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FOLDING PORTABLE COMPOUND MICROSCOPE

MAKER: JAMES SWIFT & SON

c. 1900

SIGNED: 'JAMES SWIFT & SON, LONDON No. 116'

MODEL: 'IMPROVED CLINICAL,ZOOLOGIST & FIELD MICROSCOPE' or
'PORTABLE CLINICAL AND FIELD MICROSCOPE'

DESCRIPTION HISTORY

Please Click On Any Picture for a Larger Version

DESCRIPTION: The instrument arises from a modified folding tripod foot. The rear leg is split such that when folded it passes around the fine focus, thus allowing a more compact arrangement. The two front feet are attached to the rear foot, folding forward when in use. All three feet have tight joints and firm stops in the setup position, allowing a very sturdy stand. The lacquered brass sleeve carrying the optical tube is signed 'J. Swift & Son, London, No 116' The main optical tube is nickel plated and slides through the lacquered brass sleeve which has coarse focus by spiral rack and pinion and fine focus by micrometer screw. There are stops in both the up and down extremes to prevent the main focusing sleeve from coming off the limb. There are multiple screws to allow adjustment of the focusing mechanism for wear. A hole in the limb is provided to accept an accesory such as a stage forceps or reflector(not present). A removeable double nose piece is present. The nickel-plated draw-tube is also nickel plated and finely calibrated from 13 to 21 cm, labeled each cm and marked each mm. The stage is hinged to the frame of the microscope by a sturdy tight joint. The stage clips and all screws are blued steel. The stage is 3 inches x 3 inches and has slots on the sides which could accomodate a small version of the Swift Travis mechanical roller stage, (not present) The plane and concave double sided gimbaled mirror slides up and down a tail piece. There is also a Abbe type condenser signed 'F. STANLEY & Co Ltd, OPTICIANS, 13 Railway Approach, London Bridge S.E.'. The condenser slides into the standard substage sleeve and is equipped with an iris diaphragm. Accesories include a hard leather case, 1/2 inch and 4/10 inch objectives with cans, both by Swift. There are three eyepieces: a low power, medium power, and high power. The medium power one has a pointer. The low power ocular is nickel plated and signed 'A', the other two are plane brass. The case is designed to hold two objective cans, a live box, a bottle, extra oculars and the condenser. The inside lid has elastic straps to hold a stage forceps, dropper and tweezer though these are lacking.

ASSEMBLY and DISASSEMBLY:
To close up the stand for storage, the condenser must be removed. Then the front legs are folded back and then the rear leg with the front legs folded upon it is folded back against the rear of the limb. Next the coarse focus must be fully brought up as high as it goes and the sliding optical tube inside it must also be brought up to its highest position; only then can the stage be fully folded down against the stand. Next the mirror is lifted up high enough so that when the tube is brought back down it does not collide with it. The optical tube and assembly are both brought back down as far as they will go so that the bottom of the tube now sits between the substage sleeve and the mirror, the double nose piece turned to the side.

CONDITION: The microscope is in excellent optical and mechanical condition, though there are fine scratches on both sides of the lacquered brass optical tube sleeve near the front split in the tube. There is no significant loss of lacquer however and these scratches are only visible with lighting from certain angles.



HISTORY OF THE SWIFT FOLDING PORTABLE AND RELATED INSTRUMENTS

James Swift and Son designed this folding portable microscope with its solid leather case for military doctors and traveling scientists at the very beginning of the 20th century, undoubtedly under the influence of Charles Baker's "The Diagnostic No. 1". It was reported on page 379 and pictured on page 381 of the JRMS for the year 1900. In that article it was simply referred to as 'Swift's New Portable Microscope". As the sales advertisement by J. Swift & Son, ca. 1900, states: “This microscope was originally designed to meet the requirements of the Bacteriologist who needed an instrument of utmost portability. It is particularly serviceable to Microscopical and Natural History Societies, as its extreme portability, combined with great steadiness and efficiency for high power investigations, recommends it strongly. These instruments are in very general use in India and Africa amongst those working on Malaria, Sleeping Sickness, etc., and have been supplied in great numbers to the Army Veterinary Departments, the Crown Agents for the Colonies, the United States Government, etc.” In his review of lightweight portable microscopes, Scales, in his 1909 book Elementary Microscopy, A Handbook for Beginners stated:
'But perhaps the best portable microscope yet designed to combine perfect efficiency with complete portability and moderate price is that of Swift and Son. It is beautifully finished in brass, and is suitable for travelling, for clinical and for field work, or for home use. It is furnished with both coarse and fine adjustments, the latter being markedly superior to those usually fitting to microscopes of this type. The optical tube slides in its fitting so as to allow very low-power objectives to be used, whilst the draw tube permits of an extension to 7 inches. The stage is larger than usual, and contains a substage ring fitted with Abbe condenser of full size and iris diaphragm. Thge back leg is divided so as to pass over the fine adjustment screw when folded, whilst the stage is hinged, and lies flat against the body of the microscope. The whole packs into a leather case 9 x 3 x 3 inches, with space for two objecties, live box, small bottle, and sundry minor apparatus...and costs without objectives or other apparatus, £5.'

