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I detect a certain amount of wriggling here by Frank Reed, in his response
to Trevor Kenchington's objections, and mine, to the "broader shoulders" he
gives to the variation of declination.

We all were (weren't we?) discussing how the declination would vary with
date-of-year, which (assuming a circular orbit for the Earth, as we were)
would change exactly proportionally with ecliptic longitude. So why would
we be even considering how it changes with the right-ascension of the true
Sun, which would NOT change linearly with time?

So when he explains it away by saying-

"So the difference between these two points of view amounts to a difference
in choice of independent variable."

there isn't really any such choice. Only one of those variables is relevant
to the problem in hand.

I'm glad he has cleared the matter up by concluding-

"If you graph the Sun's declination versus time, then you get straighter
sides (narrower shoulders)."

George.


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