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c. 1910


Serial number: 12345


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This is a 'Grand Van Heurck Microscope' equipped with all the feasible additional options and a nearly comprehensive set of lenses and accessories. It arises from an English tripod foot of the form often used by Watson and similar to those used by Powell and Lealand and others. The foot is oxidized gray-black with lacquered brass button toes which are cork shod. The limb is suspended by a trunnion joint with a rhodium or nickel-plated tightening handle.  The spread of the toes is 9 3/4 inches, just as quoted in the 1912 catalog. The distance from the bottom of the stand to the axis of rotation of the limb is about 6 inches. In a working position it stands about 19 inches high. Across the rear of the tripod is a bar, a protrusion on top of which is where the limb makes contact when the microscope is in the horizontal position. The protruding piece also projects forward to make contact with the limb in the vertical position. Thus there are stops for the horizontal and vertical positions of the limb. It is signed on the bottom of the rear toe with the serial number of '12345', and on the Y-shaped extension of the rear toe 'W. WATSON & SONS LTD, 313 High Holborn, LONDON.

The gimbaled plane and concave mirrors are housed in a 3 inch lacquered brass casing with knurled rings to hold the mirrors in place; mirror diameters are about 2 3/4 inches. The mirror is supported by a black yoke attached to a 1 inch long stem, which is in turn, attached to a tubular fitting which slides over the swinging tailpiece. The tailpiece swings on a brass screw attached to a downward protruding piece of the stage.

The substage support is separate from the mirror tailpiece, and also comes down from the stage. The substage has coarse focus by diagonal rack and spiral pinion. substage ff Fine substage focus* is via a knob protruding upward above the stage. This knob, unlike the main fine focus knob, is not calibrated, but does have arrows showing the direction the substage is moved; clockwise moves the substage down, counterclockwise, up. There is a ring to support a condenser which has controls for centering the condenser. The condenser housing can swing out of the optical axis on a hinge, a standard feature for the Grand Van Heurck by this time. A tiny brass handle acts on the piece locking the condenser assembly in the normal position. Another feature on this microscope is the optional mounting of the substage support ring on a sliding bar* in a dovetail fitting so that the substage may be set at any desired position, irrespective of the rackwork, which operates independently; this allows the use of all substage accessories, some of which would otherwise be too tall to install without this flexibility. This fitting has a lacquered brass knurled knob to lock it in any desired position on the dovetail slide.

A variety of condensers are with the instrument. These are outlined in the accessories section below.

The Stage of this model protrudes further than in the No. 1 Van Heurck Model, and this allows full rotation of the 5 inch diameter mechanical stage with its protruding controls, just like the Circuit Stage Van Heurck model. Stage rotation is calibrated with a silvered scale* with numbers and Vernier. It is marked in single degrees, each ten degree increment is labeled. The Vernier allows movement in fractions of 5 minutes of a degree. Pushing up engages the pinion rotation* of the stage, while pulling it down allows free hand rotation. There are controls to center the stage*, as well as locking knobs to hold the centration*. The mechanical stage has a 1 1/2 inch horizontal (X) range, and a 1 1/2 inch vertical (Y) range. The optional calibration for these stage movements* is also part of this instrument. These are calibrated 0-35 mm for the horizontal movement and 0-35 for the vertical, with a Vernier to read tenths of a mm. The stage is controlled by two concentric knurled knobs on one side of the stage, controlling horizontal motion by worm screw and vertical by double diagonal rack and spiral pinions. A single knob on the opposite side of the stage controls left-right motion only. Since the stage rotates completely, the double control could be positioned on either side. The optional stage bar* with attached clips slides in dovetail grooves on the stage top plate. There is a knurled knob which can lock this bar in position. There is a hole near the bottom which this locking knob can be screwed into. There are also two holes for the use of standard stage clips.  This stage bar also has a swing-up stop for registering the position of a slide when using the calibrated positioning controls.  

GVH fineThe limb has a longer arm than the No. 1 Van Heurck to allow it to position the nosepiece in the center of the extended optical axis necessitated by the full rotation of the stage. Coarse focus is by diagonal rack and spiral pinion whilst the fine focus is via a long lever controlled from the top edge of the rear part of the arm. This instrument is equipped with the optional two-speed 'spindle milled head'* as the fine focus knob. The knurled lacquered brass fine focus knob is calibrated and numbered from 0-10 with division increments of 0.1. It has arrows showing which directions of rotation lowers and which raises the optical tube. There is a steel pointer to register these calibrations. The instrument has a black triple nosepiece which is unsigned and has no trademarks. A large number and variety of objectives are with the instrument, and are described below with the other accessories.


There are three optical tubes with the instrument. These include the standard Van Heurck monocular tube, a Wenham binocular, and a special petrographic tube.


gvh main tubemain tube scalesverniergvh draw tubes For the standard tube, as shown in the top center picture above, and also to the left, the outermost diameter is 1 11/16 inches (63 mm) and is about 5 inches long.

This main tube has a scale indicating where the focus is set and it has a range from 0-90 mm, engraved by single mm, and labeled every ten mm; there is also a Vernier to allow positioning to one tenth of a mm. I have not seen this scale mentioned as an option or standard fitting for the Van Heurck stand in any catalog.  It is a feature commonly seen on microscopes by the American microscope maker Walter Bulloch.

