Antique Davon ‘Super Microscope’ in Brass by F Davidson & Co., London – c1920s

Antique Davon ‘Super Microscope’ in Brass by F Davidson & Co., London – c1920s

£895

Antique and in fine condition an unusual monocular instrument - "Davon" Super Microscope serial no. 59A - marked F. Davidson & Co, London - circa 1920.

Circa

1920

Maker

F. Davidson & Co., London

Country of manufacture

UK and Ireland

Categories: Scientific, Microscopy

Description

Offered for sale is a very rare and unusual monocular instrument by English makers F. Davidson & Co. of London.  It appears to be a large continental pattern instrument in brass with some great technical features that would have been at the cutting edge of optical innovation a hundred years ago.  Specifically:
 
– internal lever fine focus – similar to the system used by Watson
– mechanical over-stage with good range of x/y movement
– standard optical tube with mechanical eyepiece draw-tube operated by rack & pinion system – similar to Watson
– alternate optical-tube with further additional mechanical draw-tube** and internal optics giving Super Microscope functionality
 
** point on condition – some missing teeth to pinion gear in second draw-tube – as shown in listing photos – also small spare pinion gear will be supplied which may facilitate a repair
 
Overall a rare, quite imposing and no doubt a collectable example of a good size antique monocular brass microscope by a quality London maker – it’s the only one of these I’ve ever seen.   The instrument is numbered 59A and bears the details of its makers and serial number on the Y-shaped brass foot.  

 

 
Background to F. Davidson & Co. – source Microscope Museum:
 
F Davidson & Co were manufacturing opticians that traded from 29 Great Portland Street, London, from around 1890 until 1922, and then from 143 Great Portland Street from 1923 until 1938.
 
 
This example is a really well-engineered and characterful instrument with quite a technical write up in the pages of Davidson’s 1924 product catalogue, which I’ve copied some extracts from in the listing photos.  I’d encourage any interested readers to take a detailed look through these pages, which can be found on the Microscope Museum website.  Having read through the technical material about the so-called Critical Images that can be obtained at very high magnification, what we may in fact have here is a very early method for increasing magnification, even more so that with an Optovar that can be found on some high-end modern instruments.  The method developed by Davidson essentially uses a second compound microscope as the eyepiece, thereby achieving high primary magnification. Back in the 1920s Davidson’s invention appears to achieve this using a second set of objective lenses within the alternate optical tube, which can be adjusted for image clarity and focus using the double mechanical draw-tubes.  Some of the image results especially at higher magnifications that users reported using the Davon Super Microscope are very impressive and would probably put many a modern instrument to shame.
 
In terms of the technical details, the instrument stands on a heavy extended brass Y-shaped foot with uprights leading to the main pivot joint with tension adjustment.  There’s an upper limb with a continental pillar-type arrangement with thumb-wheel atop, however this fine focus mechanism operates an internal lever system very similar to that found in Watson’s Praxis model of a similar period.  Coarse focus is conventional rack & pinion with diagonal rack and spiral pinion, as would be expected for this period of manufacture.  There’s a good range of coarse focus travel, which allows lower power higher working distance objectives to also be used as may be required.  The instrument tilts for inclined viewing and holds in position throughout the usable range of inclination.  

With its optics, this unusual instrument has two optical tubes described as under:

Standard Optical Tube

Optical tube in lacquered brass with mechanical draw-tube operated by a rack & pinion system, as often found on high-end Watson instruments such as the Royal & Van Heurck models.  There’s also a manual draw-tube.

Complex Super Microscope Optical Tube

This optical tube assembly really is something else, it’s also in brass and noticeably extended, with two mechanical draw-tubes both operated by rack & pinion systems and both with graduation scales.  There’s also an internal system of secondary objectives located within the optical tubes which I’ve endeavoured to show in one of the listing photos, giving increased magnification functionality – probably even higher than can be achieved with an optovar, as can be found sometimes on high-end modern instruments.  The Davidson product catalogue mentions that significant increases in magnification can be achieved with little or no loss of image quality when using the Super Microscope functionality and obtaining the so-called Critical Image.  Note point on condition re second mechanical draw-tube as mentioned earlier in the listing.

There’s two original standard diameter eyepieces:

– 6x magnification
– 8x magnification

There’s three objective lens in brass on a triple turret, as under – note the instrument is RMS in terms of objective thread diameter, so plenty of other objectives should also fit:

– 1 inch Davon – approx 6x magnification 
– 1/2 inch Davon – approx 15x magnification
– 1/6th inch by James Swift & Son – approx 40x magnification

The magnification range available is therefore from around 36x to 320x and then possibly increasing those figures using the Davon Super Microscope functionality, provided the user is able to master the intricacies of the patented Davidson Critical Image system.

There’s a fully mechanical brass over-stage which is attached to the base of the continental pillar by a pair of brass thumb-screws which locate into two pre-drilled recesses in the base of the limb.  It’s a well engineered over-stage that’s a delight to use when correctly fitted, with nice smooth action to its moving parts.  It’s got thumb-wheel x/y adjusters for both axes with smooth operation.  It’s also got two arms for holding slides during inclined viewing and when the axes are being moved around which work well, with the right-hand arm sprung.  The x/y controls have a nice solid feel about them, offering good accurate control of specimen positioning.  

Turning to the sub-stage, we have a brass ring-mount that’s currently fitted with a Abbe-type condenser with centering, working iris with smooth operation and also a swing-out filter carrier. The condenser assembly sits in a height adjustable rack & pinion mount with single-sided thumb-wheel height control.

Lighting is via a plano-concave mirror in a brass carrier on a height/swing adjustable support arm and gimbal attached to the limb tailpiece, with good range of adjustment also allowing oblique illumination as may be required for various applications.  The mirror silvering is in pretty good condition to both sides with reflectivity that’s perfectly adequate. 

There’s a later case for the instrument as shown, with internal compartment and latches to keep the door closed.

The instrument and its controls have been very gently dusted, lightly lubricated and operate smoothly with few age-appropriate signs of wear and condition points as described.  With its bright lacquered finishes and the signature Super Microscope optical tubes, it’ll make a great display piece in the right setting and is also a perfectly usable instrument, with the benefit of the user being able to explore its Super Microscope functions and capabilities.  It presents really well and I’m certain it will look the part in a library or home office, especially when set up with an appropriate antique slide.  It’s quite imposing with the larger optical tube fitted with a working height of almost 18 inches.

Owing to the weight and delicacy of this antique microscope, it will be partially dismantled, carefully wrapped for shipping and dispatched by insured courier upon receipt of cleared funds.  UK shipping will be by Royal Mail Special Delivery.

Thanks for looking and just message seller if any additional photos or details of condition are required.

 

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GB Arcboutant Scientific

Arcboutant Scientific based in Glasgow Scotland, with an interest in scientific collectables dating back to 1988. Now making available carefully curated fine examples, principally of antique microscopes and associated scientific equipment by quality English and Continental makers, to collectors world-wide.

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