The Sinking City of Venice

Atlantis redux

While on our first European vacation years ago, Morgen and I visited Venice, that beautiful Italian city where the streets are paved with water. We were there for only a few days, but we enjoyed every minute of it. The place oozes history, and it’s wonderfully romantic. When we took the customary gondola ride through the city’s canals, our gondolier casually pointed toward a small house and said, “Marco Polo used to live there.” And we could believe it—if it were not for the constant noise of motor boats, it would be easy to imagine that the city looked much the same way centuries ago as it does now. But it’s not quite the same as it was in Marco Polo’s time. Whatever other changes have happened, the most significant one is that the city, as our gondolier reminded us, is sinking.

Of course, the entire planet is doomed to be destroyed when the sun explodes in 500 million years or so, but I’m not losing any sleep over that. Why should I worry about Venice? It still looks OK to me, so it must be sinking very slowly, right? Well, not really. Venice is located in a lagoon on the edge of the Adriatic Sea. When Venice was founded in the year 421, the level of the Adriatic was about 5 meters (16 feet) lower than it is today. For centuries the water level rose very, very slowly, but in the last century or so the rate has increased dramatically. With each passing year, the difference between street level and water level shrinks faster. From time to time, the city gets a brief reprieve. As recently as 2005, unusual weather patterns caused Venice to experience exceptionally low tides—so low that boats could not navigate most of the city’s shallower canals. Nevertheless, the clear trend, as observed over centuries, is in a decisively downward direction. If nothing is done and the trend continues, by 2055, a significant portion of the city’s walkways, plazas, and ground-level floors will be submerged all the time.

That Sinking Feeling

For a long time I was puzzled about just what it meant for Venice to be “sinking,” because that doesn’t fit into my categories of things a city is capable of doing. This is in fact a somewhat simplistic description of a complex problem. One part of the problem is that the city is not built on a solid foundation. Venice was originally a collection of muddy islands. In order to construct buildings, workers drove millions of pilings—thin, sharpened poles made of alder trees—through the mud and into the marginally more solid base of sand and clay beneath. Oak planks were placed on top of the pilings, and on top of the planks, several thick layers of marble (which is impermeable by water) formed the foundations of the buildings. From there on up, most of the construction was done in ordinary brick or wood. At the time the buildings were constructed, the marble was well above the high water line, so there was nothing to worry about. However, over the centuries, the weight of the buildings has driven the pilings deeper into the mushy seabed. In addition, at one time there were hundreds of wells in the city, removing water from deep aquifers. Unfortunately, these aquifers had acted as a sort of balloon of water propping up the city; when it was “deflated,” the city began to sink even faster.

But the literal sinking of Venice, which averages something like a few centimeters per century, is only part of the problem. The other part is that the surrounding water level has been rising at an alarming rate. This is partly due to the effects of global warming and partly due to centuries of poor environmental management in the entire region. But in any case, the rising waters compound the sinking problem and make the net effect quite serious.

When It Rains, It Pours

Venice has always been subject to periodic flooding—mainly in winter, and especially at high tide. This is something that residents have come to regard as a fact of life, and not a terribly troublesome one; most of them get around in boats anyway. But whereas flooding used to be something that would happen a few times a year, now it happens on the order of a hundred times a year. Because the sea level has risen, even in a modest flood, the water level rises above the waterproof marble foundations of the buildings, rapidly wearing away the less-robust building materials.

In November, 1966, a particularly bad storm caused a devastating flood that put much of the city under 2 meters (over 6 feet) of water. This caused extensive damage to both buildings and the valuable artwork they contained, and began to impress upon Venetians the need to take drastic action.

In 1970, a plan was proposed that involved the installation of large, mobile gates at the three inlets of the lagoon; these would be raised as needed to keep out high water. But for the next 30 years, a series of excruciating delays prevented any significant progress from being made. There were, of course, significant engineering problems to be solved, not to mention the problem of financing such an ambitious undertaking. But political reasons, more than anything else, held up development. Many Venetians did not want to believe their city was in imminent danger—and even to the extent that they did, there was tremendous disagreement about how best to address the problem. Some wanted to address the problem at the base—to basically “jack up” the city and install new and improved foundations. Others wanted to build a series of dikes and locks around the city—the so-called “Dutch solution”—or use a different mechanism to hold back high waters.

Holding Back the Sea

At the end of 2001, a plan was finally put in motion to keep back the high waters. A project called MOSE (an acronym for Experimental Electromechanical Module in Italian, but also an allusion to Moses) involves the construction of 78 steel gates, hinged at the bottom, installed along the sea floor at the three inlets to the lagoon. The gates, which are hollow and normally filled with water, measure 20 meters wide, 3.6 meters deep, and 20 to 30 meters high. When water levels appear to be rising dangerously high, compressed air will be pumped into the gates, causing the ends to float up to (and slightly above) the surface. In effect, they will form a dynamic dam that will appear only when needed. The gates will be tall enough to hold back water quite a bit deeper than the 1966 flood.

Although construction has been underway for quite a few years and significant progress has occurred, there are still numerous problems ahead, and the completion date has been delayed repeatedly. One issue is the 5.5 billion euro (and counting) cost, and more specifically the vast portion of that sum that has disappeared due to corruption. There are also significant environmental concerns; the project was vigorously opposed by numerous environmental groups. Among their concerns is that any interference with normal tides will increase the levels of toxic chemicals such as mercury in the waters of Venice, seriously threatening both marine life and the health of people who consume the local fish. There are also basic worries about health and sanitation. Venice has no sewer system; household waste flows into the canals and is washed out into the ocean twice a day with the tides. No one is certain quite what effect the gates will have on the city’s natural waste treatment system.

An Uncertain Future

Under the most optimistic prediction, Project Moses will be fully operational by 2022, but given the city’s history of delays, few expect it to be finished that soon. And even if it works perfectly, it is not a complete or final solution. The city will continue to sink and the water level will continue to rise. Sooner or later, the gates will no longer be able to protect the city from deterioration.

In the meantime, Venice faces an uncertain and paradoxical existence. While tourism increases to record levels, the population of the city itself has plummeted. The historic old part of the city had about 184,000 residents in 1950; today, there are fewer than 55,000. A shocking percentage of Venice’s glorious old buildings stand vacant as owners move to more stable surroundings, yet real estate prices remain astronomically high, discouraging an influx of new residents. With no one to renovate and maintain the buildings, they will fall apart faster; but the more the city deteriorates, the fewer people are willing to live there and do anything about it. Project Moses may keep the floods out, but will it enable Venice to keep its head above water?

