TM 5-6675-322-14
( 1 ) R e a d l a r g e s t n u m b e r v i s i b l e o n b a r r e l , i . e . , 1 5.
( 2 ) C o u n t f u l l d i v i s i o n s v i s i b l e b e t w e e n 1 5 a n d 2 0 , i . e . , 3 .
(3) Add: 15 + 3 = 18.
(4) Marks to below the line indicate 0.5. Mark between 18 and 19 is
v i s i b l e , s o a d d 0 . 5 , i . e . , 1 8 .5
( 5 ) R e a d h u n d r e d t h ’ s s c a l e , i . e . , 0 . 4 1.
( 6 ) T o t a l r e a d i n g:
18 + 0.5 + 0.41 = 18.91.
e.
Make elevation reading.
( 1 ) P l a c e l e f t o p t i c a l d o t o v e r p o i n t f o r w h i c h e l e v a t i o n i s t o be
determined.
(2) PIace 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 . D e t e r m i n e d i f f e r e n t i a l p a r a l l a x .
(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.
T h i s n u m b e r i s d i f f e r e n t i a l p a r a l l a x
4-10
