I had occasion to be in old RootsWeb Archives and found the following. I
found it very intersting and thought others might also. So it is copy/pasted from
its site into this
e-mail for your concideration. Enjoy as I did. Beej--Fireflower
Previously published in
MISSING LINKS: A Weekly Newsletter for Genealogists Vol. 3, No. 5, 30 January
1998
TIME LINKS: Thanks to the Internet, we can chat online in real
time with friends from all over the world. Finding a mutually
convenient time for all parties can be a challenge.
WHAT TIME IS IT?
by Karl Machamer (karl_mach1(a)prodigy.net)
TIME is determined by the deg:min:sec of longitude where you are
located. People at the east end of a State, are at a different
"True Local Time" (TLT) than those on the west end of the same
State. TIME is determined by degrees of longitude (each degree is
further broken down into 60 mins and then into 60 secs). To keep
things simple: each degree of longitude = 4 minutes of TIME.
4 mins (time) x 15 degrees (longitude) = 1 hour (time
differential).
In the USA, we use established "Standard Time" (STD) (i.e.,
Eastern, Central, Mountain, and Pacific) for everyone to refer
to. For example, without that STD, a TV show could be broadcast
by using TLT, but the TLT might be 9:17 p.m. in Wisconsin and
everyone would have to adjust. I might have to tune in at 11:43
p.m. TLT to catch the beginning of that broadcast. Thus the need
for a STD, which we have already adjusted to without even knowing
it. It is rare that where we live is actually on the Time STD
meridian, but because we all set our clocks to that STD, we all
tune in at the same TIME.
The Greenwich Mean Time (GMT) meridian = ZERO Degrees longitude,
is widely used as a reference point (in time). For each 15
degrees West Longitude we subtract 1 hour from GMT. That means,
the EST meridian being at 75 degrees West, is 5 hours from GMT.
Let's say a Field HQ tells its ships, planes, and ground forces
to begin an operation at 11:59 p.m. The problem is that they are
scattered all over the globe. To avoid confusion, it is standard
practice to issue that TIME in terms of GMT. That way each
operational unit only has to refer its starting time to GMT (not
to HQ, which might well be on the move itself).
Now, we are talking about the INTERNET here and people all over
the world might be tuning into a Real Audio broadcast of an event
or even to an IRC Chat guest. If we all referred to GMT, people
all over the world would be looking at the same reference all the
time, whereas if we used our local time STD, they would have to
figure out WHERE we are, and adjust accordingly. Since there are
thousands of Internet events daily, it makes sense to use GMT.
I know that I am five hours from GMT; others might know they are
two hours from EST. If we all start thinking in terms of GMT, the
Internet, and the world as a whole, would be better off. We live
in a shrinking world; we travel around the globe in a matter of
hours. It makes sense to use a single reference point -- that
being ZERO degrees meridian or GMT. Here is a conversion chart:
Meridian Time Differential
********** ******** ******************************
0 deg 12am GMT midnight reference (tomorrow)
75 deg WL 7pm EST minus 5 hours (today)
90 deg WL 6pm CST " 6 " "
105 deg WL 5pm MST " 7 " "
120 deg WL 4pm PST " 8 " "
(WL = West Longitude) The above changes by one hour when your
local time is using Daylight Savings Time.
GMT = Greenwich (England) Mean Time, and is typically
stated in a four-digit / 24-hour clock format. All hours
after NOON have 12 added to them; therefore, you can see:
0001 (1 minute after midnight)
0010 (10 minutes after midnight)
0100 ( 1:00 am)
1000 (10:00 am)
1200 (12:00 pm - noon)
1700 ( 5:00 pm)
2100 ( 9:00 pm)
2359 (11:59 pm)
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