Stadia - came from Greek word for a unit of length applied in measuring distances for athletic contests. It denoted 600 Greek units, or 184 meters 93 centimeters or 606 feet and 9 inches as calculated by present-day international standards.
Stadia is the plural of stadium. It is applied to the cross hairs and rod used in making measurements and method. Readings can be taken with almost all surveying instruments such as engineer's level, alidade, theodolite and engineer's transit.
Stadia consists of telescope with two horizontal hairs called stadia hairs and a graduated/stadia rod. Distances can be measured rapidly by stadia method. By observing through the telescope the apparent locations of the two stadia hairs on a vertically held rod. From the observed interval, the distance from the instrument to the rod is readily computed.
This method can also adapted in mapping requirements and is widely used for locating details and contour points in topographic surveys. More rapid than taping, and under certain conditions could be made as precise. It requires the employment of fewer survey personnel.