This listing is for a collectable early example of Watson's Van Heurck brass microscope.  It's quite an imposing instrument standing over 18 inches high when the draw-tubes and coarse focus are racked out.  This example dates to around 1895-6 based on its serial number 3849 which is engraved on the tripod just above the rear brass bun-foot. This particular example has also been in my personal collection before, so is an instrument I know very well.

The Van Heurck model range was produced by W. Watson & Sons based on a design scheme originally proposed by famous Belgian microscopist Henri Van Heurck (1839 - 1909), hence the designation afforded to this top-of-the range series of Watson instruments.  The Van Heurck, Royal and Edinburgh models of Watson microscope all bear the same signature shape and indeed the Van Heurck was essentially based upon Watson's Edinburgh design of microscopes, which they had been manufacturing in various guises since about 1887.  The signature form most commonly includes a tripod base and upper limb with vernier screw/internal lever fine focus mechanism.  As well as their larger size, the Van Heurck models also tend to have additional features over and above both Royal and Edinburgh models and also sometimes various bespoke options or accessories, because quite a number of discerning customers must have had their instruments built to their own individual specifications.  Van Heurck's aims with specifying this model's key features appears to have been to assist with his study of diatoms, especially with improvements such as sub-stage fine adjustment and fully mechanical rotating stages.  There were a number of different Van Heurck models produced by Watson with quite a complicated series of enhancements and developments, together with a range of accessories.  The Van Heurck variants were produced by Watson from around 1893, with final examples produced into the 1930s, as follows:

1893 to 1896 - Van Heurck Model A

1893 to 1900 - Van Heurck Model B - double draw-tube added - this example #3849

1896 to 1921* - Van Heurck Grand Model - concentric x/y controls and slightly larger tripod giving enhanced overall size and presence

1900 to 1923* - Van Heurck No. 1 - similar to Model B

1900 to 1923* - Van Heurck Circuit Stage - variant of No 1, with extended upper limb allowing full 360 degree stage rotation

* final versions - production would have continued beyond these dates into the 1930s

This example #3849 dating to about 1895-6 therefore appears to be a Model B, having an 8 inch tripod, which is slightly smaller than the Grand Van Heurck model's tripod and larger than the tripod normally found on other Edinburgh models in Watson's line up.  Other factors such as sub-stage fine adjustment being above and at the rear of the stage and the stage controls being non-concentric all reinforce this being a nice example of the Van Heurck Model B.  The spread of the front tripod legs measures exactly 8 inches and helpfully, there's still the original factory cork pads on the underside of the feet, which means that it can be used on polished surfaces - with care of course.

Turning to the technical details, the coarse focus is via rack and pinion with smooth action and the main tube holding in position as it should on adjustment.  It's also interesting to note that this example is fitted with tension adjustment for the coarse focus pinion, a feature that's not shown in Watson's 1896 catalogue entry for this model.  Fine focus is controlled via a separate brass thumb-wheel at the rear of the upper limb, with graduation markings and which operates a vernier screw acting on an internal lever system.  The focusing technique being to achieve near focus with the coarse thumb-wheels, then fine-tune with the single rear thumb-wheel, which only has a fairly small range of movement via its vernier screw mechanism - in fact there's an engraving on the fine focus thumb-wheel confirming that one full revolution = 1/13th mm of travel.

With its optics, this Watson microscope comes fitted with a period graduated brass eyepiece draw-tube inside another graduated brass draw-tube operated via a rack and pinion system all of which sits inside the main brass optical tube.  The draw-tube action is smooth and I've tightened up the rack and pinion reducing play in this mechanism.  Extending the draw-tubes increases the available magnification and you also have to re-focus on your specimen.  If one racks the draw-tube to the end of its range and removes it completely, there's a female RMS threaded end to which accessories such as analysers, very low power objectives or correcting lenses can be fitted.

There's also a good selection of Watson top-hat eyepieces supplied with the instrument, as under:

- 5x magnification - unbranded and probably by Watson
- 8x magnification - Watson
- 10x magnification - Watson

There are also some appropriate Watson objective lenses in brass together with an older-style Watson triple turret which rotates freely with a positive feel as the objectives align with the optical axis.  There are also additional brass objectives all detailed below, giving a really good selection of current optics:

- 2 inch about 3x magnification by C. Baker
- 1 inch about 6x magnification by C. Baker
- 1 inch Watson - about 6x magnification
- 2/3rds inch - Watson - 10x magnification
- 1/2 inch - Watson - 15x magnification
- 1/4 inch about 20x magnification by C. Baker
- 1/6th inch - Watson - 40x magnification
- 1/6th inch by Henry Crouch - 40x magnification
- 4mm Apo by R & J Beck with adjustment collar - 40x magnification

Overall therefore, the range of magnification available with this Watson with the draw-tubes set at standard length ranges from about 18x with the lowest power lens combination, up to around 400x with the highest power combination and with the benefit of good illumination.

