Dietzgen introduced this type of instrument in the 1930s, describing it as a Surveying and Timber Cruisers’ Compass of an "improved type as made by us for the U.S. Government." Dietzgen designed this compass to make "the entrance of moisture or dust practically impossible." The needle ring is graduated to degrees, and numbered in quadrants from N and S. A pinion with capstan head, located outside the box at W and marked "Declination," is used to offset the compass for magnetic variation. The National Imagery and Mapping Agency transferred this compass to the Smithsonian in 2000.
Ref: Dietzgen, Catalog (Chicago, 1938), p. 617.