National Museum of American History

A wooden bar (6-1/8" x 2" x 3/4") is attached to a flat wooden handle (17-7/8" x 2" x 1/8") by nine wooden pegs. By the 17th century, draftsmen used T-squares to help them draw horizontal lines.

David Adjaye on the National Museum of African American History

National Museum of American History in Washington DC - Discover

Smithsonian National Museum of American History

Guide to the National Museum of American History

Smithsonian National Museum of American History

National Museum of American History - Washingtonian

Ultimate Guide To The National Museum of American History

National Museum of American History

National Museum of African American History & Culture

National Museum of American History Collects History Related to

The sad & sorry Smithsonian

Presente! exhibit opens on the National Mall in Washington D.C : NPR

Flag Hall, National Museum of American History Smithsonian Institution

Ultimate Guide To The National Museum of American History

Smithsonian Museum of American History