There are two calibrated drawtubes, the outermost and lower one being calibrated from 23 to 33 and also from 14 to 23 in one tenth increments with the whole numbers labeled. The inner drawtube is calibrated from 14 to 23 and is engraved similarly. Both the lower mechanical draw tube and the upper inner drawtube each have about a 3 inch range, but the last half inch of the mechanical tube is beyond the rack's range, and so it must be manually extended to this distance if that degree of extension is desired. The inner draw tube accepts a 31 mm diameter eyepiece, but there are also adapters which allows the use of the narrower 23 mm eyepieces.


wenham The second tube is a Wenham binocular, with rack and pinion interocular distance adjustment. The Wenham prism can be pushed out of the optical axis but a stop prevents accidentally removing it completely. A disadvantage of the binocular is there is no drawtube, and so adjustments for tube length or coverslip thickness can only be made with a correction collar on the objectives. The binocular tube is about ten inches long with the interocular distance adjustment changing the length as much as  about one inch above the end of the main tube.


petrotubeThe third tube is a special petrographic tube. It has a fixed tube length of about 7 1/2 inches (180 mm, one of the German standards). This tube is not listed nor pictured in any Watson catalog that I have seen. It also has a feature different from any other Watson microscope that I know of; this is a wheel of optical elements above the nosepiece analyzer.  These consist of two different lenses both of small diameter and long focal length, an empty opening and a first order red retardation filter. 

Attached to the end of the petrographic tube is the special fitting for the five centerable objective mounts carrying Oehler objectives; the knob securing the objectives screws tighter in the counterclockwise direction, and features a tapered bottom that fits into the curved tapered side of the objective mounts. Immediately above that is a window slot for wave plates, or the calcite slider, with a shutter controlled by a tiny knob. Above the wave plate slot sits the nosepiece analyzer. The nosepiece analyzer can be slid out of the optical axis, but its vertical position cannot be varied.

The rotating disk of optical elements, sitting above the nosepiece analyzer, can be raised or lowered via a small knob on the opposite side. Next, on the upper part of the tube, is the Bertrand lens which can slide in or out of the axis and also can be moved up or down to properly focus on the rear focal plane of the objective. Above the Bertrand lens and just above a knurled ring, is another window slot with its shutter controlled by the knurled ring rotating around the tube. This shutter can be opened for admitting the included eyepiece micrometer, or left closed to exclude stray light and dust.

A special crossed web eyepiece fits the top of the petrographic tube. It has a slot to line up with a screw on the tube so it does not rotate. It also has a window which matches the window in the tube which sits above a knurled ring; rotation of the knurled ring opens and closes this slot. The eyepiece has a top element that can, via screwing it in or out, focus on the micrometer rulings.

An eyepiece analyzer, with a finely divided silver scale, fits on top of cross web eyepiece and the outer optical tube, and also has a registration slot; it also has a slot (without shutter) for the calcite plate to sit above the eyepiece, and below the eyepiece analyzer. The eyepiece analyzer has a silvered scale engraved in single degrees, numbered every ten, and with click stops every forty five degrees.


A variety of other eyepieces, objectives and other accessories are with the instrument and are described in the accessory section of this web page.

All the rack and pinion fittings have the capacity for adjustment in the event of wear, as do the slides in which the tubes and substage travel. Every part of this microscope works like it did over 110 years ago. The black finishes are an oxidized black and the lacquered brass a mildly orange yellow.

case for GVH scopeThe original case is heavy and large with a top handle but no side handles. It has dovetail joinery. There are two original accessory drawers,with original draw inserts remaining. The original magnification card has apparently been removed in the past. The inside of the case has a lot of 'furniture' added to accommodate some of the numerous accessories. These include individual fittings for such things as the first order retardation plate, eyepiece micrometer, modified Rousselet compressor, the rough-work stage plate, and the three optical tubes. Unlike some other Van Heurck cases, the microscope cannot be stored in the case with any optical tube in place; they must be stored on the furniture inside the case.


GVH options
*Virtually all optional features were ordered for this microscope, as shown in the catalog listing to the left. Some options like calibration of the focus of the main tube is not mentioned in the catalog.



GVH with access.

Accessories for this microscope include those for different types of illumination, accessories for holding or confining specimens, and accessories for different magnifications. Among the latter are eyepieces, eyepiece adapters and objectives.

Eyepieces available for this microscope and listed in the catalogs of the time include Huygenian, Compensating, large diameter Holos and smaller diameter Holos eyepieces. The cross web eyepiece is listed with other accessories for polarized light work. The eyepieces with the instrument are all either Watson Holoscopics, or Zeiss compensating types. In order to get the most out of an objective, the optical elements of the eyepiece need to be arranged to take full advantage of the objective in question. The Huygenian eyepieces work reasonably well with ordinary achromatic objectives, and the compensating eyepieces work reasonably well with Holoscopic and Apochromatic objectives. The Holoscopic eyepieces however are adjustable and can be used with any objective. Because these were the best available, the Holoscopic eyepieces were often supplied with, or purchased for the Van Heurck microscopes, to be used with the ordinary achromatic, Parachromatic, Holoscopic, or Apochromatic objectives. At the time of the manufacture of this microscope, 'Compensating' eyepieces by Zeiss, for use with Apochromatic objectives, were also offered. This set includes a selection of Watson Holoscopic eyepieces, as well as two compensating eyepieces, one signed by Zeiss, the other is also German but unsigned.

The twelve eyepieces and several other related parts currently with this stand include:


Also shown are the eyepiece micrometer slider and the calcite slider.

