NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Baffled by Baffin
From: tony
Date: 2005 Nov 24, 10:00 +0000
From: tony
Date: 2005 Nov 24, 10:00 +0000
Bruce. Thank you for your message. George. Here is the information your require: (1) Baffin spent the day before (8th July 1612) marking out a meridian line on a small island. On this occasion, he doesn?t explain his method but marks the extremities of the line with long plumblines. (2)The latitude was 65 20. The altitude was 8 51 The declination was not given on this occasion but, when given, his declinations are always about 10 to 11 days out which I guess is caused by the Julian calendar. On that basis his declination is about 20 7 N. By spherical trig, the LHA =115.386 or 7h 42m. As he always uses a 12 hour clock and always refers to time as the hours from midnight or from midday, this fits in neatly with his time of 4 17 24. (3) Even if he has made a slip in his description of the moon?s movement, how can the ?time? at London be greater. Being earlier in the day, the hour angle at London between the moon and the sun must be greater and the time earlier. But he gives the ?time? by Searle?s ephemerides to be 4 25 34 (an hour angle of 113.6). This is what is puzzling me. I would love to see the entry in the ephemerides for 9th July 1612! This problem doesn't arise with later observations which are remarkable accurate, just this pioneering one.