This hollow white plastic instrument has paper scales. One side has a 39-inch ruler, divided to 1/8" along the top and to 1/2" along the bottom. Alternate pairs of half-inches are colored orange on the bottom scale.
![](https://csoarchives.files.wordpress.com/2015/12/smithsonian-wide.jpg)
National Museum of American History
![](https://www.archkey.com/wp-content/uploads/SmithsonianAfricanAmericanMuseumD.C-scaled.jpg)
Smithsonian National Museum of African American History & Culture
![](https://www.blackpast.org/wp-content/uploads/President-Barack-Obama-Speaking-at-the-Opening-of-the-National-Museum-of-African-American-History-and-Culture-Artnet-News-scaled.jpg)
The Smithsonian National Museum of African American History and
![](https://upload.wikimedia.org/wikipedia/commons/thumb/5/52/National_Museum_of_American_History_1.jpg/220px-National_Museum_of_American_History_1.jpg)
National Museum of American History - Wikipedia
![](https://americanhistory.si.edu/sites/default/files/styles/page_hero/public/2023-11/visit_f.jpg?h=c74750f6&itok=RTZmenRx)
Visit National Museum of American History
![](https://image.architonic.com/imgArc/project-1/4/5202616/SOM-Skidmore-Owings-%26-Merrill-Smithsonian-National-Museum-of-American-History-Renovation-04.jpg)
Smithsonian National Museum of American History Renovation by SOM
![](https://a.cdn-hotels.com/gdcs/production132/d1347/35f163b3-ee91-4340-82a6-0af6babae959.jpg?impolicy=fcrop&w=800&h=533&q=medium)
National Museum of American History in Washington DC - Discover
![](https://i0.wp.com/afro.com/wp-content/uploads/2022/04/ex_hh04_20220307_003.jpg?fit=1200%2C800&ssl=1)
Three sculptures from acclaimed artist Elizabeth Catlett coming to
![](https://travel.usnews.com/images/Credit-AlanKarchmer_417.jpg)
Smithsonian National Museum of African American History & Culture Reviews
![](https://dcist.com/wp-content/uploads/sites/3/2022/12/JN2022-01018-scaled.jpg)
American History Museum Exhibit Explores Pop Culture
![](https://i.guim.co.uk/img/media/455288523531fb361d1586c6be06b5ccbbee7797/0_0_3000_1999/master/3000.jpg?width=700&quality=85&auto=format&fit=max&s=39a51b6f7adee2561e0d91b7239ecf0e)
A welcome rebuke to dead white men': The Smithsonian's African
![](https://www.nationsclassroomtours.com/app/uploads/2021/02/NMAAHC.png)
African American History Museum
![](https://cdn.wikimg.net/en/strategywiki/images/f/f0/Contra_NES_Stage_6b.png)
![](https://www.kmart.com.au/wcsstore/Kmart/images/ncatalog/f/8/69838538-1-f.jpg)
![](https://m.media-amazon.com/images/I/91vloXHj0jL._AC_UF1000,1000_QL80_.jpg)