Note: This is an updated version of an article that originally appeared on Interesting Thing of the Day on July 2, 2003, and again in a slightly revised form on March 21, 2005.

from Interesting Thing of the Day http://bit.ly/2Mdlt9V

The Sinking City of Venice

Atlantis redux

While on our first European vacation years ago, Morgen and I visited Venice, that beautiful Italian city where the streets are paved with water. We were there for only a few days, but we enjoyed every minute of it. The place oozes history, and it’s wonderfully romantic. When we took the customary gondola ride through the city’s canals, our gondolier casually pointed toward a small house and said, “Marco Polo used to live there.” And we could believe it—if it were not for the constant noise of motor boats, it would be easy to imagine that the city looked much the same way centuries ago as it does now. But it’s not quite the same as it was in Marco Polo’s time. Whatever other changes have happened, the most significant one is that the city, as our gondolier reminded us, is sinking.

Of course, the entire planet is doomed to be destroyed when the sun explodes in 500 million years or so, but I’m not losing any sleep over that. Why should I worry about Venice? It still looks OK to me, so it must be sinking very slowly, right? Well, not really. Venice is located in a lagoon on the edge of the Adriatic Sea. When Venice was founded in the year 421, the level of the Adriatic was about 5 meters (16 feet) lower than it is today. For centuries the water level rose very, very slowly, but in the last century or so the rate has increased dramatically. With each passing year, the difference between street level and water level shrinks faster. From time to time, the city gets a brief reprieve. As recently as 2005, unusual weather patterns caused Venice to experience exceptionally low tides—so low that boats could not navigate most of the city’s shallower canals. Nevertheless, the clear trend, as observed over centuries, is in a decisively downward direction. If nothing is done and the trend continues, by 2055, a significant portion of the city’s walkways, plazas, and ground-level floors will be submerged all the time.

That Sinking Feeling

For a long time I was puzzled about just what it meant for Venice to be “sinking,” because that doesn’t fit into my categories of things a city is capable of doing. This is in fact a somewhat simplistic description of a complex problem. One part of the problem is that the city is not built on a solid foundation. Venice was originally a collection of muddy islands. In order to construct buildings, workers drove millions of pilings—thin, sharpened poles made of alder trees—through the mud and into the marginally more solid base of sand and clay beneath. Oak planks were placed on top of the pilings, and on top of the planks, several thick layers of marble (which is impermeable by water) formed the foundations of the buildings. From there on up, most of the construction was done in ordinary brick or wood. At the time the buildings were constructed, the marble was well above the high water line, so there was nothing to worry about. However, over the centuries, the weight of the buildings has driven the pilings deeper into the mushy seabed. In addition, at one time there were hundreds of wells in the city, removing water from deep aquifers. Unfortunately, these aquifers had acted as a sort of balloon of water propping up the city; when it was “deflated,” the city began to sink even faster.

But the literal sinking of Venice, which averages something like a few centimeters per century, is only part of the problem. The other part is that the surrounding water level has been rising at an alarming rate. This is partly due to the effects of global warming and partly due to centuries of poor environmental management in the entire region. But in any case, the rising waters compound the sinking problem and make the net effect quite serious.

When It Rains, It Pours

Venice has always been subject to periodic flooding—mainly in winter, and especially at high tide. This is something that residents have come to regard as a fact of life, and not a terribly troublesome one; most of them get around in boats anyway. But whereas flooding used to be something that would happen a few times a year, now it happens on the order of a hundred times a year. Because the sea level has risen, even in a modest flood, the water level rises above the waterproof marble foundations of the buildings, rapidly wearing away the less-robust building materials.

In November, 1966, a particularly bad storm caused a devastating flood that put much of the city under 2 meters (over 6 feet) of water. This caused extensive damage to both buildings and the valuable artwork they contained, and began to impress upon Venetians the need to take drastic action.

In 1970, a plan was proposed that involved the installation of large, mobile gates at the three inlets of the lagoon; these would be raised as needed to keep out high water. But for the next 30 years, a series of excruciating delays prevented any significant progress from being made. There were, of course, significant engineering problems to be solved, not to mention the problem of financing such an ambitious undertaking. But political reasons, more than anything else, held up development. Many Venetians did not want to believe their city was in imminent danger—and even to the extent that they did, there was tremendous disagreement about how best to address the problem. Some wanted to address the problem at the base—to basically “jack up” the city and install new and improved foundations. Others wanted to build a series of dikes and locks around the city—the so-called “Dutch solution”—or use a different mechanism to hold back high waters.

Holding Back the Sea

At the end of 2001, a plan was finally put in motion to keep back the high waters. A project called MOSE (an acronym for Experimental Electromechanical Module in Italian, but also an allusion to Moses) involves the construction of 78 steel gates, hinged at the bottom, installed along the sea floor at the three inlets to the lagoon. The gates, which are hollow and normally filled with water, measure 20 meters wide, 3.6 meters deep, and 20 to 30 meters high. When water levels appear to be rising dangerously high, compressed air will be pumped into the gates, causing the ends to float up to (and slightly above) the surface. In effect, they will form a dynamic dam that will appear only when needed. The gates will be tall enough to hold back water quite a bit deeper than the 1966 flood.

Although construction has been underway for quite a few years and significant progress has occurred, there are still numerous problems ahead, and the completion date has been delayed repeatedly. One issue is the 5.5 billion euro (and counting) cost, and more specifically the vast portion of that sum that has disappeared due to corruption. There are also significant environmental concerns; the project was vigorously opposed by numerous environmental groups. Among their concerns is that any interference with normal tides will increase the levels of toxic chemicals such as mercury in the waters of Venice, seriously threatening both marine life and the health of people who consume the local fish. There are also basic worries about health and sanitation. Venice has no sewer system; household waste flows into the canals and is washed out into the ocean twice a day with the tides. No one is certain quite what effect the gates will have on the city’s natural waste treatment system.

An Uncertain Future

Under the most optimistic prediction, Project Moses will be fully operational by 2022, but given the city’s history of delays, few expect it to be finished that soon. And even if it works perfectly, it is not a complete or final solution. The city will continue to sink and the water level will continue to rise. Sooner or later, the gates will no longer be able to protect the city from deterioration.

In the meantime, Venice faces an uncertain and paradoxical existence. While tourism increases to record levels, the population of the city itself has plummeted. The historic old part of the city had about 184,000 residents in 1950; today, there are fewer than 55,000. A shocking percentage of Venice’s glorious old buildings stand vacant as owners move to more stable surroundings, yet real estate prices remain astronomically high, discouraging an influx of new residents. With no one to renovate and maintain the buildings, they will fall apart faster; but the more the city deteriorates, the fewer people are willing to live there and do anything about it. Project Moses may keep the floods out, but will it enable Venice to keep its head above water?

