Gromatici

The distribution of land amongst the veterans, the increase in the number of military colonies, the settlement of Italian peasants in the provinces, the general survey of the empire under Augustus, the separation of private and state domains, led to the establishment of a recognized professional corporation of surveyors.

But they also acted as judices, and could give a final decision in that class of smaller questions which concerned the quinque pedes of the Lex Mamilia (the law setting which boundary spaces were not subject to usucapio), as appears from Frontinus.

According to a constitution of Theodosius II and Valentinian III (440 AD),[13] they received jurisdiction in questions of alluvio; but some writers disagree that this crucial passage is genuine.

[15][16] The earliest of the gromatic writers was Frontinus, whose De agrorum qualitate, dealing with the legal aspect of the art, was the subject of a commentary by Aggenus Urbicus, a Christian schoolmaster.

Under Trajan a certain Balbus, who had accompanied the emperor on his Dacian campaign, wrote a still extant manual of geometry for land surveyors (Expositio et ratio omnium formarum or mensurarum, probably after a Greek original by Hero), dedicated to a certain Celsus who had invented an improvement in a gromatic instrument (perhaps the dioptra, resembling the modern theodolite); for the treatises of Hyginus see that name.

[1] Somewhat later than Trajan was Siculus Flaccus (De condicionibus agrorum, extant), while the most curious treatise on the subject, written in barbarous Latin and entitled Casae litterarum (long a school textbook) is the work of a certain Innocentius (4th-5th century).

The surveyors were known by various names: decempedator (with reference to the instrument used); finitor, metator or mensor castrorum in republican times; togati Augustorum as imperial civil officials; professor, auctor as professional instructors.