GROMATICI or AGRIMENSORES, the name for land surveyors amongst the Romans, from Lat. groma or gruma, a surveyor's measuring appliance. The art of surveying was prob ably at first in the hands of the augurs, who from early times had made use of sighting instruments for marking out the rectangular consecrated space temp/um containing the tabernaculum in which the augur observed the omens given by birds. The first profes sional surveyor mentioned is L. Decidius Saxa, who was employed by Anthony in the measurement of camps (Cicero, Philippics, xi. 12, xiv. IC). The subsequent 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 from State domains, led to the formation of a recognized professional class of highly-paid surveyors, some of whom were even honoured with the title clarissimus. Their duties required not only geometrical but also legal knowledge, as their decisions were considered authoritative in matters relating to the distribution of lands. This led to the institution of special training schools and the growth of a special literature, chiefly between the 1st and 6th centuries A.D. The earliest of the gromatic writers was Frontinus (q.v.), whose De agrorum qualitate, written from A.D. 81-96, dealt more with the legal aspect of the art. Extracts of it are preserved in the commentary of Aggenus Urbicus, a Christian schoolmaster. Under Trajan a certain Balbus wrote a manual of geometry for land surveyors (Expositio et ratio omniurn formarum et mensurarum). Also, under Trajan, Hyginus makes a definite reference to the use of the groma for laying out agricultural holdings. Later was Siculus Flaccus (de condicionibus agrorum, extant), while the most curious treatise on the subject, written in barbarous Latin and entitled Casae litterarusn, is the work of a certain Innocentius (4th-5th century). The Gromatici veteres contains extracts from official registers (probably 5th century) of land surveys, lists and descriptions of boundary stones, and extracts from the Theodosian Codex. According to Momm sen, the collection had its origin during the 5th century in the office of a diocesan governor of Rome, who had a number of surveyors under him. The agrimensores have been known by various names, e.g., decempedator (with reference to the instru ment used) ; finitor, mensor castrorum in republican times; togati Augustorum as imperial civil officials; professor, auctor as pro fessional instructors.
The best work on the Gromatici is by Blume Lachmann and Rudorff (1848) with supplementary volume, Die Schriften der rom ischen Feldmesser (1852) ; see also Letters of Cassiodorus; P. de Tissot, La Condition des Agrimensores dans l'ancienne Rome (1879) G. Rossi, Groma e squadro (Turin, 1877) ; articles by G. Humbert in Daremberg and Saglio's Dictionnaire des antiquites, and by Teuffel-Schwabe, Hist. of Roman Literature, 58; Geographical Journal, vol. lxix. (1927) con tains an illustrated article by Col. Sir Henry Lyons "Ancient Surveying Instruments" (p. 132).