What do the results of the two PEG test indicate?

The two-peg test is used to make sure the line of sight provides an accurate reading and determine how much of an adjustment is necessary. This should be done by the installer periodically to make sure the instrument is correctly leveled so it provides accurate readings.

How do you check for collimation error?

The collimation error is compensated by multiplying the correction by the BS and FS length difference and adding it to the elevation difference. This requires the length of each sight be captured as the readings are taken.

What is pegging a level surveying?

peg adjustment—A method of adjusting a leveling instrument of the dumpy-level type to make the line of collimation parallel with the as the spirit level, using two stable marks (pegs) the length of one instrument sight apart.

What does a Cowley level do?

Most likely Cowley levels were however used as a modern rotating laser by setting the cursor at a certain level after which the levels of points around the instrument were verified.

What is the collimation error?

The error in alignment between the optical axis of a telescope and the declination axis of its equatorial mount; the two should be exactly perpendicular if the telescope is to track stars precisely.

What does collimation error cause?

Collimation error is the largest potential source of systematic error for area leveling with unbalanced sight lengths, even with geodetic-quality levels. The Leica NA3003 User Manual states the “the standard deviation of a collimation error determined once only under normal atmospheric conditions is about 2 seconds.”

What is a automatic level?

A dumpy level, builder’s auto level, leveling instrument, or automatic level is an optical instrument used to establish or verify points in the same horizontal plane. It is used in surveying and building with a vertical staff to measure height differences and to transfer, measure and set heights.

What is an RL line?

RL (Reduced level) is any spot height that has been compared with another or datum using a level line or HOC. Reduced levels can be below the HOC or above the HOC. An RL is a comparative height when compared with a datum.