(i)The Object vane consists of metal vane with a vertical hair. The main principle of compass surveying is traversing. The surveyor’s compass is usually mounted over a tripod and leveled by using ball and socket mechanism. Compass surveying is mainly employed in areas that is free from local attraction. In practice compass is generally employed to run a traverse. It contains a prism which is used for accurate measurement of readings. Lost your password? Therefore, this can be used for surveying the land area with undulations which is crowded and large. A line of sight helps to sight the other end of the survey line through the compass. A meridian is any direction such as True Meridian and Magnetic Meridian and Arbitrary Meridian. Whenever in traversing compass is used for making angular measurements, it is known as compass traversing or compass surveying. All Rights Reserved. Compass surveying is the branch of surveying in which directions of survey lines are determined with compass and the lengths of the lines are measured with a tape or a chain. When the line of sight is directed towards a line, the magnetic needle points towards magnetic meridian and the angle which the line makes with the magnetic meridian is read at the graduated circle. Quantity of Cement and Sand Calculation in Mortar, Types of Foundation for Buildings and their Uses [PDF], Tips to Avoid Reinforcement and Embedment Congestion in Concrete Members, Thumb Rules and Specifications for Design of Reinforced Concrete Beam. Focusing the Prism: Till the readings are observed sharp and clear, the prism attachment is slid up and down for proper focusing. Afterwards turn compass-box until the ranging rod at the station is bisected by horse-hair of objective vane. If it is not used as a hand instrument, a tripod is used to support the instrument for levelling. In such an area, the method of traversing is adopted. Login to The Constructor to ask questions, answer people’s questions, write articles & connect with other people. Whole Circle Bearings (WCB) – In this system, the bearing of the line is measured with magnetic North or South in the clockwise direction. It is one of the most convenient and portable forms of the magnetic compass. This direction is known as magnetic meridian. The main principle of compass surveying is traversing. 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This method does not requires the need to create triangles. It contains a prism which is used for accurate measurement of readings. B.B – F.B   =    180       then both stations free from local attraction. They are: Prismatic compass is a portable magnetic compass which can be either used as a hand instrument or can be fitted on a tripod. e.g. A prismatic compass helps to conduct both sightings and reading simultaneously. They can be done only in the circumstances where the internal parts of the prism is disturbed or damaged. Also Read: What is Whole Bearing System (WBS) and Quadrantal Bearing System (QBS) in Surveying? However, this will require the magnetized needle, a line of sight and a graduated circle. If it is downward west of true Meridian then it is called negative or westward Meridian. Explained, Brick Size – Advanced Guide for Civil Engineers and Everyone, The Complete Vastu Shastra : Vastu For House , Home (Tips With images), Bricks – A to Z Information Construction Material. The greatest advantage of this compass is both sighting and reading can be done simultaneously without changing the position. (ii)The eye vane consists of a small metal vane with slit. A compass surveying is performed by means of a magnetic compass which helps to determine the angles and the direction of the survey lines. Some of the important equipment used in surveying includes theodolite, compass, auto-level, chains and tapes, levelling staff etc. He is an Author and Co-Founder at ProCivilEngineer.com Website. Er. Compass surveying is mainly employed in areas that is free from local attraction. If the surveying area is large, chain surveying is not adopted for surveying rather compass surveying is employed. How to rectify the old cement pipeline leakage problem? Virgin Hyperloop Conducts First Passenger Test in Las Vegas. It uses a prismatic compass for measuring magnetic bearing of line and the distance is measured by chain. Magnetic Compass Used in Surveying -Principles & Types. As shown in figure-3 above, the readings increase in clockwise direction i.e. The figure-3 below shows the system of graduation in a prismatic compass. What is the reinforced concrete deep beam and where it used? If the magnetic needle is not perfectly straight or if it is sluggish, readings may not be accurate. It can be attached either to the box or to the needle. Can this type of brick bond be used for bearing walls? The magnetic bearings of a line can be determined by a magnetic compass. Fly Ash Bricks – Why Everyone Recommend this in 2020? This is merely dependent on the type of compass employed for the measurement. The main features of a Magnetic compass are: The purpose of the magnetic needle is to establish the magnetic meridian. Become VIP Member. In compass traversing, the compass is used to determine the direction of survey lines of the framework of the traverse for measuring the angles which these lines make with the magnetic meridian. In compass surveying the direction of survey line called the bearing of line is defined as the angle made by the line with the magnetic meridian. At this position note down the reading. A compass surveying is performed by means of a magnetic compass which helps to determine the angles and the direction of the survey lines. How to Select the Right Curing Method for Structural Concrete Elements? . Compass survey uses the principle of traversing. The whole housing is then supported by means of a tripod or a suitable stand. What are the Methods of Interpolation of Contours. Compass consists of cylindrical metal box of about 8-12 cm diameter in the center of which is a pivot carrying a magnetic needle which is already attached to the graduated aluminum ring. A graduated circle is employed to read the directions of the lines. Read More at https://www.researchgate.net/publication/277611855_Compass_measurement_-_still_a_suitable_surveying_method_in_specific_conditions. Please enter your email address. The error in direction produced in a single survey line does not affect other lines. PRECAUTIONS This is the working principle of a magnetic compass. This method is generally used for plotting precise work, mainly a theodolite traverse, both closed and open. In compass surveying the direction of survey line called the bearing of line is defined as the angle made by the line with the magnetic meridian. It is less precise compared to other advanced methods of surveying. The bearings can be measured either in the whole bearing system (WBS) or Quadrantal Bearing System (QBS). It can be held in hand or in a tripod stand for carrying out the measurement. The bearing of a line is its directions relative to a given meridian. The principle of compass surveying is traversing. Imperfect sighting of the ranging rods and inaccurate leveling also causes error. Close traverse starts from one traverse station and closes either on same or on another traverse station whose location is already known. Compass Surveying | Types of Compass | Advantages & Disadvantages of Compass Surveying with Example | In this Article we are discussing what is compass chain surveying , the definition of chain surveying, how many types of chain in surveying. For example- 5° 30′, 16° 00′, 35° 30′, The essential parts of the prismatic compass are listed below. b) Compass Surveying. In this method, the position of different points are plotted on a plan with reference to two lines yy 1 (y-axis) and xx 1 (x-axis) which are respectively parallel and perpendicular to the meridian (Fig.