What Happened to the Fusee? The Tiny Chain That Steered Captain Cook Across the World

What happened to the *fusee* — the tiny brass cone and steel chain that sat between the spring and the wheels of John Harrison's H4, Captain Cook's K1 and the Bounty's chronometer, and then quietly vanished from the pocket watch? A mainspring lies about its strength: strong when wound, weak when it runs down. The fusee fixed that with leverage — a chain pulling from the narrow top of a cone at the start of the day and from the wide base at the end. It appears in Konrad Kyeser's Bellifortis around 1405, in the Burgundy clock and in Leonardo's notebooks, and in 1762 it carried H4 to Jamaica only about five seconds out after two months at sea. The chains themselves were made by hand in Christchurch, Dorset, where workhouse girls as young as nine riveted links finer than thread. Then the pendulum, the balance spring and the French going barrel took away the fusee's job — and England held on too long. It survived at sea until satellites took over, inside wartime Hamilton chronometers, and in 1994 it came back in A. Lange & Söhne's Tourbillon Pour le Mérite. Today it is one of the most prized details in the most expensive watches in the world. Chapters 0:00 January 1762 — five seconds after two months at sea 1:36 The spring that lies 5:56 A crossbow and a duke 10:08 From gut to chain 15:24 The longitude prize 19:00 Five seconds to Jamaica 21:44 Our trusty friend the Watch 26:21 The chain girls of Christchurch 30:25 The Swiss let go 33:27 Clocks that never let go 35:43 The last voyages 39:04 The chain comes back Sources: Royal Museums Greenwich (H4, K1, K2, fusee-cutting engine); Linda Hall Library; British Museum (Lépine calibre, Earnshaw chronometer); Red House Museum, Christchurch; Historic England listing for Hart's factory, Bargates; History of Science Museum, Oxford; A. Lange & Söhne; Ferdinand Berthoud; Wikipedia (Fusee, Longitude rewards, Hamilton Model 21). Music: Consecrated Ground; Motions (CC0). Full credits: Sources-and-Credits.txt MORE FROM MY OTHER CHANNEL What Happened to Babbitt Bearings? The Soft Metal That Kept Heavy Machines Running    • What Happened to Babbitt Bearings? The Sof...   What Happened to Lignum Vitae Bearings? The Tropical Wood Trusted Inside the First Nuclear Submarine    • What Happened to Lignum Vitae Bearings? Th...   What Happened to Mechanical Governors? The Devices That Controlled Engines Before Electronics    • What Happened to Mechanical Governors? The...   Why Flat Leather Belts Disappeared — The Power Transmission System Every Factory Once Used    • Why Flat Leather Belts Disappeared — The P...   What Happened to Grease Cups? The Old Lubrication Device Once Found on Nearly Every Machine    • What Happened to Grease Cups? The Old Lubr...   What Happened to Oil-Ring Bearings? The Loose Metal Ring That Oiled Giant Motors Without a Pump    • What Happened to Oil-Ring Bearings? The Lo...   What Happened to Cone Pulleys? The Simple Speed Control System Every Old Machine Needed    • What Happened to Cone Pulleys? The Simple ...   What Happened to Line Shafts? The Factory Power System That Once Ran Entire Industries    • What Happened to Line Shafts? The Factory ...   Subscribe:    / @lostmotionarchive07   🔔 More videos every week:    / @lostmotionarchive07   #Fusee #Horology #WatchHistory #Longitude #JohnHarrison #ForgottenTechnology