NavList:

Thanks to Alex for starting this stimulating discussion and his clear summary.

I've had a number of features relating to sight reductions reinforced by this discussion.

In my mind we have two explanations, time was off or anomalously large refraction of the terrestial dip.

It is too bad we did not have sights from a range of azimuths. A time error would move the lops either east or west according to the sign of the time error, while an anomalous dip error would produce uniformly larger or smaller altitudes independent of azimuth. Bowditch points out that in the case of anomalous dip refraction the centroid of multiple ( 3 or more ) lops would still produce a good fix, though the triangle or whatever would be larger.

I still believe anomalous dip ( ie larger than normal refraction ) raising the apparent horizon is the cause of these measurements. The conditions for such anomaly we know existed, a large temperature difference between the air and water with the water colder. A time error would explan the results but no independent evidence that such was the case. I think Ocam's razor says to go with the obvious cause.

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