The thirty two (32) objectives with the microscope include Parachromatic, Holoscopic, and Apochromatic. Apochromatic objectives by Watson themselves were first offered a little after the time this microscope was produced. In earlier years, Watson supplied apos by other makers, especially Zeiss. Objectives with this microscope at this time include eight Watson parachromatics, one low power (4 inch) objective by Swift, fourteen Watson Holoscopic, six Apochromatics (five by Watson, one by Zeiss) and five Oehler petrographic objectives in individual centerable mounts. As noted below, the Watson Apochromats were made slightly later than the likely production date of this microscope. In addition, as of 1906, Holoscopic objectives were limited to focal lengths of 1 inch and shorter, so at the time this instrument was sold, available lower power (longer focal length) objectives were either ordinary achromats or parachromatics. Lower power Holos objectives became available later that decade, but the longest length apochromatic remained the 2/3 inch, even through 1928. Eventually the plain achromats, also known as the 'Argus' series were no longer offered, the Parachromatic series then being the lowest class Watson made. Also notable, is that although the 2 inch objective in this collection is a Holos, it is not signed as such nor is its can labeled that way. Nevertheless, it must be a Holos as its n.a. is very high, and of the stated size for a 2 inch Holos objective in the Watson catalogs. Similarly, the 1 inch Parachromatic objective is not labeled on the objective or the can as such but must be as it has two sets of optical elements, and has a n.a. of 0.21.

The thirty two objectives currently with the instrument, all by Watson except as noted are:

para obj
  • Swift 4 inch
  • Parachromatic 3 inch
  • Parachromatic 2 inch
  • Parachromatic 1 1/2 inch
  • Parachromatic 1 inch
  • Parachromatic 2/3 inch (earlier version)
  • Parachromatic 2/3 inch (later version)
  • Parachromatic 1/6 inch
  • Parachromatic 1/8 inch
holos obj
  • Holoscopic 3 inch (75 mm)
  • Holoscopic 2 inch (50 mm)
  • Holoscopic 37 mm
  • Holoscopic 25 mm
  • Holoscopic 24 mm
  • Holoscopic 16 mm
  • Holoscopic 12 mm ( inch)
  • Holoscopic 8 mm (1/3 inch)
  • Holoscopic 6 mm
  • Holoscopic 4 mm (1/6 inch)
  • Holoscopic 4 mm (1/6 inch)
  • Holoscopic 2 mm (1/12 inch, oil imm with iris for dark ground work)
  • Holoscopic 2 mm (1/12 inch)oil immersion
  • Watson Apochromatic Metallurgical 16 mm (5/8 inch)
  • Watson 8 mm (1/3 inch)
  • Zeiss Apochromatic 4 mm (1/6 inch)with correction collar
  • Watson Apochromatic 4 mm (1/6 inch)
  • Watson Apochromatic 2 mm (1/12 inch, oil imm.)
  • Watson Apochromatic 2 mm (1/12 inch, oil imm, with iris for dark ground work)
Pole obj
  • 3X by Oehler in centerable fitting
  • 10X by Oehler in centerable fitting
  • 20X by Oehler in centerable fitting
  • 60X Fluorite by Oehler in centerable fitting
  • 1/12 oil immersion by Oehler in centerable fitting

It should be noted that as of the 1912 catalog, Apochromatic objectives by Watson were not yet offered, rather those by Carl Zeiss were listed in the back of the catalog. In the earlier 1906 catalog, apochromats offered included those by Leitz, Zeiss and Powell & Lealand. In 1910 or thereabouts therefore, Watson Apochromats were not yet available. The Grand Van Heurck microscope described on this web page, then would have had Parachromatic objectives by Watson, Holoscopic objectives by Watson, and/or Zeiss Apochromats, the Watson Apochromats added only later. Watson started to make their own apochromatics objectives sometime between 1914 and 1917. These could then easily added to the complement of the lenses with this microscope, as it would still be in service at that time. Unfortunately because of the use of fluorite as part of the lens system and glues that were not long lasting, most earlier Zeiss apochromats from that era have become defective due to delamination. The later Zeiss Apochromat in this set is intact.

Some readers may wonder how to compare these objectives to modern ones which are engraved as to magnification rather than focal length. A table listing the available Watson objectives, their focal lengths, n.a., and approximate magnification are provided on the Watson Objective Page. That page also relates some of this information to mechanical tube length. One should be aware that even now, as in the past, magnification is not only a function of the eyepiece and objective, but also the optics of ones own eyes; these differ from person to person so magnification will differ slightly between individual users of the same microscope. Put another way, even with a '10X' eyepiece and a '10X' objective, the true magnification will almost never be exactly 100X.

A variety of condensers
and other stage and substage apparatus were available at the time this instrument was produced and many of these are now with the instrument. The substage apparatus includes:

vh condensers


Parachromatic Watson condenserThis condenser was apparently introduced by Watson about 1896 and was still being offered in the 1940s. The parachromatic condenser fits into a condenser housing that is unsigned but has the convenient feature of a Sloan-type quick change fitting allowing the optical components to be easily slide out to be exchanged for another. This housing is unsigned, but there are fittings within the case for all of its parts.  Similar quick change fittings for the substage condenser can also be seen on the much later 'Swift Symposium' Model in this collection.

The 'Macroilluminator'
provided a large even achromatic illuminationn for low powers, especially for powers lower than a 1 inch objective, and would be quite suitable for use with the 2, 3 and 4 inch objectives with the instrument at this time. It would also be used with the Holostigmat lenses designed for photomicrography. This condenser is signed: 'MACROILLUMINATOR, W. Watson & Sons, Ltd, London, 6980'. It was available from no later than 1906 and continued to be offered throught the 1940s.


aplanatic low power illuminator The 'Aplanatic Low Power Holoscopic' condenser is suitable for objectives with N.A. of 0.65 or lower. It screws into a mount which can also house the 'Holoscopic Oil Immersion Condenser,' also now with the instrument. The low power Aplanatic Holos is signed:,'Holos, 2/3 in. .50 N.A.' on one side, and 'W. Watson & Sons, London on the other. It was available from no later than 1906 and continued to be offered throught the 1940s.


