The measurement of distances is an integral part of surveying. Many methods have been used to measure distances, from the knotted ropes of Egypt, to glass tubes or wood or metal bars fitted end-to-end, to today's electronic distance measurement instruments (EDMI). The image on the left, circa 1728, shows English surveyors using an odometer to measure a distance. The instrument on the right is a Laser Scout 1000, a hand-held, reflectorless EDMI made by Riegl.
That Was Then…
In the "antique" image, which dates back to 1728, English surveyors use an odometer to measure a distance.
The odometer was possibly invented by the Greek scientist Archimedes (ca. 287 BC – ca. 212 BC). Around 23 BC, the Roman architect and engineer Vitruvius described an odometer that was based on the number of times a four-foot in diameter chariot wheel turned in one Roman mile. The arrangement of wheel, handles, and gears led to the surveying contraption being referred to as a "clock on a wheelbarrow." It was often used in 19th century America to measure roads for county atlases.
…This Is Now
The Riegl electronic distance measurement instrument shown in the photograph is currently used by the National Geodetic Survey's Airport Surveys Program. The pistol grip instrument has been by used since 1996 to measure accurate distances without a reflector and will consistently measure to the top branches of a tree at distances over 4,000 feet (1,200 meters). It is used during airport surveys to determine or verify obstruction locations and heights.
About the Images
- Date: 1728
- Material: Not available
- Source: Not available
- Instrument/technique shown: Odometer
- Date: 2006
- Material: Photograph
- Source: Dave Hucks, NOAA, NGS
- Instrument/technique shown: Riegl electronic distance measurement instrument
Answers.com. (2006). Odometer. Retrieved on September 27, 2006 from: http://www.answers.com/topic/odometer
Bedini, S. A. (2001). With Compass and Chain- Early American Surveyors and Their Instruments. Frederick, MD: Professional Surveyors Publishing Company, Inc.
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