Answer: astrolabe

AnswerCrossword Clue
ASTROLABESextant forerunner
ASTROLABENavigation tool
ASTROLABEForerunner of the sextant.
ASTROLABEPredecessor of the sextant.
ASTROLABESextant's predecessor
ASTROLABESextant's forerunner
ASTROLABEOld navigational instrument
ASTROLABEOld navigation instrument
ASTROLABESextant predecessor
astrolabeastronomical instrument for taking the altitude of the sun or stars and for the solution of other problems in astronomy and navigation: used by Greek astronomers from about 200 b.c. and by Arab astronomers from the Middle Ages until superseded by the sext
astrolabea compact instrument used to observe and calculate the position of celestial bodies before the invention of the sextant