US Patent, 1,394,264, crossing signals
name: label: Collection Creator
content: Adler, Charles, Jr., 1899-1980 (engineer, inventor)
setName: label: See more items in
content: Charles Adler, Jr. Collection
label: See more items in
content: Charles Adler, Jr. Collection / Series 4: Patents and Inventions
unitdate: label: Date
content: 1921 October 18
container: label: Container
content: Box 11, Folder 20
dataSource: label: Archival Repository
content: Archives Center, National Museum of American History
objectType: label: Type
content: Archival materials