Abrams SC-1, Technical Manual

Page: 19 / 39

OPERATION
sun.
This factor is expressed in minutes on
the
date bar of
the
sun
compass,
opposite the appropriate
date.
g.
Changing Mean Solar Time
to
Local Apparent Time.
(1) When the equation
of
time
is applied
to
the
mean
solar
time
for our position,
the
result
is
the local apparent time (true
local sun time)
for
the position.
The
equation of time
is
ex
pressed
in
minutes as
a
plus or minus factor according
to
the
accompanying sign
on
the date bar.
It
should
be
added or sub
tracted
to the mean
solar time as the sign indicates.
The
time
piece,
after
the equation
of
time
is
applied is now
set
at local
apparent time and must
be
maintained at
this
time as long
as
it is
used
with
the
sun compass
in
any
one
locality.
(2) Actually, the entire conversion process
from
local watch
time
to
local apparent time
for
a
locality
requires only
a
few
seconds
when the required data is available.
The
data re
quired and an outline
of
the conversion process
follows
:
h.
Outline of
Time Conversion Process.
(1) Ascertain from military authorities that the timepiece
to
be
used
with
the sun
compass
is
keeping accurate time
in
ac
cordance
with
the time adopted
for
use
in this
locality.
(a)
Determine whether local time
is
the
standard time
for
the
zone
in
which the
locality
lies, or whether
a
fast
or day
light
saving time
is
used.
If
a
fast
time
is
used, ascertain the
number
of hours it
is faster than
the
standard time, and cor
rect the time piece to standard time.
It
is
possible to determine standard time by
time sig
nals
sent
out
by
many observatories either
daily, hourly,
or
sometimes, continuously
every
second
or every other
second
;
to
various
parts of the
world for
the purpose
of giving
accur
ate time.
They
are sent out by
radio
or over telegraph or tele
phone wires.
(2) Determine your position
(your
local meridian) to
the
nearest
degree
from
a
map or
from
instruments.
(3)
Locate the time meridian
upon
which
local standard
time
is
based (see
figure
6).
(4)
If
your
local meridian
(your position) is
east of the
time
meridian
add
four
minutes
for
each degree to
local stand
ard
time.
To
each degree
west
of
the time meridian subtract
11