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Replying to my posting stating-
|
| >The locus of an observer who was somewhere unknown on that circle
becomes,
| >after that displacement, not a circle at all. It's distorted, and
the
| >greatest distortion occurs in directions at 45 degrees (and 135,
225,
| >315 degrees) to the direction of travel.

Herbert Prinz replied-

| I don't understand this. Shifting the circles in an east-westerly
| direction does not distort them at all. Therefore shifting them
| north-south must distort them the most. No?

Not so, Herbert. If you shift every point on a circle (or any other
geometrical figure) in an East-West direction by a certain number of
DEGREES, then its shape and size remain quite unaltered; that's true.
But it's not what we are doing here. We are shifting by a certain
number of MILES, East or West, so points that are in higher latitudes
get shifted more, in longitude, than those near the equator, and a
similar eggy distortion is the inevitable result. However, the
situation is a bit more complex that I first thought when I wrote
those words at the top of this posting, and although I am quite
confident that they are true for directions of travel due N, S, E, or
W, I am less sure whether they apply just as well to courses in
between them. That needs a bit more pondering.

Here, I wish to record a first. This is, as far as I can recall, the
first time on this list that Herbert Prinz has EVER been caught out in
getting something wrong. And I doubt if it will ever happen again.

| >I haven't come across the A'Hearn and Rossano paper, but it
certainly
| >seems worth looking up.
| >
| I will send you a copy. It may take a few days.

Thank you, Herbert; that is kind.

George.

   

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