Offered for sale we have a rare variant of the Edinburgh model microscope by W. Watson & Sons Limited of London.  It’s a specialist model, being the Metallurgical variant of Watson’s popular Edinburgh H model, designed specifically for incident light microscopy and the study of surface features on solid/opaque specimens such as metallic surfaces and the like.  This example dates to around 1917 based on the sequential Watson production number of 23322 which is engraved onto the rear tripod leg.  It appears to be in original condition as far as I can tell and has obviously been well used during its service life and looks to be an ex-works example.

 

 

In terms of condition the brass-work such as thumb-wheels are showing signs of age and heavy use-related tarnishing and although the instrument has had a light clean and lubrication, there’s no disguising the fact that this a well used example that’s seen years of service, most probably in a works or laboratory setting.  It actually works really well for different sepcimen types with ambient and incident illumination as shown in the listing photos, so please read on if you’re interested in this specialist and quite collectable antique instrument.

Overall, the range of magnification provided by this metallurgical Watson is therefore around 72x.  This will increase further if you extend the eyepiece draw-tube and you also have to re-focus – see below re how to do this for incident illumination – it’s slightly different to the norm!

 

The instrument tilts for inclined viewing, holding in position as it should and can be tightened at the main pivot as may be required.  The stage is a fully mechanical brass stage as found on the Edinburgh H model adapted for metallurgy.  It has a solid top plate that’s fitted with a couple of specialist sprung stage clips, which are able to accommodate samples of varying thicknesses and are fine for holding samples steady during viewing and inclination.  The stage has height adjustment via rack and pinion with single-sided thumb-wheel control on the left hand side.  The stage is therefore in theory able to accommodate samples of different thicknesses up to around 3 or 4cm, for inspection via incident illumination.

 

This being a metallurgical instrument, there’s no technical sub-stage.  There’s also no case with the instrument at present.

 

A shown in the listing photos I was examining the surface features of various items:

– solid brass casting approx 1cm in thickness – ambient light
– silicon chip set in a conventional slide – ambient light
– damaged bronze coin set into an aluminium plate – incident illumination using lamp

 

I was using different lighting techniques including ambient light which is usually fine for low power objectives and incident illumination using a desk lamp for example as shown.  It’s also usually possible to utilise a bull’s-eye type condenser for low power work.  

 

For higher magnification study of surfaces, it’s normal to use a vertical illuminator as fitted to this instrument.  When correctly set up this channels a beam of light from a suitable light source down through the objective lens – towards the end of the listing photos you can see me demonstrating how to use the vertical illuminator that’s supplied with this microscope.  I was using a Watson microscope lamp (6V Dalek type) powered by a Watson PSU and shining the focused beam of light into the aperture of the vertical illuminator.  Inside it’s got a reflector and when correctly adjusted, this beam is then reflected down through the objective, off the sample, back through the objective and onwards up to the eyepiece for inspection.  Once the light path is established with a vertical illuminator in place, it’s normal to use the stage height adjustment for control of coarse focus, so as not to disturb the established light path.  Fine focus can be used in the normal manner.   This type of incident illumination when correctly set up works really well and you should be able to see a bright spot of light on the object under examination.  

 

Note:  the Watson lamp and power supply unit are shown for testing purposes only to show the incident illumination functionality and capabilities of this instrument and are not part of this listing.

 

In summary, a very interesting and useful antique instrument for incident microscopy from quality makers W. Watson & Sons Ltd.

 

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