A straight line test was performed utilizing $3$ points to see if your instrument has a combined EDM$/$instrument constant

error. The test was performed twice by reoccupation of all points to determine if your error is significant. Note all

distances are horizontal. The height of the instrument and height of the targets was measured for each observation.

a$.$ Compute the mark to mark elevation differences for each observation, $A-B,B-C,$ and $A-C.$

b$.$ Compute the average elevation differences for the observation set, $A-B,B-C,$ and $A-C.$

c$.$ Compute the average horizontal distances for the observation set, A$-$B$,$ B $-$ C$,$ and A$-$C$.$

d$.$ Compute the combined EDM$/$prism error for the observation set.

e$.$ Compute the vertical closure for the observation set.