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Early Achromatic Microscopes by Charles Louis Chevalier, 1804-1859

A complete and exhaustive historical overview of the Chevalier dynasty and the microscopes they produced appears on Brian Stevenson's website. Louis Vincent Chevalier was the pioneer of the achromatic microscope. Starting with the first “Selligue”-type microscope released around 1824, Chevalier developed a series of achromatic microscopes two of which are represented in this collection. In his review before the Royal Society in 1830, Joseph Jackson Lister noted that Chevalier of Paris having manufactured some of these instruments, appears to have observed the great error in the position of Selligue's glasses; he retained their construction, but turned their plane sides foremost; and making them of shorter focal length and more correctly achromatic, produced in 1825 a microscope far superior to the former. His deepest glasses are not more than 0.4 inches in focal length, and two of these were united in his earlier instruments for his highest power; but this was the only combination retained in them, and all his glasses were restricted to apertures too small to show difficult test objects. However, during the 1930s the Chevalier family had already produced highly advanced microscopes that gradually contributed to improvements made to the structure and focusing techniques resulting from the increase in resolution and magnification of the instruments.

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Seligue - Chevalier early achromatic experimental microscope, ~1820

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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.

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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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Analyses of the optical system

The early achromatic chest microscope came with an assemblage of objectives and other components of optical parts. Two objectives (A, B, seen above with their inner parts dismantled) were achromatic, another three (C, D, E) were non-achromatic. The role of the other brass components is unclear. The two achromatic objectives contain each a small cylindrical tube, each one of which contains one doublet (see below). In objective A the cylinder slides freely into the tube while in objective B it screws into the end of it. Four discoidal lenses fitting the internal diameters of the tubes were found, two were still inserted into objective A. It was unclear whether each two of the lenses were originally inserted into each objective, or whether all four of them originally came from one of them. All four lenses bear a film of some sticky matter on one side, now blackened with dirt. Therefore, they may have been glued to each other in the past in pairs by some optical resin and inserted into the objectives.

The two composite objectives were dismantled and their internal brass cylinders containing the assumed doublets, as well as the four free lenses, were taken out. The internal lenses within the brass cylinders were held in place by brass circlips (photo below), and it was decided to open only the one from objective B. It contains two lenses, dry-set together, one is double convex and the other is a double-concave cylinder. No glue or balsam was holding these lenses together.

The results of the chemical analysis of the lenses are provided in the table below. The "Balance" is the concentration of the light elements of atomic number 1-11, which the portable XRF is incapable of identifying. The ± sign refers to the limits of detection for each element.

Physical and chemical analyses of the lenses

The optical components were subjected to scientific analyses in the Laboratory for Microarchaeology at the Ben Gurion University of the Negev, Israel. Non-intrusive elemental analysis of the lenses was carried-out using a Niton™ XL3t GOLDD+ XRF Analyzer set to the "Mining" calibration, providing a list of elements from Mg to U. Screening was made for 30 seconds per "filter", summing up in 120 seconds for each analysis. The data was set to be displayed in weight percent. These tests were aimed at providing some preliminary information about the optical system, first and foremost to clarify if it is indeed made of achromatic doublets and if so, try to reconstruct its general setting.

The lenses were photographed under a Zeiss Stemi-2000 stereomicroscope equipped with upper LED ring illumination. 

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© Microscope History all rights reserved

© Microscope History all rights reserved

Molecular study of the coating on the lenses

The resin remains were attempted to be analyzed using a Rikagu™ Progeny ResQ 1064nm handheld Raman spectrometer. The aim of this study was to reveal the composition of the matter remains coating lenses 1-4.

The Raman indicated that the four lenses were coated by turpentine made from tree resin. It indicates that the lenses were glued (presumably in couples) by an optical-quality mounting resin. 

The elemental concentrations of the lenses indicate that while the double-convex lens of the doublet in objective B is made of high silica-lime "crown glass", the double concave cylindrical "negative" lens attached to it was made high lead-alkaline + silica "flint glass". This clearly testifies to an achromatic doublet of an early and very simple type. The four free lenses bearing the resin/balsam remains were all found to be of a more or less similar composition, all being made of crown glass but with somewhat lower contents of calcium (Ca) as compared with the "positive" lens from the doublet.

