NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Henry Halboth
Date: 2013 Feb 22, 23:29 -0500
Brad wrote: "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."
I agree, it is not unlikely that the navigator got his ephemeris from some "simplified" almanac, e.g. Bowditch. I have Bowditch 20th edition, 1851, giving data "for the year 1848, which will answer nearly for the years 1852, 1856, 1860" and for three more years after these; for 1851 ("or nearly for 1855, 1859, 1863") EoT is stated as 1m11s and declination 23d21m for Dec 27th.
Attached is an excel file giving a summary of the 20 observations reduced, starting December 24th and ending January 9th. It is possible to "run" these data against an almanac for different years and find out the year that gives the smallest residual error.
In Frank's picture there are 10 observations per page, the first 5 are on the left page, right column, top down, obs 6 to 10 in the left column. Obs 11 to 15 are on the right page, left column, top down, and obs 16 to 20 in the right column, top down.
The vessel was eastbound, into the Mediterranean. During the period a net distance of some 2300 miles was covered in 16 days, giving an average speed of 6.0 knots. The chronometer was gaining 5 seconds a day.
There may be typing or interpretation errors ...
Lars 59N 18E
----------------------------------------------------------------
NavList message boards and member settings: www.fer3.com/NavList
Members may optionally receive posts by email.
To cancel email delivery, send a message to NoMail[at]fer3.com
----------------------------------------------------------------Attached File: 122462.summary-c1870.xlsx
