Ten real historic navigation instruments: sextant, octant, Davis quadrant, cross-staff, marine chronometer, nocturnal, traverse board, pelorus, mariner's astrolabe, and sun compass. Photograph credits: 1. File:Sextant-MnM 11 NA 11-IMG 5980-black.jpg; Rama; CC BY-SA 3.0 FR; https://creativecommons.org/licenses/by-sa/3.0/fr/deed.en; https://commons.wikimedia.org/wiki/File:Sextant-MnM_11_NA_11-IMG_5980-black.jpg; 2. File:Octant (AM 643640-1).jpg; Auckland War Memorial Museum; CC BY 4.0; https://creativecommons.org/licenses/by/4.0/; https://commons.wikimedia.org/wiki/File:Octant_(AM_643640-1).jpg; 3. File:Davis quadrant-MnM 11 NA 97-IMG 5987-black.jpg; Rama; CC BY-SA 3.0 FR; https://creativecommons.org/licenses/by-sa/3.0/fr/deed.en; https://commons.wikimedia.org/wiki/File:Davis_quadrant-MnM_11_NA_97-IMG_5987-black.jpg; 4. File:Cross-staff-MnM 11 NA 5-IMG 5989-black.jpg; Rama; CC BY-SA 3.0 FR; https://creativecommons.org/licenses/by-sa/3.0/fr/deed.en; https://commons.wikimedia.org/wiki/File:Cross-staff-MnM_11_NA_5-IMG_5989-black.jpg; 5. File:Chronometer-MnM 13 NA 1-IMG 6378.JPG; Rama; CC BY-SA 3.0 FR; https://creativecommons.org/licenses/by-sa/3.0/fr/deed.en; https://commons.wikimedia.org/wiki/File:Chronometer-MnM_13_NA_1-IMG_6378.JPG; 6. File:Nocturnal-MnM 11 NA 83-IMG 5953.JPG; Rama; CC BY-SA 3.0 FR; https://creativecommons.org/licenses/by-sa/3.0/fr/deed.en; https://commons.wikimedia.org/wiki/File:Nocturnal-MnM_11_NA_83-IMG_5953.JPG; 7. File:Traverse board Forum Marinum.jpg; MKFI; CC BY-SA 4.0; https://creativecommons.org/licenses/by-sa/4.0/; https://commons.wikimedia.org/wiki/File:Traverse_board_Forum_Marinum.jpg; 8. File:Pelorus (instrument).jpg; Stahlkocher; CC BY-SA 3.0; https://creativecommons.org/licenses/by-sa/3.0/; https://commons.wikimedia.org/wiki/File:Pelorus_(instrument).jpg; 9. File:Astrolabe de marin, France, 1603.jpg; Rama; CC BY-SA 4.0; https://creativecommons.org/licenses/by-sa/4.0/; https://commons.wikimedia.org/wiki/File:Astrolabe_de_marin,_France,_1603.jpg; 10. File:Coles Universal Sun Compass 6314c.JPG; Clem Rutter; CC BY-SA 3.0; https://creativecommons.org/licenses/by-sa/3.0/; https://commons.wikimedia.org/wiki/File:Coles_Universal_Sun_Compass_6314c.JPG;