History of Surveying I

 

From its origins to the 15th century

Our grateful thanks go to the Association pour la Mémoire du Patrimoine de l’Equipement (Association for Remembrance of the Heritage of Equipment), which supplied the illustrations shown below from the section <> , as well as a great deal of information on the history of surveying.

« Que nul entre ici s’il n’est d’abord géometre ». (Let no man enter here who is not firstly a surveyor). This famous maxim that Plato had engraved on the pediment of his Academy in the 3rd century BC illustrates the importance of this discipline since ancient times. In making surveying an essential tool in philosophy, the Athenian scholars had initiated a real conceptual revolution, ie man had a duty to take measurements globally, no longer restricting himself to specific examples but now taking a wider view.

However, the creation of what was not yet called surveying is even older and evolved for much more basic reasons :In the year 8000 BC, the start of agriculture on the edge of the Mediterranean basin soon gave rise to the first towns and it became necessary to establish the area of each cultivable parcel of land; a clay Babylonian tablet dated around 4000 BC has been discovered which records such subdivision of the terrain.

Later, in ancient Egypt, the land surveyors were given the task of demarcation of the land bordering the Nile in order to collect taxes for the pharaoh. This they did using mathematical formulae to estimate the surface area. In 570 BC, Pythagoras proved that the earth was round, by the projection of his shadow on the surface of the moon during an eclipse. Subsequently, in 230 BC, Eratosthenes calculated the distance between two towns with the aid of a gnomon, simply a stick which projected a shadow indicating the angle formed by the Sun. It would not be until the 17th century that the Dutchman Snellius improved the process by using trigonometry.

The slow progression of instruments

Let us return to the past, however, to Mesopotamia, where the first specific instruments of measurement were invented, eg the cross-staff, a shaft on which a runner slid in order to measure angles and cord used to measure distances . Later, around 100 BC, Heron of Alexandria explained the principle of a dioptre, the forerunner of the theodolite, which enabled horizontal as well as vertical angles to be measured.

Subsequently there were no major innovations but rather a slow development through the centuries which was dictated by the needs of successive empires. Rome wished to define the extent and shape of conquered territories; they had to build roads and facilities (aqueducts etc) and surveyors contributed with their set squares, levels, plumb lines etc.

A treatise drawn up in the 14th century by a surveyor named Bertrand Boysset, shows that techniques did not undergo much change during this period. The author claimed the title of <>, of such importance was this instrument to him, ie a surveying set square, with which he was also able to measure levels. The compass was invented in China in the 4th century but would not be used in the West, in particular by surveyors, until the 15th century.

In the 15th century BC the Egyptians took measurements with the aid of a knotted cord.
In the 15th century BC the Egyptians took measurements with the aid of a knotted cord.
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In the Middle Ages, the measuring rod was one of the main instruments used.
In the Middle Ages, the measuring rod was one of the main instruments used.
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