Gerber Variable Scale, Model TP007100B

Gerber Variable Scale, Model TP007100B

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Usage conditions apply
This rectangular aluminum instrument has a scale of reciprocal inches, unevenly divided and labeled RI; a scale of equal parts, labeled I and numbered by ones from 1 to 10 and by tens from 15 to 95; and a logarithmic scale labeled L10. An aluminum slide on top of the scales has a plastic indicator with a hairline. The slide is attached to a spring that expands and contracts within a clear plastic housing above the scales. It has 103 coils, 100 of which are calibrated. Every tenth coil is colored red, every fifth coil is blue-green, and the rest are white. A second spring is numbered by twos from 0 to 10.
Below the scales is marked: THE GERBER SCIENTIFIC INSTRUMENT COPMANY HARTFORD, CONN. GERBER VARIABLE SCALE ® MODEL TP007100B U.S. PAT. NO. 2843935 U.K. PAT. NO. 845215 MADE IN U.S.A. A brown leather case is lined with black velvet marked: The Gerber Scientific Instrument Co. (/) Hartford, Connecticut. A small manila envelope inside the case holds an Allen wrench. The case fastens with Velcro and slides into a white cardboard box.
The instrument assists in replotting curves (if, for example, a user wished to multiply all values plotted by a given factor) and in interpolating contour lines from observed data. It can also be used to convert between proportional scales, for instance when enlarging or reducing an engineering drawing. Heinz Joseph Gerber (1924–1996) invented the device while he was studying aeronautical engineering at Rensselaer Polytechnic Institute in 1945, a few years after escaping Nazi-controlled Austria with his mother. He and a partner established the Gerber Scientific Instrument Company in Hartford, Conn., to manufacture the Gerber Variable Scale. Gerber ultimately held about 650 U.S. and foreign patents for calculating instruments, digital drafting machines, and robotic and electronic manufacturing systems for products from electronics to textiles. The firm was renamed Gerber Scientific, Inc., in 1978.
Compare to 1994.3104.01. For an instruction manual, see 1994.0113.04.
References: Arthur Bartlett, "A Quick Spring to Success," Nation's Business (October 1949): 43–45, 62–64; Heinz Joseph Gerber, "Instrument for Measuring, Interpolating, Plotting and the Like" (U.S. Patent 2,843,935 issued July 22, 1958); "Our Founder," Gerber Scientific,
Currently not on view
Object Name
scale in case
date made
ca 1980
Gerber Scientific Instrument Company
place made
United States: Connecticut, Hartford
Physical Description
aluminum (overall material)
plastic (overall material)
leather (overall material)
fabric (overall material)
cardboard (overall material)
velcro (overall material)
overall: 3 cm x 33.1 cm x 7.4 cm; 1 3/16 in x 13 1/32 in x 2 29/32 in
ID Number
accession number
catalog number
Rule, Calculating
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Scale Rules
Data Source
National Museum of American History
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I also used this scale to locate seismic instrumentation sites on topographic maps. After ascertaining the location visually in the field on the topographic map. And then back in the office to determine the latitude and longitude. This was before GPS instruments existed. Later a gps location was determined in the field and located more accurately with the Gerber on the top map.
I used this instrument from 1962-1967 when I was in Range Safety to draw radar tracking charts for every launch from Cape Canaveral Florida. This instrument was essential for accuracy due to the fact that the paper (42P Sepia) would stretch from severe heat during the copying process. The negative that the copies were from were made of Mylar. There was a 12” tick mark from the center of the chart on the negative which we used to calibrate the Gerber scale. Prior to launch, the real-time tracking plotter was also calibrated with the tick mark. Drawing these charts without a Gerber scale would have been extremely difficult.

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