Chapter 1 Surveying Chapter 1 Surveying Part 650 Engineering Field Handbook
United States Department of Part 650 Agriculture Natural Engineering Field Handbook Resources Conservation Service Chapter 1 Surveying Chapter 1 Surveying Part 650 Engineering Field Handbook Issued October 2008 Cover illustration: Roman groma The early Roman surveyors used an instrument called the groma to lay out their cities and roads by right angles. The word “groma” is thought to have come from the root Greek word “gnome,” which is defined as the pointer of a sundial. The importance of turning right angles is shown in the layout of several cities in northern Italy, as well as North Africa. The land was subdi- vided into 2,400 Roman feet square. Each square was called a centuria. The centurias were crossed by road at right angles to each other. The roads that ran north-south were called cardines, and the roads that ran east-west were called decumani. The groma was also used to locate and place monumen- tation for property corners. Once the centurias were in place, maps were drawn on bronze tablets giving a physical representation of the centuria. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, re- prisal, or because all or a part of an individual’s income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA’s TARGET Center at (202) 720-2600 (voice and TDD).
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