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> From: "George Huxtable" 

> This attention being given to appendix G distracts from the real value of
> John Karl's book, and I understand that in the new edition, this, and a few
> other matters, are corrected.

What I do get from this is star-to-star distances have been published in at
least two texts I know of, all which seem to fall a bit short of actually
doing the calculations for the moment, and adjusting refraction for
sea-level barometric pressure, altitude, and temperature; but close to the
theoretical value, although not always spot on.

Discussion of this star-to-star nonsense (as I have recently learned) is
waste of electrons, George.

"Accuracy of Measuring Inter-Stellar Distances.

page 129,  refers to methods of determining index error, and specifically
mentions inter-stellar angles as a means of checking sextant accuracy.  He
concludes it is impracticable as the superimposition of stars cannot be made
accurately enough,  and "the error in the readings is unacceptably large".
He places the error as large as 5 minutes of arc, which even I find
surprising and considerably larger than I would have thought.  He also makes
the point that I have mentioned of different eye acuities having an effect:
namely the ability of judging continuity of a line as opposed to
superposition of points."

Personally when swinging the sextant I perceive I am judging lines, or at
least as I was taught in visual perception (the key word here being
"perception," or why a movie flickering at 28 frames per second looks like
fluid motion.)

Thanks to terms like "rigorous and scientific vs. "anecdotal evidence" I see
the light. I would have preferred an MIT, Princeton etc. study over Yale or
Harvard (lawyers and MBA's vs. the sciences) but how can one argue with hard
scientific evidence like, "Observations were made on land; on a small boat
yawing at anchor; reaching in a force 3 wind at sea;  Beating into force 4
wind etc ...

"I note the error in most cases including the 'ideal' conditions was a sigma
of around 0.33 minutes of arc.  This means an accuracy range of 0.66 minutes
of arc is to be expected in 68% of observations;  and 1.32 minutes of arc in
95% of all observations."

The results are not really too bad under field conditions IMHO.  Just for
openers, rigorous?  What size (length and beam) is a small boat? Light,
medium or heavy displacement?  Keel type?  Wind direction/duration and fetch
or frequency and amplitude of waves/swell?  Test subjects experience and
instruments?  On board measurements of pitch, roll and yaw? Measurement from
the top of a wave/swell? Anchored??

Oh well, back to the coconuts ;-)

Bill B.



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