Still studying!
I have The Macmillan & Silk Cut Nautical Almanac from 1981 which pre-dates WGS84 and they make reference to the NM being 6046 feet at the equator and 6108 feet at the poles. Conversions to metres = 1842.82m and 1861.71m. Remarkably similar to WGS84 derived figures of 1842.9m and 1861.57m. Just goes to show the old ways take some beating!
I also have to hand "The Oxford Companion to Ships & The Sea" by Peter Kemp printed 1976. There is a passage included in it I nearly understand which I think is very relevant and might clear some of my confusion up if I understood it correctly as follows:
"Geographical latitude, also called true latitude is equivalent to the true altitude of the elevated celestial pole at the place. This is always greater (except at latitude 0 or 90) than the corresponding angle at the earths centre, which latter angle is called the geocentric latitude of the place."
I do understand the part about the elevated celestial pole but it is the suggestion that any random point on earth can have 2 latitudes depending on the method used in calculating it.
Can anyone offer further explanations.
Thanks
Mike
1 answer