Figure 1. (Top) a rare microscope slide from Moritz Ohlenburger, ca. 1888. (Bottom) a more common slide from the Moritz Hensoldt optical works. The slide labels are very similar to each other.
Moritz Ohlenburger, 1854 - 1938
by Brian Stevenson
Last updated November 2021
Microscope slides and optical instruments made by Moritz Ohlenburger are quite rare. He appears to have produced them over a fairly brief period during the late 1880s. He is especially notable for being a close relative of microscope-maker Moritz Hensoldt (1821-1903). Ohlenburger worked with Hensoldt before and after he ran an independent optical business.
Figure 1.
(Top) a rare microscope slide from Moritz Ohlenburger, ca. 1888. (Bottom) a more common slide from the Moritz Hensoldt optical works. The slide labels are very similar to each other.
Figure 2.
Photomicrographs of a thin sectioned mineral from the Calvarienberg in Poppenhausen, prepared by Moritz Ohlenburger (see Figure 1). Both were photographed with a 3.5x objective lens and a C-mounted digital SLR camera. The left image was photographed with normal transmitted light, and the right image with crossed polarizing filters.
Louis Moritz Ohlenburger was born on May 21, 1854 in Haiger, Hesse (Germany), a town close to Wetzlar. He was a son of Philipp Ludwig and Auguste Margarethe Amalie Ohlenburger. Father Philipp owned a hatmaking business.
Moritz Ohlenburger was a nephew of Moritz Hensoldt's wife, Christine Ohlenburger Hensoldt (1829-1903). Christine was also born in Haiger.
Moritz Ohlenburger began an apprenticeship with Moritz Hensoldt in January, 1869. He left the firm in 1874 to join the military. He returned to Wetzlar in February, 1876, working as a journeyman with Hensoldt.
He began his own business during the late 1880s: In 1888, Zeitschrift für Mathematischen und Naturwissenschaftlichen Unterricht reported on a telescope made by, "Die junge optische Werstatt von Moritz Ohlenburger in Wetzlar" ("the young optical workshop of Moritz Ohlenburger in Wetzlar"). Miklós Konkoly-Thege's 1890 Handbuch für Spectroscopiker im Cabinet und am Fernrohr described a spectrometer that included "einem achromatischen Objectiv aus Jenenser Glas von M. Ohlenburger in Wetzlar von 45 mm Oeffnung und 43 cm Brennweite" ("an achromatic lens made of Jena glass by M. Ohlenburger in Wetzlar with 45 mm aperture and 43 cm focal length"). Ohlenburger's business appears to have been short lived, as it is not known to be described elsewhere. Moritz Hensoldt's great-granddaughter, Christine Benz-Hensoldt, informs me that "I found in the family letters also that there were an optical craft business Ohlenburger at Haiger (the city from were the Ohlenburger family is coming from) - or in Wetzlar - taken over by Hensoldt in 1888. Their optical products seem to be very similar to the products of Hensoldt".
In 1891, Ohlenburger rejoined the Hensoldt optical company in a senior management position. By 1900, he had become a silent partner in the Hensoldt business, by investing 28100 Marks. Porezag writes that a 1901 report listed the following partners and contributions to the Hensoldt company: Moritz Hensoldt (53400 Marks) Carl Hensoldt (59900 Marks), Waldemar Hensoldt (49300 Marks), Moritz Ohlenburger (55000 Marks), Ludwig Herlau (15000 Marks), A. Zobel (18000 Marks) and lawyer Grunewald (18000 Marks).
In July, 1901, "Wetzlar Optische Werke M. Hensoldt & Sohne GmbH" was incorporated with Directors "Waldemar Hensoldt, Fabricant, Carl Hensoldt, Fabricant und Moritz Hensoldt Ohlenburger, Kaufmann". It is notable that the Waldemar and Carl Hensoldt (Moritz Hensoldt's sons) were each described as "manufacturer", while Ohlenburger was described as being a "merchant".
Moritz Ohlenburger married Anna Margarethe Winter in 1902. He died on December 21, 1938, in Haiger.
Figure 3.
A 1902 photograph that is thought to be of Moritz Ohlenburger. Adapted from Porezag, 2001, for nonprofit, educational purposes.
Figure 4.
1902 photograph of Moritz Hensoldt with managers and employees of M. Hensoldt und Söhne. Moritz Hensoldt is the frail, elderly man in the front (he died in 1903 at the age of 81). The man to his left, who is looking at Moritz, is his son, Waldemar. The other man in a suit, in the back row, is thought to be Moritz Ohlenburger (see Figure 3). Adapted from Porezag, 2001, for nonprofit, educational purposes.
Acknowledgements
My sincere thanks to Christine Benz-Hensoldt for generously sharing information about her family.
Resources
Adressbuch für die Deutsche Mechanik und Optik und Verwandte Berufszweige (1898) "Hensoldt, M., Optische Werkstatt"
Benz-Hensoldt, Christine (2007) Zwei Pioniere der Optik: Carl Kellners Briefe an Moritz Hensoldt, 1846-1852, Verlag Kempkes, Gladenbach
Death record of Louis Moritz Ohlenburger (1938) accessed through ancestry.com
Konkoly-Thege, Miklós (1890) Handbuch für Spectroscopiker im Cabinet und am Fernrohr, W. Knapp, Halle, page 163
Marriage record of Louis Moritz Ohlenburger and Anna Margarethe Winter (1902) accessed through ancestry.com
Nassauische Kunst- und Gewerbe-Ausstellung in Wiesbaden (1863) "Ohlenburger Louis Kappenmacher in Haiger", page 227
Porezag, Karsten (2001) Hensoldt, Geschichte eines Optischen Werkes in Wetzlar, Vol. 1, Porezag, Wetzlar
Zeitschrift für Instrumentenkunde (1888) Die wissenschaftlichen Instrumente und Apparate auf der diesjährigen Versammlung zu Köln, pages 430-435
Zeitschrift für Mathematischen und Naturwissenschaftlichen Unterricht (1888) Die wissenschaftliche Ausstellung der 61. Versammlung deutscher Naturforscher und Ärzte in Köln, Vol. 19, page 636