The astrolabe is an instrument used to measure the height of the stars, such as the polar star and the sun, above the horizon. It was very used by sailors and the information it provides allows us to calculate the latitude of the place where we stand.
The equivalent to the actual and modern GPS
The compass rose is used to aid the determination of the direction in relation to the north pole. It was very used by sailors and its information allows us to calculate the longitude of the place where we stand.