History...The Dioptra

The oldest historical record - begin in Egypt, Hetorodotus recorded

i. Sesostris (about 1400 B.C) - Devided the land of Egypt into plots for the purpose of taxation

ii. Early surveyor were called ropestretcher - measurement were made with ropes

iii. Greek thinker - Heron, the author The Dioptra, which related to method of surveying a field, drawing a plan and making related calculations.


(note : wikipedia source - A dioptre, or diopter, is a unit of measurement of the optical power of a lens or curved mirror, which is equal to the reciprocal of the focal length measured in metres (that is, 1/metres). For example, a 3 dioptre lens brings parallel rays of light to focus at 1/3 metre. )


Taken from T. P. Tassios , Ancient Greek Technology - Measuring Instruments, FIG Working Week in Athens, May 22-27, 2004 (http://www.fig.net/news/news_2004/athens/ancient_exhibit.htm)



The "dioptra" devised by Heron is a portable surveying instrument for making accurate geodetic measurements. It measures azimuths, heights, lengths and angular distances.
The apparatus, which was mounted on a tripod about 50 cm tall, pivoted on a circular plate and was moved around horizontally by a worm screw , driven by a small handle. The top plate was mounted on a toothed semicircular plate and was adjusted in the vertical plane by another worm drive. Angles could be read off the top disc, which was scored with two lines crossing at right angles. The sighting and reading elements were made of bronze.

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