NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Yvon Massé
Date: 2023 May 2, 15:18 -0700
[references NavList post from 2004: https://navlist.net/Letchers-Lunars-Math-FrankReed-may-2004-w15950]
I complete the Frank Reed's topic of May 2004 after a long research about the formula:
P = HP*{y + 0.000145*HP*cot D*[(cos h_moon)² – y²]}
that appeared in an article on the lunar distance but that I did not understand. I didn't know how to use it either.
I finally came across George Huxtable's text:
https://www.siranah.de/sources/About_Lunars_by_George_Huxtable_2002.pdf
which led me to John Letcher's and I had the explanation I was looking for. I finally found the Frank's topic and since I had previously been led to another hypothesis, I propose to expand on it.
To find this formula, it is also possible that John L. was inspired by the work of William Chauvenet, Spherical and Practical Astronomy of 1863, that he used to validate his results. You can find this work digitized by Google here:
https://books.google.fr/books?id=6JlzJHd15vQC
[...see APPENDIX]
