
Tide-Predicting Machine No. 2 - Hooke
https://en.wikipedia.org/wiki/Tide-Predicting_Machine_No._2
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juliangamble
If you want to know about Tide-Predicting Machine No. 0 - read the following
from Charles Pezold:

 _In the late 1860s and early 1870s, British scientist William Thomson—later
known as Lord Kelvin—developed a technique based on Fourier analysis to
mathematically predict the pattern of tides for particular seaports. Never
just a theoretical physicist, Thomson then designed a machine to carry out
these calculations. One of these tide-predicting machines is on view in the
Science Museum in London. Today we categorize this machine as a special-
purpose analog computer. While it’s certainly interesting from a technical
perspective, it also has a surprising role in the history of 19th century
science: William Thomson began his research into the tides in the midst of the
Darwin Wars following the 1859 publication of The Origin of Species, and part
of the impetus behind this astonishing machine was nothing less than to prove
Darwin wrong. From the clash of thermodynamics, geology, and evolution, the
era of analog computing was born._

You can read more here: [http://www.charlespetzold.com/blog/2016/12/Computer-
of-the-T...](http://www.charlespetzold.com/blog/2016/12/Computer-of-the-Tides-
Chapter-1.html)

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betterunix2
I love mechanical computers like these. The engineering is amazing, and bugs
are not considered a fact of life in these systems. One thing I often wonder
about is how many mechanical computers/state machines are still in operation
and why.

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jeffwass
You might like this video about the US Navy fire control computer. Mechanical
yet also programmable. Eg with cam-based calculation modules like 1/x or
differential gearings to perform addition :
[https://m.youtube.com/watch?v=gwf5mAlI7Ug](https://m.youtube.com/watch?v=gwf5mAlI7Ug)

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bacon_waffle
Thanks for the link! I had meant to look these up after watching videos of
some Hamming lectures
([https://www.youtube.com/playlist?list=PL2FF649D0C4407B30](https://www.youtube.com/playlist?list=PL2FF649D0C4407B30))
where he mentions using "gun directors" for various problems.

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emmelaich
Mentioned in a previous HN thread where I contributed this comment:

[https://news.ycombinator.com/item?id=15830348](https://news.ycombinator.com/item?id=15830348)

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steve19
I love mechanical computers. Does anyone know of any basic mechanical
computers still used in everyday life?

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dfox
One probably still relevant usecase for mechanical state machines are
elevators. Original design of push button controled elevators is surprisingly
simple and involves mechanically implemented state machine where the carriage
itself is part of the controller mechanism (the overall idea is that on each
floor there is switch that gets flipped by the passing carriage that signals
whether the carriage is above or below that floor), such systems are certainly
still used (second generation of automatic elevator controllers implement the
same logic "electronicaly" by means of johnson counters built from mechanical
relays instead of the distributed electromechanical logic).

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vinceguidry
"Old Brass Brains," a better personification for an analog computer I have not
seen.