HOIC The 'Holoscopic Oil Immersion Condenser', is suitable for use with the highest power objectives and has an immersion front which may be removed for use with dry objectives of medium to high power. It is signed: 'HOLOSCOPIC OIL IMMERSION CONDENSER,  W. Watson & Sons Ltd London' and also:  '1.30 n.a.,  3843'. It was available from no later than 1906 through the 1940s.



universal watson condenser Large diameter condensers include the Universal,(shownto the left). This   also fits into the same housing as the HIP condenser shown below. It was available from no later than 1906 and continued to be offered throught the 1940s.


Large condenser The instrument came to me with this condenser. Like the Universal, it has a larger diameter and a removable front element. The front element has a simple press-fit. This condenser is in a housing that has both a slide-out filter ring and an iris diaphragm. The optical component screws in to the housing and no part of this apparatus is signed, nor does it match any illustrations in the Watson catalogs.


HIP Another mount holds the 'Holos Immersion Paraboloid' (HIP) which has an immersion front. It was available from no later than 1906 and continued to be offered throught the 1940s. The HIP can be used not only with oil immersion objectives, but also with moderate to high power dry objectives. When used with dry objectives, it still must be oiled to the bottom of the slide.  In these cases it can be used with a nosepiece iris ('Davis Shutter') without the need for a funnel stop but for oil immersion objectives, a funnel stop would be preferred. The paraboloid is signed:'Holos Immersion Paraboloid, No. 8068, slips 1.6 mm. The latter refers to the thickness of the slide with which the condenser is designed to work with (+/-20%). It is also signed 'W. Watson & Sons Ltd, London. The housing for the HIP has an iris but no flip out filter/stop holder like the other housings have, as this would have no purpose for a dark ground condenser. This condenser was introduced about 1909 and was reported in the JRMS of that year, part 5, p 647. The disadvantage of this dark ground condenser is that the maximum N.A. of the objective must be 0.95 or less, requiring higher N.A. objectives to be stopped down with a funnel stop, or by the use of a Davis (nosepiece) shutter.

nelson dgAbout 1925, another dark ground condenser, designed by the eminent microscopist E.M. Nelson was released by Watson as Nelson's Cassegrain Dark Ground Illuminator. This condenser, which fits the same housing as the Holos Immersion Paraboloid, was also called Nelson's Reflex Condenser. This illuminator was designed for slides of 1 to 1.2 mm thickness. It was supplied with 2 different diameter stops, although only one labeled 16 is present with this example. This condenser has the advantage of allowing the full N.A. of oil immersion objectives to be used with N.A. up to 1.40. This type of high power dark ground condenser is much less complex and easier to manufacture than the cardioid type*, though the latter is usually optically superior.

*as found for example on Beck's Focussing Dark Ground Illuminator.


The large 'Polarizer for Petrological Work' comes with a large size prism and rotating flange divided and numbered with stops every 45 degrees. There was an optional condensing lens to fit over the polarizer but this is not present. This would have been useful for viewing conoscopic figures at high powers.


For lower power dark ground illumination, stops are provided both for the larger diameter 'Universal' condenser housing (not shown), and also for the Holos Oil Immersion condenser housing. There are also inserts for oblique illumination, and color filters as well.


Also with the microscope, as an alternative to the fixed stops, is a 'Dark-Ground Expanding Stop' originally called a 'Expanding Spot for Dark Ground Illumination' also known as a 'Traviss Stop'. W. R. Traviss first exhibited this device at the December 1906 meeting of the Quekett Microscopical Club and it was subsequently reported in the February 1907 edition of 'Knowledge & Scientific News' and in more detail on pages 362-364 of the JRMS for 1907.   This stop fits the filter holder for the smaller diameter fittings of the 'Holos Oil Immersion Condenser' and the 'Aplanatic Low Power Holoscopic Condenser.' The aperture can be varied from about 5/16 to inch; this range is smaller than the two ranges quoted in the 1912 catalog. With smaller diameters, this stop is suitable for a higher power range of objectives than the larger diameter example shown in the 1912 catalog. One would conceivably need both this one and the larger range examples to be able to provide appropriate stop sizes for a wide range of objectives.


Other accessories included five vertical illuminators. The first and third noted below are no longer with this microscope.

One is the type with a coverslip used as the reflector by Beck; this type of vertical illuminator was in use from the middle of the 19th century. This Beck illuminator, redundant with the next illuminator, is no longer with this microscope.

A second vertical illuminator by Watson, is similar to the first, but with the improvement of variable apertures for light entrance. It came in a signed can.

zeiss vert ill Another illuminator is a Zeiss prism type of vertical illuminator with oxidized-black finish. This illuminator is no longer with the microscope,since the combined illuminator in the next entry has the option of using a prism included in the kit.

vert illumin Later the Watson 'Combined Vertical Illuminator' set was offered and is also with this instrument. The Watson 'Combined Vertical Illuminator' was first offered by Watson   after 1921, and is shown in the 1923 catalog (thanks to Dr Joe Zeligs for this information). The Combination illuminator came in a signed case, providing the option of a tiny prism or coverslip for reflecting the illuminating light beam.

vert illumin
Finally, a 'Watson-Conrady Condenser Vertical Illuminator' is also with the set and was the most advanced type of vertical illuminator available for many years. Vertical illuminators are used for illumination of solid or opaque objects with higher power objectives.   Light comes in from the side, and is reflected downward onto the object by the angled coverslip or tiny prism. The light is then reflected off the opaque object vertically, either around the tiny prism or through the coverslip.


rough stageThere is a also an accessory stage plate 'for rough work' which slides in from the front of the stage into the dovetail slots which also accept the slide support bar.