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Microscope achromatique “Selon Euler perfectionné" by Charles Chevalier, 1833-5


Achromatic microscope by Charles Louis Chevalier (1804-1859), between 1832 and 1851, was the period he occupied the address which is engraved on the microscope. Many features in it indicate a very early date of this sequence. It is signed "Microscope achromatique / Perfectionné par / Charles Chevalier / Ingénieur Opticien Breveté / 163 Palais-Royal / à Paris". The total height is between 45 and 55 cm. The optical tube, complete with its flat-shaped plug and simple pull, consists of an eyepiece with two plano-convex lenses (180 and 260 mm) measuring 600 mm in height and a lens formed by two doublets. The tube is screwed on a reclining rectangular angled arm on which the stage is mounted (adjustable by a rack whose wheel is of ivory as in the early production of Chevalier) and a large concave mirror (perhaps renewed). Finally, everything is attached to a cylindrical column with a folding tripod foot. The illumination prism that appeared in the first form of Selligue-type achromatic microscopes is here replaced by a simple bull's eye lens held by a ring to the objective. Also present, on the plate, are two clamps to hold the preparations of transparent objects and, under the plate, the variable diaphragm type The Baillif. This early model of a secondary form, post-Selligue, was called "perfected" achromatic microscope by the best French manufacturer of microscopy of the first half of the nineteenth century, Charles Chevalier. It probably dates to around 1833-5.

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Charles Louis Chevalier (born Paris, Apr 19th 1804, died Paris, Nov 2th 1859) was an optician and instrument maker. He was son of the optician Vincent Jacques Louis Chevalier who himself was son of an optician, Louis Vincent Chevalier who had founded the family's company in Paris in 1765. The company of Vincent and Charles Chevalier was famous for the achromatic lenses which were invented by father Vincent, and the lens/prism optics they both had invented for camera obscuras. In 1825, the cousin of Nicéphore Niépce came to the Chevaliers to buy achromatic lenses for his experimental cameras. He told the Chevaliers about his cousin's first efforts to achieve persisting photographs. That was when Louis Jacques Mandé Daguerre just got interested in similar experiments. Later Chevalier gave him the address of Niépce, the first step for Daguerre to become a photography inventor himself. In 1832 Charles founded his own company.

Chevalier was one of the first to use multiple lenses screwed together to achieve higher magnifying power, but chromatic aberration, which had plagued the users of microscopes since their beginnings, was still a problem with the lens combination. In 1830 Chevalier, with the help of another French microscope maker, M. Selligue, started to make horizontal microscopes, after a design shown to him in 1827 by Giovanni Amici, an Italian instrument maker. Charles Chevalier first worked in partnership with his father Vincent, eventually inheriting the shop and becoming well known for the construction of horizontal microscopes. They did not fully solve the problem of chromatic aberration. (Sources: golub collectioncamerapedia)

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References: MHS 51388

Charles Chevalier, "Petit Modèle “Achromatique Universel” microscope, ca. 1834

Charles Chevalier’s small model of the Universal Achromatic microscope, as illustrated in plate 3 of “Des Microscopes” (see Figure below). Charles’s son, Arthur, wrote that this model was invented in 1830, and won a Gold Medal for Charles at the 1834 Exposition des Produits de l’Industrie.

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In 1834, Charles Chevalier presented his 'universal microscope' that could be arranged as a vertical, horizontal, and inverted (chemical) microscope. Its high price, however, was subject to criticism.
The present microscope demonstrates that Chevalier considered this criticism and developed a smaller and cheaper model, based on his existing small 'simple and compound model'. He kept the tube, stage, mirror, and optics, but added a second column, as well as two joints and a prism. Ironically, the resulting small universal model could be transformed into a simple microscope as well, contrary to the original and much more expensive large model.
In comparison to this very early unsigned example, later production models were one-third larger in size, had a drawtube, a double-sided mirror, a stage that could be inverted, and removable nosepieces.

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James Ransome (1782 – 1849)

The microscope box bears a brass plate with stylized writing engraved with the name James Ransome. This plate identifies the original owner of the microscope with James Ransome (1782 - 1849), a manufacturer of agricultural equipment and components of railroads. On the coming of railways, the Ransomes became the largest manufacturers of railway chairs, a patent being obtained for casting them. A patent was also taken out for compressed wood keys and treenails for securing the chairs and rails, and many millions of these were produced.

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