alt Hacker NewsTides are weirder than you think
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https://www.youtube.com/watch?v=AxC770lpSLw shows one of the old tide prediction mechanical computers briefly mentioned in this article. It is effectively doing an inverse Fourier Transform, summing all the various 30+ sinusoids that affect the tides.
out the back door of my house, down through the field and woods to the water is a 12 min walk at high tide, and another 12 min + walk to the water at low tide, 53 vertical feet between the two. I know ,not the slightest thing about tides, other than what my senses tell me when walking the shore, and I suppose the practicalities of beach walking along cliffs are similar to planning and predicting arival times for ships loaded to the maximum draft, the money to be made there bieng the motivation behind the push to understand tides.
> Kelvin’s machine automates the second half of that task. As the pulleys spin, they pull on a common chain by the correct amount for each of the calculated components. A year’s worth of tidal tables can be put together in half an hour, if you know the components. Even better, you can “guess and check” the components by comparing your machine’s output to past records, and adjusting the pulleys until you get something that works correctly.
I didn't know they already had machine learning and model fitting algorithms in the 1800s, but here we are...