Camille Sebastien Nachet.
1799 - 1881.
by Roland Mortimer, Brazil
Microscopy is something we all have in common and enjoy. So much has been written about what we can see, so let's turn our minds to the one thing we all take for granted, our instruments, for without them the pleasure would be absolutely lost. The range and great diversity of instruments we all have is amazing to say the least. I'd like to show you a few of the microscopes I have by a probably not so well known manufacturer who began making his microscopes in a small workshop based at ; 16, rue Serpente, Paris in 1839.
The first is a small, all brass model he calls his modéle pétit, which means small model, probably sold as a student model or even as an expensive toy. The main tube is pushed/pulled up/down for coarse focus and fine focus is achieved by the knurled micrometer screw at the lower rear of the pillar. The 'button' objective is simply a single lens, which gives a maximum power of 250 diameters with the No. 2 eye-piece. There is a perforated brass wheel below the stage with various sizes of hole acting as a simple form of iris. This instrument dates from between 1856 - 1862.
Nachet moved his business to 17, rue St. Séverin, Paris in 1862. In 1851 Nachet was awarded a gold medal at the Great Exhibition for the quality of the workmanship of his instruments. Among his numerous inventions he is credited with splitting the rays in a binocular microsocope so as to produce a stereoscopic image.
The second instrument is a little more complicated. Nachet calls this his No.2 Grand model. As you can see it's all brass, mounted on Roman pillar-like trunnions. Coarse focus is obtained via rack and pinion (the teeth are almost horizontal) by turning the single knurled knob. Fine focus is obtained via the knurled knob situated at the top of the pillar which supports the tube. This is a single spring system, the spring is compressed as the screw is turned clock-wise thus forcing the pillar to move slowly down the brass prismatic column inside the pillar, when the screw is released the spring forces the pillar in an upward direction.
The stage has a simple X/Y mechanical stage operated by the two wheels mounted on either side of the stage. There is an ungraduated draw- tube to adjust tube length. The mirror is attached to a gimble which allows the same to be placed in almost any position for various illumination effects. The condenser is simply a lens in carrier which is a push fit into the condenser tube. The microscope dates from ca. 1875. The address inscribed on the rear of the base is; Nachet, 17, Rue St. Séverin, Paris.
The third instrument is what Nachet calls his Large Perfected Model and probably dates from around 1880. This instrument is very similar to the Grand model with the following differences; the mechanical stage has a round, black, glass plate surrounding the aperture in the stage. The front edge of the stage is graduated and in the centre of the stage base there is a graduated rule. The condenser is simple but much improved from the former models, and there is also an iris diaphragm which swings in/out of centre. The whole is placed on a small dovetail piece, and is raised/lowered by a unique lever system. The double mirror can be removed and replaced by unscrewing the brass cover ring and is mounted on an articulated gimble to give the various illumination effects. I believe this model to be from around 1880 because it does not have the "modern" innovations of the 1890 model, i.e. graduated main tube, improved condenser/iris with stops and adjusting coaxial screw system.
The fourth and last microsocpe I have by Nachet is a small folding model from ca. 1910. This model is all brass, but is lacquered black according to the style of the period. The arms of the base are in the form of elongated "S" shapes and fold together. The stage revolves and folds through 180 degrees and can be locked in position by a simple handle. The condenser and iris are raised/lowered by a screw action with pin stops to guarantee centre position. The double mirror is mounted on a simple swinging arm to enable it to be folded, when packing the instrument. The draw tube is graduated, and coarse focussing is achieved by rack and pinion, fine focussing by the knurled wheel mounted on top of the pillar. The instrument is signed A. Nachet, Paris on the main tube. The whole instrument folds very neatly into a very small volume for travelling or packing.
Any comments, criticisms or additional information concerning the above manufacturer would be gratefully welcomed.
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