Temporary Adjustments of Prismatic Compass | Guide to Surveying

Temporary Adjustments of Prismatic Compass | Compass Surveying

In this article, we will be discussing step by step method for making Temporary adjustments in Prismatic Compass necessary for carrying out Compass Surveys.

  1. Fixing the compass to thr tripod
  2. Centering the compass
  3. Levelling the compass
  4. Sighting the object
  5. Observation of bearings

Fixing the compass to the tripod

The box of prismatic compass is fixed to a spindle of ball and socket joint. By the ball and socket arrangement, this can be quickly levelled and rotated in any direction.

Centering the compass

The prismatic compass is centered over a survey station correctly by means of a plumb bob or by dropping a pebble from the centre of the instrument.

Read moreTemporary Adjustments of Prismatic Compass | Guide to Surveying

Designation of Bearings | Compass Surveying

Designation of Bearings | Guide to Compass Surveying

In my previous article, I discussed different types of Bearings in Compass Surveying. In this article, we will discuss in brief different designations given to the bearings depending on measurement of angles.

Designation of Bearings

  1. Whole circle bearing
  2. Reduced Bearing (RB) or quadrantal bearing (QB)
  3. Fore Bearing (FB) or forward bearing (FB)
  4. Back bearing or Backward bearing (BB)
  5. Calculated bearing

Whole Circle bearing

Bearings measured from north in a clockwise direction is termed as whole circle bearing.

The value varies from 0 degrees to 360 degrees.

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Guide to Compass Surveying | Open and Closed Traverse

Compass Survey | Guide to Surveying and Levelling

Compass Survey is also known as Angular Surveying.

The branch of surveying in which the position of the object is located by angular measurements taken by the compass is known as “Compass Surveying”.

Purpose of Compass Surveying

When the area to be surveyed is relatively large, then the area cannot be divided into triangles.

For example:

Towns, colonies etc.

When the survey work is to be completed quickly

When the area is full of obstacles which prevent chaining.

Compass Surveying is unsuitable in areas having magnetic rock, iron core, power lines etc which attracts a magnet.

Traversing

A traverse is formed by joining the points on the ground by means of series of connected straight line.

There are two types:

  1. Open traverse
  2. Closed traverse

Read moreGuide to Compass Surveying | Open and Closed Traverse