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MODEL:

THE PARAGON MICROSCOPE

or the

IMPROVED WALES MICROSCOPE(1906, 1910)

DATE: c. 1900 (c. 1891-1910)

MAKER: JAMES SWIFT & SON

SIGNED: J. SWIFT & SON, LONDON

SERIAL NUMBER: 9734

First Year listed in Swift Catalog: 1891, (no longer listed in the 1913 catalog)

DESCRIPTION HISTORY

DESCRIPTION:

Swift & Son signature This Wale limb microscope, which is well made, is supported by a special foot in which the grooved limb glides for inclination. The microscope can be clamped at any degree of inclination via a knurled knob on the right side of the foot. The foot is actually one part as opposed to many other smaller Wale limb instruments (including the original) that have two parts grasping the microscope limb between them. The grooved limb slides between two sets of four points, the depth of which is controlled by screws on each side of the support of the foot. The shape of the foot provides extra clearance under the stage for ease of manipulation of the substage apparatus. The foot is signed 'J. Swift & Son, London.

The substage slides in a dovetail to be completely removable if desired. It has focusing by rack and pinion and centering adjustments. The supplied condenser uses a 1 inch objective, (which is readily removed and replaced), for optics and has a filter holder and iris. The plano and concave mirror is on a gimbal that is attached to a slide on the swinging tailpiece that is separate from the substage condenser support.

Coarse focus is by diagonal rack and spiral pinion, while fine focus, on the left side of the microscope is Swift's patented 'Climax' fine adjustment, the control knob being horizontal and very close to the coarse adjustment knob. The stage can rotate 360 degrees with separate controls for X and Y motion. Back and forth motion is by diagonal rack and spiral pinion in the center, while left-right motion is by worm screw. The surface of the mechanical stage has a demascened finish. Two moveable black slide holder are present, which slide in dovetail fittings. One has spring clips to push against the slide the other with clips to hold it down. there is a hinged slide register on one side of the latter. One of the two slide-holders has a upright brass fitting for a stage forceps or other similar apparatus.

Like most Swift instruments, this microscope is provided with many adjustments for wear. There is a double nosepiece objective changer. In addition to the one inch Swift objective for use as a condenser there are also a 2 inch and a 1/2 inch Swift objective with this microscope. There is no case with it however.



HISTORY OF THE SWIFT 'WALES LIMB' MICROSCOPES AND THE SIDE FINE ADJUSTMENT

The Paragon, a microscope much larger than the earlier and smaller Swift Wale limb model 313, was offered in the Swift catalogs from 1891 through at least 1910; by 1913 it was no longer listed in the catalog. In the 1906 and 1910 catalogs this exact model is refered to as the 'Improved Wales Microscope.'   The Paragon in the earlier catalogs appear to be slightly smaller, and do not have the four screws at the top of the foot. This can be confusing. Options included a silvered scale on the rotational stage movement, and a vernier scale for X and Y motions of the mechanical stage. Other options were binocular tubes, and a concentric fine adjustment to the substage.

Swift 1910 Catalog Listing The American microscope maker George Wale invented the grooved inclination system which bears his name about 1879. The first illustration of it that I am aware of was published in the American Journal of Microscopy and Popular Science, Vol 4, No 4, Page 93 (1879) and also in the J. of the RMS, vol II, p624 in the same year. This illustration, although clearly showing a portion of the Wale limb, accompanied a brief article about rotating stage clips for Wale's stage. The first article in a Journal fully illustrating the Wale 'New Working microscope' was in 1880, in the Journal of the RMS, Vol 3, page 1046.

In 1881, the JRMS featured an image of the Swift microscope number 313, showing that the English makers were 'swift' to adopt this design! Swift was so impressed with this design, that, according to Davis as of 1889, they intended to feature it as their primary type of limb; it was therefore available in many models up to and including Swift's biggest Wale limb microscope he called the 'Paragon' shown on this page. The advantage of the Wale limb is that the center of gravity, and therefore the stability of the microscope, did not change regardless of the angle of inclination. Swift's version is an improvement over Wale's design, because in Wale's case the limb groove was just part of an iron casting; in Swift's examples this groove was machined into the oxidized brass limb for smoother operation. The Wale method of inclination was also incorporated by many other maker's including Schrauer, Bausch & Lomb (in their 'American Concentric Microscope'), Watson & Sons, and the ultimate version, the Wenham 'Radial' Microscope by Ross. Although initially intended simply to provide stability during inclination, the principal was applied to allow very oblique illumination. The Ross Radial microscope provided many adjustments to provide virtually any kind of oblique illumination. Similar elaborate 'radial' arrangements were also made by Beck, Watson, and many other makers.

swift fine adjustment Another feature of this microscope is Swift's invention of a vertical long-lever fine adjustment, controlled from the side of the microscope. Control of the fine focus from the side rather than the top of the limb (as was customary before), later became a standard feature of the modern microscope. The idea of fine focus control from the side was probably first used on Powell and Lealand's early stands, although they soon changed its location to the top of the arm. It was Swift in England, and Berger in Germany who revived this idea, Berger's design being far superior because, among other reasons, it is much less likely to wear out in prolonged use than a lever.

It appears that the 'Swift Wales' microscopes of the type pictured above here were offered from no later than 1881* until at least 1910. In 1883 Swift offered their 'Radial Inclining Microscope' with a Wale limb. In 1914 an improved version of Wale limb was offered on the elaborate Swift 'Photographic Petrological Microscope'. This tradition continued in the even later (c. 1925), and equally elaborate,'Symposium' Model. The Paragon is one of the larger Wale Limb models as shown in the images shown at the bottom of the page.


*See the JRMS, Series II, volume I, 1881, pages 296-298.

Wale limb microscopes


The author would like to gratefully acknowledge the kind assistance of James Solliday and Dr Joe Zeligs for valuable catalog information, and advice about the discussion of this instrument.