The fully mechanical circular brass stage is well engineered and a delight to use.  It's got twin thumb-wheel x/y adjusters on the right hand side of the stage, vernier scales for both axes and is currently fitted with a specimen holder for holding slides steady during inclined viewing and when the axes are being moved around.  The freely running x/y controls also offering good accurate control of specimen positioning, which is a real advantage for higher magnification work.  The stage also rotates to left and right, but does not complete a full 360 degree rotation - you would need a Circuit Stage or Grand to get that feature on a Van Heurck model.  The instrument also tilts for inclined viewing, holding in position as it should; there is no limb tension lever present and the pivot can be tightened manually as required.

Turning to the sub-stage, we have a Watson Abbe-type top-mount condenser in a ring-mount with centering controls comprising brass thumb-screws, with height adjustable rack and pinion system, plus additional vernier fine adjustment via a vertically mounted thumb-wheel located above and to the rear of the stage.  There's a single-sided brass thumb-wheel for coarse adjustment of the height.  The condenser assembly also has a working iris to control lighting levels and there's a 35mm swing-out carrier fitted for adding coloured, opaque of dark-field filters.  Lighting is via a larger 2.25 inch plano-concave mirror in a brass carrier on a height and swing adjustable brass support arm and gimbal, with period silvering that's in very good period condition to both sides.  The mirror gimbal has been tightened so that the mirror holds position on adjustment.

There are some very useful period accessories supplied with this instrument as below:

- live box in brass by Watson - for viewing liquid specimens such as pond water
- polariser and analyser - unbranded and possibly by Watson - which fit into the optical tube and also replace the standard condenser for polarised light work, these are supplied in a period Watson box as shown in the listing photos and are useful for viewing thin-section minerals, fibres, chemical crystals and other subjects suitable for study using polarised light
- 35mm blue filter, opaque filter and a dark-field stop in a small container
- erecting lens - this fits to the internal draw-tube and when added to the optical path presents a right-way-up image in the eyepiece
- stage micrometer 0.1 and 0.01mm plus an eyepiece graticule for top-hat eyepieces with 0 to 100 scale - together these accessories allow accurate measurements of samples under magnification
- Watson branded lens tissue x 2
- Watson branded accessory boxes all within a wooden storage box

The instrument and its controls have been gently cleaned, very lightly lubricated and operate smoothly with age-appropriate signs of wear as one would expect for a quality instrument of this vintage.  This instrument presents amazingly well with lovely gleaming brass-work that catches the light beautifully.  There are some signs of tarnishing, lacquer loss and spotting here and there which is what you'd expect for an instrument of this age that's been both used and well looked after throughout its life.  Overall, it's in pretty good shape for its age.  This example is essentially a very nice collectible early Watson Van Heurck in the right condition for a collector and it'll make a great usable instrument and also a stunning display piece.  It presents rather well while being used as a desk-top instrument and will also look the part in a library or home office setting, especially when set up with an appropriate antique slide.

There's currently no storage case with this example and I will endeavour to source a suitable example in the near future and add to the listing if/when I can.  This instrument has some scale, standing around 15 inches high racked down when an eyepiece is fitted, so it may be quite difficult to obtain a suitable case that's large enough to accommodate a Van Heurck instrument of this size, especially with the wide spread of the tripod legs.

Owing to the weight and delicacy of this antique microscope and its accessories, it will be partially dismantled, very well wrapped for shipping and dispatched by insured courier upon receipt of cleared funds.  Yes, it's expensive, but it will be quite difficult to find another such example with a good selection of period Watson accessories, because Van Heurck instruments don't come to market that often and when they do, there can be fierce competition for the finest examples.  So, if there's a gap in your collection for a Van Heurck, or if a Van Heurck is something of a grail piece, as it was with me for a long time, then maybe you've finally found one. 

Overseas buyers please use the eBay Global Shipping option if available for your territory, or contact seller for alternative shipping options and costs.

Thanks for looking - please also check out my other listings if you get the chance.