Q1: One of the Lehmann's rules of plane tabling, is

ANS:A - location of the instrument station is always distant from each of the three rays from the known points in proportion to their distances

Lehmann's rules

1. If the position of plane table station is inside the great triangle, its plotted position should be chosen inside the triangle of error.

2. If the position of the plane table station is outside the great triangle, its plotted position should be chosen outside the triangle of error.

3. The plotted position of the plane table should be so chosen that its distance from the resistors is proportional to the distance of the plane table station from the field positions of the considered objects.

4. The plotted position of the plane table should be so chosen that it is to the same side of all the three rays.

4(a). If the position of the plane table station is outside the great circle, its plotted position should be so chosen that
It lies on the same side of the ray to the most distant point as the intersection k of the other two rays.

The intersection of two rays to the nearer points, is midway between the plotted position of the station and the ray to the most distant point.
lehmann+rule+plane+table+survey.

4(b). If the position of plane table station is outside the great triangle but inside the great circle, the plotted position of the station is so chosen that the ray to the middle point lies between plotted station position and the intersection of the rays to the two extreme points.