It was offered in the 1906, 1910, AND 1913 catalogs by Swift. It was not offered in the Swift catalog of 1892. This microscope was available with monocular tube or binocular tube. Standard stage clips were supplied but the stage is grooved on its sides to accept either the simple wheeled roller glide stage, or the Traviss Mechanical Roller stage. Another option offered was a focusing mechanism for the substage sleeve(by vertical wormscrew), with the further option of adjustments for centering. Equipped with a suitable condenser and all these options, it could certainly do anything a large full sized microscope could do at the time.

HISTORY OF THE LIGHT-WEIGHT FOLDING PORTABLE ACHROMATIC MICROSCOPE
Small microscopes were common even from the time of Van Leuwoenhoek. Portable compound microscopes were common early on as well. Miniaturized compound microscopes which broke down to fit in the pocket were also common, the most famous of which is the Gould model which predated the achromatic era. Later, other manufacturers made achromatic miniature microscopes designed to fit in the pocket, like the model 75 by Spencer from the first third of the 20th century.

After the beginning of the achromatic era, small folding achromatic compound microscopes, such as Browning's New Portable were produced in substantial numbers and variations, even through the first half of the twentieth century. But while these instruments were light, they were somewhat difficult to use for serious high power work.

The more substantial but still folding, lightweight, and portable compound microscope was devised long before the achromatic era. For example, small versions of the Jones Most Improved microscope, were produced, an example of which is in this collection.

PandL Portpl scopeOne of the earliest practical folding achromatic portable microscopes, suitable for serious work, was first constructed by Powell & Lealand. P & L's Portable, later called the No.4, was one of the earliest of this type and was shown in John Quekket's book as early as 1848(left). Although the basic design remained unchanged, the most important addition in later versions was the focusable and centerable substage as can be seen in this example on this website(right). One disadvantage of this model was the need to unscrew the main optical tube for folding and packing it up.

As time went on, and especially from about 1880, all the major manufacturers came up with their own versions of 'portable' microscopes, most were bigger and stouter than pocket microscopes but often much lighter than the full size stands, and able to fold up into a much smaller case than a full sized microscope. Although the P & L No.4 was fully capable of almost any work, the portables of other manufacturers lagged behind and the cost of the P & L portable put it out of reach of most. Some 'portable' microscopes with more advanced features would fold up but were heavy and relatively large once assembled. Baker New PortableBaker Diagnostic Starting about 1890, most makers produced lightweight microscopes of good quality, but without standard features like a condenser, and very few with mechanical stages, so high power critical work was not feasible unless special extra accessories were adapted. Judging from examples on the market today, most of these were never adapted for high power work and were used mainly for low power microscopy. As time went on and more serious use of highly portable instruments became a common need, the instruments evolved. An example of this evolution can be seen in the history of the Baker 'New Portable Compound Microscope(left)' as it became the 'Diagnostic' model(right). It began in 1887 as a compact folding microscope with a solid stage and good balance, but without provisions for the features that would allow it to be used to good effect with e.g.oil immersion objectives. As illustrated by the example on the right, it gradually evolved over the next 50 years or more into a first class instrument capable of anything its big brothers could do.

At the same time that folding lightweight microscopes were becomming popular, 'portable' microscopes which were much heavier, and when assembled were close to the size of a bench microscope, were also produced. Although they could fold or break down into a smaller-than-full-size package, and were suitable for almost any kind of microscopy, these instruments, as exemplified by the Spencer model 60h in this collection, were quite heavy. The lightweight folding portables then persisted as another option through the first half of the twentieth century. Starting in the last third of the 19th century, alongside the serious folding portables, small portable compound microscopes intended for 'household use' or children were also very common. These less sophisticated 'household' types are also reviewed on this site, but these are really not meant for serious work like the microscope pictured on this page.

W.F. Stanley: