James Powell Swift ‘Best Compound Microscope No. 1A’ c1854-1870

A fascinating early binocular microscope, engraved on the base plate,

Above this, in a later smaller font,

Supplied by

Broadhurst Clarkson & Co.

63 Farringdon Road

London EC

This microscope is a binocular ‘Ross bar-limb’ type. The ‘bar-limb’ is the substantial square section which pivots about the uprights, to which is attached the stage and racked sub-stage. It was designed by the leading London instrument maker Andrew Ross in 1842. The bar limb has a small brass plate screwed to the front, providing a hole on each side of the limb for attachment of accessories (this is also copied from Ross).

The microscope has detachable ‘Wenham’ binocular tubes, which can be used for stereo-microscopy - named after Francis Herbert Wenham (1824-1908) - who used an achromatic prism above the objective lens to split the light beam. The nose-piece on this instrument also has a ‘Nicol’ prism mounted above the ‘Wenham’ prism - each residing in a sliding brass box so that they can be introduced or removed from the light path. The ‘Nicol’ is an analyser/polarizing prism, named after the Scottish physicist William Nicol (1768-1851). Note: Both of the prism boxes can be removed by unscrewing the small round end-handles. 

The tubes have a rack and pinion mechanism to adjust the width between the eyepieces (the inter-ocular distance). There are two sets of eye pieces of different magnifications. A wheel at the base of the tubes can be used to fine focus the objective lens. Objective lenses can be screwed directly to the base of the tubes or to an attachable two-lens turret.

There is an adjustable X-Y stage that can also be rotated horizontally giving excellent ability to manipulate the viewed specimen. There is a dove-tailed sliding bracket to hold slides (or a live box) firmly in place against the fixed back rail.

Beneath the stage there is a dovetailed rack and pinion substage accessory holder. The holder collar has a ‘bayonet’ slot at the bottom. There is an ‘Abbe’ condenser complete with diaphragm and pivoting filter holder that fits into the top of the collar. The ‘Abbe’ condenser is named after the German physicist Ernst Karl Abbe (1840 – 1905) who developed it in 1870.

Beneath the substage assembly, and protruding from the ’bar-limb’ is a tube fitted with an adjustable collar holding a plano-concave light mirror, one side flat with the other side concave. This has a single rotatable crank arm. 

James Powell Swift (1828-1906), son of Thomas Swift, watchmaker, apprenticed with Andrew Ross (a leading London maker of microscopes, hence the similarities of Swift’s early instruments to those of Ross). In 1854, aged 26 years old, he set up his own workshop at 15 Kingsland Road, London. In 1870, he changed his location to 128 City Road. The date of this microscope is thus between 1854 and 1870.

In the catalogue of about 1865, from 15 Kingsland Road, The 'Best Compound No. 1A’ is very similar to this instrument excepting for the substage condenser and a single crank arm on the mirror.

This microscope was designed, by James Swift, for both conventional and polarized light microscopy. The arrangement allowed for simultaneous use of both prisms thereby resulting in a stereoscopic image using polarized light. From the Swift catalogue,

Note: Around the time that Swift relocated to 128 City Road, in 1870, he presented a specialized substage achromatic condenser to the Royal Microscopical Society (described in ’English Mechanic and Mirror of Science’, Vol. 11, 1870. His address in this article is given as City Road).

The microscope is in a beautiful custom-made mahogany box with hand cut dovetail joints. The box has a door on each side and comes with original key (one escutcheon is missing). There is 'Broadhurst & Clarkson' plaque inside one door.

One pair of eye piece lenses with side shields. Optics are excellent and have been cleaned (see photographs). Note: the inner projection on one of the eye shields has been filed down. This was probably related to eye comfort. The Wenham tubes consist of a vertical right hand tube with an angled left hand tube.

A second pair of eyepieces with a higher magnification than the shielded pair. I would say this is  approximately 1½ x to 2x - Optics are excellent and have been cleaned (see photographs).

