Changes

A ''Sextant''' is an instrument used for navigating on the sea by sighting on a star and determining its elevation above the horizon.  It is excellent for determining latitude, but accurate longitude measurements require good timepieces as well, capable of working on ships which pitch and roll on the waves.

A '''Sextant''' is an instrument used for navigating on the sea by sighting on a star and determining its elevation above the horizon.  It is excellent for determining latitude, but accurate longitude measurements require good timepieces as well, capable of working on ships which pitch and roll on the waves.