Tide for First Place
July 1, 2017 11:00 AM   Subscribe

Think the Colossus was the first computer? Think again! Taking data from tide gauges, complex mechanical tide prediction devices came into use in the early 1800s. The Doodson-Légé Tide Predicting Machine could calculate tide times and heights simultaneously, and is currently on display at the National Oceanographic Centre in Liverpool
posted by emilyw (14 comments total) 27 users marked this as a favorite
Wait… I thought tides were governed by a fairly simple set of equations that anyone with a little time on their hands could work out with a pencil and paper. Not so? Off to read…
posted by Anticipation Of A New Lover's Arrival, The at 11:58 AM on July 1 [1 favorite]

Colossus was the first somewhat general purpose programmable computer, although it did not run stored programs from its memory and ran them instead from a "read only memory" switchboard, and computationally it was not quite equivalent to a Universal Turing Machine. While it was optimized for a range of cryptanalyitical tasks it could have been repurposed without rebuilding it. For example, it might have been possible to use Colossus to calculate artillery range tables, even though it had not been built for that purpose and they were generally made in those days by other purpose-built mostly analog computers. But it was not Turing complete.

The tide computers, like the artillery range table generators of their day, were not general purpose, and were purpose-built for their function, and could pretty much not be used for anything else. Purpose built computers/calculators of this type were a big deal in the late 19th century and even well into the era of actual digital computers, which were much more expensive. Here's one that does Fourier transforms.

Excepting the never-built in its day Babbage Difference Engine and the poorly documented and lost Conrad Zuse Z3, the first known operating Turing complete digital computer was ENIAC, which still was not a stored-program computer, being programmed by a jumper cable switchboard.

The first known stored program computer was Williams Tube testbed "Manchester Baby" in 1948, but it was not considered adequate for practical work. The Manchester Mark I, EDSAC, and CSIRAC were the first Turing complete computers capable of running mutable programs out of random access memory, as nearly all modern computers do, and they all appeared in 1949.
posted by Bringer Tom at 12:34 PM on July 1 [14 favorites]

This is so cool, I didn't know about these. Never realized how much tricky stuff was involved with measuring tides, even before we get to predicting them. Thanks for the post!
posted by LobsterMitten at 12:39 PM on July 1

This is fascinating, thanks for posting it!
posted by metaBugs at 12:41 PM on July 1

Excepting the never-built in its day Babbage Difference Engine

It was the poor neglected Analytical Engine that was (theoretically) Turing complete, but its name doesn't sound anywhere near as cool as the "Difference Engine", so I expect it will continue to be overlooked. Although, to be fair, there were some "difference engines" (or at least other non-Turing complete calculation engines based upon Babbage's difference engine designs, if not actually called "difference engines") built in the 19th century.

I do very strongly feel the attraction of steampunk when thinking about this stuff. It can be very hard to capture how exciting the 19th century must have felt except by projecting our own technological aspirations onto it. Although the two of Phillip Pullman's Sally Lockhart books that I've read do come close without quite tipping over into a sort of steampunk, particularly the first one. The Shadow in the North does start to edge into steampunk territory, at least in terms of the technology.
posted by howfar at 1:16 PM on July 1 [3 favorites]

If we're talking about the first computer including analog and purpose-built ones then forget any sort of artillery calculator and anything designed by Babbage is out of the running too: the Antikythera Mechanism from thousands of years ago qualifies as do water clocks from further thousands of years before that.

Still fascinating to know about these tide computers though, thanks for the post!
posted by XMLicious at 1:56 PM on July 1 [4 favorites]

Since the Doodson-Légé was being built the same time as the Manchester SSEM, I'd say they really were tide.

Mind you, try to get the wavy machine to verify primes and you'd be on to plums.
posted by scruss at 2:24 PM on July 1

Yeah, Antikythera if we're being loose, otherwise nothing implemented until EDVAC or later.
posted by Segundus at 2:26 PM on July 1

Didn't von Neumann build one in the basement of the Institute for Advanced Studies at Princeton? Since he invented the von Neumnan architecture I assumed that was the first.
posted by msalt at 2:42 PM on July 1

Von Neumann's computer was EDVAC, which also came online in 1949. It was used until 1961 when it was replaced by a machine called BRLESC.
posted by Bringer Tom at 5:34 PM on July 1 [2 favorites]

So EDVAC camed after EDSAC? I get confused by all the very similar acronyms. Thanks!
posted by msalt at 6:26 PM on July 1 [1 favorite]

  Von Neumann's computer was EDVAC

EDVAC was Mauchly & Eckert's, and wasn't really commissioned properly until 1951. von Neumann's machine was the IAS Machine, and it wasn't operational until 1952. The US was a bit slow to get started with the whole stored program computer thing due to Mauchly & Eckert's patent bickering.
posted by scruss at 7:04 PM on July 2 [1 favorite]

Fantastic- I'd love to see one of these tide calculation machines in action!
posted by Secretariat at 9:13 AM on July 10

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