Watson Best Stage ForcepsA Watson 'Best' stage forceps with curving support also accompanies the instrument.




safety stage Another stage accessory is the Watson 'Safety Stage'. This very uncommon accessory is made of hard rubber ('Vulcanite'), with some lacquered brass parts and 'stage clips', which gently push up on the slide to hold it against the brass retaining knobs. This takes advantage of the upward curving center of the stage clips to push up on the bottom of the slide.  Should the user accidentally force the nosepiece and objective onto the slide itself, the springy stage clips give way, preventing damage to both slide and objective. It is signed in white letters on the Vulcanite: 'W WATSON & sons 313 HIGH HOLBORN, LONDON'. This stage was offered in the catalogs from 1885 to 1906.



davis shutter The 'Davis Shutter' is a nosepiece iris diaphragm. It can be used to increase the depth of focus, and also for dark field work, except with highest powers where a funnel stop* would be preferred. It was first suggested by Dr Royston-Pigott in 1869 for erroneous purposes, however it was first noted for its usefulness for 'increasing penetration' as described above on page 262 of the JRMS of 1882.  When the shutter is used to increase depth of field, resolution is reduced.   This instrument has one unsigned and another signed by Swift.

*A funnel stop is a tapered tube which fits inside the objective to narrow the diameter of the image emerging from the rear element of the objective, while blocking the more peripheral rays of light.  



botterhill troughA 'Botterhill Trough' (left) is also among the accessories. Viewing moving organisms with a microscope has always been a challenge. Various types of apparatus have been devised to contain and/or restrain such organisms. They vary from a simple small container to more sophisticated compressoria. One type of container is a trough and the type invented by Botterhill was offered by Watson from 1893 through the early 20th century. The Botterhill trough was first reported in the JRMS Volume 3, part 1, pages 148-149 in 1880 but was not offered in the 1883 Watson catalog.  In the 1880 report it specified the outer trough plates be made of brass, but they were soon offered made of Vulcanite as well, and the 1893 listings by Watson offered them in Vulcanite. The apparatus consists of two pieces of thin glass separated by a piece of 'India Rubber' and these resting inside the container of two Vulcanite plates each with a circular cutout and beveled edge. Three screws apply pressure to keep the apparatus water-tight. The thickness of the rubber spacer between the glass plates can be varied to suit the thickness of the animal being studied. The apparatus can be disassembled easily to allow the plates and rubber to be cleaned or replaced. According to George Davis, in 'Practical Microscopy of 1889, this device was first manufactured by Thomson and Capper of Liverpool, who also were the first to make Botterhill's 'Microscopic Life Slide' an example of which is also in this collection. The Life slide was noted in the 'English Mechanic and World of Science of June 3, 1881 page 298.



rousselet compressorThis is a Watson variation of Rousselet compressor, which was described by Rousselet in the 1893 volume of the JRMS. It illustrates the Watson modifications on the original Rousselet design. As shown here, it uses quick release fittings to hold the upper glass in place. Although this made changing the upper cover glass fast and easy, it was a distinct disadvantage over the method of gluing the top glass on, which then forms a seal, so that fluids like immersion oil would not seep under the top cover slip from above. (see Rousselet, CF, A Description of the Rousselet Compressorium, JQMC vol IX, 1904-1906 p 137-8). Please click on the image for more details and images.



oil bottle This little bottle for immersion oil fits in a wooden cup on the door of the case.



depression slideDepression slides, usually made of solid glass now, were at one time made mostly of brass. They are used to study a small amount of liquid such as pond water, but unlike the compressor and some live boxes, have no mechanism to immobilize any swimming creatures.  Another disadvantage, if used with a coverslip,  is lack of facility of adding liquid as the original is evaporating.  Botterhill's life slide is a superior design in that respect. 



. This stage micrometer is used to calibrate the eyepiece micrometer for each objective.



. This 'Mica Selenite Stage' provides three different selenites in a slider with a rotatable mica disc above controlled by the knurled knob in center. This device would reveal a wide variation in colors of polarized objects-a very entertaining accessory. Click on the image to see the effects of this accessory.



Selenite StageThis 'Selenite Stage' was a bit more expensive than the 'Mica-Selenite Stage' as it uses a geared mechanism to rotate the central well. The selenites were provided individually and as such could be used singly or combined. This accessory was offered by Watson for over sixty years! It gives a slightly wider variety in choice of effects than the Mica-Selenite Stage. Click on the image to see the effects of this accessory.



liveboxThis is a livebox, intended to allow observation of living specimens. It consists of a short tube or barrel, the top of which is covered with glass. A liquid or solid specimen can be placed here. The cap, with a glass top can then be pushed down over this barrel of the slide to contain the specimen, either with no pressure or with some degree of pressure as desired. The degree of pressure applied cannot be varied as precisely as it can be in the modified Rousselet compressor shown above. This livebox has the typical small holes to either side of the cylinder, also found on other Watson liveboxes. Rousselet also popularized an improved livebox(though it was invented much earlier), and Watson was among those who made them (see next entry).



