<Ul> <Li> Back staff, the best known of which is the Davis' quadrant . It could measure the altitude of the sun without having the navigator directly observe the sun . </Li> <Li> Cross staff, an older instrument long out of use . </Li> <Li> Kamal Very simple instrument used primarily by Arabian navigators . It consists of a small board with a knotted piece of twine through the center . The observer holds one of the knots in his mouth and extends the board away so that the edges make a constant angle with his eyes . </Li> <Li> Mariner's astrolabe Derived from the astrolabe, it was developed in late 15th century and found use in the 16th to 17th centuries . It was replaced by the back staff and later by the octant and sextant . </Li> <Li> Quadrant A very simple instrument which used a plumb bob . </Li> </Ul> <Li> Back staff, the best known of which is the Davis' quadrant . It could measure the altitude of the sun without having the navigator directly observe the sun . </Li> <Li> Cross staff, an older instrument long out of use . </Li> <Li> Kamal Very simple instrument used primarily by Arabian navigators . It consists of a small board with a knotted piece of twine through the center . The observer holds one of the knots in his mouth and extends the board away so that the edges make a constant angle with his eyes . </Li>

Which instrument is used for finding the position and movement of ships and planes