BBC - A History of the World - Object : Nocturnal or Nightdial
Nocturnal | Canada Science and Technology Museum
Nocturnal Anglais, an instrument for measuring time at night, with lunar date and time scales, 17th century (wood) by
Jamestown Settlement & American Revolution Museum at Yorktown - The nocturnal was an instrument used by 17th century navigators to determine time at night. The wooden instrument is engraved with the months