Note: This is an updated version of an article that originally appeared on Interesting Thing of the Day on July 2, 2003, and again in a slightly revised form on March 21, 2005.

from Interesting Thing of the Day http://bit.ly/2Mdlt9V

Winds with Names

More than just a bunch of hot air

Our article about the Chinook winds discussed an unusual meteorological phenomenon, but one thing it didn’t touch on was the peculiarity of a wind having a name in the first place. That strikes me as odd, like a temperature or a humidity level or a barometric pressure having a name. I mean, I get it: we give hurricanes and certain other storms names, and that serves a useful purpose, but just calling the movement of air in a certain way at a certain time by a proper noun seems weird.

Be that as it may, we were able to find quite a few other examples of winds that have names. Here’s a representative sampling—by no means a complete list:

• Bora: A cold, north-eastern katabatic wind that blows along the east coast of the the Adriatic Sea (including Greece, Russia, and Turkey).
• Brickfielder: A hot and dry summer wind in Southern Australia.
• Cape Doctor: A dry south-easterly wind that blows over part of Western Cape Province in South Africa, so named because of its apparent effect of clearing away pollution.
• Chinook: A warm winter wind in the western United States and Canada.
• Fremantle Doctor: A cool summer sea breeze on the coast of Western Australia.
• Halny: A strong, warm föhn wind storm in the Carpathian mountains of Poland and Slovakia.
• Khamsin: A hot, sandy wind in Egypt.
• Mistral: A cold, forceful wind that blows in southern France and into the Mediterranean Sea.
• Santa Ana: A hot, dry wind, usually in autumn, in southern California and northern Mexico.
• Sirocco: A powerful wind that blows from the Sahara through North Africa and Southern Europe.

from Interesting Thing of the Day http://bit.ly/30NlswZ

Solar Sails

The next big thing in space travel

If you wanted to cross the ocean by ship, you’d probably choose an engine-driven vessel over a sail-driven vessel. The engine will get you where you’re going faster; it enables the ship to be much larger than it could be if it were driven by a sail; and it requires much less manual intervention to keep it going. Besides, you won’t be at the mercy of unpredictable winds. In oceangoing vessels, the technological progression from sails to internal-combustion engines solved a great many problems while creating only a few new ones, such as the need to obtain and store significant quantities of fuel and the pollution that results from burning that fuel. Of course, since the planet is conveniently spherical, you’re always a finite distance from the nearest port where you can fill up. If, on the other hand, you wanted to circumnavigate the globe without stopping for fuel, sails would be the way to go. The trip would take longer and the ship would be smaller, but you’d never have to worry about running out of gas.

This is the very thinking behind an ostensibly retro design for spacecraft: by ditching the fuel and engines you can enable much longer journeys, albeit with some trade-offs. Outfit your ship with a giant sheet of lightweight and highly reflective material, and you’ve got a solar sail, a propulsion system that can take you to the distant reaches of the galaxy without any fuel—pushing you along with the gentle power of light from the sun.

What Goes Around

Solar sails are by no means a new idea. In fact, German astronomer Johannes Kepler floated the idea by Galileo in 1610. Kepler imagined “heavenly breezes,” though, and had no concept of the scientific principles that would actually come into play. In 1871, James Clerk Maxwell, a Scottish physicist, predicted that electromagnetic radiation (including light) should exert a small amount of pressure when an object absorbs or reflects it; Russian physicist Peter Lebedev first demonstrated the effect in a laboratory in 1900.

A little more than 20 years later, another Russian physicist named Fridrikh Tsander proposed using this radiation pressure to push a spacecraft along using a large but very thin mirror. In the early 1970s, NASA funded research into solar sails, and for a while proposed that they be used to propel a probe that would rendezvous with Halley’s Comet in 1986 (though the necessary technology turned out to be unavailable at the time). Today, NASA and numerous other groups are actively developing solar sail designs, and several spacecraft powered by solar sails have already been deployed.

Light Pressure

The whole idea of light exerting pressure seems counterintuitive. I’ve personally stood in front of some very bright spotlights without so much as a wobble. And I know from my rudimentary understanding of physics that photons, the particles that make up light, have no mass. Nevertheless, under the right circumstances, light can indeed provide a push. The math, frankly, is beyond me, but according to scientists who seem to know what they’re talking about and can back it up with impressive-looking equations, photons do indeed exert a gentle pressure on objects they hit—and the pressure is roughly twice as great if the object reflects the light than if it absorbs the light, so solar sails would effectively be giant mirrors. But the key word here is gentle. I’ve read various analogies for the strength of the sun’s push, but one I particularly liked, on a NASA webpage, said that if you had a mirror the size of a football field, the pressure of the sun’s light would be about the same as the weight of a first-class letter.

In space, a small amount of pressure goes much further, because other factors such as gravity, air friction, and wind don’t get in the way. Even so, if a solar sail is going to push a spacecraft of any significant mass, it must be enormous. And therein lies a problem: with greater size comes greater mass—not so much from the sail itself but from the support structure that’s needed to keep it rigid and connect it to craft’s payload. The greater the mass to be pushed, the greater the size of the sail that’s needed, and so on. Thus, in solar sail design, thinner and lighter materials are almost always better. Sail thickness is measured in micrometres (µm)—millionths of a meter—with some being as thin as 2 µm. (By comparison, the average human hair is about 80 µm thick.) This brings up a second problem: fragility. You’ve got to fold or roll up a huge sheet of material that’s a zillionth of an inch thick, get it into space, and then unfurl it perfectly—without ripping or mutilating it, and without creating a support structure so massive that it’ll cancel out the sail’s low mass. One promising material is a type of porous carbon fiber that’s much thicker than the polymer films most researchers have used, and yet lighter in weight because of its unusual structure; it’s also highly rigid, durable, and heat-resistant.

Still More Uses for the Force

Proposed solar sail designs have used a wide variety of shapes, from simple squares to disks to pinwheels. As with wind sails, you can change the angle of a solar sail in order to steer the craft; designs that incorporate numerous smaller sails provide greater directional control. But one thing you will not see is a solar sail shaped like a parachute—since light travels in straight lines, that would make for a highly inefficient design. Interestingly, that’s exactly the shape of a certain fictional solar sail—the one used by Count Dooku’s spaceship in Star Wars: Episode II—Attack of the Clones.

Besides having an inappropriately shaped sail, that ship somehow managed to zip across the galaxy at a startling speed as soon as the sail unfurled. Real solar sails, because they generate so little force, accelerate quite slowly. On the other hand—and this is what makes them an intriguing option for long-term missions—the velocity continues to increase over time, there being no friction to counteract it. The result is that over a period of months or years, a craft powered by a solar sail could reach speeds far in excess of any rocket-powered design. However, as the craft gets farther and farther away from the sun, the radiation pressure also decreases, so it’s not as though the rate of acceleration can continue to increase indefinitely. Even so, a vehicle with a very lightweight solar sail could reach the orbit of Pluto in about 7 years. (The Pioneer 10 probe, launched in 1972, took 11 years to reach that point.)

