What do Geiger counters, medical scanners, aeronautical sensors, space sensors, and photon detectors have in common?

If you said that they're all sensors of one sort or another, you're obviously correct. If you said that they're all sensors for detecting radiation, you're even more correct.

In fact, you can list many different traits that they all have in common. They all fit pretty easily into a few categories.

The reason I asked, though, is due to one very specific and shared quirk: they're all largely built out of salvaged shipwrecks.

Each of these devices requires high levels of sensitivity, meaning that they can't be radioactively contaminated themselves—not even a little bit.

Unfortunately, the overwhelming majority of steel we’ve produced worldwide since the Trinity nuclear bomb test (in 1945; the first time humans detonated a nuclear weapon) is contaminated with higher-than-normal levels of radionuclides (radioactive particles) such as Cobalt-60.

This has been McCoy Fields, man of steel.

This occurs because both the Bessemer process, converting molten pig iron into steel, and the modern BOS steel-making process involve atmospheric gas, with little bits of radioactive particulate drawn in from the atmosphere and planted in the steel.

Though the amount of radioactive materials in the air has dropped drastically since 1963, when nations enacted the Partial Nuclear Test Ban Treaty, radiation still lingers in steel. And we keep recycling our old radioactive steel as scrap metal.

Because of all this, devices that require low levels of radioactive contamination—like our sensors and scanners—can’t use modern steel. Which means that we must use steel produced before the Trinity test.

The best sources of this? Sunken ships—most notably, the scuttled German WWI battleships at Scapa Flow in Scotland.

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Quotable

Oh, Yard Ramp Guy, I might just sink your battleship with this one:

“A person without a sense of humor is like a wagon without springs. It’s jolted by every pebble on the road.”

— Henry Ward Beecher

One of my favorite museums is the Arabia Steamboat Museum in Kansas City, MO. The museum has one of the largest collections of pre-Civil War American artifacts in the world, and it's almost all from the wreck of the Arabia, a paddlewheel steamboat that sank in 1853.

The Arabia was discovered in 1987 by two families that risked everything they owned in their search. Because the Missouri river has shifted over time, they located the Arabia a half-mile away from the river. Excavation began in 1989. Mud preserved the ship almost perfectly.

Artifacts from the Arabia fill the entire museum, which is a huge place that still feels cramped from the size of the collection. The crown jewel of the museum is the actual paddle wheel and driveshaft—and not just sitting there, either. They're both kept in constant motion, though not by the original engine.

While America of the 1800s has a good claim for being the golden age of paddle boats, their use stretches much, much further back in time…and so, naturally, we travel now from Missouri to China.

During the 1130s in China, the Son Dynasty employed heavy deployment of paddlewheel boats. They weren't steam powered, obviously, but instead driven by pedaled treadmills. Even in the 1130s, paddlewheels weren't new; they'd been in use for a long time, but Yue Fei, the Song general, took them to an entirely new level.

These river-faring paddle ships could carry hundreds of soldiers and sailors, were armor plated, were propelled by up to 24 paddle wheels, and utterly dominated the rivers. The largest of them were armed with immense derricks, capable of swinging wrecking irons against other ships and shore-mounted fortifications, along with deck-mounted trebuchets capable of firing incendiary shells and smoke bombs.

Such ships remain utterly unique in the history of the world. No other civilization has built anything like them. And these weren't the last experiment with paddle-driven warships in China. While the Mongols were besieging a pair of cities linked by a huge pontoon bridge, paddle ships were in ample use by both sides. The Chinese defenders used an immense, hundred-strong fleet of paddle ships to run the blockade, while the Mongols created paddle ships with immense circular saw blades attached to them to cut through the bridge.

This sounds absolutely like something out of a cartoon, but it really worked.

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Quotable

Oh, Yard Ramp Guy, paddle around this one:

“You don't paddle against the current, you paddle with it. And if you get good at it, you throw away the oars.”

— Kris Kristofferson

Marengo Cave is an enormous, beautiful natural cave in Indiana. It's easily traversable for tourists, isn't particularly muddy or wet, and is absolutely beautiful.

A group of children discovered the cave in 1883, and the townsfolk—immediately recognizing a potential tourist attraction—quickly declared it a protected site. A few years ago, Marengo Cave was declared a US National Landmark.

It's not the only cave in Marengo, Indiana, though.

The Marengo Warehouse is an old underground limestone quarry located just a few miles away from Marengo Cave. Opened in the 1800s, it contains almost four million square feet of storage space (more than 100 acres), about a quarter of which is in use. The owners converted it from a mine to a storage warehouse in response to competition from much larger limestone quarries.

All sorts of rumors swirl around the warehouse. For example, the Center for Disease Control supposedly stored supplies there for a long time, but the only actual government property inside are some 10 million MREs. The other contents of the warehouse include 400,000 tires and some 23 million pounds of frozen fruit, most of which are intended for use in yogurt.

The Marengo Warehouse is nowhere near unique. All around the world, we’ve converted limestone mines into storage spaces and business parks. This depends on how we mine the limestone. Since the 1950s, miners have worked carefully to ensure that the leftover space is actually useful, carefully removing 12-foot thick chunks of stone in grid-shaped patterns. When mining is completed, very little construction is needed to ready a cave for other purposes.

The underground limestone quarries are extremely stable. Limestone is made of compressed, ancient, tiny seashells. It's three times stronger than concrete, and has been used in construction for more than three thousand years.

Me…in my man cave.

Of course, there are certain concerns with use of the quarries. Ventilation is a much greater concern than in other mines, so electric forklifts are generally required instead of those powered by propane powered. And, while the older quarries are generally extremely stable, the geological strata above and below the facility must be monitored, to watch for shifting or cracking rock layers.

Now, I’m way too hopeful a man to get all bothered by doomsday scenarios, but if you really want to start preparing for all possibilities, those limestone caves might one day save the human race. I’ll stick to my man cave…when Maggie lets me, of course.
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Quotable

Oh, Yard Ramp Guy, just me here, staying on topic with my quotations:

“The cave you fear to enter holds the treasure you seek.”

— Joseph Campbell