Persian Drah

This wooden rectangular rule is reported to be a Persian drah, or pic, a unit of length measure used in surveying and architecture. According to Russ Rowlett, the pic (or pik) was a traditional unit of distance in the Eastern Mediterranean and Near East. An "arm" unit, like the ell, the pic varied considerably. A typical value was about 28 inches (71 centimeters). This example is divided on one side in pencil and on the other with carved notches. The divisions on the pencil side are at: 3.0, 6.3, 9.6, 12.7, 25.3, 28.3, 31.6, 37.8, 50.3, 53.4, 56.6, 59.8, and 62.7 cm. The divisions on the notched side are at: 12.5, 15.7, 18.8, 21.8, 25.0, 37.9, 41.0, 44.2, 47.1, 50.2, 56.2, 59.2, and 62.3 cm.
The pencil side is marked at the right end: teheran (/) dept of State. In 1892, the U.S. Department of State transferred this object to the Smithsonian.
Reference: Russ Rowlett, How Many? A Dictionary of Units of Measurement, July 11, 2005,
Currently not on view
Object Name
scale rule
date made
19th century
Physical Description
wood (overall material)
overall: 1.3 cm x 75.3 cm x 3.4 cm; 1/2 in x 29 21/32 in x 1 11/32 in
place made
Îrān: Tehrān, Tehran
ID Number
accession number
catalog number
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Measuring & Mapping
Scale Rules
Data Source
National Museum of American History, Kenneth E. Behring Center


Add a comment about this object