Felsenthal Graphical Site Table

Computing devices have been manufactured for military purposes since at least the early 17th century. Around the end of World War II, the Chicago firm of Felsenthal designed an instrument like a slide rule for aiming a variety of howitzers, or short cannons, used by the U.S. Army, including the 155 mm size. The Fort Sill, Okla., bookstore sold these slide rules for $1.50.
This wooden graphical site table has a white coating on both sides. The indicator is clear plastic with wooden edges held together with brass screws. The bottom of the base has a scale marked: Site and Vertical Interval. On one side, the slide has a scale for range and scales for the Target Above Gun (TAG) and Target Below Gun (TBG) with charges of 4 or 5. This side is marked: HOW., 155-MM (/) MI (/) SHELL, M107 (/) FT 155-Q-2. The other side of the slide has another scale for range and TAG/TBG scales for charges of 1, 3, 6, and 7. The back of the instrument has instructions and examples of use. Both sides of the slide, the base, and the back are all marked: 25045.
Compare to 1977.1141.27, whose markings suggest that this instrument was made before 1964. For a graphical firing table, see 2005.0271.02. For Felsenthal company history, see 1977.1141.01 and 1977.1141.02.
References: "Graphical Site Table," The Field Artillery Journal 35, no. 9 (September 1945): 548; Elizabeth R. Dickinson, "The Production of Firing Tables for Cannon Artillery," U.S. Army Ballistic Research Laboratory, Report No. 1371 (Aberdeen (Md.) Proving Ground, November 1967), 75–80; Johnnie F. Pearson, Jr., "Fire Direction Center Operations in Viet Nam," 5, 19, http://83rd_artillery.home.comcast.net/~83rd_artillery/Artillery_Info/Artillery_Misc_Files/FDC_Operation_2012_040312.pdf; accession file.
Currently not on view
Object Name
slide rule
date made
mid-20th century
Date made
Felsenthal Instrument Co.
Physical Description
wood (overall material)
plastic (cursor material)
metal (part material)
overall: 1.6 cm x 37 cm x 6.8 cm; 5/8 in x 14 9/16 in x 2 11/16 in
place made
United States: Oklahoma, Fort Sill
ID Number
catalog number
accession number
Science & Mathematics
Rule, Calculating
Slide Rules
See more items in
Medicine and Science: Mathematics
Slide Rules
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Gift of Ben Wharton Rau and Margery Felsenthal Rau
Additional Media

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