US 1,474,911 (elevator equalizer) General Tractor Corporation and Otis Elevator Company
name: label: Collection Creator
content: Pratt, Charles Richardson, 1860-1935
setName: label: See more items in
content: Charles Richardson Pratt Papers
label: See more items in
content: Charles Richardson Pratt Papers / Series 5: Inventions
unitdate: label: Date
content: 1921 - 1924
container: label: Container
content: Box 8, Folder 1
dataSource: label: Archival Repository
content: Archives Center, National Museum of American History
objectType: label: Type
content: Archival materials