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Graphical Firing Table M17 Slide Rule

Graphical Firing Table M17 Slide Rule

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Description
This one-sided rule is made of two types of wood and painted white on top. The top edge is beveled and has a scale for 1:20,000 yards. The top of the base has scales for 100-yard shift, 33 1/3 yards, and range, with D and K scales at the bottom. The D scale is a standard logarithmic scale for multiplication, but the K scale is not a logarithmic scale for cubes. The bottom of the base is marked: GRAPHICAL FIRING TABLE. The top right corner is marked: B180971. The bottom right corner is marked: B180972. The clear plastic indicator has white plastic edges. A black wheel is inside the bottom edge of the rule.
Originally the instrument would have had three slides, including one with a standard logarithmic C scale, but this example has only one slide. The slide was used to position an 8-inch M1-type howitzer armed with high explosive M106 shells, M51 and M67 fuses, and charges of 5, 6, or 7. The howitzer was a U.S. Army cannon introduced around 1942 and used into the 1950s. One side of the slide is for setting the cannon at a high angle and has scales labeled ELEV., 10 M Si (change in elevation), DRIFT, and TF (time of flight). The other side is for setting the cannon to fire at long range and has scales labeled ELEV., c, DRIFT, and FS (fuse setting). The left end is marked: LONG RANGE (/) FT 8-J-1. This mark indicates the corresponding firing table. The right end is marked: GFT M17 (/) C81758.
The back has tables for accounting for the influence of changes in temperature and wind direction. A third table provides range limits for charges from 1 to 7. The right end is marked: TABLE, GRAPHICAL FIRING, (/) M17 (/) STOCK NO. 6574317 (/) 81873. A dark brown leather case has a belt loop and a strap for tying it to the leg. Two additional vertical pockets inside the case held the additional two slides. The flap is marked: CASE, CARRYING (/) M23 (/) D4130. Clark McCoy attributed the rule to Keuffel & Esser, a prominent New York slide rule manufacturer. For another graphical firing table, see 1977.1141.25. One use for the ENIAC and other early electronic digital computers was to compute artillery firing tables.
References: Dr. Ing. Federico Ramirez Santa-Pau, "The Artillery Graphical Firing Table: A Description of a Specialized Slide Rule," Journal of the Oughtred Society 9, no. 2 (2000): 17–20; Clark McCoy, "Graphical Firing Table Slide Rule," http://www.mccoys-kecatalogs.com/KECollection/GraphicalFiring/K&E_GF_1.htm.
Location
Currently not on view
Object Name
calculating rule
slide rule
date made
ca 1945
maker
Keuffel & Esser Co.
place made
United States: New Jersey, Hoboken
Physical Description
wood (overall material)
plastic (cursor material)
paper (part material)
metal (part material)
leather (case material)
Measurements
overall: 6.5 cm x 51.5 cm x 11.5 cm; 2 9/16 in x 20 9/32 in x 4 17/32 in
ID Number
2015.0024.08
accession number
2015.0024
catalog number
2015.0024.08
Credit Line
Gift of Mabel Eller
subject
Mathematics
Rule, Calculating
Artillery
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Slide Rules
Data Source
National Museum of American History
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