The Almanac of Collapsing Records

The Sea Clock Keeps Time — the Atlantic to Jamaica, 1761

The deck of a warship crossing the Atlantic toward Jamaica, November 1761

November 1761 — a British ship two months out of Portsmouth on a westward Atlantic passage, carrying a brass sea watch under lock and key to be tested against the oldest problem at sea, the finding of longitude

Something the size of a saucer was quietly ending the oldest argument at sea. This breach reads the SAILOR ON DECK on the westward Atlantic passage of 1761: two months of water in every direction, the ship's position a matter of estimate and argument, and each day the officers unlocking a case to wind a brass watch that keeps London time regardless of the sea. The witness is read only at the deck work and the watching — the tedium, the wet, the long uncertainty of the crossing held plainly in the background, the machine itself the whole marvel. The fragment is the subject's own: the day a small careful thing proved right against everyone's guessing — and the memory beneath it of a time something patient and unglamorous in their own life turned out to be exactly correct.

From the record

longitude at sea could not be reliably determined in the 1750s, and ships navigated largely by dead reckoning, latitude sights, and estimate
John Harrison's fourth timekeeper, H4, was a large watch about five inches across, made of brass and steel with a white enamel dial
H4 was carried aboard HMS Deptford, which sailed from Portsmouth in November 1761 bound for Jamaica
the watch was kept in a locked case and, by the terms of the trial, was wound daily in the presence of witnesses, the keys held between several officers
on arrival at Port Royal, Jamaica, the longitude computed from the watch was found to be in error by only a few miles after the crossing
the crossing took roughly two and a half months, and the watch was carried back to England the following year for further examination

The era door

a squat oak cabin door with iron hinges gone green with salt, the wood swollen tight in its frame, a rope becket for a handle stiff with tar

THE ATLANTIC — NOVEMBER 1761

Walk this day yourself — free

A guided walk with Wallace — you are placed inside the record as a witness, and you carry a memory of your own back out. Free, ~20 minutes.

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MEMORY IS RESISTANCE · IN SERVICE OF VELOCITY · YEAR 3037