1. 
   Groma
   Roman engineers used a groma as a surveying device to build roads, aqueducts and buildings; a groma consisted of a wooden stand with crossbar from which weights were hung; the weights on the end of each crossbar assured that the groma was kept perpendicular to the ground.
   Found op http://ablemedia.com/ctcweb/glossary/glossaryi.html
   
   
2. 
   groma
   Greek surveying tool used for creating straight lines and right angles. As a survey tool the groma was the singular most important instrument of the mensores, or Roman military surveyors, and their commander, the praefectus castrorum (camp prefect). The groma was used to mark out the 2 main axes of ...
   Found op http://www.encyclo.co.uk/visitor-contributions.php
   
   
3. 
   Groma
   Surveying instrument.
   Found op http://www.encyclo.co.uk/local/20764
   
   
4. 
   groma
   ¹ survey tool A groma was the singular most important instrument of the mensores, or Roman military surveyors, and their commander the praefectus castrorum. The groma was used to mark-out the two main axes of the camp; the cardo decumanus which pointed in the direction from which the main danger ...
   Found op http://www.roman-britain.org/military/military_glossary.htm
   
   
5. 
   groma
   (from the article `surveying`) There is some evidence that, in addition to a marked cord, wooden rods were used by the Egyptians for distance measurement. They had the groma, which ...
   Found op http://www.britannica.com/eb/a-z/g/72
   
   

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