Surveying Instruments - Practical Boundary Surveying - page 80

Gun , because it takes Shots on Targets . A Target can be a prism, a prism pole or
a crew member holding a plum bob string. The target is the thing that is sighted
by the instrument person for the purpose of measuring angles and, when the target
contains a prism, for measuring distances.
Line is the direction in which the instrument telescope is pointing. More pre-
cisely, it is the direction in which the vertical cross hair is pointing. When a tar-
get is exactly centered in the vertical cross hair, the target is said to be On Line .
Taking Line means sighting a fixed target with the instrument. Taking line is
accomplished by moving the horizontal tangent screw on the instrument until the
vertical cross hair on the instrument is perfectly aligned with the fixed target.
The meaning of the term Give-Me-Line depends on who is saying it. Give-
me-line can be a request by the instrument person to the rod person to hold the
target over a point so the instrument person can sight the target and set zero on the
instrument. Setting Zero means locking an angle of zero on the instrument vernier
or display when the telescope is pointed at the target. It is also referred to as zero-
ing the instrument or saying the instrument is zeroed . For example, when measur-
ing an angle with the instrument it is first necessary to zero the instrument on the
target from which the angle is to be measured. Give-me-line can also be a request
by the instrument person to the rod person to hold the target over a point so the
instrument person can measure an angle (and usually a distance) to the point. So,
when the instrument person asks the rod person to give-him-line on a particular
stone bound, the rod person must walk over to the stone bound and hold the prism
pole on the bound so that the instrument person can locate it. To Locate means to
turn an angle and distance to some object, usually some piece of physical evidence
such as a stone monument or drill hole.
Give-me-line can also be a request by the rod person to be put on line by the
instrument person. In this case, the direction of the line has already been fixed by
the instrument person. As an example, if we need to establish a point between a
distant target and the instrument, the instrument is first locked onto a target. The
rod person then stands between the instrument and the target. The instrument per-
son instructs the rod person to move right or left until the rod is exactly on line.
Another example would be where the initial field work and calculations have been
completed and the crew has returned into the field to set the final lot corners. The
instrument person sets the instrument on a traverse point and calculates the angle
and distance from the traverse point to the lot corner to be set. The instrument per-
son then turns the instrument to the correct angle and instructs the rod person to
move to the line so she can set the point. In this case, in addition to being on line,
the rod person will also need to be a specific distance from the instrument, so the
EDM will be used to measure the distance from the total station to the prism pole.
When the instrument person gives line he must communicate with the person
holding the target in order to tell her to move left or right so that she is on line.
Some surveyors prefer to tell the rod person to move north or south or east or west
rather than left or right because left or right depends on whether the rod person is
facing the instrument or whether she has her back to the instrument. Additionally,
when using left and right, the direction is always relative to the rod person not the