Description

Offered for sale is a well engineered desk-top model microscope in anodised & lacquered brass finish by Negretti & Zambra of London.  It dates to around the 1900 to 1910 period.  This Edwardian example is in all-original condition as far as I can tell and has clearly been pretty well looked after by its former custodians. Despite its compact dimensions, it’s packed with technical features, some of which are normally only found on larger more expensive models of microscope, making this an attractive proposition for a collector.  

Background to Negretti & Zambra – source Microscope Museum

Negretti & Zambra were founded in 1850 by Enrico (Henry) Negretti (1818–1879) and Joseph Zambra (1822–1897) trading until the late 20th century. The firm produced scientific and optical instruments and also operated a photographic studio in London. They were appointed opticians and scientific instrument makers to Her Majesty Queen Victoria, Prince Albert, King Edward VII, the Royal Observatory and the British Admiralty.  In 1859 the firm produced a large catalogue containing more than 2,000 items and instruments, including microscopes.  The firm’s 1908 catalogue included various types of instruments, including binoculars and microscopes. During 1914 – 1918 the company supplied the Ministry of Munitions and developed various innovations including early aviation instruments. In 1947 the firm was listed as manufacturers of industrial, aeronautical and meteorological instruments. In 1948 they become a Limited Company, being acquired by Meggitt Holdings in the 1980s.

On the technical side, the construction is an anodised tripod foot, with twin uprights, pivot with tension adjustment available and a continental-style pillar upper limb also in anodised brass finish.  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 1 inch objective with fairly high working distance, being able to achieve sharp focus.

Turning to the optics, this microscope comes fitted with a brass optical tube slider that fits inside the outer anodised tube, giving about 1 inch manual adjustment.  There’s further coarse adjustment via a conventional rack & pinion system with diagonally-cut rack giving in excess of another inch of coarse focus travel.  Fine focus adjustment is via a single thumb-wheel atop the continental-style pillar also with smooth action.  

There’s a single eyepiece that with good illumination produce excellent images – approx 6x magnification top-hat style

There are two vintage objectives along with a double brass turret by Beck, which rotates freely with a positive feel.  The objectives are as follows:

– 2/3rds inch para inch by Watson -10x magnification
– 1/6th inch para by Watson – 40x magnification 

Overall, the range of magnification provided ranges from about 60x to a perfectly respectable 240x.

The brass stage is a very interesting circular design with the following features:

– Integral wheel-of-stops with 4 apertures available.
– Ebonite (or similar) top layer.
– Mechanical over-stage that attaches via two slender thumb-screws.  The over-stage has exposed rackwork with concentric x/y thumb-wheel adjusters to the right-hand side, so it’s a variant of the Turrell design of mechanical stage that’s usually found on much larger (and more expensive) instruments.  There’s a brass carrier for holding slides with two sprung clips and this system works well for retaining slides during inclined viewing, with x/y controls also offering good control of specimen positioning, which is a useful feature to have on a compact instrument.  The y-axis also holds position well on inclination.  

Turning to the sub-stage, we have an Abbe-type condenser in 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.  

Lighting is via a plano-concave mirror on a slider and gimbal set-up on the limb tail-piece with excellent silvering to both sides.

This is a great visual and nice working example of a compact desk-top model in brass with excellent originality along with very useful features normally found on larger models, 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 no storage case with this example.

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

Thanks for looking.