liveboxThis is a livebox, intended to allow observation of living specimens, similar to the preceding entry. This later version was popularized about 1887 by Charles Rousselet, FRMS, though it turns out it was invented much earlier, by Blankley as reported in the English Mechanic and World of Science, No. 305, Jan 27, 1871, p 437. It is similar in some ways to the Varley livebox. In this variation, the lower glass is a raised 'tablet' with chamfered edges at the bottom of the cylinder. The upper portion or 'cap', instead of fitting around the outside of the bottom cylinder fits inside it. Also instead of the glass on the top of the second cylinder, it is on the bottom, so as to meet the tablet. Furthermore this upper cylinder is actually a double cylinder with its inside part threaded to the outer part, thus holding the glass in place. This allows the glass to be changed in or out without the need for glue. This livebox has two holes similar to the preceding example but this one is signed: 'W. Watson & Sons Ltd., London'. This would date this to after 1908. This design is like Rousselet's form, not the early twentieth century modification by Merlin. These types of live boxes were also made by Smith, Ross, Swift, and likely others. For more images of this livebox, please click on the image. An example of this type of livebox sold by Swift around 1877 is on this site.



object markerThis device is an 'object marker.'   It is used to inscribe a circle around an area of interest on a slide or coverslip on a slide. It makes use of a small diamond. In use, the microscopist centers the area of interest, and then replaces the objective with this device. It is spring loaded. As the optical tube of the microscope is lowered onto the slide, the spring applies just enough pressure. The user rotates the diamond via the knurled ring. A small knob adjusts the size of circle the marker produces; it is difficult to use the device if a very small diameter circle is chosen. This device was first invented by Leitz in the first decade of the twentieth century, and then copied by Watson. It is not listed in any Watson Catalog that I could find. Another form of object marker also fitting on the nosepiece, was used to simply stamp an area with ink. This stamping device was devised earlier than the diamond marker, and obviously made a circle that was not as durable, though more easily seen with the naked eye than the diamond mark. In the twentieth century, Nikon produced a modern form of stamping object marker which actually had an ink resevoir.




Henri Van HeurckThe famous Belgian microscopist, Henri Van Heurck(1839-1909) was the manager of his family business manufacturing paints and varnishes. He became famous as a botanist, expert microscopist, photomicrographer, and especially diatomist. More than one diatom species is named in his honor. The basic plan for the Van Heurck stand was based on the earlier Edinburgh stand, a model devised with the advice of an Edinburgh professor. For more historical information about the various models of the Edinburgh microscope see the Edinburgh B page and the Edinburgh H page.

edinburgh Watson & Sons had been making microscopes since about 1874. For some time in their early production, their microscopes were similar to other contemporary makers, but soon they started to produce a variety of interesting designs, including their own variation of the Walter Bulloch Biological No. 2, and also a version loosely based on Wale's New Working Microscope.   In 1887, Dr Edington, a Lecturer in Bacteriology from the University of Edinburgh, suggested the first form of the Edinburgh stand; according to Watson's delivery records, the first example was sold on November 29, 1887. This stand was the inspiration for the Van Heurck stand, and like the Van Heurck, started out with a continental foot, but was soon ordered more often with a tripod foot. Like the Van Heurck, it was improved progressively over the years. This culminated in the Edinburgh 'D' and 'H' models, (an example of 'D' is shown to the left), which had most of the basic features of the (later) 'Royal' model. In fact, when the Royal was first introduced, it was actually slightly smaller than the Edinburgh H.  The various Edinburgh stands were at first indicated by the numbers 1,2,3, and 4, but by 1890, the letters A,B,C and D were used. 

In 1889 or before, with all of his expertise, Van Heurck suggested the design of a microscope to his specifications, and this was the first model of the Van Heurck microscope made by W. Watson and Sons. The first entry for a  Van Heurck in the Delivery Books was for serial number 2641 on March 17, 1891*:
vh entry
VHAThis microscope was pictured in the first edition of Van Heurck's book also dated 1891.  This first version is identical to the 'Watson No. 4 Van Heurck Stand A' seen in the 1893 catalog. Study of the illustrations shows that this initial Van Heurck differed from the original Edinburgh mainly in two features-the fine adjustment for the substage, and the ability to rotate the entire mechanical stage. Van Heurck preferred to do all of his photomicrography with a vertically oriented microscope which is why he preferred his microscope to be made with a continental horseshoe foot and supported on a single pillar, so as not to interfere with substage adjustments during the, (then) delicate operation, of photomicrography with high power objectives. At the same time, many others preferred the horizontal position for photography. For this reason, his stand was also offered with the more stable English tripod foot which provided a much more stable stand for photography in the horizontal position. Many more examples with an English tripod exist than with the horseshoe foot, as the tripod quickly became more popular.

*An engraving of the Van Heurck 'A' stand found in a bound volume of catalogs as the first page of an 1889 Watson catalog. This microscope was not listed in the catalog, and the page, which is also slightly smaller than the pages in the rest of the catalog, has a horizonal fold suggesting it was not original to that catalog, and was simply tipped in, in front of the rest of the Watson 1889 catalog when it was bound together with the other catalogs in this bound volume of catalogs. Therefore, although the author of this web page previously thought this might be an original part of the catalog, and dated the first Van Heurck microscope to 1889, it seems that this is not true. A search for another 1889 Watson catalog has not been successful so far. We are grateful to Jeroen Meeusen, the owner of this 1889 catalog, for pointing out this information.

