Now that you've completed Section 1 of this unit covering double
proportionate or four-way measure, let's continue with Section 2A.
In Section 2A of this lesson, you will apply your knowledge of double
proportionate methods to a problem with several lost corners. Learn
the importance of and basis for index correction in resurvey work,
and solve a problem using a new method, three-point control.
In the first part of this lesson, we dealt with the field problem
where only one corner had been lost, while in all four cardinal
directions, the nearest corners were existent. What if several corners
had been missing? Here, all the corners identified by arrows are
lost. How should we go about finding them? Or as a last resort,
Well, unfortunately there is no magical way to determine the proportionate
position for all the lost points at once. Here is where you must
apply the insight and perseverance of a master detective and the
intelligence and affability of a traveling salesman to do your job.
You must ask yourself and any reliable witnesses available -- what
about all the other corners which potentially surround each lost
corner. Are they all lost?