On Mon, 12 Mar 2007 11:34:41 -0400, Wilbur Hubbard wrote:

There seems to be a contradiction between 5 and 6. Longitude not based
on time, yet the need for an accurate timepiece? You seem to overlook
the obvious, both time, as we measure it, and longitude are based upon
the same thing, a revolving earth.

No contradiction. Only misconceptions in your mind. Let me explain one
more time. This time please get your head out of your ass.

1) Astronomers plotted celestial bodies and made tables telling where
these bodies would be in the sky and when.

2) a sextant and tables of celestial body positions can be used to tell
you your geographical position on the face of the Earth.

3) the TABLES don't work without accurate time because the angles change
as time changes. A second of time matters. This is because the Earth
rotates.

4) The lat/lon grid system is an arbitrary one. It is based on the
properties of a sphere and has NOTHING to do with time. Time could stop
but the grid system would remain exactly the same. Picture actual lines
painted on the Earth's surface. These lines remain even if time stops.
Time has NOTHING to do with the grid system

5) Time IS USED to reference the exact angle of a celestial body as it
appears from a given GP on the face of the sphere which GP is defined by
the lat/lon grid.

Longitude is NOT based upon a revolving Earth. Longitude lines exist as
an artificial series of lines space on the Earth's surface by geometric
parameters. Time is not involved one iota. The Earth could stop rotating
yet the Meridians of Longitude would still exist.

Really? Well, I'm sure you noticed that the longitude lines converge at
the poles. Let's "arbitrarily" move them, to converge on say Dallas,
think your navigation would work, with or without a timepiece? Don't
think so. The grid is *not* arbitrary, and for all your calculations to
work, as you admit, you need a reference. That reference is time.