Procedure:
1. Select a convenient point C such that you can easily see both given points A and B from it.
2. Let your colleague (rear chainman) hold the tape at point C and move in the direction C–A until you reach a position in which you can conveniently hold the tape horizontally.
3. Let the rear chainman orient you in the line C–A and pull the tape.
4. If the length between points A and C is more than the tape length, select convenient points between these points and align them in straight line by ranging.
5. Record the distance you used in the above step.
6. The rear chainman will move from point C to the pin you fixed in step 4, and the whole procedure will be repeated until you reach point A.
7. Repeat step 2 up to 6 starting from A going to C.
8. The distance between A and C will be the average of the distance C-A and A-C.
9. Calculate half the distance A-C. Point ‘a’ should be along the line A-C at half the distance A-C.
10. Locate point ‘a’ on the line A-C.
11. Repeat steps 2-9 for line B-C.
12. Locate point ‘b’ on the line B-C.
13. Measure the distance a-b in the same manner you measured the distances A-C and B-C.
14. Distance AB can be estimated by the following equation:
AB = 2 * ab