Group of 4 Alumicolor Triangular Architect's Scales

These 6-3/4" aluminum triangular rules are each a different color (gold, silver, red, blue), but they all bear the same scales. The first side has an inch scale, divided to 1/16" and numbered by ones from 1 to 6, along one edge. The other edge has scales for 3/32" and 3/16" to the foot. Between these scales is a scale divided to 3/32", numbered from left to right by fours from 0 to 60 and from right to left by twos from 0 to 28. The gold and silver rules are marked: ARCHITECT ALUMICOLOR Code 121 made in El Salvador (3).
One edge of the second side has scales for 1-1/2" and 3" to the foot. The other edge has scales for 3/4" and 3/8" to the foot. Between these scales is a scale divided to 3/8", numbered from right to left by twos from 0 to 12 and from left to right by ones from 0 to 6. The red rule is marked: Cod. 121 ARCHITECT. The blue rule is marked Cod. 121 made in El Salvador.
One edge of the third side has scales for 1" and 1/2" to the foot. Between these scales is a scale divided to 1/2", numbered from right to left by twos from 0 to 8 and from left to right by ones from 0 to 4. The blue rule is marked: ARCHITECT ALUMICOLOR. The order of the second and third sides is also reversed on the blue rule, compared to the other three rules. All four rules are photo-anodized to make the scales a permanent part of the surface.
Alumicolor refers both to a manufacturer of drafting tools, length measures, and promotional items, and to the company's proprietary process for anodizing aluminum. The firm's headquarters are in the United States, and its factory is in El Salvador. In 2012 Alumicolor offered these architect's scale rules as model number 3010 for $6.50 each. Hearlihy & Co., a Springfield, Ohio, supplier of drafting instruments and developer of technology education curriculum modules founded by the donor's parents in 1969, continues to distribute these rules.
References: Alumicolor: Made to Stay, Promotional Products Catalog, vol. 12 ([Fort Collins, Colo.], 2012), 3,; "About Hearlihy,"; accession file.
Currently not on view
Object Name
scale rule
date made
ca 1985
Physical Description
extruded aluminum (overall material)
overall: 1 cm x 17 cm x 2.5 cm; 13/32 in x 6 11/16 in x 31/32 in
place made
El Salvador
ID Number
accession number
catalog number
Drafting, Engineering
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Scale Rules
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Gift of Daniel A. Hearlihy
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