Path: utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!usc!elroy.jpl.nasa.gov!decwrl!hayes.ims.alaska.edu!accuvax.nwu.edu!nucsrl!telecom-request
From: 0002909785@mcimail.com (J. Stephen Reed)
Newsgroups: comp.dcom.telecom
Subject: Re: Spring Ahead, Fall Behind
Message-ID: <14610@accuvax.nwu.edu>
Date: 12 Nov 90 06:23:00 GMT
Sender: news@accuvax.nwu.edu
Organization: TELECOM Digest
Lines: 60
Approved: Telecom@eecs.nwu.edu
X-Submissions-To: telecom@eecs.nwu.edu
X-Administrivia-To: telecom-request@eecs.nwu.edu
X-Telecom-Digest: Volume 10, Issue 813, Message 3 of 8


David Tamkin (and others) have just rescued a small portion of my
mental health!

Tamkin recently responded to an item on the "leap second":

>> [Philip Gladstone:]
>> A point to note is that the leap second which is inserted (or
>> removed) is the last second before 00:00:00 *GMT*.

> Leap seconds are never removed.  The whole reason that we have leap
> seconds is that the second was redefined in the late 1960's by some
> physical or atomic standard (just as the meter was redefined around
> the same time and the inch followed); there was a choice between a
> definition that was slightly too short for 1/86,400 of an average
> solar day and having to add leap seconds occasionally and one that
> was slightly too long with a result of needing to skip leap seconds
> occasionally.

I remember vividly being a callow lad of 13 on June 30, 1972, when the
leap-second was announced in the papers for that night, as a curiosity
item.  It scared me to death!  Why?  Because I was credulous enough
(as a brainy but unworldly kid would be) to take the AP wire
reporter's explanation at face value.

The way it was phrased, the explanation implied that the earth was not
keeping pace with accurate clocks <because the earth was revolving
more slowly all the time.> (True, in one sense, but far from the whole
truth!)

So I got out my dad's Bowmar Brain (arithmetic functions only, ten
cubic inches, $299.95) to figure the number of seconds in a day, and
then to divide that by five.  (For the article predicted the need for
a leap second every four to five years.  This ended up being
conservative, as someone else noted -- we've had ten or twleve since.)

The quite natural result was that the earth would stop revolving in
about A.D. 19252.  (86,400 seconds/day divided by 5 being 17,280
years.)  And, of course, this would be The End.  Not in a geologic
epoch, when the Sun turns nova, but in 700 human generations.  I was
scared stiff!

As I matured, I suspected that something was wrong with that
explanation of the leap second, but I put it at the back of my mind.
Nonetheless, you don't shake pubescent fears that easily out of your
subconscious.

Later, I read that the mean solar day had been estimated to have
shortened by as few as ten minutes over the past three billion years
of geologic evidence.  Still, though, this nagged at me.

Thank you, Mr. Tamkin et al., for saving my mental equilibrium by
<finally> stating the connection between clocks, the earth, and the
leap second.  Now on to more important things, like predicting when
we'll "liberate" Kuwait.


Steve Reed
Liberty Network, Ltd. * P.O. Box 11296 * Chicago, IL 60611
0002909785@mcimail.com