For fine measurement, when a scale is drawn using a straight line connecting the opposite angles of a rectangle , it is called corneal scale. This scale is named after the diagonal connecting the opposite angles of the rectangle . Linear distances can be measured in the primary and secondary stages using a simple scale. However, in the practical stage , especially in the case of land surveys, subtle measurements are often required which cannot be done on a simple scale . The corneal scale is used to measure such fine distances. That is, after the initial and second stages, the smaller distances of the third stage can be measured by this scale. This scale is also known as Gunter's Scale because the surveyor Gunter used it extensively in land surveying .