TB 9-5220-212-40
NOTE
For north perimeter line, the value obtained in (d) above is
21.28 per sample table. To find column 6, station 1 value, add
21.28 to station 0 value of -179. The rounded-off value is -158,
which is entered for station 1. Station 2 value is calculated by
adding 21.28 to value to station 1 (not rounded off), rounding
off result to nearest whole number. The remaining values for
column 6 are calculated by repeating the sequence.
(f) Complete values for column 7 by adding respective stations of columns
5 and 6.
(16) Repeat technique of (15) above for remaining perimeter lines.
(17) Calculate values for column 6 and 7 in table 5 for north-south centerline (north
to south) as indicated in (a) through (f) below:
(a) Enter value from table 4 north perimeter line, column 7 center station in
columns 6 and 7 for station 0 of north-south center line.
NOTE
In table 4, value is shown as -154.
(b) Enter value from table 4, south perimeter, column 7, center station in
column 7 last station of north-south centerline.
(c) Subtract column 5 last station value from column 7 last station value and
enter result in column 6 for last station.
(d) Subtract column 6 last station from station 0, divide by number of stations
(not counting station 0), and change sign of answer.
(e) Complete column 6 by making an arithmetic progression, using answer
obtained in (d) above and technique described in (15) (e) above.
(f) Complete values for column 7 by adding respective stations of columns
5 and 6.
(18) Repeat technique of (17) above for east-west centerline.
lowest points. Find difference between the 2 values and divide by 2. Record this + value as
surface plate accuracy.
(20) Compare surface plate accuracy recorded in (19) above with plate specifications
listed in table 1. The surface plate will be within tolerance specified. If not, proceed to (21)
through (23) below.
NOTE
Surface plates that meet AA, A, or grade B accuracy must be
labeled with appropriate grade. For surface plates that do not
have grade AA, A, or grade B accuracy, prepare a test report
and deviation. Plot and state accuracy and furnish report to
user.
in figure 2.
17
