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Hartnack & Prazmowsky (Bezu & Haussier Suc.rs) model IIIA , Paris 1885-1896

Hartnack & Prazmowsky, model IIIA (Pairs). The turret holds a Hartnack no.4 and a Watson 1 inch objective. In front of the microscope are the Hartnack no. 3 and no. 6 objectives.


This microscope has been built by the Paris branch of the Hartnack & Prazmowsky firm. The signature bears the additional names Bezu & Haussier. They were working in the Paris branch and took up the factory after the death of Prazmowsky in 1885, up to 1896, when the Paris branch was acquired by Nachet. This allows a firm dating of the microscope between 1885 and 1896.

The instrument is a model III A, introduced by Hartnack in the 1870's and one of the most popular at those times. It is used in the book "Practical Histology" published in 1881as an example of one the most suitable microscope for histological studies. It was sold in 1872 at the price of 220 Frs.

Excerpt from the book "Practical Histology", 1882 illustrating the Hartnack III A model


Excerpt from the 1872 Hartnack's catalog


My microscope came fitted with three oculars (no. 2, 3 and 4) and three objectives (no. 3, 4 and 6), plus an Abbe condenser with Iris diaphragm and a bullseye condenser for epi-illumination. Since I collect old microscopes not just to display them, but first of all to use them, I added to this already rich dotation a double rotating nosepiece signed by the prestigious British firm R&J Beck Ltd. (dating in the 1890's) and two Watson objectives of 1 inch and 1/6th inch focal length (equivalent to a 10X and 60X magnification power) of the same age, which I had as spares from other microscopes. The picture shows the microscope with the Hartnack no. 4 and the Watson 1 inch objectives mounted on the nosepiece. Upfront can be seen the Hartnack no. 3 and no. 6 objectives. The Abbe condenser and iris diaphragm are mounted on a pivot, allowing them to be rotated out of axis for microscope use with low magnification objectives. The Abbe condenser and iris diaphragm can be also removed from the substage holder, in order to fit different substage accessories, for example a polarizing prism (not included in this instrument). There is also a field diaphragm consisting on a rotating wheel with four different apertures, fixed under the stage. The double plano-concave mirror can be rotated around its axis and it is mounted on a swinging arm, allowing its inclination off-axis for oblique illumination.

The coarse focusing is made by moving up and down the optical tube, while the fine focusing is regulated by a micrometric screw on top of the pillar. Magnifications can be adjusted also thanks to a draw tube, that allows the use of objectives made for both the continental or the British mechanical tube length. The objective thread is a standard 0.7 inch. The stand is inclinable, allowing comfortable use. There was also the original wooden case.

The optics are superb, as expected from an Hartnack's instrument, as shown below with a modern slide of a section of rat cerebellum.


Rat cerebellum, t.s. showing the three main layers as seen with the Hartnack IIIA microscope, objective no. 4 and ocular no. 3.


Due to their excellent optical quality, Hartnack's microscopes soon were counted among the favorites by scholars and were widely diffused in the major Universities all over Europe. Among known users of Hartnack's optical instruments were:

- Charles Darwin. Darwin acquired in 1847 a "Large no.1" Smith&Beck compound microscope, probably the most advanced instrument of those times, for the fabulous sum of £36 (equivalent to several thousands today's pounds), to be used in the classification of barnacles. On March 1st 1874, being aware of the newly developed water immersion objectives by Hartnack, he wrote to Hartnack to order one those objectives, whose performance he later praised a lot in a letter to his son Francis.

- Louis Pasteur. He used a Hartnack microscope for his studies on the sickness of silkworms in the 1870's. Such an instrument is now on display at the London Science Museum.

- Sigmund Freud. Freud learned histology during his residence as a medical student at the Zoological Station in Trieste in the 1870's. Later, he published some important studies on the histology of nerve cells, cited by Cajal in his textbook of 1897. For his histological work, Freud used a Hartnack microscope.

