Opera Glasses, Folding

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When closed, this ingenious device appears as a simple tube covered with dark leather. When opened it is a binocular instrument. The “BTE SGDG” inscription on the focusing knob indicates that it is based on a French patent. The objective lenses are 29 mm diameter. The frame is nickel plated.
John Browning in London described an instrument of this sort as a “Portable Binocular.” McAllister in Philadelphia described it as an “Articulated Pocket Opera Glass.”
Ref: John Browning ad in Nature 20 (May 1, 1879): title page.
William Y. McAllister, Illustrated Catalogue of Spectacles, Opera Glasses, Opthalmoscopes and Meteorological Instruments (Philadelphia, 1882), p. 49.
Currently not on view
date made
19th century
place made
overall: 4 1/2 in; 11.43 cm
overall: 4 5/8 in x 1 3/8 in; 11.7475 cm x 3.4925 cm
ID Number
catalog number
accession number
Credit Line
Jane and Mary Henle
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Medicine and Science: Physical Sciences
Science & Mathematics
Data Source
National Museum of American History