TM 5-6675-323-14
(1) Read largest number visible on barrel, i.e., 15.
(2) Count full divisions visible between 15 and 20, i.e., 3.
(3)
Add:
15+3=18.
( 4 ) Marks below the line indicate 0.5. Mark between 18 and 19 is
visible, so add 0.5, i.e., 18.5
(5) Read hundredth's scale, i.e., 0.41.
(6) Total reading: 18 + 0.5 + 0.41 = 18.91.
e.
Make
elevation
reading.
(1) Place left optical dot over point for which elevation is to be
determined.
(2) Place right optical dot over same point in right photograph.
(3) Look through stereoscope and turn micrometer knurled knob until optical
dots are fused and apparently contact ground at point.
(4) Read micrometer scale, and record reading to hundredths of millimeters.
f.
Determine
differential
parallax.
(1) When elevation reading at unknown point is smaller than datum reading,
assign minus value (lower elevation).
(2) When elevation reading at unknown point is greater than datum reading,
assign plus value (higher elevation).
(3) Determine numerical difference between datum reading and elevation
reading.
This number is differential parallax (
p).
10-10
