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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: TEN lunars stars?
From: Frank Reed CT
Date: 2003 Dec 18, 20:18 EST
From: Frank Reed CT
Date: 2003 Dec 18, 20:18 EST
Herbert Prinz, you wrote:
"To narrow down the search, as I said yesterday, the earliest source that I could instantly check is the Connoissance from 1790. It does not show Beta Cap. This is relevant because the French got their data from Maskelyne. Moore, The New Practical Navigator, 1800, says explicitly that the almanac lists 9 stars. Earlier editions (I checked that of 1794) do unfortunately not list the distance stars explicitly."
I'll try to check a few more almanacs sometime in the next week. But you're right, plenty of sources are explicit about nine stars after 1800, so I would guess it must have been stable for at least five years.
And:
"It now occurs to me that a better explanation than national character may be found in the changing latitude of the moon. The latter swinging in a band of 10 degrees causes the same swing over a period of 18 years to appear in the distance from Altair at conjunction."
Aha. That's clever. It would be worth checking to see if it matches the numbers.
"What I don't understand, though, is why both stars would have been used in the same year? "
Beta Cap would have been a great choice if it weren't so faint, and I agree with your earlier suggestion that this was the problem. Presumably, Maskelyne and others who prepared the almanac got feedback from navigators who used the tables, and they probably told him Beta Cap was hopeless.
Frank E. Reed
[X] Mystic, Connecticut
[ ] Chicago, Illinois
"To narrow down the search, as I said yesterday, the earliest source that I could instantly check is the Connoissance from 1790. It does not show Beta Cap. This is relevant because the French got their data from Maskelyne. Moore, The New Practical Navigator, 1800, says explicitly that the almanac lists 9 stars. Earlier editions (I checked that of 1794) do unfortunately not list the distance stars explicitly."
I'll try to check a few more almanacs sometime in the next week. But you're right, plenty of sources are explicit about nine stars after 1800, so I would guess it must have been stable for at least five years.
And:
"It now occurs to me that a better explanation than national character may be found in the changing latitude of the moon. The latter swinging in a band of 10 degrees causes the same swing over a period of 18 years to appear in the distance from Altair at conjunction."
Aha. That's clever. It would be worth checking to see if it matches the numbers.
"What I don't understand, though, is why both stars would have been used in the same year? "
Beta Cap would have been a great choice if it weren't so faint, and I agree with your earlier suggestion that this was the problem. Presumably, Maskelyne and others who prepared the almanac got feedback from navigators who used the tables, and they probably told him Beta Cap was hopeless.
Frank E. Reed
[X] Mystic, Connecticut
[ ] Chicago, Illinois
