Plane table accessories or equipments required to carry out survey
The instruments required to carry out the plane table survey are as follows:
• Plane table: It consists of board, 750×600 mm and about 25 mm thick. It is mounted on a tripod.
• Alidade: This is the instrument, about 45 cm long which is used on the plane table for taking sights. It is made up of metal or wood.
• Spirit level: It is a small metal tube containing a small bubble of spirit. It is used for levelling the plane table.
• Compass: It is made up of rectangular box of non-magnetic metal. It is used to make the north direction on the map.
• U Fork or Plumbing Fork with Plumb Bob: It is a metal strip bent in the shape of a U having equal arm lengths. The top arm is pointed and the bottom arm carries a hook for suspending a plumb bob. It is used for centering the table over a station.
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