AGA Geodimeter Model 6

This photograph shows a model of a Geodimeter. Geodimeters, like other light-based electronic distance measuring instruments, worked by measuring the amount of time required for a beam of light to travel to a reflector and back. These instruments were used by the Coast and Geodetic Survey from the 1950s through the 1970s. The particular model was used by the Survey in the mid- to late-1960s.

AGA Geodimeter Model 6

Four views of a 6A, including the sighting telescope visible in the bottom right image. Credit: Charlie Glover

Improvements in Geodimeters since their inception in 1953 increased the utility of these instruments for measuring distances in a range of conditions.

The Model 6 series shown in the photograph, first marketed in 1964, was developed with the intent to lower weight and power consumption, increase daylight range, and make pointing on the target prisms simpler. The vacuum tubes that comprised the "innards" of the equipment and could take considerable time to warm up were replaced by transistors. Lightweight, rechargeable batteries replaced the heavy 12-volt car battery earlier models had relied on for power.

Historic Reference

This model was mostly used by the Coast and Geodetic Survey earthquake fault crossing parties measuring Earth movement in California.

  • Distance Measurement Instrument Shown: AGA Geodimeter, Model 6
  • Location: Corbin, VA
  • Manufacture Date: 1960s
  • Dates of Use: Mid to late1960s
  • Photo Date: 2006

Works Consulted

Smith, J. R. (1983) Geodimeter 1947-1983. Unpublished.

Burger, T. C., Tomlinson, R. W. (1975). Electronic Distance Measuring Instruments. Washington, D. C.: American Congress on Surveying and Mapping.

Personal e-mail correspondence with Charlie Glover, 6/21/2006.