Kamal or Al-Kemal

Replica of an Arab instrument for determining latitude, developed in the 9th century. From the 9th century onwards, Arab navigators used the simple Kamal or Al-Kemal to recover their latitude relative to their home port by measuring the altitude of the North Star above the horizon. For each port, a knot was tied in the cord, which was held between the teeth to indicate the latitude at which one had to sail east or west to reach that port.