were obviously not very successful in this competitive environment, as by 1906, they were no longer making microscopes, and instead continuing with the manufacture of camera lenses.