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Object Name: drum-type compound microscope
Date: 1845-1846
Inventory Number: 1117
Classification: Microscope
Maker: Georges Oberhaeuser
1798 - 1868
Owner: Louis Agassiz
1807 - 1873
Cultural Region: France
City of Origin: Paris
Dimensions: 27 x 13 x 10.5 cm (10 5/8 x 5 1/8 x 4 1/8 in.) box: 13 x 19.5 x 32 cm (5 1/8 x 7 11/16 x 12 5/8 in.)
Materials: wood, brass
Description: A large drum microscope with two rack and pinion sets, one for coarse focus and one for varying tube length. The latter must be the "Grossissement variable." The lead-filled base has a square opening for illuminating the flat/concave substage mirror rotatable only about a horizontal axis. The stage and upper parts of the stand can be rotated on the base. A vertical pillar holds an arm and the tubes, but there is no fine focus provided.

Small, wooden box covered in stamped-leather box holds the objectives and diaphragms in a wooden insert. Lid lined in ivory silk.

Flat mahogany box to hold the microscope and accessories is a replacement. It is the style of Nachet boxes. Brass handle and plate on top is inscribed with a doctor's name.
Accessories: objective (11); diaphragm (3); all in stamped leather box; 1 ocular; mahogany box (not original).
Signed: Georges / Oberhaeuser, / breveté, / Place Dauphine, 19, / Paris.
Inscribed: on arm: Microscope / achromatique, / à / Grossissements / variables.
on rim of base: No. 1194.
on replacement box: Dr. R. M. / Hodges.
Historical Attributes: Owned and used by Louis Agassiz in his study of jellyfish.

In May 1849, Agassiz presented an account of observations he made with this microscope on the nervous system in jellyfish. His claim that coelenterates (jellyfish and their relatives) possess a nervous system was met with scepticism, and he retracted his findings in 1862. His original observations were later proved correct.

Mackie, "Louis Agassiz," discusses Agassiz's microscopy with an Oberhaeuser compound microscope, with attention to particular objectives he used and what these could have resolved.
Curatorial Remarks: See file for description of some restoration, and a detailed sketch by E. Gay of an Oberhaeuser he apparently restored for Mrs. Marie Prince Jones of South Hamilton. It was also owned by Agassiz and looks like fig. 287 in Harting. It had a fine focus mechanism but no racks and pinions, like this one. According to Dr. Lewis's notes, the dates of purchase and manufacture of this microscope are unknown. However, from Harting, Lib. 735, p. 703 one can estimate a probable date of 1845-46. Follow up on Mackie (see published references) by testing the objectives. Photographs of Louis Agassiz (1998-1-0934) show a similar but not identical Oberhaeuser drum microscope on the table.
Primary Sources: Pieter Harting, Das Mikroskop (Braunschweig: Friedrich Vieweg und Sohn, 1859), fig. 287.
Louis Agassiz, “Contributions to the Natural History of the Acalephae of North America. Part I. On the naked-eyed medusae of the shores of Massachusetts, in their perfect state of development” Memoirs of the American Academy of Arts and Sciences, new ser., 4, no. 2 (1850): 221-316, plates 1-8.

Provenance: Louis Agassiz, purchase circa 1846; Ernst-Lewis Collection, 5/18/36.
Published References: G. O. Mackie, "Louis Agassiz and the Discovery of the Coelenterate Nervous System," Hist. Phil. Life Sci. 11 (1989): 71-78.
Related Bibliography in CHSI Library: Das Mikroskop: Theorie, Gebrauch, Geschichte
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