Azimuth Circle
date: label: date made
content: 1941
name: label: maker
content: Ritchie
notes: label: Description
content: This circle was designed to fit atop a U.S. Navy Standard Compass.The inscriptions read "E. S. Ritchie & Sons, Inc. Brookline, Mass." and "2867" and "NEGUS, New York." The Ritchie ledgers, now held by Ritchie Navigation, indicate that it was made on April 10, 1941 and sold to T.S. & J.D. Negus, a New York firm that sold navigational instruments. The U.S. Naval Observatory transferred it to the Smithsonian in 1966.
label: Description
content: This circle has two mechanisms for taking sights. In one, the rays of the sun are reflected from a cylindrical convex mirror to a right-angle prism on the opposite side of the ring, and then through a cylindrical lens below, appearing on the card as a bright bar of light. The other consists of sight vanes, hair line and reflector, for taking bearings of terrestrial objects.
label: Description
content: E. S. Ritchie received his first patent (#49,157) for an azimuth circle in 1865, and another (#481,625) in 1892.
label: Description
content: Ref: G. Dutton, <i>Navigation and Nautical Astronomy</i> (Annapolis, Md., 1948), pp. 33-34.
label: Location
content: Currently not on view
place: label: place made
content: United States: Massachusetts, Brookline
setName: label: See more items in
content: Medicine and Science: Physical Sciences
label: See more items in
content: Navigation
label: See more items in
content: Measuring & Mapping
creditLine: label: Credit Line
content: U.S. Naval Observatory
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: PH.327715
label: catalog number
content: 327715
label: accession number
content: 283654
objectType: label: Object Name
content: azimuth circle
physicalDescription: label: Measurements
content: overall: 10 in; 25.4 cm
label: Measurements
content: overall in box: 4 1/4 in x 11 3/8 in x 11 1/2 in; 10.795 cm x 28.8925 cm x 29.21 cm