NavList:

Hello, Frank!

You wrote: “Wow. I want to imagine you recording all this with an ink quill in a great parchment book, because that is a work of devotion! “

Yes indeed this work is my passion. And lunars are my passion. Long lasting hobby J

You wrote: “I especially like that you investigated micrometer eccentricity. I have tested for it on a few sextants. I haven't yet found one with convincing micrometer error, but I'm convinced it's more common than most navigators would expect.”

Micrometer error is a type of error that is rarely mentioned in publications. The sextant expert Bill Morris wrote in his blog: “Most peaple will be surprised at the size of these errors”. I would like to recomend everyone to read an article in his blog on this topic (link here ). He presents graphs with the results of investigations of the micrometer error of  several sextants (look at the end of the article).

I found another very interesting scientistic article on research results of sextant errors in internet (from 1970s). The language is russian. But if someone is interested in this topic I can translate it (russian is not my native language, but I understand it quite well). Link here

You wrote: “I suspect that a navigator interested in doing a calibration like you describe could get by with far fewer observations, right?”

Yes, of course these 645 sets of observations are not the minimum to calibrate a sextant.  After collecting data from the first group of the sets that covered all the range of the sextant arc I coud draw a rough correction line. I am used to documenting all the measurements to evaluate the tolerances and changes in time. And additionally I have quite reliable results for calibrating the arc.

Modris Fersters