Ten real marine and ship chronometers: Kendall K1, Harrison H4, Arnold, Dent, Earnshaw, Frodsham, Hamilton Model 22, a Russian ship chronometer, a Beagle instrument, and Ulysse Nardin. Photograph credits: 1. File:Kendall Chronometer K1 1769.jpg; Book author:Greenhiil, Basil, 1920-2003; Public domain; ; https://commons.wikimedia.org/wiki/File:Kendall_Chronometer_K1_1769.jpg; Scaled and letterboxed into 9:16 preview with title/caption bars 2. File:Harrison H4 chronometer.jpg; Colonel Warden; CC BY-SA 3.0; https://creativecommons.org/licenses/by-sa/3.0/; https://commons.wikimedia.org/wiki/File:Harrison_H4_chronometer.jpg; Scaled and letterboxed for vertical video; replaces duplicate K1 scene 3. File:Marine chronometer by John Arnold & Son, London, c. 1795 - Clockmakers' Museum - London, UK - DSC05424.jpg; Daderot; CC0; http://creativecommons.org/publicdomain/zero/1.0/deed.en; https://commons.wikimedia.org/wiki/File:Marine_chronometer_by_John_Arnold_%26_Son,_London,_c._1795_-_Clockmakers%27_Museum_-_London,_UK_-_DSC05424.jpg; Scaled and letterboxed into 9:16 preview with title/caption bars 4. File:Marine Chronometer- Arnold & Dent, No. 1131.jpg; Will Fisher; CC BY-SA 2.0; https://creativecommons.org/licenses/by-sa/2.0; https://commons.wikimedia.org/wiki/File:Marine_Chronometer-_Arnold_%26_Dent,_No._1131.jpg; Scaled and letterboxed into 9:16 preview with title/caption bars 5. File:Marine chronometer by Thomas Earnshaw, London, c. 1800 - Clockmakers' Museum - London, UK - DSC05419.jpg; Daderot; CC0; http://creativecommons.org/publicdomain/zero/1.0/deed.en; https://commons.wikimedia.org/wiki/File:Marine_chronometer_by_Thomas_Earnshaw,_London,_c._1800_-_Clockmakers%27_Museum_-_London,_UK_-_DSC05419.jpg; Scaled and letterboxed into 9:16 preview with title/caption bars 6. File:Frodsham chronometer mechanism.jpg; User:Ktr101; CC BY-SA 4.0; https://creativecommons.org/licenses/by-sa/4.0; https://commons.wikimedia.org/wiki/File:Frodsham_chronometer_mechanism.jpg; Scaled and letterboxed into 9:16 preview with title/caption bars 7. File:Movement of the hamilton model 22 world war two time period ships chronometer.jpg; Bonsairolex; CC BY-SA 3.0; https://creativecommons.org/licenses/by-sa/3.0; https://commons.wikimedia.org/wiki/File:Movement_of_the_hamilton_model_22_world_war_two_time_period_ships_chronometer.jpg; Scaled and letterboxed into 9:16 preview with title/caption bars 8. File:Russian Ship Chronometer.jpg; Morn the Gorn; CC BY-SA 3.0; https://creativecommons.org/licenses/by-sa/3.0; https://commons.wikimedia.org/wiki/File:Russian_Ship_Chronometer.jpg; Scaled and letterboxed into 9:16 preview with title/caption bars 9. File:Beagle Chronometer V front.jpg; Graeme Bartlett; CC BY-SA 3.0; https://creativecommons.org/licenses/by-sa/3.0; https://commons.wikimedia.org/wiki/File:Beagle_Chronometer_V_front.jpg; Scaled and letterboxed into 9:16 preview with title/caption bars 10. File:Brodski hronometar, mehanički, Ulysse Nardin.jpg; Miloš Jurišić; CC BY-SA 3.0; https://creativecommons.org/licenses/by-sa/3.0; https://commons.wikimedia.org/wiki/File:Brodski_hronometar,_mehani%C4%8Dki,_Ulysse_Nardin.jpg; Scaled and letterboxed into 9:16 preview with title/caption bars