Faber-Castell 6787 Rietz Simplex Slide Rule

This inexpensive one-sided white plastic (Geroplast) five-inch linear slide rule has a transparent plastic indicator. A five-inch scale along the upper edge of the rule is divided to 32nds of an inch. Scales on the base and on the front of the slide are not lettered, but the scales on the top of the base correspond to K and A scales and the scales on the bottom of the base correspond to D and L scales. Scales on the slide correspond to B, CI, and C scales. The scales on the back of the slide are labeled sin, sin/tg, and tg. This arrangement of scales is known as the "System Rietz," developed by the German engineer Max Rietz in 1902.
The left end of the slide is marked: CASTELL. Underneath the slide is marked: [logo of weighing scales] A. W. FABER [logo of castle on its right side] CASTELL [logo of castle on its right side] 67/87 RIETZ (/) MADE IN GERMANY. Under the slide is also stamped: I. MOLELLA. Date codes on the back appear to read 53 and 1. The brown leather case is marked: FABER- (/) CASTELL (/) 67/87 (/) Made in Germany.
Faber-Castell of southern Germany introduced the 67 series of slide rules in 1952 and sold them through about 1976, although the form of logo on this example was only in use from 1952 to 1956. The date codes suggest a manufacture date of January 1953.
The owner of the slide rule, Isaac Giancinto Molella (1908–1982), was in the Cornell University class of 1932. He worked for General Electric as an electrical engineer at Electronics Park in Syracuse, N.Y., in 1953, and as a technical representative for the U.S. Air Force at radar sites in North Africa and Europe between 1954 and 1957.
References: Dieter von Jezierski, Slide Rules: A Journey Through Three Centuries, trans. Rodger Shepherd (Mendham, N.J.: Astragal Press, 2000), 28, 34, 53–61; Panagiotis Vinetsianos, "A. W. Faber Castell Slide Rules: The Relationship Between Date of Manufacture and Indication of Brand Name, Model Number, and Model Name," Journal of the Oughtred Society 9, no. 1 (2000): 3–6; accession file.
Currently not on view
date made
Faber, A. W.
place made
Deutschland: Bayern, Geroldsgrün
Physical Description
plastic (overall material)
leather (case material)
overall: .8 cm x 16.2 cm x 4.6 cm; 5/16 in x 6 3/8 in x 1 13/16 in
ID Number
accession number
catalog number
Credit Line
In Memory of Isaac Giacinto Molella
Rule, Calculating
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Slide Rules
Data Source
National Museum of American History, Kenneth E. Behring Center


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