- Robert Koch. Koch performed his studies on Anthrax with a Hartnack microscope, bought for him by his wife.

- Giulio Bizzozero. Bizzozero was a world-famous histologist from Pavia (Italy), friend of Camillo Golgi, who made seminal discoveries. For example, he was the first to understand the role of platelets in coagulation. For his microscopical studies on platelets, Bizzozero used a Hartnack microscope.

- Camillo Golgi. Golgi is, together with Ramon Cajal, the father of nuerohistology and of modern neurosciences. He discovered the "black reaction", a staining method that allowed for the first time the visualization of the network of the axons and dendrites of neurons in histological sections. Today, surviving microscopes used by Golgi can be seen in the Museum for the History of the University of Pavia and in the Golgi Museum at Corteno Golgi (BS), his birthplace in the Italian Alps. In Pavia two microscopes are on display, one from Hartnack and one from Zeiss. The Corteno Golgi collection has three microscopes, all by Hartnack. One, in particular is a model III A, identical to the one in my collection.


Hartnack model III A, owned by Camillo Golgi and on display in the Golgi Museum at Corteno Golgi (BS), Italy.


The main differences with respect to my model are the smaller mirror mounted on a different kind of swinging arm and the absence of the Abbe condenser and iris diaphragm. These small details are explained by the fact that Golgi's microscope has been manufactured by the Potsdam branch of Hartnack, while mine comes from the Paris branch.

Another original document showing the great popularity of the Hartnack model III A, comes from the report on the scientific discoveries of the British oceanographic expedition of the research ship H.M.S. Challenger. The Challenger's expedition (1872-1876), funded by the Royal Society, circumnavigated the globe dredging and sampling the oceans floor and life forms and measuring all sort of physical-chemical parameters. Basically, this scientific endeavor established the foundations of modern oceanography. A quotation from the book reads: "...a Hartnack microscope was alwayas at hand...".


Frontispiece and excerpt from pag. 3 of the scientific report of the Challenger expedition (1885), quoting the presence of a Hartnack microscope in the ship's laboratory.


In the book, there is an engraving reproducing the zoological laboratory, as shown below. Four microscopes are illustrated: a Beck "popular" binocular model (bottom right of the table) for low magnification observations, a dissection simple microscope (middle right), a small compound microscope, probably for dissection or nematode worms studies (top right) and a Hartnack III A (left side of the table), which was used for high magnification observations.


Illustration from the scientific report of the Challenger expedition, published in 1885, showing the microscopes used in the ship's laboratory. The Hartnack IIIA is clearly visible on the left side of the table.


Thus, this microscope model has been instrumental to many seminal scientific discoveries in the late XIX century.


Edmund Hartnack

Hartnack worked in Berlin in the precision mechanic shop of Hirschmann in Berlin and in 1847moved from Germany to Paris, joining his uncle Georges Oberhauser, a skilled optician. In 1860, Hartnack acquired the control of the firm and started producing microscopes signed "Hartnack, Paris". In 1864, he was joined by the mathematician and astronomer Adam Prazmowsky, changing the name of the firm into Hartnack&Prazmowsky. Their instruments were greatly appreciated for their excellent optical quality. In 1870, at the onset of the French-Prussian war, Hartnack moved to Potsdam, where he founded another branch of his business, leaving Prazmowsky in charge of the Paris factory. Thus, from 1870 to 1885 (the year of Prazmowsky's death), microscopes were produced signed "Hartnack & Prazmowsky, Paris" and "Hartnack & Prazmowsky, Potsdam". In 1885, the Paris production was continued by Bezu & Haussier, under the name "Hartnack & Prazmowsky, Bezu & Haussier & C.ie Su.rs". In 1896, the Paris branch was acquired by Nachet, while Hartnack continued his work in Potsdam. The firm Hartnack still existed after the death of the founder in 1891, well into the early XX century.

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