Watson Service Petrological Microscope – No. 53875 – circa 1933 

Offered for sale is a lovely collectable inter-war Service petrological microscope in lacquered brass finish by W. Watson & Sons Limited of London.  This example dates to 1933 based on the sequential Watson production number of 53875 which is engraved onto the main tube.  This inter-war example is in all-original condition as far as I can tell and has been well looked after by its former custodians, presenting a great opportunity to acquire a usable vintage petrological instrument that’s ideal for both thin-section mineral examination along with other polarised light microscopy applications.

The Service model was the mid-size model of Watson’s range of microscope offerings and the back-bone of its microscope range, first appearing in the Watson catalogue around 1919 and remaining in production right up until the mid 1960s – first as the Service (this example), then Service I Research and Service II Student’s model (these both had a more streamlined shape) and then finally the Watson Barnet Service.  So, this model essentially had quite a long production run of nearly 50 years – initially in brass like this example, them from from the late 1940s onwards in nickel/chrome finish.  This long production run giving us very firm evidence about how capable this model of microscope was in its heyday, so much so that this model often found its way into hospitals and educational establishments.  Being a specialist petrological variant of the Service model this example may have seen service with a number of geologists or petrologists at various times during its 92 year lifetime. 

This example also benefits from a good set of period Watson lenses and it’s also got brass-work such as thumb-wheels which are showing only minor signs of age-related tarnishing and the instrument has in general cleaned up really well.  The Service is essentially an excellent piece of British quality optical engineering showing its quality in every component, based on the right materials, solid construction and great design.  Feel the weight of it for one, despite being a mid-size vintage microscope it’s still quite heavy with all that steel and brass.  This is a sturdy good quality Service petrological microscope in excellent original condition, fully working, with no real signs of wear and not much in the way of chipping to the painted surfaces.  It’s got a great look and just the right signs of age for an inter-war example, making it a good proposition for a collector. 

In terms of construction, there’s a heavy Y-shaped iron foot, with twin uprights to a pivot, with tension adjustment and Lister-style upper limb also in iron. Both stage and sub-stage fittings attach directly to the limb tail-piece, giving a very stable well-engineered design.  Turning to the optics, this Watson is fitted with a chromed eyepiece draw-tube with graduation markings.  The main tube is in brass with coarse focus via rack and pinion with a nice smooth action, with the main tube holding in position throughout its working range as it should.  Fine focus is a vernier screw/cam arrangement which also moves smoothly with the right level of resistance to the touch.  This being a specialist petrological variant of the Service model, the main tube is fitted with a nicol prism analyser on an in/out slider as demonstrated.

The instrument is supplied with an appropriate vintage Watson specialist eyepiece with integral draw-tube that with good illumination produces sharp images:

– 6x magnification micrometer eyepiece with 0 to 100 scale

There are also some other eyepieces by other manufacturers supplied giving a good selection, as under:

– 7x wide-field by Lomo
– 10x wide-field by Meopta
– 10x 25mm by Beck

It’s also got two nice vintage brass objectives which look to be the originals and a Watson double turret which rotates freely with a positive feel as the objectives slot into viewing position as follows:

– 1 inch – Watson Parachromatic – 6x
– 1/4 inch – Watson Parachromatic – 25x

(the objective lenses have their correct Watson Bakelite storage canisters) 

Overall, the range of magnification provided by this Watson therefore runs from about 36x to around 250x with good illumination.  The polarising functionality is in good working order with polarisier and analyser providing extinction when crossed.  For testing purposes I was using thin-section mineral and chemical crystal slides.

The instrument tilts for inclined viewing, holding in position as it should and can be tightened at the pivot if necessary.  The stage is a specialist circular petrological variant that rotates with just the right resistance to the touch.  It’s also fitted with a 360 degree scale and a pair of original brass stage clips that are fine for holding a slide steady especially when using inclined viewing. 

Turning to the sub-stage, we have a specialist polarising sub-stage for rotation fitted with a nicol prism polariser with rotation and swing out capabilities.  Lighting is via a plano-concave mirror on an adjustable brass support arm and gimbal that slots into the under-side of the limb tail-piece, with good functional silvering to both sides. 

This is a really good visual and excellent working example of Watson’s specialist petrological variant of the Service model in highly original condition with nice period optics and it’s essentially very much a usable and collectable instrument, especially in view of the excellent cosmetics, period retro look and its gleaming brass-work.  There is also the correct storage case with this example, with internal lens rack, carry-handle and a working lock and key.  The case also has the Watson guarantee card giving the exact date of manufacture as 19th September 1933, which is nice to see and confirms the matching numbers status of this example, which is increasingly hard to find for period Watson instruments.

The microscope and case will be very well wrapped for shipping, including partial dismantling, individual wrapping and labeling of components and the stand will be fixed to its case with a transit bolt, just as Watson themselves would have done when they originally supplied this instrument back in 1933.

Thanks for looking.