| A training manual in conducting a workshop in the design, construction, operation, maintenance and repair of hydrams |
|Session 4: Measuring heads and distance (2-4 hours)|
TO FIND OUT IF THE SIGHT LEVEL NEEDS TO BE CALIBRATED, SIGHT FROM POINT "A" ON TREE (OF OBJECT #ONE) TO TREE (OBJECT #TWO) AND MAKE A MARK, POINT "B". THEN SIGHT FROM POINT "B" BACK TO ORIGINAL TREE (OBJECT #ONE) AND MAKE A MARK AT THIS POINT "C". IF THE SIGHT LEVEL IS PROPERLY CALIBRATED POINTS "A" AND "C" SHOULD BE THE SAME AND AT THE SAME LEVEL AS POINT "B". IF THEY ARE DIFFERENT,
THE POINT MIDWAY BETWEEN "A" AND "C" (POINT "D") SHOULD BE LEVEL WITH "B". CALIBRATE YOUR SIGHT LEVEL TO THIS LINE.