& INSTRUMENTS & ACCESSORIES: Triangles, Straight Edge, Metric Scale, Divider, Pencil, Pen, Eraser, Tracing Paper, Cartolina, Scotch or Masking Tape, and Electronic Calculator. $ PROCEDURE : 1. This problem is an indoor lab exercise which highlights a type of office/drafting work required in topographic mapping. It will be assumed that the given data were taken from an actual field obser- vation. 2. The lab instructor has the option to use the prepared data, revise it, or give a new set of data. 3. The accompanying tabulation gives elevations of points over the area of a 50 m by 60 m tract of land. The elevations were obtained by the grid method using 10-m squares. Point A-1 is located at the northwest corner of the lot and point G-6 at the southeast corner. All elevations are in meters. POINT A B C D E F G I 2 1522.82 1559.25 3 4 5 6 1413.45 1362.12 1290.56 1451.65 1391.05 1340.00 1480.37 1400.72 1371.58 1460.00 1410.28 1393. 19 1436.73 1479.15 1495.65 1451.30 1434.05 1470.35 1520.44 1490.68 1545.25 1565.00 1519.50 1485.10 1440.00 1441.32 1462.38 1395.45 1425.68 1506.44 1409.56 1453.68 1545. 15 1430.00 1465.40 1452.98 1458.16 1490.23 1475.10 1470.75 4. The requirements for this lab exercise are : with a contour interval of 20 meters. The proportional spacing of a) Construct a contour map using a horizontal scale of 1:125 LABORATORY EXERCISES 197