The usage chain might make entire process a little bit tedious, so a steel tape is in that place. Theodolite, sextant are used for taking angles, Aneroid barometer for measuring elevations.

While determining base line, some of methods are adopted in which usage of rigid bars is one of m. The usage of rigid bars involves in formation of certain classes of which Colby is present.

The classification of survey field into a triangulation system helps in covering entire area, but main intention is to have accuracy in measurement values obtained.

The main objective of using satellite station is to place instrument in surrounding places of point where object has been pre constructed. This involves in enhancing technical knowledge and also in improving false stations.

The base line measurement serves as an important source in process of triangulation. It helps in determination of station points and elevated, peak points in a terrain which help in remaining fields like signals, towers etc.,

Bilby tower is one of types of tower, which is named after inventor, which can uplift observer as well as lamp to a height of 30 m minimum and to a maximum of 40 m. Manual power is needed for upliftment.

The measured base line can contain some errors which will decrease accuracy of output. While using steel and brass wires this possibility increases. So in order decrease prone of having less accuracy, corrections are applied without considering certain parameters.

The corrected angle can be determined by using formula,
Corrected angle = ? + ?₁ ? ?₂. On substitution, we get
Corrected angle = 50?46? + 12?24? ? 13?36?
Corrected angle = 49?34?.

The elevation of a station can be determined by \(h = \frac{D^2 (1-2m)}{2R}\) and from taking its reference h2 will be calculated. It requires certain parameters like keeping line of sight at a height of 2-3 m above point of tangency.

Correction of sag can be given as,
C_s = l*W² / (24*n²*p²). On substitution, we get
C_s = 100*1 / (24*6²*9²)
C_s = 0.00142.