Compass - Surveying tools and Instruments

Prismatic Compass

• Least count is 30 min
• Graduation provide in only one side i.e Clockwise
• 0 degree are on a south direction
• used to measure whole circle bearing
• Needle is a broad Needle (Not ace as a index)
• Tripod is not compulsory
• Sighting and Reading taking can be done simultaneously
• Prismatic compass with agate cap
• Graduated ring and needle are connected

Surveyor compass

• compass-least count is 15 min
• Graduation provide on both direction i.e. clockwise and anticlockwise
• zero are on a both north and south direction
• used to measure reduce bearing
• Needle is of Narrow Needle.(Act as a Index)
• Tripod is Compulsory
• Sighting and reading can not be done simultaneously
• Box and graduated ring are connected

Trough compass

• It is used in plane table to mark North direction
• In this compass two graduated scale are provided with readings

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