Sail On

After many years of ground-based and suborbital testing, as well as a few noteworthy failures, an interplanetary solar sail spacecraft (Japan’s IKAROS probe) was first successfully deployed in 2010. NASA launched the NanoSail-D2 later in 2010. And The Planetary Society launched and successfully tested a small solar sail-powered spacecraft called LightSail 1 in 2015; LightSail 2 is scheduled to launch in June, 2019. Numerous other solar sail projects are in various stages of planning.

Among the future missions envisioned for spacecraft propelled by solar sails are probes sent to explore the inner planets, monitoring stations near the sun, and deep-space exploration. Some proposals even use a giant laser here on Earth, instead of the sun, to push the craft along. Manned missions, however, are a much more distant possibility; a spaceship big enough to hold passengers would require an unfathomably gargantuan sail, and the slow acceleration would be rather inconvenient considering human lifespans. But if we ever encounter a ship sent a long time ago from a galaxy far, far away, it may very well have been carried along by a solar sail.

Note: This is an updated version of an article that originally appeared on Interesting Thing of the Day on June 19, 2006.

from Interesting Thing of the Day http://bit.ly/2VZS9n0

Take Control of Your Digital Legacy

How do you want to be remembered by future generations? You can make a will to handle your physical possessions, but what about your digital life—photos, videos, email, documents, and the like? What about all your passwords, social media accounts, backups, and every other aspect of your digital life? Over the years, I got so many questions about this sort of thing that I decided to write a book about it—Take Control of Your Digital Legacy—and it has turned out to be one of my post popular titles.

If you’re not at the stage of life where you can think about this for yourself, consider that you may have to do so for your parents or other relatives. It’s not all about posterity either, since following my advice will also help loved ones access your key accounts and important info if you’re incapacitated, which can happen at any time—or even if you just decide to go on a long vacation.

This book, like all Take Control titles, comes as an ebook, and you can download any combination of formats—PDF, EPUB, and/or Kindle’s Mobipocket format—so you can read it on pretty much any computer, smartphone, tablet, or ebook reader. The cover price is $15, but as an Interesting Thing of the Day reader, you can buy it for 30% off, or just $10.50.

from Interesting Thing of the Day http://bit.ly/2VNuZjH

___-of-the-Month Clubs

Old marketing gimmicks never die

Hark back with me to the Dark Years (or the Good Old Days, depending on your point of view)—the time before any object a person desired could be delivered to one’s door within days (if not hours), with no more effort than a few taps on a smartphone screen. I’m old enough to remember a time before Amazon.com—indeed, before the internet itself—when discovering, locating, and procuring a variety of any particular type of merchandise actually presented a challenge. Way back in the days when we had to wait for checks to clear and then allow 6–8 weeks for delivery, the notion that a previously unknown specimen of one of our favorite things would arrive automagically on our doorstep once a month was quite compelling.

I had experienced, and then long forgotten about, thing-of-the-month clubs when, in the early 2000s, my Christmas gift from my mother was a subscription to the Fruit of the Month Club. Once each month, Airborne Express arrived at our door with a box of fresh fruit. The selection changed each month. In December, for example, it was Mandarin oranges; in April it was kiwi and pineapple. The fruit was always of good quality, and the shipments were just infrequent enough that I was always slightly surprised when each package arrived. Although the shipments were fairly small, they were always a welcome treat that didn’t require a trip to the market—and the subscription was something I never would have thought to purchase for myself.

They Deliver for Me

Before my fruit started arriving, I had heard of the Book-of-the-Month Club but had only a vague notion that other kinds of things were available on a monthly subscription plan. Now, however, I seem to find ___-of-the-month clubs every time I turn around. In most cases, the general idea is the same: for a fixed fee, you get a six- or twelve-month subscription, with a different selection of your chosen product arriving each month. This can be an easy way to experience new tastes and broaden your horizons a bit. (You can also, of course, have Amazon or another retailer automatically send you refills of exactly the same staple items on the schedule of your choice, but that’s different from having someone select a different item in a given category for a monthly surprise.)

What other sorts of ___-of-the-month clubs are there? A quick web search turned up hundreds, ranging from the delightful to the bizarre. Things you can receive by monthly subscription include: candles, chocolate, coffee, cookies, craft beer, fruit, gourmet cheese, hot sauce, jam, leggings, oysters, pasta, pastries, pickles, potato chips, socks, tea, trout flies, wine…well, I could go on, but you get the idea. I haven’t seen armchair-of-the-month or vaccine-of-the-month clubs, but with very few exceptions, it appears one can now receive a curated monthly example of virtually any item needed for survival or leisure by subscription.

Reader’s Dozen

And then, of course, there are books, the item-of-the-month that started it all. The original Book-of-the-Month Club was founded in 1926, designed as a way to get new books into the hands of people living in rural areas without easy access to bookstores or libraries. A panel of judges selected a new volume each month, sent at a respectable discount to subscribers. The following year, The Literary Guild—another variation on the same theme—started business. Many decades later, after a series of mergers and acquisitions, both clubs still exist. If you enjoy reading the types of books the book-of-the-month club offers, it can be a convenient way to stay on top of the latest bestsellers and keep your library well-stocked at a reasonable price. As for me, I already accumulate books far faster than I can read them, so I’m more likely to subscribe to consumable products.

Notwithstanding the fact that I write a ___-of-the-day column, I find the notion of monthly subscription clubs strangely appealing—in an endearingly retro sort of way. Since it’s easy to purchase almost anything instantly online these days, this type of subscription program is a bit of an anachronism. My suspicion is that clubs like these continue to thrive not so much for the convenience they provide but because people like novelty…and they like getting packages. If you can justify a subscription by convincing yourself that you’re saving money, all the better—but when you get right down to it, there’s just nothing like opening a box of goodies.

Note: This is an updated version of an article that originally appeared on Interesting Thing of the Day on May 11, 2003, and again in a slightly revised form on October 24, 2004.

from Interesting Thing of the Day http://bit.ly/2Qn2Z5v

Winds with Names

More than just a bunch of hot air

Our article about the Chinook winds discussed an unusual meteorological phenomenon, but one thing it didn’t touch on was the peculiarity of a wind having a name in the first place. That strikes me as odd, like a temperature or a humidity level or a barometric pressure having a name. I mean, I get it: we give hurricanes and certain other storms names, and that serves a useful purpose, but just calling the movement of air in a certain way at a certain time by a proper noun seems weird.

