Tiêu đề 109 Compass Surveying.pdf ✅

MSTC 109: Compass Surveying 1. Compass A compass is a device used to determine the directions of courses. It consists of a magnetic pin that can freely rotate to point at the north. • Pocket Compass – The most common compass which can be easily handheld. • Surveyor’s Compass – A more developed compass mounted on a tripod to ensure level holding. • Transit’s Compass – A surveyor’s compass mounted on a transit. When the surveyor is nearer to the north pole, the attraction in that direction is stronger. The same is true when the surveyor is closer to the south pole. Due to the unbalanced attraction, the pin tilts slightly lower to the nearer pole. The tilt angle is called the magnetic dip of the compass. 2. Bearing and Azimuth The bearing of a line is its acute angle subtended from the north or south directions. The letters "N" or "S" are put before the acute angle measurement to indicate the reference direction. The letters "E" or "W" are put after the acute angle measurement to indicate which direction the line turns from the reference.