altimeter
Date: circa 1940
Inventory Number: 2004-1-0359
Classification: Altimeter
Subject:
Maker: Kollsman Instrument Company (1928-present)
Cultural Region:
Place of Origin:
Dimensions:
9.3 × 8.2 × 13 cm (3 11/16 × 3 1/4 × 5 1/8 in.)
Description:
Cylindrical altimeter consisting of an aneroid barometer housed in a black circular case, with a glass face over the scale. The scale runs from 0-9, and has two pointers, one longer and one shorter. A small window to the right side of the face also gives a numerical reading.
For a complete technical information, read the 1936 patent here.
For a complete technical information, read the 1936 patent here.
Signedon back plaque: KOLLSMAN INSTRUMENT COMPANY INC. / BROOKLYN NEW YORK
Inscribedon plaque: Contract No. W535 AC-9064 / MFR's Part No. 325-03 / Spec. No. 94-27758 / MANUFACTURED UNDER U.S. PATENTS / 1,930,899 2,034,909 U.S. REISSUE / PATENTS 18, 808, [damaged], 079 FOREIGN / PATENTS OTHER PATENTS PENDING / KOLLSMAN INSTRUMENT COMPANY INC. / BROOKLYN NEW YORK
on face: 1000 feet / 10000 feet / ALTITUDE
scale runs from 0-9, clockwise
on face: 1000 feet / 10000 feet / ALTITUDE
scale runs from 0-9, clockwise
FunctionSimilar to a basic aneroid barometer, this instrument uses a relatively large partially evacuated metal chamber, which is sensitive to small changes in atmospheric pressure. The minute contractions and expansions of the chamber are amplified by internal clockwork, and reflected on the dial. Falling atmospheric pressure translates to an ascending condition, while increasing atmospheric pressure translates to a descending condition. This chamber is placed inside a closed box, and can be exposed to the atmosphere via the small metal tap that protrudes from the front of the case.