Screws are a magnificent invention. I've talked about them plenty – think of them simply as ramps wrapped around an axle – so why wouldn't I be interested? They’re simple machines and they literally help batten down the hatches. I figure it’s time to unscrew the lid on their history.

Our old friend Archimedes probably invented the screw. Archimedes' screw is used to pump water uphill, usually for irrigation, through a tube with a metal screw inside: as you turn the screw, the threads scoop up water and push it to the top.

Archimedes' screw

Me, rummaging for my turnscrew.

Have you noticed a pretty major use that's missing here?

That's right: screws weren't used as fasteners. Instead, there were nails, welding, dowels and pins, etcetera, etcetera. This list of “alternatives” is substantial. In fact, we didn’t use screws as fasteners for nearly two millennia after Archimedes invented them.

What was missing? The screwdriver. (Fun fact: we used to call screwdrivers “turnscrews.”) We didn’t invent the screwdriver until the 1500s. Even then, we rarely tended to use screws as fasteners.

The final piece of the puzzle? The creation of machine tools necessary for manufacturing metal screws. Until that happened, they were just too much trouble to produce in large quantities.

Since we optimized that production angle, we haven't stopped turning them out.

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Archimedes' screw gif by Silberwolf (size changed by: Jahobr), CC BY-SA 2.5, via Wikimedia Commons.

Let's say there's a traveling salesman trying to hit a certain group of towns during a week. (I know, I know: eCommerce is eclipsing the traveling salesman these days, but I’m Old School, so bear with me.) To save time, this traveling salesman wants to calculate the best possible route between all the cities—the route with the absolute shortest possible distance—before he returns to the starting city.

Sounds easy: just add up all the shortest distances between cities. Right?

Wrong.

In fact, if you tried the calculations on a home computer, the sun would have already devoured the Earth in its death-throes, billions of years in the future, by the time your computer finished the calculations. (The problem is actually what they call an NP-complete problem, and it’s really complicated, and it makes my head spin, and good luck.)

That's why Google Maps only optimizes routes with no more than ten waypoints in them because going beyond that just requires too much time and computing power. For those of us without the patience to wait billions of years, there are workarounds to the Traveling Salesman Problem.

A Solution to the Problem

One of the best ways is to use something called a genetic algorithm, which begins with a handful of random solutions to the problem…and usually ends up being terrible. So, it then tinkers slowly with each one, discarding all but the best solutions. Eventually, after enough cycles of this, the algorithm produces a route that, while not the absolute best, seems reasonable enough.

The practical applications of the Traveling Salesman problem should be obvious. To shipping companies alone, it represents a ton of time and money. Other industries that are concerned with it include semiconductor manufacturers and paper mills.

We also have a large number of variants in this challenge, including the appropriately named Traveling Politician Problem.

There's an enormous underground chamber just north of Tokyo. The Underground Temple—also known as the G-Cans Project, or the Metropolitan Area Outer Underground Discharge Channel—is a flood water diversion facility.

“Enormous” might be an understatement. It’s more than 25 meters high and 177 meters long. The concrete room is held up by 59 immense, 500-ton concrete pillars. In addition to the main chamber, there are five huge underground silos, each 65 meters deep and 32 m­ in diameter. You could quite literally fit Godzilla in one of those.

Construction on it began in 1992 and didn't complete until 2009. The whole thing is essentially the world's largest drain. The silos and the Temple are linked by hundreds of miles of underground pipes. The entire complex is nearly four miles across.

Tokyo has suffered from frequent floods throughout its history—not just from heavy rain, but also from typhoons and tornadoes. G-Cans was built to withstand even the most massive, once-every-other-century floods. Its 14,000 hp turbines and 78 pumps are capable of pumping more than 200 tons of water per second into the nearby Edogawa River.

The architects and construction crew faced a number of major difficulties in the construction. Earthquake proofing was one of the biggest hurdles. Another: preventing buckling and sagging in the ground overhead as they dug out the complex; it is directly underneath a city, after all.

There was a little criticism about the steep price tag ($2 billion) and the fact that Tokyo already possessed significant flooding defenses. Still, given how prone to natural disasters the city is, I certainly think they made the right call.

So, they have the flood prevention thing covered. Of course, there are still earthquakes, volcanic eruptions, tsunamis, typhoons, Godzilla, and those horrifying giant Japanese hornets to worry about.