VHB As noted above, the Van Heurck instrument, as designed by the diatomist, was at first provided on a continental foot with a single pillar. Early examples had a standard one inch diameter main optical tube, as pictured in the image in the preceding paragraph. In the 1893 catalog the 'No. 4 Van Heurck Stand A' had a 1 inch diameter main optical tube with a single calibrated draw tube with tube length variable from about 160 mm to 260 mm. The 'No. 4 Van Heurck Stand B,' as shown to the left, had a double drawtube, the lower draw wider, (but still only 1.5 inches in diameter), and controlled by rack and pinion. In the 'B' stand the combined tube length could be varied from about 142 to 305 mm. It could be ordered as pictured with a continental foot, or for a slightly higher price with a tripod foot. The Van Heurck was apparently not yet considered the 'top of the line' instrument as No. 1 was the impressive 'Watson Swinging Substage Microscope,' No. 2 was the 'Scientist's,' and No 3. was the 'Research.'

VHB1896GVH-1896In 1896, stand 'A' was no longer listed, but the usual Van Heurck was still called the 'B', available with a continental or, as seen to the left, a tripod foot  Also in 1896, the 'Grand Model Van Heurck Microscope Stand' (right) was first listed in the catalog. At that time it was listed as identical to the B stand except for three new features: 1)concentric controls for the mechanical stage (after Terrell), 2)complete rotation of the stage, and 3)a slightly larger foot with the Grand, the spread of the foot 'more than ten inches'.

By 1898, the Edinburgh stand, which had been steadily improved, reached its final model in the 'H' but even the H continued to have small improvements added over the years.

VHCSThe 'Circuit Stage Van Heurck' was apparently first introduced about 1899 (as quoted in the Illustrated Annual of Microscopy for 1900). Like the Grand Model, it had complete rotation to the stage, but was otherwise identical to the smaller Van Heurck (now just called the Van Heurck without a letter or number), including the stage controls. Later on, the basic model simply became the 'No 1 Van Heurck'. 

Although listed in the Watson 1900 catalog, the Circuit Stage Van Heurck was not illustrated in that volume. The engraving to the left, from the 1902 catalog, illustrates the Circuit Stage Van Heurck with the optional Watson-Males two speed fine adjustment. It should be noted that from the start, the Terrell type stage could be ordered as an option for the Circuit Stage Model, thus some might look like a 'Grand' but would be distinguishable only by size.

To satisfy growing demand for a stand as perfect as the Van Heurck but slightly smaller and therefore less costly, the 'Royal' model was introduced about 1899-1900 as well. The major distinguishing feature between this and the No 1 Van Heurck, was the inability to rotate the mechanical stage (although some models with a rotating top plate are known); it was also of slightly smaller size than the Van Heurck, and initially was even slightly smaller than the Edinburgh H stand. In fact, it is a common misconception that the 'Royal' is generally a larger stand than the 'Edinburgh H' and this is not true. The tripod heights, arm/limb size, foot spread and stage are of identical size in many examples; what makes the 'Royal' appear larger is the larger diameter optical tube and drawtubes including the rack and pinion draw tube. Without these differences and the fact that some 'Royals' have a substage fine focus, the Edinburgh H and the 'Royal' could not be differentiated from one another. This is confirmed by the examples in my collection; the 'Royal' and Edinburgh are virtually identical in size and differ mainly in the diameter of main optical tube, the Royal's double draw tube, and fine focus for the substage.

The Van Heurck microscope was offered with many options, and some of these options were to leave off certain standard features for a discounted price. As noted above, it was eventually offered in three different models: the 'No. 1', the 'Circuit stage' and the 'Grand.' At any given time, the Grand was the largest. As noted above, the introduction of the Grand preceded the 'Circuit Stage' Model by about three years. These stands changed over the years and the 'Grand' Model from early years was more like the Circuit Stage model of later years, except for the size. Several features eventually distinguished the Van Heurk microscopes from the Edinburgh H and the 'Royal'. The first was a rotating mechanical stage (not to be confused with ability of the top plate of the stage to rotate, found on some other Watson stands as an option including some Edinburgh models), and the second was the double drawtubes, with the outer bottom one being adjustable by rack and pinion* .   Another feature found on these instruments (initially standard, later optional), was a fine focus for the substage, a feature found on relatively few microscopes at the time. Van Heurck himself preferred this to be controlled by a knob projecting vertically from the stage, as seen in the example at the top of this web page, but another option, quickly offered (and seen on the 'Royal' model in this collection), was to place the substage fine focus under the stage projecting horizontally, just above the coarse substage focus control. This below-the-stage version was apparently devised to satisfy some critics who complained that the vertical control interfered with stage access, but it was also slightly less expensive than the vertically projecting version.

Eventually many features and option of the Van Heurck were offered on the slightly smaller and less expensive Royal model. The one feature that was never offered on the ' 'Royal' ' was the rotating mechanical stage (although some models may have a rotating top plate, the entire stage does not rotate as a unit as in the Van Heurck models).  Although the 'Royal' was almost otherwise the equal of the Van Heurck, it should not be referred to as a ' 'Royal' Van Heurck' as Watson clearly distinguished it from all the Van Heurck models and never claimed it was a Van Heurk (see the discussion of this issue on the Royal Web Page.   In fact, Watson stated in their catalog that they produced the 'Royal' because of so many requests to modify the Edinburgh stand to include the features of the Van Heurck such as rack and pinion drawtube and fine focus to the substage. So in fact, the 'Royal' , like the Van Heurck was a derivative of the Edinburgh, but the 'Royal' started as an Edinburgh, not as a Van Heurck. It would, in fact be more appropriate to call it a ' Royal Edinburgh' as it is about the same size as the Edinburgh H, differing mainly in the diameter of the main optical tube and its double draw tubes. For a direct comparison of the Edinburgh H and the Royal, see the Royal and Edinburgh comparison Web page on this site.

