A Levelling Sheet, Reduced Twice, With the Check LEVEL
If the three totals disagree, something is wrong now, while the instrument is still up, rather than in three weeks when a drain runs uphill.
The run
Leave the closing level empty on a run that does not close back onto a known point; the arithmetic check still applies, and it is the half that catches most mistakes.
The readings
StationBacksightIntermediateForesightRemarks
A change point carries both a foresight and a backsight: the reading that closes one setup and the reading that opens the next, to the same staff position.
The check
The sheet
The working
Questions people ask about LEVEL