NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Measuring Dip in the 18th Century
From: Gary LaPook
Date: 2014 Jan 1, 12:23 -0800
From: Gary LaPook
Date: 2014 Jan 1, 12:23 -0800
I included his explanation of how he measured the maximum declination.
gl
From: Alexandre Eremenko <eremenko@math.purdue.edu>
To: garylapook@pacbell.net
Sent: Wednesday, January 1, 2014 8:42 AM
Subject: [NavList] Re: Measuring Dip in the 18th Century
gl
From: Alexandre Eremenko <eremenko@math.purdue.edu>
To: garylapook@pacbell.net
Sent: Wednesday, January 1, 2014 8:42 AM
Subject: [NavList] Re: Measuring Dip in the 18th Century
Gary, > I have also attached the June page showing Wright's > determination of the Sun's maximum declination as 23� 30' > north while the > modern value is 23� 26.3' a difference of only 3.7'. Did you take into account that obliquity of the ecliptic decreases at the rate about 0'.7 per century? More precisely, 46".8 per century. This implies that Wright wrote it correctly. I have not read the book yet:-) but I assume that he was using some astronomical tables available at that time, or did he determine all astronomical constants himself?? Alex. I have also included > Wright's explanation of how he determined the Sun's declination. > > http://en.wikipedia.org/wiki/Gregorian_calendar > > gl > > gl > > Attached File: http://fer3.com/arc/img/126089.march declination table from > wrights book.jpg > > Attached File: http://fer3.com/arc/img/126089.june declination from > wrights book.jpg > > Attached File: http://fer3.com/arc/img/126089.explanation of declination > determine by wright_page_1.jpg > > Attached File: http://fer3.com/arc/img/126089.explanation of declination > determine by wright_page_2.jpg > > > : http://fer3.com/arc/m2.aspx?i=126089 > > > >
: http://fer3.com/arc/m2.aspx?i=126097