Be that as it may, we were able to find quite a few other examples of winds that have names. Here’s a representative sampling—by no means a complete list:

• Bora: A cold, north-eastern katabatic wind that blows along the east coast of the the Adriatic Sea (including Greece, Russia, and Turkey).
• Brickfielder: A hot and dry summer wind in Southern Australia.
• Cape Doctor: A dry south-easterly wind that blows over part of Western Cape Province in South Africa, so named because of its apparent effect of clearing away pollution.
• Chinook: A warm winter wind in the western United States and Canada.
• Fremantle Doctor: A cool summer sea breeze on the coast of Western Australia.
• Halny: A strong, warm föhn wind storm in the Carpathian mountains of Poland and Slovakia.
• Khamsin: A hot, sandy wind in Egypt.
• Mistral: A cold, forceful wind that blows in southern France and into the Mediterranean Sea.
• Santa Ana: A hot, dry wind, usually in autumn, in southern California and northern Mexico.
• Sirocco: A powerful wind that blows from the Sahara through North Africa and Southern Europe.

from Interesting Thing of the Day http://bit.ly/30NlswZ

Solar Sails

The next big thing in space travel

If you wanted to cross the ocean by ship, you’d probably choose an engine-driven vessel over a sail-driven vessel. The engine will get you where you’re going faster; it enables the ship to be much larger than it could be if it were driven by a sail; and it requires much less manual intervention to keep it going. Besides, you won’t be at the mercy of unpredictable winds. In oceangoing vessels, the technological progression from sails to internal-combustion engines solved a great many problems while creating only a few new ones, such as the need to obtain and store significant quantities of fuel and the pollution that results from burning that fuel. Of course, since the planet is conveniently spherical, you’re always a finite distance from the nearest port where you can fill up. If, on the other hand, you wanted to circumnavigate the globe without stopping for fuel, sails would be the way to go. The trip would take longer and the ship would be smaller, but you’d never have to worry about running out of gas.

This is the very thinking behind an ostensibly retro design for spacecraft: by ditching the fuel and engines you can enable much longer journeys, albeit with some trade-offs. Outfit your ship with a giant sheet of lightweight and highly reflective material, and you’ve got a solar sail, a propulsion system that can take you to the distant reaches of the galaxy without any fuel—pushing you along with the gentle power of light from the sun.

What Goes Around

Solar sails are by no means a new idea. In fact, German astronomer Johannes Kepler floated the idea by Galileo in 1610. Kepler imagined “heavenly breezes,” though, and had no concept of the scientific principles that would actually come into play. In 1871, James Clerk Maxwell, a Scottish physicist, predicted that electromagnetic radiation (including light) should exert a small amount of pressure when an object absorbs or reflects it; Russian physicist Peter Lebedev first demonstrated the effect in a laboratory in 1900.

A little more than 20 years later, another Russian physicist named Fridrikh Tsander proposed using this radiation pressure to push a spacecraft along using a large but very thin mirror. In the early 1970s, NASA funded research into solar sails, and for a while proposed that they be used to propel a probe that would rendezvous with Halley’s Comet in 1986 (though the necessary technology turned out to be unavailable at the time). Today, NASA and numerous other groups are actively developing solar sail designs, and several spacecraft powered by solar sails have already been deployed.

Light Pressure

The whole idea of light exerting pressure seems counterintuitive. I’ve personally stood in front of some very bright spotlights without so much as a wobble. And I know from my rudimentary understanding of physics that photons, the particles that make up light, have no mass. Nevertheless, under the right circumstances, light can indeed provide a push. The math, frankly, is beyond me, but according to scientists who seem to know what they’re talking about and can back it up with impressive-looking equations, photons do indeed exert a gentle pressure on objects they hit—and the pressure is roughly twice as great if the object reflects the light than if it absorbs the light, so solar sails would effectively be giant mirrors. But the key word here is gentle. I’ve read various analogies for the strength of the sun’s push, but one I particularly liked, on a NASA webpage, said that if you had a mirror the size of a football field, the pressure of the sun’s light would be about the same as the weight of a first-class letter.

In space, a small amount of pressure goes much further, because other factors such as gravity, air friction, and wind don’t get in the way. Even so, if a solar sail is going to push a spacecraft of any significant mass, it must be enormous. And therein lies a problem: with greater size comes greater mass—not so much from the sail itself but from the support structure that’s needed to keep it rigid and connect it to craft’s payload. The greater the mass to be pushed, the greater the size of the sail that’s needed, and so on. Thus, in solar sail design, thinner and lighter materials are almost always better. Sail thickness is measured in micrometres (µm)—millionths of a meter—with some being as thin as 2 µm. (By comparison, the average human hair is about 80 µm thick.) This brings up a second problem: fragility. You’ve got to fold or roll up a huge sheet of material that’s a zillionth of an inch thick, get it into space, and then unfurl it perfectly—without ripping or mutilating it, and without creating a support structure so massive that it’ll cancel out the sail’s low mass. One promising material is a type of porous carbon fiber that’s much thicker than the polymer films most researchers have used, and yet lighter in weight because of its unusual structure; it’s also highly rigid, durable, and heat-resistant.

Still More Uses for the Force

Proposed solar sail designs have used a wide variety of shapes, from simple squares to disks to pinwheels. As with wind sails, you can change the angle of a solar sail in order to steer the craft; designs that incorporate numerous smaller sails provide greater directional control. But one thing you will not see is a solar sail shaped like a parachute—since light travels in straight lines, that would make for a highly inefficient design. Interestingly, that’s exactly the shape of a certain fictional solar sail—the one used by Count Dooku’s spaceship in Star Wars: Episode II—Attack of the Clones.

Besides having an inappropriately shaped sail, that ship somehow managed to zip across the galaxy at a startling speed as soon as the sail unfurled. Real solar sails, because they generate so little force, accelerate quite slowly. On the other hand—and this is what makes them an intriguing option for long-term missions—the velocity continues to increase over time, there being no friction to counteract it. The result is that over a period of months or years, a craft powered by a solar sail could reach speeds far in excess of any rocket-powered design. However, as the craft gets farther and farther away from the sun, the radiation pressure also decreases, so it’s not as though the rate of acceleration can continue to increase indefinitely. Even so, a vehicle with a very lightweight solar sail could reach the orbit of Pluto in about 7 years. (The Pioneer 10 probe, launched in 1972, took 11 years to reach that point.)

Sail On

After many years of ground-based and suborbital testing, as well as a few noteworthy failures, an interplanetary solar sail spacecraft (Japan’s IKAROS probe) was first successfully deployed in 2010. NASA launched the NanoSail-D2 later in 2010. And The Planetary Society launched and successfully tested a small solar sail-powered spacecraft called LightSail 1 in 2015; LightSail 2 is scheduled to launch in June, 2019. Numerous other solar sail projects are in various stages of planning.

Among the future missions envisioned for spacecraft propelled by solar sails are probes sent to explore the inner planets, monitoring stations near the sun, and deep-space exploration. Some proposals even use a giant laser here on Earth, instead of the sun, to push the craft along. Manned missions, however, are a much more distant possibility; a spaceship big enough to hold passengers would require an unfathomably gargantuan sail, and the slow acceleration would be rather inconvenient considering human lifespans. But if we ever encounter a ship sent a long time ago from a galaxy far, far away, it may very well have been carried along by a solar sail.

