NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: How Many Chronometers?
From: Robert Eno
Date: 2009 May 06, 17:13 -0400
From: Robert Eno
Date: 2009 May 06, 17:13 -0400
I'd like to chime in here (no pun intended) The methods described by the group seem to be dependant upon taking observations with relatively course nautical instruments. Seems to me unless you are one hell of a superb navigator, you would not be able to discern what is a clock error vs. what is an observation error. Determining your longitude and/or time via lunar distances for example, is only as accurate as the observer and his sextant and with so many variables (temperature, observer error, instrument error, refraction etc.) is it realistic for one to expect that he can determine chronometer error by this means? Unless your chronometer is out by hours. I may be way off base here so feel free to correct me. Robert ----- Original Message ----- From: Brad MorrisDate: Wednesday, May 6, 2009 4:57 pm Subject: [NavList 8164] Re: How Many Chronometers? > > Hi Jim > > True, it is a clock with a known rate, but the rate can change! > Let us assume for a moment a mechanical chronometer. As the > lubrication ages, the rate changes. In the literature, you can > see instances of a sea rate and a land rate. Temperature can also > affect the rate. For an electronic (quartz) chronometer, a very > run down battery will have a slowing rate. > > For any of these items, how would you know the rate was changing? > Greg suggested comparison to other chronometers. Henry and I have > suggested celestial observations with a known longitude. > > We can even see Worsley and Shackleton, attempting to correct > their chronometers by lunar occultations, when stuck on the ice in > the Weddell Sea. > > Best Regards > Brad > > > -----Original Message----- > From: NavList@fer3.com [NavList@fer3.com] On > Behalf Of James N Wilson > Sent: Wednesday, May 06, 2009 4:39 PM > To: NavList@fer3.com > Subject: [NavList 8163] Re: How Many Chronometers? > > > Brad: > > I guess I thought that a chronometer was defined as a clock with a > constant rate of change. > > Jim Wilson > ____________________________________________________________ > New to Digital Photography? Click Here. > > > > "Confidentiality and Privilege Notice > The information transmitted by this electronic mail (and any > attachments) is being sent by or on behalf of Tactronics; it is > intended for the exclusive use of the addressee named above and > may constitute information that is privileged or confidential or > otherwise legally exempt from disclosure. If you are not the > addressee or an employee or agent responsible for delivering this > message to same, you are not authorized to retain, read, copy or > disseminate this electronic mail (or any attachments) or any part > thereof. If you have received this electronic mail (and any > attachments) in error, please call us immediately and send written > confirmation that same has been deleted from your system. Thank you." > > > > --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---