In marine navigation (as in astronomy), spherical trigonometry calculations only allowed angles to be resolved to the nearest 90 degrees (we are talking of the days before calculator or even slide rules, when the navigator was lucky if he had a logarithm table).
For most calculations, the result was always shown from the "polar" directions first (north or south), with the "direction" of the angle (East or West).
Thus angles would be given as N 57 E (the modern version is 057°), N57W (360 - 57 = 303° in modern system), S57E (180 - 57 = 123°) and S57W (237°).
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In some calculations (usually relating to the direction of sunrise or sunset), a navigator would calculate the "amplitude", which is measured from the Prime Verticals (East or West), so that sunset would be said to be at W17N (287°) for example.
This was done this way because there was (and still is) an easy trig formula to calculate the amplitude. But this system is not used for anything else.
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Yes, it means just that.
In marine navigation (as in astronomy), spherical trigonometry calculations only allowed angles to be resolved to the nearest 90 degrees (we are talking of the days before calculator or even slide rules, when the navigator was lucky if he had a logarithm table).
For most calculations, the result was always shown from the "polar" directions first (north or south), with the "direction" of the angle (East or West).
Thus angles would be given as N 57 E (the modern version is 057°), N57W (360 - 57 = 303° in modern system), S57E (180 - 57 = 123°) and S57W (237°).
---
In some calculations (usually relating to the direction of sunrise or sunset), a navigator would calculate the "amplitude", which is measured from the Prime Verticals (East or West), so that sunset would be said to be at W17N (287°) for example.
This was done this way because there was (and still is) an easy trig formula to calculate the amplitude. But this system is not used for anything else.
It means 57 degree North of the Equator and 57 degree East from Greenwich Meridian.