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.

Comments

Re:Moon...

[techno-vampire]

Yes, a full moon was important, as well as acceptable weather conditions. However, the state of the tides was also important. The planners wanted the landing to take place before dawn, on a rising tide. Not only did that expose more of the beach obstacles, it meant that grounded landing craft would be afloat again sooner, making them able to bring in reinforcements sooner. And, if the landings didn't take place on June 6, the next time the tides would be right would be in two weeks, without a full moon.

Tide prediction probably saved the human race

[140Mandak262Jamuna]

In the evolution of humans, genetics show a bottleneck about 75000 years ago. Some catastrophic global event, probably a volcanic eruption, nearly wiped out all the hominids that were ancestors of Homo sapiens, in Africa. The best evidence suggests the only bands that survived the event clung to life in the east African coast near the southern end of the continent. They seem to have subsisted on shell fish and other crustaceans collected during the low tide. There are some telltale marks of intelligence about that band. Scratches on stone tools that could be decorations or ownership marks, shells with holes punched through them to make garlands of shells, using fire to sharpen and temper their stone tools etc.

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.

Great Leap Forward,it is.

[140Mandak262Jamuna]

I did not know Nazi's were using this phrase. I give rats tail to Nazis. I have seen "Great Leap Forward" being used in this context, to the unknown combination of traits that changed our species from anatomically modern H sapiens to behaviorly modern H sapiens. It is not something I coined. I'm not going to abandon it and cede permanent ownership to the Nazis.

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!