On Tuesday, April 11, 2017 at 6:59:19 AM UTC-6, Gerald Kelleher wrote:
Over the last 100 years it became popular to announce that 'clocks measure time'
but such a declaration is cheap and unworthy of any individual .

In one sense, it is true that phrase is inaccurate. Time is not something we can
handle and manipulate, and so clocks don't measure it the way that a yardstick
measures cloth.

But I don't think that this is your point.

A mechanical clock, whether it uses a spring or a pendulum or a quartz crystal,
is intended to behave in an unvarying way; to repeat a certain beat, a certain
motion, over and over, taking the same duration for each repetition.

The Equation of Time shows that the daily apparent motion of the Sun in the sky,
over the course of a year, exhibits variations with respect to the time that
mechanical clocks indicate.

If I am baking a cake in an oven, and at a certain temperature, it will take 30
minutes for it to be done, it won't matter if I am baking that cake on April 3rd or June 20th, even though the sundial runs slightly faster on the first date and
slightly slower on the second. The cake is baking on its own, not tied to the
great astronomical cycles, in the same way that the hairspring of a clock moves
on its own, not tied to the great astronomical cycles.

This is why today we use clock time for our purposes of daily living, and not
sundial time.

We even have leap seconds, because we regulate our clocks by the average length
of the day over a hundred years ago, and some of those clocks are accurate
enough to detect that the Earth's rotation has slowed very slightly in that
time.

This is due to the increased mechanization of our world and the importance of
computer networks and the like.

John Savard