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Early Achromatic Chest Microscope, ~1800

 

This is an enigmatic and thus far unparalleled microscope. It features many 18th century characteristics, yet the optics point at a very early 19th century date.

This microscope is undoubtedly inspired by the English Nairne type Chest Microscope, a term referring to a Cuff-style compound microscope mounted to a mahogany box, or "chest". This form was introduced ca. 1760 by Thomas Nairne (worked: 1748-93) and became a staple instrument throughout Nairne's solo career and well into his partnership with Thomas Blunt (1774-93), his former apprentice.. It was quickly copied by most of the leading microscope makers both within Britain and in continental Europe. However, the form seen here, still showing many 18th century characteristics, depicts many improvements and it is by far more sophisticated than Nairne's original design. Also in terms of optical quality it suppresses Nairne's microscope and some other pre-achromatic models (i.e., the Culpeper type). 

The microscope seen here is housed in a solidly made oak chest with few inner compartments for the accessories. Five objectives and two peculiar lieberkuhn reflectors undoubtedly belong originally to the set. The brass forceps, two tiny unfitting stage stops and few other brass parts that came with it seem to be unoriginal additions. When opened, a dovetailed part of the sidewall can be removed in order to allow free movement of the single-sided plane mirror as the stand is erected. The  stand is fixed in the base of the box by a compass joint. The pillar rises or collapses into the chest, enabling convenient use of the microscope at any angle. Atop the pillar is another compass joint secured by two knurled knobs, allowing for the tilting of the optical tube forward and downward, suggesting that perhaps it was designed for a special inspection or aquarium purpose. While this feature is known from Benjamin Martin's Universal Microscope, it is unique amongst chest microscopes. The small stage can be rotated into position or out of the way when the stand is resting into the chest. It is double sided, one side is designed to take the archaic bone sliders, while the other was perhaps holding a plate for opaque specimens, or a wet cell for aquatic or botanical inspections. 

The most astonishing detail is revealed when the optics are examined. Today there are five objectives, having a unique and very small thread of merely 9 mm. in diameter. Three of the objectives are tiny button type, two are longer and contain doublets, presumably of an early achromatic type. Two Lieberkühns are included, one (for the lower magnifications) can be screwed to a special thread around the objective base (similarly to Delebarre's microscope), the other, for the higher magnifications, can be slid along the objective's tube. When the eyepiece sliding cover unit, a typical 18th century feature, is screwed out, the field of view becomes very wide and the optical quality is impressive.

© Microscope History all rights reserved

© Microscope History all rights reserved

The big question about this mysterious microscope relates to the identity of the maker and the date of production. So far, we neither found a similar instrument in any of the collection catalogues, nor in auction or private collection records. If indeed it is an achromatic microscope, it must be placed at a very early phase of the 19th century. This issue is still under investigation and updates will follow.

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