Saturday, December 28, 2013

Surveying Note for GATE PSUs- part 4

Hello there,
Here is another post for your preparation of GATE and PSUs examinations.
  • A gate cap is fitted with a prismatic compass
  • The temporary adjustments of a prismatic compass are Centering, Leveling and Focusing the prism respectively in order.
  • Swinging is the process of turning the telescope about the vertical axis in horizontal plane.
  • Size of a Theodolite is specified by the diameter of the lower plate.
  • If the lower clamp screw is tightened and upper clamp screw is loosened, the Theodolite may be rotated on its inner spindle with a relative motion between the vernier and the graduated scale of lower plate.
  • A telescope is said to be inverted if its vertical circle is to its right and the bubble of the telescope is down.
  • The cross hairs in the surveying telescope  are placed much closer to the eye-piece than the objective piece.
  • For the adjustment of horizontal axis, the spire test is used for its permanent adjustment.
  • The adjustment of horizontal cross hair is required when the instrument is used for levelling.
  • Error due to displacement of the station signal can not be eliminated by repetition method of angle measurement.
  • The error due to eccentricity of inner and outer axes can be eliminated by reading both verniers and taking the mean of the two.
  • In the double application of principle of reversion, the apparent error is four times the true error.
  • Error due to line of collimation not being perpendicular to the horizontal line can be eliminated by taking mean of both face observations.
  • If a tripod settles in the interval that elapses between taking a back sight reading and the following foresight reading, then the elevation of turning point will increase.
  • If altitude bubble is provided both on index frame as well as on telescope of a theodolite, then the instrument is levelled with reference to altitude level on the index frame or altitude level on telescope if it is to be used as a level.
  • A 'level line' is a line parallel to the mean spheroidal surface of earth.
  • Turning point is the station where both back sight and fore-sights are taken
  • A rise and fall method provides us check on back-sights, foresight as well as on intermediate sights.
  • In internal focusing type of telescope a concave lens is provided.

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