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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

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