Following two main principle of surveying

1) To work from whole to the part

2) To locate a new station by at least two measurement (linear or angular) from fixed reference point

1) To work from whole to the part

• This principle first establish control point with high precise and then establish minor control point

• To work from whole to the part means larger area from the area to be surveyed is first considered and then smaller part are consider

Example- consider a very large are alike a town to be surveyed

First of all control point A,B,C,D,E are locate with great care within the boundary of area of town

The area which is obtain from this control point is divide into number of triangle .which are further sub divided into small triangle by method of triangulation

E.g. Tringle CED is dividing into small triangle pqr.

2) To locate a new station by at least two measurement (linear or angular) from fixed reference point

• According to the second principle the new station should always fixed by at least two measurement (linear or angular) from fixed reference point

• Linear measurement refer to horizontal distance measured by chain or tape

• Angular measurement refer to magnetic bearing or horizontal angle taken by a prismatic compass or theodolite

Example- from known position P and Q the position of new point R is fixed or located by measuring any of following

By the perpendicular RS and distance QS see in fig (a)

By the two lengths PR and QR see in fig (b)

By the angle α measured at Q and length QR see fig(c)

By the angle β measured at P and length QR see fig (d)

By the two angle α and β measured at Q and respectively see fig (e)

fig.(To locate a new station by at least two measurement (linear or angular) from fixed reference point )

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