TIL because pendulum clocks are unreliable at sea, the first attempt at a marine chronometer was undertaken in 1673 utilizing a balance wheel and spring for regulation instead of a pendulum. This opened the way for the first modern pocket watches and wristwatches.

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This was a HUGE deal because until then there wasn’t any real reliable way to measure longitude. Latitude was easy, all you needed was a sextant to measure the sun’s angle at noon and the compare it to a printed chart, but once you were out of sight of land there was really no way of knowing how far east or west you were. The simplest solution was to have a clock that was set to GMT and then compare how far off it was from local noon. But that requires a decently accurate time piece, which is where our dude comes in. It was a massive leap forward in marine navigation and accelerated the Age of Exploration. It can’t be overstated how much this affected European imperialism.


It’s an amazing story of John Harrison fighting the European scientific community that the device he built worked accurately even on water, in waves, different temperatures and different humidity. Took him 40 years to prove it.


There’s an excellent exhibition about this in the National Maritime Museum in Greenwich, London. Well worth a visit. Edit: it’s the Royal Observatory not the NMM, I stand corrected!


I was gifted the book “Longitude “ many years ago by a customer at the bar where I worked. Harrison’s story is incredible and a wonderful read. The same customer suggested I read “Two years before the mast” , also a great read. Enjoy!


Pendulum Clocks didn’t work well on your wrists either…