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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Mathematical Notation in 18th cent. Maskelyne's British Mariners Guide)
From: Paul Hirose
Date: 2013 Jun 19, 19:16 -0700
From: Paul Hirose
Date: 2013 Jun 19, 19:16 -0700
Geoff South wrote: > I am working through the mathematical background to 18th navigation, in particular, the contemporary mathematics behind the lunar distance method. I have a copy of Maskelyne's British Mariners Guide, 1763, and cannot understand the notation he uses for longitude eg; > "with the sun's longitude, 1S. 19d. 14m, > the moon's longitude, 8S. 11d. 53m. etc" I used to be puzzled too by the sign notation in the old almanacs. The Preface for 1834 contains a committee report on improvements to the almanac. Item 2 says, "The next point of consideration was of minor importance, and of a less general nature; viz. the proposal to abolish the use of signs, as indicating arcs of 30° in the division of the circle. With the view therefore of preserving uniformity in the arrangement of the values in the Nautical Almanac, and considering it in most cases more convenient in practice, the Committee recommend that the use of signs should be abolished also, and that the degrees should in all cases be reckoned from 0 to 360." http://books.google.com/books?id=L_QNAAAAQAAJ&pg=PR16 I hope you are aware of the Board of Longitude papers online at Cambridge University: http://cudl.lib.cam.ac.uk/collections/longitude --