The Groma by David Barney

Roman empire commonly used the Groma as a device to survey land for development. The origin of the device predates the Roman empire. Roman architect Vitruvius described the Groma as coming from the ancients. The device served many needs for military, agricultural, and civic needs. The Groma assisted the military in the construction of fortifications. For agriculture, the Groma served the purpose of identifying where to distribute land for landowners. Civil engineers used the Groma to survey land for creating roads and laying out land for streets and towns. Agrimensors, who were Roman surveyors, were the primary users of the Groma.

The Groma with the plumb lines aligned

The Groma would be placed in a certain location and used to measure angles between points from the location of the device itself. The Stelletta part of the Groma held the plumb lines known as Curnicula on its two crossed pieces of wood. The Ferramento held the Stelletta using its iron pole. The user of the Groma would position the Ferramento perpendicular to the ground. The Stelletta was rotated to aim towards a point aimed at the desired point once the Groma was ready.

Parts of the Groma

Other surveying devices besides the Groma existed in ancient Roma. Mathematician Heron of Alexandria wrote about the Groma’s inferiority to the Greek device known as the Dipotra. Despite this, the Groma’s design was simple which made it more easily accessible. The Groma led to several great Roman works that still exist today. Technologies such as aqueducts, canals, and roads required the precision of the Groma to be built. These technologies would themselves improve the standard of living for Roman citizens. The Groma would impact defensive measures through its use for projects such as Hadrian’s wall which fortified Rome’s most northern border. The Groma assisted in the planning and construction of many Roman infrastructure technologies that in turn lead to other technologies.

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Bob Stafford. “The Groma: The Tool That Built An Empire – Edited Entry.” h2g2, 2007.

Claudio Rossi. COME FUNZIONA LA GROMA Estratto Da: MISSIONE IN ATTICA Un’indagine Dell’agrimensore Quintilio e Del Liberto Hicesius, 2016.

“Roman Groma.” Ram’s Horn Educational, LLC, 2013.

“Roman Surveying.” Surveyors Historical Society, 1990.

Tandy, F., and Matteo Della Corte. “‘Groma’: The Ancient Land-Surveying Instrument.” Archaeological Journal 77, no. 1 (January 17, 1920): 207–12.

Titus Cornelius Fecit. “How to Use the Roman Groma.” De Legione Romana, 2012.

2 Replies to “The Groma by David Barney”

  1. Great post. I specifically liked the pictures that you implemented, they were very helpful in visualizing the Groma and its parts and ways of operation. I was unaware that the Groma was such an important tool in the Roman Empire.

  2. This is a great article about the Groma! I have never learned about this device before, and your article gave me a good idea about its functions and how it was made. The pictures also helped me to learn the different parts of the Groma. The Groma sounds like a great device that took part in the creation of many other technologies.

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