[LEAPSECS] alternative to smearing

[Zefram]

Preben Norager wrote:
>           The clock track either the sun (apparent time), or the seconds
>(mean time).

That's not correct.  Both apparent and mean solar time are described
in seconds, and in both cases that's the angular second (1/86400
circle) rather than the second of physical time.  Both are also very
much concerned with the sun, and remain synchronised with it over the
long term.  The difference between the two is merely a matter of whether
periodic smoothing is applied to the orbital motion of the Earth around
the sun.

>When the Nautical Almanac in 1833 substituted mean for apparent solar time,
>an important step was taken. From now on chronometry was to rely on
>mechanical clocks,

I can't make sense of this paragraph.  As a practical matter, mean and
apparent solar time are largely interchangeable, due to the ease of
applying the well-known equation of time.  The change in the almanac
presumably does reflect the use of marine chronometers to maintain
Greenwich time, and the concomitant revolution in the navigational
approach to longitude.  But neither as applied to Greenwich nor to the
navigator at sea did this involve any diminution of solar observation.
The need for direct solar observation *was* reduced in the 19th century,
but not by the use of mechanical clocks: rather, the substitute was
observations of other astronomical bodies, enabled by progressive
improvements in the modelling of planetary motion.

>                                             If we agree to use the
>proleptic gregorian calendar (ISO 8601) there is really no need for leap
>seconds.

How so?  Whether to maintain long-term synchronisation of the time-of-day
clock with solar time seems entirely orthogonal to the question of how
to label the days.

>                                                                    because
>the julian period count apparent solar days.

No, there's no tie between Julian Dates and apparent solar time.  JDs can
be used equally well with apparent and mean solar time.  JDs are in
fact also used with a great many other time scales that do not maintain
synchronisation with these.

-zefram