Abrams SC-1, Техническое руководство

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OPERATION
(point
A)
lies
on
the local meridian
which
is
cl<
sest
to the
92
degree
longitude meridian.
(b) The date on which the problem is
bein^
Drked
is No
vember
8, 1943,
and the time which
military authorities
have
furnished is 10:38 A.M.
Wartime,
which
is
one
hour
faster
than standard time
for this
zone.
The
problem
is
worked as
follows
:
(1) Set the timepiece accurately to
10:38.
(2) Note the time 10:38
on a sheet
of paper and subtract
one
hour
to
determine local standard time.
The resulting
time
is 9:38
A.M. This
is standard time throughout the
zone.
(S)
From
the map
we
determine how many
degrees
east or
west our location is from
the
true meridian
for this
zone.
Our
position
is
nearest
the
92
degree
longitude
line
and is
2
degrees
west of
the
time meridian
on
the
90
degree
longitude line. We
must subtract
4
minutes
for
every
degree
we are west
of
the
time meridian,
so
our correction is
4
x
2=8
minutes.
This
subtracted from
9 :38
results
in
the time of
9 :30,
which
is
the
mean
solar time
for
our position.
(4)
To
complete
the
problem and find local apparent time,
we
must apply the time equation
factor from
the date
bar
to
the
time
of
9
:30.
(a) By
observing
the
date bar,
we
see
the equation
of
time
factor
opposite
the
date line which represents
the 8th
of No
vember
is
a
+
16
minutes.
(6) Adding
the
16
minutes to the
mean
solar time of 9:30
results in the local apparent time of
9 :46
A.M.
This is
the
time to which we
will
set
the timepiece to
be used
with
the
sun
compass.
2.
DETERMINING
LOCAL
APPARENT
TIME
DIRECTLY
FROM
THE
SUN
COMPASS.
o.
It
is
possible to determine local apparent time directly
from the sun compass
without referring
to
standard
time,
if
one
can determine true north.
It
is not an accurate method of
de
termining local apparent time and should
be used
only
a«
an
alternate method.
(1) To
ascertain true north it
is necessary
to
correct
a
mag
netic compass reading
for
declination.
15