Improvement in Duplex telegraph instruments, 1872-1874 (including keys and circuits).
name: label: Collection Creator
content: United Telegraph Workers.
label: Collection Creator
content: Western Union Telegraph Company
setName: label: See more items in
content: Western Union Telegraph Company Records
label: See more items in
content: Western Union Telegraph Company Records / Series 12: Patent Materials / 12.1: By Patentee
container: label: Container
content: Box 456, Folder 10
dataSource: label: Archival Repository
content: Archives Center, National Museum of American History
objectType: label: Type
content: Archival materials