Note: This is an updated version of an article that originally appeared on Interesting Thing of the Day on June 19, 2006.

from Interesting Thing of the Day http://bit.ly/2VZS9n0

Take Control of Your Digital Legacy

How do you want to be remembered by future generations? You can make a will to handle your physical possessions, but what about your digital life—photos, videos, email, documents, and the like? What about all your passwords, social media accounts, backups, and every other aspect of your digital life? Over the years, I got so many questions about this sort of thing that I decided to write a book about it—Take Control of Your Digital Legacy—and it has turned out to be one of my post popular titles.

If you’re not at the stage of life where you can think about this for yourself, consider that you may have to do so for your parents or other relatives. It’s not all about posterity either, since following my advice will also help loved ones access your key accounts and important info if you’re incapacitated, which can happen at any time—or even if you just decide to go on a long vacation.

This book, like all Take Control titles, comes as an ebook, and you can download any combination of formats—PDF, EPUB, and/or Kindle’s Mobipocket format—so you can read it on pretty much any computer, smartphone, tablet, or ebook reader. The cover price is $15, but as an Interesting Thing of the Day reader, you can buy it for 30% off, or just $10.50.

from Interesting Thing of the Day http://bit.ly/2VNuZjH

___-of-the-Month Clubs

Old marketing gimmicks never die

Hark back with me to the Dark Years (or the Good Old Days, depending on your point of view)—the time before any object a person desired could be delivered to one’s door within days (if not hours), with no more effort than a few taps on a smartphone screen. I’m old enough to remember a time before Amazon.com—indeed, before the internet itself—when discovering, locating, and procuring a variety of any particular type of merchandise actually presented a challenge. Way back in the days when we had to wait for checks to clear and then allow 6–8 weeks for delivery, the notion that a previously unknown specimen of one of our favorite things would arrive automagically on our doorstep once a month was quite compelling.

I had experienced, and then long forgotten about, thing-of-the-month clubs when, in the early 2000s, my Christmas gift from my mother was a subscription to the Fruit of the Month Club. Once each month, Airborne Express arrived at our door with a box of fresh fruit. The selection changed each month. In December, for example, it was Mandarin oranges; in April it was kiwi and pineapple. The fruit was always of good quality, and the shipments were just infrequent enough that I was always slightly surprised when each package arrived. Although the shipments were fairly small, they were always a welcome treat that didn’t require a trip to the market—and the subscription was something I never would have thought to purchase for myself.

They Deliver for Me

Before my fruit started arriving, I had heard of the Book-of-the-Month Club but had only a vague notion that other kinds of things were available on a monthly subscription plan. Now, however, I seem to find ___-of-the-month clubs every time I turn around. In most cases, the general idea is the same: for a fixed fee, you get a six- or twelve-month subscription, with a different selection of your chosen product arriving each month. This can be an easy way to experience new tastes and broaden your horizons a bit. (You can also, of course, have Amazon or another retailer automatically send you refills of exactly the same staple items on the schedule of your choice, but that’s different from having someone select a different item in a given category for a monthly surprise.)

What other sorts of ___-of-the-month clubs are there? A quick web search turned up hundreds, ranging from the delightful to the bizarre. Things you can receive by monthly subscription include: candles, chocolate, coffee, cookies, craft beer, fruit, gourmet cheese, hot sauce, jam, leggings, oysters, pasta, pastries, pickles, potato chips, socks, tea, trout flies, wine…well, I could go on, but you get the idea. I haven’t seen armchair-of-the-month or vaccine-of-the-month clubs, but with very few exceptions, it appears one can now receive a curated monthly example of virtually any item needed for survival or leisure by subscription.

Reader’s Dozen

And then, of course, there are books, the item-of-the-month that started it all. The original Book-of-the-Month Club was founded in 1926, designed as a way to get new books into the hands of people living in rural areas without easy access to bookstores or libraries. A panel of judges selected a new volume each month, sent at a respectable discount to subscribers. The following year, The Literary Guild—another variation on the same theme—started business. Many decades later, after a series of mergers and acquisitions, both clubs still exist. If you enjoy reading the types of books the book-of-the-month club offers, it can be a convenient way to stay on top of the latest bestsellers and keep your library well-stocked at a reasonable price. As for me, I already accumulate books far faster than I can read them, so I’m more likely to subscribe to consumable products.

Notwithstanding the fact that I write a ___-of-the-day column, I find the notion of monthly subscription clubs strangely appealing—in an endearingly retro sort of way. Since it’s easy to purchase almost anything instantly online these days, this type of subscription program is a bit of an anachronism. My suspicion is that clubs like these continue to thrive not so much for the convenience they provide but because people like novelty…and they like getting packages. If you can justify a subscription by convincing yourself that you’re saving money, all the better—but when you get right down to it, there’s just nothing like opening a box of goodies.

Note: This is an updated version of an article that originally appeared on Interesting Thing of the Day on May 11, 2003, and again in a slightly revised form on October 24, 2004.

from Interesting Thing of the Day http://bit.ly/2Qn2Z5v

Oil from Garbage

Modern-day alchemy

Well, I’ve got some good news and some bad news. The good news is that there may be an elegant solution on the horizon to the gigantic problem of garbage—and not just the kind that gets dumped in landfills, but hard-to-recycle plastics, too, along with agricultural wastes, used tires, and just about everything else. More good news: we might get to reduce dependence on foreign oil and pay less for gasoline in the process. The bad news? More cheap oil to burn means more carbon dioxide going into the atmosphere, perpetuating the already dire problem of global warming.

The technology that makes it possible to do this is called the thermal depolymerization process, or TDP for short. It was developed for commercial use a couple of decades ago by a company called Changing World Technologies (now owned by Canadian firm Ridgeline Energy Services), and its first full-scale plant operated for a number of years in Carthage, Missouri. Now various other firms are taking the same technology in other directions. In any case, the idea behind TDP is not new—in fact, it’s millions of years old. Take organic matter, subject it to heat and pressure, and eventually you get oil. Of course in nature, “eventually” is usually an inconvenient number of millennia; TDP shortens that time to hours, if you can believe that.

A Well-Oiled Machine

TDP is a surprisingly straightforward five-step process. First, raw materials are fed into an industrial-grade grinder where they’re chopped up into extremely small bits and mixed with water. The mixture is then subjected to heat and pressure, breaking molecular bonds and reducing the material to simpler components in as little as 15 minutes. The next step is reducing the pressure dramatically to drive off the water; in the process, some useful minerals such as calcium and magnesium settle out as valuable byproducts. The remaining slurry is sent into a second reactor, which uses even higher temperatures to produce a hydrocarbon mixture. Finally, a distillation step divides the hydrocarbons into vaporous gas (a mixture of methane, propane, and butane), liquid oil (similar to a mixture of gasoline and motor oil), and powdered carbon.

