Compound microscope by Hartnack, 1876/77
Signed: E.Hartnack Paris & Potsdam
Case: 28 x 14 x 10,5 cm
This is a stand VIII microscope by Eduard Hartnack Potsdam (or Paris?) of 1876/77. The instrument is made entirely out of lacquered brass and is the smallest horse-shoe base offered by Hartnack. Raw adjustment is via sliding-tube, the fine focus is achieved via a prism-adjustment in the column. The table is equipped with a hard-rubber layer.
The horse-shoe base is protected by a fine leather-layer in order to avoid damage of the microscope and table and vice-versa.
The mahogany case has a lid padded with velvet silk and a small compartment for slides and cover glasses. The brand-mark in the case shows the serial number 17278.
The pull-out-tube has the standard-length of 160mm introduced by this workshop in Paris as it was still run by Oberhäuser. Illumination is achieved with a concave-mirror and a cylindrical aperture-stop with three different inserts. This cylinder may be pulled out on a dovetail slide to the side in order to enable changing the aperture without moving the object to be examined and without changing the position of the mirror.
The objectives and aperture-stops are housed in a small leather-covered box with the serial-number burned inside as well. The optical equipment consists of the objectives No.3, No.5 and No.7 and two eyepieces No.2 and No.3. The microscope allows a magnification up to 300 linear with eyepiece No.3 and objective No.7.
This microscope-stand was offered already in the early 1860ies and was equipped with the hard-rubber-plate for the table in the early 1870ies. This stand VIII was modified with a condenser-system and offered as stand IV in the early 1890ies.
Compared with this description the microscope is complete (missing only the 12 slides and 12 cover-glasses as well as the tweezers and scalpel) and has an additional eyepiece.
E. Hartnack (1826-1891) was one of the most respected makers of his times. He joined the firm of his uncle, Georges Oberhaeuser (1798-1868), in Paris in 1857, and assumed full control of the firm in 1860. He moved to Potsdam, Germany, in 1870, as a result of the Franco-Prussian war and left his partner, A. Prazmowski, in Paris. The Parisian branch of the business was eventually taken over by Nachet et Fils. Hartnack continued the manufacture of microscopes with the same skill and innovation that made his uncle famous. He is credited with the first use of water-immersion lenses in the commercial production of microscopes and the adoption of the substage condenser in his later instruments.