The Van Heurck was a work in progress and was continually improved and changed over the years. Early on, the main outer optical tube was as small in diameter as others but it was gradually enlarged to accommodate photography, initially one inch, then one and a half inches in diameter and later, this became two inches in diameter; this increase in tube diameter was also seen on the later versions of the 'Royal' microscope. The size of the foot changed many times over the years as well. The condenser housing on the model shown on this page could be swung out of the optical axis, but that feature was a change from earlier, not only to the Van Heurk models but also to the 'Royal' and the Edinburgh too. Initially the mirror was on a swinging support, as is seen in the Grand on this website, but this was abandoned in later models.

As more improvements were made, many were offered as options. It is a common misconception that the 'Grand' Model had more features by nature, but in reality, as time went on, all the Van Heurk microscopes had almost all the same optional features, except as noted below. These option included calibrated verniers for the stage X and Y motions, graduated rotation to the stage, rack and pinion stage rotation, adjustable centering of the stage, locking for the stage centering position, and rotation to the substage.  A two speed Males-Watson fine focus was eventually an option on the Van Heurck with separate adjustment wheels for each speed; this option could be ordered on most other Watson microscopes at that time; see the Holos Fram, for example.   Another option was the location of the substage fine focus as noted above; eventually the very presence of the substage fine focus was an option.

The main permanent differences between the three models of Van Heurcks were the ability to fully rotate the stage on the Circuit stage and Grand Models (but not on the the No. 1 where the stage could rotate, but not 360 degrees), the concentric mechanical stage controls for the Grand (but also available as an option for the Circuit Stage Model, starting in 1900), and the size of each stand, the Grand being the largest, the No 1. and the Circuit stage being smaller.   Because of all the possible combinations of options, and also because their size changed over the years, few Van Heurck Models are exactly alike. A chronology of these developments follows, and a comparison of some of the features of these microscopes is noted in the table below.


*-It becomes even more confusing, because eventually, even the rack and pinion adjustment for the drawtube could be ordered as an option on 'lower class' microscopes such as the Edinburgh stand.


The following table lists options (including optional deletions) for the Edinburgh, Royal and Van Heurck Models. It may be incomplete, as the author has not had access to every single Watson catalog relevant to the period.

1893 Horseshoe foot, single draw,
Mechanical Stage with separate controls for horizontal and vertical motion which rotates but not a full 360 degrees,  Substage Fine Adjustment, Projecting upwards in back of stage, clamping lever for inclination Joint.  The mechanical draw-tube length can  vary from 160 to 260 mm. 
Tripod foot, Binocular Body,  Centering Screws to stage with clamping, Rackwork rotation to stage, Divisions to stage, Divisions to Horizontal and Vertical movements of stage, Rackwork rotation to sub-stage,  Clamping of substage centering,
1896 The 'A' Stand is no longer offered in the catalog
1893 Double Draw, with one Mechanical Draw tube, otherwise same as 'A'  but with the extra draw-tube , the mechanical tube length has a longer range of from 142 to 310 mm. Tripod Foot, Binocular Body
1896 Tripod Foot now standard, otherwise same as 1893 same as 1893, except now the Horseshoe foot was optional
1900 Same as Van Heurck B of 1896 Same as 1896  with additional option of Strnger's fine adjustment
1902 same Same but also the Males-Watson fine adjustment and the Spindle head fine adjustment AND hinged substage which can be turned aside out of the optical axis
1906 same same
1912 same except now the substage fine adjustment is an option Choice of above or below stage substage fine adjustment
1918 same except now all Van Heurcks have hinged substage standard, which allows the substage to be turned aside  and out of the optical axis same as 1912
1921 same as 1912, but now the substage bar extension sliding on dovetail to allow greater range of accessories of different heights as was previously only offered for the Grand, then the Circuit stage, is now offered for all Van Heurcks 
1900 Identical to No. 1 but with complete stage rotation Identical to No. 1
1906 Same as 1900 Same as 1900
1912 same except now the substage fine adjustment is an option Choice of above or below stage control of substage fine adjustment
1918 same except now all Van Heurcks have hinged substage standard, which allows the substage to be turned aside  and out of the optical axis same as 1912, but now the substage bar extension sliding on dovetail to allow greater range of accessories of different heights as was previously only offered for the Grand 
1921 same as 1918 same as 1918
1923 ---- ----
1896 Identical to the Van Heurck 'B' Stand, with the addition of concentric controls for the mechanical stage, and extension of the stage and arm forward to allow complete stage rotation and larger overall size. Identical to Van Heurck 'B' model.
1900 Identical to Circuit stage Model, but larger Identical to Circuit stage model but optionally the same stage as the No. 1 instead of fully rotating, reduced the price by 3 pounds. 
1902 Identical to Circuit stage Model, but larger Identical to Circuit stage model but optionally the same stage as the No. 1 instead of concentric controls, reduced the price by 3 pounds.   Also option of Stringer's fine adjustment, or Males-Watson Two speed fine adjustment, or Spindle Milled-head fine adjustment, all at extra cost.
Optional hinged  substage so it can be swung out of the optical axis.  
Also a substage bar extension sliding on dovetail to allow greater range of accessories of different heights.
1906 Identical to 1902 Same as 1902 but also offered the Scop Mechanical Stage instead of the usual circuit stage, price the same as the standard model.
1912 same same as 1906
1918 same except now all Van Heurcks have hinged substage standard, which allows the substage to be turned aside  and out of the optical axis
1921 Same Side Limb or Horizontal fine adjustment for same price.

The author would like to thank Drs. Joe Zeligs and Allan Wissner for help, references and advice pertaining to some of the historical information on this page.