This compound monocular was designed for use with the Brinell Ball Test for determining the hardness of a piece of metal. Here, a small ball is pressed into a sample, and the resulting indentation is examined with a Brinell microscope. Johan August Brinell, a Swedish engineer, proposed the test in 1900. The results are given in BHN (Brinell hardness numbers).
Ref: Bausch & Lomb, Microscopes, Microtomes and Accessories (Rochester, 1922), p. 100.
Currently not on view
Object Name
microscope accessory
date made
early 20th century
case: 2 1/8 in x 8 3/4 in x 2 1/2 in; 5.3975 cm x 22.225 cm x 6.35 cm
microscope: 7 in x 1 3/4 in; 17.78 cm x 4.445 cm
ID Number
catalog number
accession number
catalog number
Science & Scientific Instruments
Science & Mathematics
See more items in
Medicine and Science: Medicine
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
New Eyes for the Needy, Inc.

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