I think the answer is in your previous post, that is the year is more stable
than the day as compared to the same clock.
And this measurement very likely has been actually made.
Antonio I8IOV
Right.
Defining a second as 1 / 86400 of the length of a mean
solar day is also problematic because you first have to
calculate the mean. How many days or years do you
take the average for?
For a while the second was re-defined as a fraction of
a year instead of a fraction of a day.
Fortunately the definition quickly evolved into a multiple
of a cesium transition (the 9192631770 number), an
apparatus a national lab could build or buy from hp, etc.
The problem was that telling someone that a second is
1 / 31556925.9747 of the tropical year 1900 is not an
easy thing to calibrate a quartz clock by. Hard to get
that year back in your lab in order to re-measure it.
The goals of a units standard in metrology are not just
extreme accuracy and stability. It is also desirable for
a standard to be reproducible, reliable, and commercially
manufacturable; perhaps also affordable and portable.
/tvb
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