NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Brad Morris
Date: 2013 Feb 21, 21:35 -0500
Hi Lars
It matters not what the actual Equation of Time was. It matters only in the volume of Bowditch that the scrap of paper was found in! I think it highly likely that our navigator got his EoT value from a table found within.
Also, to eliminate dates, we need to know the publish date for that volume. Since our navigator is not a time traveler, he must have used his scrap of paper after that date.
So we need two things from Frank (1) A scan of the EoT Table and (2) Publish date of the volume.
Regards
Brad
Frank asked: "How confident are you in the year of the observations?"
Well, as the subject included "c.1870" I searched a couple of years before and after 1870 and got "the best fit" for declination and equation of time to 1871, December 27th. But as pointed out there was a 2 seconds discrepancy in EoT.
Since the observation I looked at, top left, was made only 8 minutes before noon GMT, you could expect that the navigator would have used the noon figure for EoT. He (or she ?) used 1m10s, but the NA of 1871 shows 1m12s.
Now, looking at other years, the same date, we find 1875 1m12s, 1879 1m12s, 1883 1m12s. Going the other way, 1867 1m11s, 1863 1m12s, 1859 1m10s, 1855 1m10s.
So maybe the year was 1855 or 1859. Is that plausible?
Lars
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