1. Navigational History
(Mariners Education/Navigation)

... navigational sciences were highly developed, making use of a magnetic compass and a rudimentary instrument known as a kamal, used for celestial navigation and for measuring the altitudes and latitudes ...

2. Marine Navigation
(Mariners Education/Navigation)

... or patterns. Longitude (λ) Lines of longitude appear curved in this projection, but are actually halves of great circles. Latitude (φ) Lines of latitude appear horizontal in this projection, but ...