The ‘Abbe’ condenser optics are excellent and have been cleaned. The diaphragm works well. The swingout holder takes 35mm filters and can be rotated.

There are a miscellany of five excellent objective lenses in various cases as follows;

1: Case marked ‘E. Leitz Wetzlar’ 7. Lens similarly marked ‘E. Leitz Wetzlar’ 7. Distance from bottom of lens to specimen when focused approx. 1mm. Optics cleaned and excellent. Single lens element unscrews correctly. 

2: Case marked ‘J. Swift London’ 1/4”. Lens unmarked. Distance from bottom of lens to specimen when focused approx. 1/8” (3mm). Optics cleaned and excellent. Lens elements and collar unscrew correctly

3: Case marked ‘Baker London’ 2/3in. Lid has RMS retaining thread. Lens unmarked. Distance from bottom of lens to specimen when focused approx. 1/2” (12mm). Optics cleaned and excellent. Lens elements and collar unscrew correctly

4: Case marked 1 ½”. Lens marked ‘2’. Distance from bottom of lens to specimen when focused approx. 3/4” (19mm). Optics cleaned and excellent. Lens elements unscrew correctly. 

5: Case marked 3”. Lens marked ‘C. Zeiss’. Distance from bottom of lens to specimen when focused approx. 2 1/4” (57mm). Optics cleaned and excellent. Single lens element unscrews correctly. 

Lacquer is original. All moving parts function well. Tilt very firmly set.

There is some typical age-related deterioration to the mirrors, mainly to the concave side.

The Wenham prism is chipped along one edge (see photographs). It is retained in the holding box with a dab of glue to either side. This would probably have been with Canadian Balsam. When cleaning the prism I replaced it with a bit of Uhu glue which is easy to remove if adjustment is required.

The Nicol prism is Icelandic Spar - Calcite and over 150 years old. It is fragile and the top surfaced is impaired at the periphery with dirt/corrosion (see photographs) . It works reasonably well and could be replaced. I have left it in place to retain historic integrity. Note: The Science Museum in London has Swift Nicol prism examples, in its collection, donated by the firm 1900-1936.

The box is very robust, beautifully made and fitted out. It has a heavy flush-folding brass handle at the top. There is a door on either side of the case. Both doors have good functioning locks (Note: one has lost its escutcheon). The ’rear’ door is for storing the Wenham tubes when detached from the instrument. There are also slots for a dismantled bulls eye condenser and stage tweezers (missing). There is a fixed rack with three holes for lenses/accessories suspended from the top. The diameter of the three felt-lined recesses are 1 5/16” (33mm) which is the diameter of the eye-piece tubes.  Note: when storing the Wenham tubes this should be done first as the door will not open if the main body base has already been slid in from the ‘front’ door. This is because the arc required for the Wenham tubes to swing out is impaired by the body of the microscope. The eyepiece holding tubes should be fully racked down. When unpacking the instrument the main body of the microscope should be removed first before attempting to open the ‘back’ door.

Note: There is a large piece missing from the recess that holds the base of the tubes. This probably occurred due to shrinkage ‘pinching’ that prevented the tubes from nesting. This does not affect storage and is cosmetic.

The front of the case has storage racks for the four eyepieces, 5 objective lenses, two smaller circular recesses and a nest for the two-lens turret attachment.

Note: When the main microscope base is placed in the sliding holder it should be upright and the toggle catches engaged. The condenser should be removed and placed in its circular housing recess on the base and secured with the toggle.

Microscope maximum height with eye tubes extended by 1 7/8” and focus column fully extended   24” (61cm). Triangular tri-foot base ia 19cms x 19cms.

Case 27cm x 24 cm x 32cm high

Weight cased: 11kg (Heavy item to package and post securely - this will be fully insured)

This is an important early binocular microscope, with innovative prism features, by a famous London instrument maker. It is ‘museum quality’ and in excellent condition. 

Please examine photographs as these form part of the condition report.