Description

Offered for sale is a Thos. Armstrong & Bro of Manchester brass microscope serial no. 665

Background to Thos Armstrong

In 1825, Joseph Armstrong started a business as jeweller and silversmith at 261 Deansgate, Manchester. After Joseph died in 1851, his elder son Thomas continued managing the business, which was expanded to manufacture spectacles and optical instruments. In 1868, Thomas took his brother George in partnership and the firm was renamed as Thomas Armstrong & Brother. The company grew considerably between 1877 and 1891, employing 15 people including Thomas and George’s younger brother Alfred. Around 1887, the company acquired additional premises on St Mary Street. Towards the end of the 1890s, Thomas’s son, Frank Armstrong, also started working in the company, which expanded further into Liverpool in 1904 with the opening of a branch at 112 Bold Street. In the meantime, the company’s headquarters in Manchester moved to larger premises at 78 Deansgate. In 1920, the company was sold to Leonard Douglas Kidson, of 1 Booth Street, Manchester, but Frank Armstrong continued with the company for a further 10 years. In 1965, the company was taken over by Harrisons Opticians, which, in 1968, was taken over by Dollond & Aitchison, which itself was absorbed into Boots Opticians in 2009.

This listing is for a fine original condition example of an Armstrong microscope in anodised and lacquered brass – it dates to around 1910 based on its serial number 665.  It’s got virtually no signs of use/wear that I can find anywhere on the instrument, with almost factory-fresh lacquer finishes, which is amazing given the instrument’s age. 

The construction of this example is an anodised brass tripod, with lacquered brass feet, that’s reminiscent in terms of design to Watson’s Edinburgh range of microscopes, yet this Armstrong is slightly smaller in scale.  The tripod in turn supports a pivot to which is attached the brass stage and a continental-style column with upper limb and rack & pinion coarse focus.

Turning to the technical details, the coarse focus rack and pinion has a good smooth action throughout its working range and holds in position on adjustment.  Fine focus is operated via a separate brass thumb-wheel located at the rear of the upper limb which moves the limb and also has a smooth action.  The fine focus adjustment is graduated with each division = 1/500^th of an inch of fine focus travel

With the optics, this microscope comes fitted with a period graduated brass eyepiece draw-tube inside a brass main optical tube and there’s a vintage 6x magnification eyepiece that with adequate illumination produces good age-appropriate images. 

There are three period objectives in total all by Armstrong in their correct brass canisters and a double brass turret, which rotates freely.  The objectives are as follows:

– 1.5 inches – 4x magnification
– 2/3rds inch – 10x magnification
– 1/6th inch – 40x magnification

Overall therefore, the range of magnification available ranges from about 24x with the lowest power lens combination, up to around 240x with the highest power combination.

The specimen stage is brass with what looks like an ebonite top surface layer that’s currently with a pair of slide clips for holding specimens, which work well.

Turning to the sub-stage, we have a plug-in condensing lens in a brass friction-fit mount that’s standard 39mm diameter.  This sits in a height adjustable rack and pinion carrier system with single-sided brass thumb-wheel to adjust the height, along with a swing-out feature allowing easy swapping or maintenance of the condenser hardware.  Lighting is via a plano-concave mirror in a brass mount that’s on a height-adjustable brass support arm with slider and gimbal, with period silvering that’s in perfect condition to both sides.

The instrument’s controls and friction surfaces have been very lightly lubricated and operate smoothly with a nice feel and there’s very little in the way of age-related signs of wear to the various moving parts.  This instrument presents exceptionally well with brass-work that really catches the light superbly.  This example is essentially a very usable antique instrument that will also make a great display item in a library or home office setting, especially when set up with an antique slide. 

There’s an original storage case with this example with internal fittings, carry handle and lock, with additional cupboard latch.

Accessories:
– live box
– bull’s-eye desk-top condensing lens for illumination of opaque specimens
– polarising hardware comprising sub-stage rotatable polariser and nosepiece analyser – note that the analyser can be fitted to the end of the brass eyepiece draw-tube which has female RMS thread

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