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How Analog Tide Predictors Changed Human History (hackaday.com)
szczys writes: You'd think tide prediction would be quite easy: it comes in, it goes out. But of course it's driven by gravity between the moon and earth and there's a lot more to it. Today, computer models make this easy, but before computers we used incredible analog machines to predict the tides. The best of these machines were the deciding factor in setting a date for the Allies landing in Europe leading to the end of the second world war. From the Hackaday story: "In England, tide prediction was handled by Arthur Thomas Doodson from the Liverpool Tidal Institute. It was Doodson who made the tidal predictions for the Allied invasion at Normandy. Doodson needed access to local tide data, but the British only had information for the nearby ports. Factors like the shallow water effect and local weather impact on tidal behavior made it impossible to interpolate for the landing sites based on the port data. The shallow water effect could really throw off the schedule for demolishing the obstacles if the tide rose too quickly. Secret British reconnaissance teams covertly collected shallow water data at the enemy beaches and sent it to Doodson for analysis. To further complicate things, the operatives couldn't just tell Doodson that the invasion was planned for the beaches of Normandy. So he had to figure it out from the harmonic constants sent to him by William Ian Farquharson, superintendent of tides at the Hydrographic Office of the Royal Navy. He did so using the third iteration of Kelvin's predictor along with another machine. These were kept in separate rooms lest they be taken out by the same bomb.
This may have affected the timing of the invasion somewhat, but IIRC the days were determined primarily by the moon and the weather. You had a window each month where you had minimal light because the moon wasn't lit or was barely lit. Then there was bad weather, so they called off one planned date.
You'd think Tide prediction would be quite easy, it comes in, it goes out.
Unless you're Bill O'Reilly:
“Tide goes in, tide goes out. Never a miscommunication. You can’t explain that. You can’t explain why the tide goes in.”
Not trolling; just sayin' apparently not as easy as one might think - even way back in 2011.
It must have been something you assimilated. . . .
Unless you RTFA, "Kelvin's predictor" has no fucking meaning.
she lifts oceans,,, who believes her reflective magnetic resonance cannot help us heal (intentionally) & feeling compelled to breed like bunnys since/until forever... little miss dna cannot be wrong,, free the innocent stem cells they have not harmed anyone either... creation is colorblind so far as anyone really knows the moms are our creators... makes sense... hand in hand we stand...
Just like today, they used computers to predict tides. That they computers were relatively primitive and consisted of gears and chains doesn't mean they weren't computers, basically clocks.
None the less, those clocks/computers are beautiful and incredible feats of engineering.
In hardly 30,000 years they expanded all across Africa, broke out of Africa, set up nascent populations all across Arabia, Persia, India, Andaman Nicobar Islands (this is important), Malaysia, Java, Sumatra, Papua New Guinea and reached Australia.
Andaman islands is important because the first clade in the cladogram of world languages is Andamanese and Non-Andamanese. It is very clear to me, as a layman, not a strict scientist, the Great Leap Forward that happened 75000 years ago in our history was the development of abstract language and the ability to exploit coastal resources.
So yeah, tide prediction changed our history. But not 75 years ago in Europe, but 75000 years ago in South Eastern Africa.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
They think we'll just lap this stuff up. But I'm here to wave it off. Not just to rip tides, but to surf something else entirely. This kind of article-fishing eventually turns into website breakers. Which is to say, the editors are all wet.
I've fallen off your lawn, and I can't get up.
Not to say that they are more elegant, but they are elegant, and another example thereof. Sorry English is such a shitty language that it routinely introduces serious ambiguity with as few as three words.
In any case, Naval fire control computers were cool as shit back in the 1950s.
https://www.youtube.com/watch?...
Not to say that they are more elegant, but they are elegant, and another example thereof. Sorry English is such a shitty language that it routinely introduces serious ambiguity with as few as three words.
FWIW, English only allows you to be ambiguous, you could have written "other elegant computer"...
put them in separate buildings?
That seems like doubling the probability of getting screwed by a bomb. Was there some reason they could replace either machine but not both of them?
https://www.youtube.com/watch?...
Table-ized A.I.
Our (United States) No. 2 tide prediction machine was kept in the basement of the Dept. of Commerce during the war.
It is now on display at the National Ocean Service headquarters in Silver Spring, Maryland.
I worked in the tide prediction office for more than 30 years. One of my coworkers was the last person to actually use the machine in the early 1960's.
" it's driven by gravity between the moon and earth and there's a lot more to it."
I'm pretty sure the gravity of the Sun has something to do with it as well.
They were in Liverpool which had not been subjected to any serious bombing since 1941. The risk from the air would have been a precision attack (hard to do).
A German agent placing a bomb in the room it was in was another possibility. One agent would find it hard to place two bombs without discovery, and given how well penetrated the German agent network was in the UK in 1944, if there were two agents working together one would have likely have been a British agent.
http://www.pbs.org/wgbh/nova/e...
http://schools.yrdsb.ca/markvi...
http://www.ncbi.nlm.nih.gov/pm...
But I did know the Nazis were using the Swastika symbol. So what? I will proudly and happily use the Swastika for what it is, a Hindu symbol and a decorative motif from ancient India. I recently ran into a group Indians and their priest in the Starbucks (@ State College PA) The women were wearing white saris with ornate decorative borders. The motifs in their border? The Swastika and the Star of David alternating in a series!
Not sure how many noticed the irony!
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
You missed the point. If both machines were critical then taking out either machine would suffice. The agent (or plane) now has to hit either room to thwart the British. A German bomber would have double the probability of success when the machines were in two rooms.
http://tvbythenumbers.zap2it.c...
"Laplace’s hydrodynamic approach to tide prediction was first put into use by William Thomson, who would later become Lord Kelvin."
Dude scienced so hard he leveled up like motherfucking Gandalf.
It's basic, layered security principles.
Neither machine was irreplaceable, however neither machine was *easily* replaceable either.
Also, either machine could do *part* of the job needed, but not the *whole* job needed. There were other, similar (though less accurate/precise) machines elsewhere that could be pressed into service if needed while one destroyed machine was being replaced. You can use those other machines either to generate the inputs for the second machine, or process the outputs of the first machine. Your results will be correspondingly less accurate/precise, but should still be usable.
You minimize the risk of total destruction by separating the two machines, so that you don't loose the whole shebang in one incident.
You also *increase* the odds of catching a bomber by forcing them to go through *two* sets of security to plant their bombs. Since they can only *hope* to destroy both by bombing them at the same time, catching them at *either* attempt will probably save *both* machines.
If the machines are in the same room, *any* single event can destroy both of them.
If the machines are in different rooms, it takes correspondingly larger events to destroy both of them, and additionally restricts the scenarios in which they can both be destroyed in the first place.