All that to say: garbage in, (black) gold out. The process itself produces no waste materials, unless you count water, which can be recycled in the system. The gas can be used to produce heat for the machine itself; oil can be sent to refineries to be made into a variety of useful products; carbon can be turned into everything from water filters to toner cartridges; and the remaining minerals can be used as fertilizer.

Virtually any organic material can be fed into a TDP apparatus. By making adjustments to the combinations of temperature, pressure, and cooking times, various input products (referred to as feedstock) can produce a wide range of output products; the proportions of, say, gas to oil to carbon will depend on the composition of the feedstock. The first fully operational TDP system was used to recycle the waste at a turkey processing plant. All the turkey parts that weren’t used as meat—skin, bones, feathers, and so on—were fed into the machine, thus solving a serious waste problem (up to 200 tons per day) while creating commercially valuable products. But TDP can also process discarded computers, tires (even steel-belted radials), plastic bottles, agricultural waste, municipal garbage…you name it.

Almost nothing is too messy or too scary for TDP to handle. It can make clean, safe materials out of sewage, medical wastes, dioxins, and other biohazardous materials. Even anthrax, for crying out loud. Apparently the only kind of material this system can’t handle is nuclear waste—I guess you can’t have everything.

Pouring Oil on Troubled Water

Thermal depolymerization is still finding its footing for commercial use, though similar processes have been known for many years. The problem was that they were always too expensive to operate; it cost more for the fuel to decompose the garbage than the resulting materials were worth. The inventors of TDP claim that it is highly energy-efficient—better than 85% in most cases. If that is true, if it continues to be true on a large scale, and if demand is sufficiently high, then TDP may eventually be able to produce oil more cheaply than drilling, and get rid of garbage as a convenient side-effect—or vice-versa, if you prefer.

As fantastic as TDP sounds, the process does have its critics. Some engineers have expressed skepticism that the energy efficiency could be even close to what proponents claim. Even supposing that it were, the oil needs of the United States are currently so massive that if all the agricultural waste in the country were processed into oil, it would still be just a drop in the bucket (so to speak). In other words, so the argument goes, the process holds more promise as a method of recycling and waste reduction than it does as a source of fuel.

The more optimistic viewpoint is that if TDP comes into widespread use, we won’t run out of oil as long as we have garbage. But that also means there will be less incentive to reduce oil consumption or seek out cleaner alternative power sources. Ah, but I suppose every silver lining must have its cloud.

Note: This is an updated version of an article that originally appeared on Interesting Thing of the Day on August 3, 2003, and again in a slightly revised form on June 4, 2004.

from Interesting Thing of the Day http://bit.ly/2W0pL9i

Ischigualasto

Triassic Park in Argentina

I have a special fondness for deserts and other barren landscapes. Partly, I’m sure, it’s because of their rugged natural beauty, but I also find the lack of people and the coinciding lack of noise quite refreshing. I’ve spent plenty of time in desert regions of North America, South America, and the Middle East. One spot I missed during my trip to Argentina back in 2004 would undoubtedly have made it onto my list of favorite desert places. Located in the San Juan province in northwest Argentina, Ischigualasto Provincial Park is remote, hot, amazingly dry, and generally inhospitable, but nevertheless manages to draw over 30,000 tourists each year.

Smorgasbord of Fossils

The park takes its name from the Ischigualasto Formation, a large basin of sedimentary rock that was once a lush tropical swamp and is now a paleontologist’s playground. It contains a vast number of fossils, but its significance runs much deeper than that. It’s the only known place on the planet that contains a complete fossil record for the entire Triassic Period—a span of about 45 million years at the start of the Mesozoic Era, which began roughly 245 million years ago. What’s so significant about this period of time is that it’s when the first dinosaurs and the first mammals appeared. As a result, Ischigualasto is the best place to look for fossils of intermediate species.

A great many of the fossils in Ischigualasto are of plant-eating reptiles called rhynchosaurs, while many others are of cynodonts. Several websites I consulted unhelpfully explained that cynodonts are a group of therapsids, which are of course an order of synapsids. In English, cynodonts were a type of mammal-like reptile, a species that nicely illustrates evolution in progress. The word cynodont means “dog teeth,” referring to their mammal-like tooth structure. They walked on two legs, were covered with hair, and were warm-blooded—yet, like reptiles, they still laid eggs. You can also find some dinosaur fossils in Ischigualasto, and although there aren’t as many of them, they’re extremely significant because they’re among the oldest dinosaur remains in the world.

It’s the Rocks, Stupid

The fossils, however numerous and significant they may be, are not Ischigualasto’s biggest attraction. Tourists come to see the park’s rock formations. The Ischigualasto Formation is nicknamed “Valley of the Moon,” and although the pictures I’ve seen don’t remind me of the moon, they do certainly have an otherworldly appearance. As in Sedona, Arizona, many of the rocks and hills have a striking reddish cast, due to large concentrations of iron oxide. One rock formation, known as The Mushroom, has a broad stone cap sitting atop a much narrower column. This basic geometry, which in some cases appears to defy gravity, is typical of the formations, some of which have evocative names like The Sphinx, The Worm, and The Submarine. One particularly unusual area is a relatively flat expanse called The Ball Court, which is is covered with hundreds of natural stone spheres that evoke images of soccer balls. The park also contains petroglyphs and other artifacts of the area’s ancient human inhabitants.

Owing to its great scientific importance and its uniquely beautiful landscape, UNESCO named Ischigualasto Provincial Park, along with neighboring Talampaya National Park, a World Heritage Site in 2000. This recognition has helped to publicize the park’s existence, though the great majority of tourists come from within Argentina. Most visitors take a guided driving tour, which lasts two to four hours. People do sometimes camp in the park, but those who do are strongly urged to bring plenty of food, water, sunscreen, and shade, and to prepare for extreme temperatures (not only hot during the day but also very cold at night) and a persistent wind. Also bring your own soccer ball: kicking stone spheres puts you at an evolutionary disadvantage.

Note: This is an updated version of an article that originally appeared on Interesting Thing of the Day on July 26, 2006.

from Interesting Thing of the Day http://bit.ly/2HRhlHt

Pontcysyllte Aqueduct

Engineering marvel of the Canal Age

Before I knew much about aqueducts (whether ancient or modern), I imagined they would be constructed to bring water to areas that had none. While they can serve that purpose, I’ve since learned that aqueducts have been built in places with plenty of water—such as a river valley.

