When a level rod is "rocked"

$($a$)$ eliminates the need to ever read three wires

$($b$)$ the rocking motion should be as fast as possible

$($c$)$ allows one to better interpolate past $0\mathrm{.}01$ ft $.$

$($d$)$ requires the instrument person to read the lowest reading of any wire

Three collinear points $A,B,$ and C are used to determine if an EDM requires a constant correction to all

measured lines. Horizontal distances $AB,BC,$ and $AC$ are measured to be $150\mathrm{.}12ft,140\mathrm{.}23ft.,$ and

$290\mathrm{.}37$ ft $.$ respectively. The correction that needs to be applied to every measured distance is

$($a$)-0\mathrm{.}01$ ft $.$

$($b$)+0\mathrm{.}01$ ft $.$

$($c$)-0\mathrm{.}02$ ft $.$

$($d$)+0\mathrm{.}02$ ft $.$

Direct and reverse zenith circle readings to the same object are $80-00-10$ and $279-59-40$ respectively.

The correction that needs to be applied to every zenith circle reading is

$($a$)+5$ seconds

$($b$)-5$ seconds

$($c$)+10$ seconds

$($d$)-10$ seconds

The two ends of a $50$ ft $.$ tape are off in elevation relative to each other by $0\mathrm{.}5$ ft $.$ This creates an error

in the horizontal distance in this length of tape by

$($a$)0\mathrm{.}06$ ft $.$

$($b$)0\mathrm{.}001$ ft $.$

$($c$)0\mathrm{.}03$ ft $.$

$($d$)0\mathrm{.}1$ ft $.$

A differential leveling instrument

$($a$)$ has only a vertical and no horizontal motion

$($b$)$ has eliminated any need in surveying for trigonometric leveling

$($c$)$ is checked for systematic error via a peg test

$($d$)$ must be set up exactly over all turning points