Surveying notes for GATE, PSUs - Part 5

Hello there,
How have you been? Here is 5th part of one liners for the preparation of the GATE and PSUs.

• Error due to curvature and refraction can be neutralized by setting the level midway between the two stations.
• Height of instrument method of levelling is quicker and less tedious for large numbers of intermediate sights.
• The rise and fall method provides a check on the reduction of intermediate point levels.
• If the staff is not held vertical at a levelling station, the reduced level calculated from the observation would be less than true R.L.
• The difference between a level line and a horizontal line is that a level line is a curved line while horizontal line is a straight line.
• The sensitivity of a bubble tube can be increase by increasing the diameter of the bubble tube.
• With the rise in temperature sensitivity of a bubble tube decreases, because with rise in temperature the liquid expands and bubble gets smaller.
• Refraction correction partially eliminates the curvature correction.
• As applied to staff readings, the corrections for curvature and refraction are respectively "-" and "+".
• The correction for refraction as applied to staff reading is +1/7[d^2/(2R)].
• Sensitivity of a bubble tube is designated by radius of level tube.

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