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Stephen:
I have also
held, for years, that if time is to be expressed in am and pm terms (as is
almost inevitable with traditional analog watches and clocks), that midday
should be expressed as 12:00 noon and midnight as 12:00 mid.
However, if,
for mechanical reasons, "noon" and "mid" are not possible, I have further held
that noon should be 12:00 am and midnight should be 12:00 pm. As you or someone
else mentioned, pm stands for "post meridiem" (not post meridian, by the way).
Midnight is, quite obviously twelve hours after the meridian, so the use of
12:00 am is nonsensical. Noon is the culmination of the ante meridiem period,
for which all the other times are shown as am.
Depending on
the resolution of the clock, the second or the minute after noon and midnight
would be pm and am, respectively.
I theorized,
here (to several objections), that the use of am for midnight and pm for noon
started with the advent of digital clocks (specifically, the early
electromechanical ones). To show 12:00 noon as 12:00 am and 12:00 midnight as
12:00 pm would have increased the complexity of the mechanism, so the
manufacturers compromised, as the error would only be visible for one minute (or
one second).
My childhood
memories (in England) are of a 12:00 pm midnight. I could also have sworn that,
at the time I emigrated to Canada (1957), that was also the Canadian usage. I'm
not sure whether or not Joe Reid every disputed that. I believe Chris Keenan
did. However, as he is much much younger than I am, his experience is
post-digital-clock.
Someone
argued, in this thread, that midnight should be 12:00 am, because it's followed
by 12:01 am. I would counter that it should be 12:00 pm, because it immediately
follows 11:59 pm. Both statements are equally valid (or equally nonsensical,
depending on where one is standing).
The fact is,
though, that we're stuck with a logically questionable convention which is
totally overcome by moving to the universal use of the 24-hour clock, running
from 00:00:00 to 23:59:59. I don't think anyone on this list is going to dispute
that.
Bill Potts,
CMS
Roseville,
CA
http://metric1.org [SI Navigator]
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