NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Sine curve to approximate declination
From: Wolfgang K�berer
Date: 2004 May 21, 16:56 +0200
From: Wolfgang K�berer
Date: 2004 May 21, 16:56 +0200
May I add some historical points to the discussion about graphical solutions for finding the declination of the sun. The method described by Jim Thompson in his post of Wednesday 19 has been described by Portuguese writers on navigation in the early 16th century. You can find a (rather obscure) drawing showing this method in Francisco Rodrigues manuscript "Livro de Marinharia" of about 1513 (first published by Armando Cortesao around 1940), it also appears in the writings by Joao de Lisboa (around 1514) and in the Ribeiro planisphere of 1529. The first published description of this method can be found in Martin Cortes "Breve Compendio de la Sphera y de la Arte de Navegar" (1551). That book was translated into English a couple of years afterwards and was in fact the first manual of navigation in the English language preceding Bourne`s "Serten Rules" by several years. Regards, W. Koeberer
