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.

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