Description

Watson Bactil – circa 1930 Wide-body Model in Lacquered Brass with Matching Numbers and Nicol Prism Accessories

This listing is for a superbly engineered vintage original Bactil model microscope in lacquered brass finish by W. Watson & Sons Limited of London.  It dates to 1930 based on the sequential Watson production number of 46144, which is engraved onto the main optical tube and comes complete with matching numbers storage case.  

This inter-war example is in all-original condition as far as I can tell and has clearly been pretty well looked after by its former custodians. This Bactil also benefits from a good set of lenses, nicol prism polariser and analyser, an original brass mechanical over-stage and a nice period storage case.  It presents really well with some age-related dullness/oxidation to its black paintwork here and there, but very few other age-related blemishes anywhere on the instrument and probably most importantly, lovely gleaming brass-work detailing throughout.  The brass-work really catches the sun and glints with a lovely warm yellow/golden glow as I hope the listing photos demonstrate.  

The Bactil is essentially an excellent piece of British optical engineering built from quality materials, with solid construction, great design and skilled workmanship and in this period many hours of hand-finishing and it’s hard to believe that it’s actually 96 years old, so almost an antique. This is a sturdy good quality microscope in original condition, fully working, with no significant signs of wear that I can find, so it’s got a great look and patina and a nice brass example from 1930.  

On the technical side, the construction is a heavy iron foot, with twin uprights, pivot with lever-operated tension adjustment and Lister-type upper limb also in iron.  Both coarse and fine focus move freely through their working ranges with little wear evident.  There’s a good range of coarse focus movement and I’ve been using the instrument with a low-power 2 inch objective with very high working distance, being able to achieve sharp focus.

Turning to the optics, this Watson Bactil microscope comes fitted with a narrow diameter graduated brass eyepiece draw-tube inside an optical tube in brass, which accentuates the wide-body look to the brass main optical tube.  There’s a selection of appropriate vintage eyepieces that with good illumination produce excellent images:

– 6x magnification
– 7.5x magnification by C. Baker – with internal cross-hair graticule (would benefit from internal clean)
– 10x 25mm magnification by R & J Beck

There are three vintage objectives along with a triple brass turret, which rotates freely with a positive feel as the objectives slot into position.  The objectives are as follows:

– 2 inches by Swift 3x magnification – very low power and high working distance
– 16mm Apochromatic by R & J Beck -10x magnification
– 1/6th inch Parachromatic by Watson – 40x magnification 
(All objectives have appropriate period canisters)

Overall, the range of magnification provided by this Watson Bactil therefore ranges from about 18x to a perfectly respectable 400x.

A nicol prism analyser is currently fitted to the eyepiece draw-tube, which has an RMS threaded end for this very purpose.  Note:  with the analyser fitted the draw tube doesn’t fully retract.

The stage is a standard Watson factory-fitted ebonite item with metal core stage.  It’s fitted with a Watson mechanical over-stage that attaches via two slender bolts that fit through the holes where stage clips normally locate.  The over-stage has twin x/y thumb-wheel adjusters to the right-hand side and two clips for holding slides with one of them sprung and this system operates well for retaining slides during inclined viewing, with x/y controls also offering fine control of specimen positioning, which is useful for higher magnification work.  The y-axis also holds position well on inclination.  

Turning to the sub-stage, we have a specialist model of Watson condenser that’s top-mounted to a brass ring-mount, which in turn sits in a height adjustable rack and pinion system with single-sided height control and there’s also centering via a pair of brass thumb-screws.  The condenser lens is an unusual RMS example that’s marked as under:

– Parachromatic 2/7 in 1.0NA, Less Front Lens 4/10 in 0.35NA

There’s also a graduated iris and a 20mm diameter swing-out filter carrier that comes with a set of dark-field and oblique stops and selenites or other filters can also be fitted here.  The condenser has plenty of vertical height adjustment and adequate reach for oiling to the back of slides for higher magnification applications.  This is quite unusual with an over-stage fitted and testament to the robust technical design and know-how behind this model of Watson microscope.  

To the underside of the condenser mount is currently fitted a nicol prism polariser with 360 degree rotation.  The nicol prisms achieve extinction when crossed and are perfect for polarised light applications such as thin section mineral and chemical crystal slides.  For testing I was using thin section mineral slides as shown in the listing photos.  Both polariser and analyser can be removed easily for standard brightfield applications.

Lighting is via a plano-concave mirror which is in very good condition on its adjustable brass support rod and gimbal set-up, with excellent silvering to both sides.

This is a great visual and working example of Watson’s Bactil model in brass with excellent originality along with very useful quality polrised light capabilities, making it quite an interesting proposition for a collector.  It’s in highly original unmolested condition with a good specification, nice optics and it’s essentially a collectable brass example.  

There’s also the correct original wooden case with internal storage racking and working lock and key, which is also in decent condition and it’s interesting to note that the original Watson guarantee card is attached to the inside of the case door, which confirms that the date of manufacture was 8th October 1930.

Owing to the weight and delicacy of the microscope and case, it will be partially dismantled, very well wrapped for shipping and dispatched by insured courier upon receipt of cleared funds.  

Thanks for looking.