Museo della centuriazione romana (Borgoricco) 02

The ''groma'' or ''gruma'' was a

Roman Roman or Romans most often refers to: *Rome, the capital city of Italy *Ancient Rome, Roman civilization from 8th century BC to 5th century AD *Roman people, the people of ancient Rome *''Epistle to the Romans'', shortened to ''Romans'', a letter ...

surveying instrument Instruments used in surveying include: * Alidade * Alidade table * Cosmolabe * Dioptra * Dumpy level * Engineer's chain * Geodimeter * Graphometer * Groma (surveying) * Laser scanning * Level * Level staff * Measuring tape * Plane table * Pole (su ...

. It comprised a vertical staff with horizontal cross-pieces mounted at right angles on a bracket. Each cross piece had a plumb line hanging vertically at each end. It was used to survey straight lines and right angles, thence squares or rectangles. They were stabilized on the high ground, and pointed in the direction it was going to be used. The helper would step back 100 steps and place a pole. The surveyor would tell him where to move the pole and the helper would set it down. The same name was given to: * the center of any new military camp, i.e. the point from which was traced the regular grid by using the ''groma'' instrument * the center of a new town, from which the

gromatici ''Gromatici'' (from Latin '' groma'' or ''gruma'', a surveyor's pole) or ''agrimensores'' was the name for land surveyors amongst the ancient Romans. The "gromatic writers" were technical writers who codified their techniques of surveying, most ...

(surveyors) began to lay out cardo and

decumanus In Roman urban planning, a decumanus was an east–west-oriented road in a Roman city or castrum (military camp). The main decumanus of a particular city was the Decumanus Maximus, or most often simply "the Decumanus". In the rectangular street gr ...

grid, with a plough and a pair of oxen The groma surveying instrument may have originated in

Mesopotamia Mesopotamia ''Mesopotamíā''; ar, بِلَاد ٱلرَّافِدَيْن or ; syc, ܐܪܡ ܢܗܪ̈ܝܢ, or , ) is a historical region of Western Asia situated within the Tigris–Euphrates river system, in the northern part of the F ...

Greece Greece,, or , romanized: ', officially the Hellenic Republic, is a country in Southeast Europe. It is situated on the southern tip of the Balkans, and is located at the crossroads of Europe, Asia, and Africa. Greece shares land borders with ...

before the 4th century BC. Subsequently, it was brought to Rome by the

Etruscans The Etruscan civilization () was developed by a people of Etruria in ancient Italy with a common language and culture who formed a federation of city-states. After conquering adjacent lands, its territory covered, at its greatest extent, rou ...

and named cranema or ferramentum.

Notes

External links

BBC: h2g2: The Groma: The Tool That Built An Empire

University of Arizona – Archaeological Mapping Lab
{{Authority control Surveying instruments Historical scientific instruments