CC0 · no rights reserved
Patent Model for Parallel Rule and T-Square by Eugene Towne
From the collection of National Museum of American History. Free to download, adapt and use — no permission needed.
About this work
This instrument has a wooden handle attached by a large brass thumbscrew to a brass protractor that is divided to single degrees and numbered by tens in both directions from 10 to 170. The protractor is screwed to a rectangular brass piece that slides in a groove in a rectangular wooden guide-piece. The guide-piece has brass clamps and thumbscrews for affixing the instrument on a table. The protractor is also attached by a split nut to a metal screw shaft that runs the width of the instrument. A thumb rest and gear on the left clamp rotates the screw shaft.
National Museum of American History’s own descriptionCredit linePatent Model for Parallel Rule and T-Square by Eugene Towne. 1877. Towne, Eugene J.. National Museum of American History. CC0.
