NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Transcription of Worsley's Log
From: Brad Morris
Date: 2009 Mar 16, 17:58 -0700
From: Brad Morris
Date: 2009 Mar 16, 17:58 -0700
Hi George Now that I have some confidence in the digits and have the spreadsheet, I can next investigate his chronometer and chronometer error. On 7May1916, Worsley indicates that his "chron[ometer] was much slower than I had allowed".. While we can only estimate his rate, we can certainly investigate his initial error. On 24Apr1916, Worsley writes that the longitude of Cape Belsham is his only opportunity of "rating" his chronometer. The important criteria in this calculation are an exact knowledge of his latitude, longitude, the alitutde of the body and the chronometer reading. I examined my navigational charts of the Antarctic Penninsula and extracted the position of Cape Belsham. The chart number is 29104 (NSN 7642014012241) "King George Island to Clarence Island" with Elephant Island smack in the middle of the chart. Cape Belsham is clearly marked. I make the latitude to be South 61 degrees 6 minutes 22 seconds and the longitude to be West 54 degrees 53 minutes 45 seconds. Next, I used my spreadsheet to enter exact values. On 24Apr1916, Worsley writes that his chronometer was slow by 10 minutes 51 seconds and then proceeds to use 24.40.1 as his chronometer reading. From this we can expect that his chronometer actually read 24.29.10 (+10.51 = 24.40.1). Using 24.29..10; the equation of time for the day 1 minute 53 seconds and the exact latitude, I can vary the chronometer error until the precise longitude is obtained. To obtain the precise longitude, I must use 13 minutes 28 1/2 seconds. That is, while Worsley makes his chronometer 11 minutes 55 seconds slow, I am an ADDITIONAL 2 minutes 33 1/2 seconds slower. That is a substantial difference, to say the least. Best Regards Brad --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---