Eyepiece Micrometer
date: label: date made
content: 1865
notes: label: Description
content: The U.S. Naval Observatory acquired an 8.5-inch transit circle by made by Pistor & Martins in 1865, and used it to determine positions of standard and miscellaneous stars, the Sun and Moon, and major and minor planets. This filar micrometer was used at the eye-end of that instrument. It has horizontal and vertical screws and spider lines, as well as a set of Rogers levers so that several measurements can be made at one time and recorded later. These levers were designed by Joseph Addison Rogers (1840-1917), a young man who graduated from Yale in 1860, received a Ph.B. in civil engineering from Yale in 1861, and then went to work at the Naval Observatory.
label: Description
content: Ref: “Modification of the Micrometer Head, devised by Mr. Joseph A. Rogers, Aid U.S. Naval Observatory,” <i>Astronomische Nachrichten</i> 63 (1865): 77-78.
label: Location
content: Currently not on view
topic: label: Subject
content: Science & Scientific Instruments
setName: label: See more items in
content: Medicine and Science: Physical Sciences
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: PH.327702
label: accession number
content: 283654
label: catalog number
content: 327702
objectType: label: Object Name
content: eyepiece micrometer
physicalDescription: label: Measurements
content: overall: museum housing: 5 1/2 in x 8 in x 7 3/4 in; 13.97 cm x 20.32 cm x 19.685 cm