Micrometer
date: label: date made
content: ca. 1930-1932
notes: label: Description
content: This micrometer was invented by John Mischker and patented in 1932 (US1853134A). It has a reversible and adjustable gauge member, or spindle, and caliper frame, or sleeve. One can insert the gauge member, equipped with measuring marks of 0.025 inch graduations, from either side of the caliper frame, allowing for the measurement of both the inside and outside of many objects. Different frames can be used with the measuring gauge, allowing for further versatility of the instrument. A thumb-controlled ratchet pawl on the frame stops the barrel and is reversible as well. The micrometer is metal with a red finish on the inside of the caliper frame. On the red part of the body of the frame is a metal tag inscribed with the words, “PATENT APPLIED FOR,” indicating that this version of Mischker’s micrometer was created before the patent was received. This micrometer provides an example of the mechanical and technical innovation in the 1930s, even despite the Depression taking place.
label: Description
content: John Mischker was a machinist and craftsman based in Milwaukee, Wisconsin. Upon the invention of this micrometer, he was a former craftsman at the Cutler-Hammer plant, an organization that manufactured electrical controls for use in lamps, military aircrafts, and submarines. Mischker additionally invented a pair of electric hedge trimmers, also accessioned along with the micrometer.
label: Location
content: Currently not on view
setName: label: See more items in
content: Work and Industry: Mechanical and Civil Engineering
creditLine: label: Credit Line
content: Rachel F. Mischker
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: 1987.0422.01
label: catalog number
content: 1987.0422.01
label: accession number
content: 1987.0422
objectType: label: Object Name
content: micrometer
physicalDescription: label: Measurements
content: overall: 4 1/8 in x 2 3/8 in x 1/2 in; 10.4775 cm x 6.0325 cm x 1.27 cm