One example of this is a first-century aqueduct system constructed by the Romans in Southern France to carry water from the Eure spring in Uzès to a water tower in Nîmes, about thirty miles (fifty kilometers) away. In this case, it was the spring water in particular that the Romans coveted, using it to supply the fountains, sewage systems, and spas of the flourishing town. As part of the aqueduct system, the Romans built the now-famous Pont du Gard, a bridge that enabled the channel of water to cross over the Gard river and to continue on its way to Nîmes. In a way, it was like they built a river (or stream, if you will) above another river; rather remarkable to a non-engineer like me.

The Pont du Gard is remarkable for a number of other reasons, including: its longevity, having remained largely intact over the last two thousand years; its size, being the highest aqueduct ever built by the Romans (at 49 meters in height); and its incredible engineering, being composed of large stones that fit together without the use of mortar. Now it’s a UNESCO World Heritage Site, and every year large numbers of visitors from around the world come to see this amazing construction (including me in 2013—it was an awesome sight). Originally built to serve the social and business interests of Nîmes, the Pont du Gard now serves as a potent reminder of human ingenuity.

Channeling Ideas

A slightly less famous and considerably younger version of the Pont du Gard can be found in Northeast Wales. The Pontcysyllte Aqueduct, built between 1795 and 1805, was created to carry the Llangollen canal over the valley of the River Dee; another river-over-a-river construction. In this case, the Llangollen canal, which connects three major rivers—the Dee, the Severn, and the Mersey—was originally part of the Ellesmere canal, a route built to connect the coalfields and ironworks of the town of Wrexham with the sea.

The creation of the Pontcysyllte Aqueduct (about which more in a moment) was one among a series of large-scale construction projects that began in the late 1700s and continued into the 1830s. These projects were sparked by the opening of the Bridgewater canal in 1761, created by the third Duke of Bridgewater (a great example of an aptonym if ever there was one) to provide an efficient means of transporting coal from his coal mines in Lancashire to the booming industrial city of Manchester. This canal, which included a large aqueduct over the River Irwell, proved so profitable to the Duke that it encouraged many others to build canals of their own.

Canal Knowledge

Before the development of railroads, canals were the first means of mass transport of goods in Britain. The canal-building craze started by Bridgewater helped to fuel the so-called Industrial Revolution, which saw a change from a primarily agrarian society to one in which trade and manufacturing could be undertaken on a massive scale. The reason for the incredible success of the canal system lay in its great improvement over the traditional method of transporting goods.

While Britain had always relied upon waterways as a means of transport, being surrounded by water and possessing many large navigable rivers, those areas of the country not in proximity to a body of water could be accessed only by road. However, roads at that time were mostly built of mud, and could become impassible in bad weather. In addition, there was a limit to how much cargo could be transported by horse and cart, usually around one to two tons. In comparison, the new canals could accommodate boats carrying 30 tons, with only one horse needed to pull the load as it walked beside the boat on specially created towpaths. This dramatically increased the rate at which goods could be shipped, and brought incredible profits to the companies that operated the canals.

There were limitations to this mode of transport, though; in order to save costs, canals were often built quite narrow. This meant only specially designed “narrow boats” could navigate the canals. In addition, because canals are constructed bodies of water with no current, the speed of travel was limited to the speed of the “horsepower” involved, although this problem was less prominent in later years as steam and electric powered boats were developed.

Gradually, with the rise of the railroad, the canal system came to be less and less economically viable. Although the canals were still in commercial use well into the 20th century, their dominance was greatly overshadowed by other modes of transport. Unlike other European countries, such as France, Germany, and the Netherlands, which modernized their canal systems to accommodate larger vessels, the British system did not undergo the same kind of overhaul and fell more and more into disuse.

Fortunately, the canal system in Britain was reborn in the 1960s and ’70s when it came to be associated with holiday travel. Now these historic canals are frequently used by boaters and tour operators seeking a new form of vacation activity.

Canal Retentive

The first commercial canal built by Bridgewater was designed by James Brindley, a man with very little formal education, but who nonetheless went on to become one of the best-known engineers of the 18th Century. Following in his footsteps, Thomas Telford was only four years old when the Bridgewater canal was opened, but came to prominence after he oversaw the construction of the Pontcysyllte Aqueduct from 1795 to 1805.

The aqueduct has many notable features, including its great length (1007 feet; about 300m), its structural ingenuity (in its use of tapered support columns), and the construction of the metal trough in which the water is carried. In order to reduce the weight of the masonry pillars, they were built wider at the bottom than at the top, allowing the aqueduct to reach a great height. The masonry was held in place by a mortar made of lime, water, and ox blood. The metal trough carrying the water (and the boats) was built from cast iron sections joined together and caulked using flannel dipped in boiling sugar, and then sealed with lead.

Canal Plus

In 2005, the Pontcysyllte Aqueduct celebrated its 200th Anniversary, and in recognition of its cultural importance, was submitted to UNESCO as a potential World Heritage Site (which it was awarded in 2009). Like the Pont du Gard, it receives many visitors and has become a significant tourist attraction. Boat rides along the aqueduct are popular, often traveling to and from the town of Llangollen, the site of the International Eisteddfod, a music festival that takes place every year in July.

As with the Pont du Gard, a purely commercial endeavor has now become something to celebrate. Although the canal system, including the Pontcysyllte Aqueduct, no longer drives the economic engine of Britain, the ingenuity of those who designed these marvels continues to amaze and inspire all who see them.

Note: This is an updated version of an article that originally appeared on Interesting Thing of the Day on June 21, 2006.

from Interesting Thing of the Day http://bit.ly/2WjKAvG

The Fata Morgana Effect

Fairy castles in the air

When people accuse you of building castles in the air, they are not usually congratulating you on an incredible engineering feat, but more likely trying to bring you back down to earth with a thud. Synonymous with daydreams, pipe dreams, and all other dreams unlikely to come to fruition, castles in the air are at best a hopeful vision, and at worst, a hopeless illusion.

Although the phrase “castles in the air” (the original phrase was “castles in Spain”) is most often used to describe imaginary constructions, it can also be used to describe a very real optical phenomenon—the fata morgana effect—in which different levels of hot and cold air distort the appearance of objects on the horizon to make them look like, well, castles in the air.

Tempting Fata

Fata Morgana is the Italian name for Morgan le Fay, the half-sister of King Arthur in Arthurian legend. Reputedly a sorceress and able to change shape at will, Morgan le Fay was sometimes said to live below the sea in a crystal palace that could also rise above the surface. The fata morgana effect was so named for the superstitious belief among sailors that she created illusory visions to lure men into a false port and to their death. The term first entered English usage in 1818, when it was used to describe an occurrence of the phenomenon in the Strait of Messina, a narrow body of water between Sicily and the region of Calabria in southern Italy.

Technically, fata morganas are a type of mirage, related to those visions of water in the desert, or less exotically, to those seeming pools of water on the highway on a hot day. However, the latter two are examples of inferior mirages, while fata morganas are classified as superior mirages. It’s not that fata morganas are inherently better than the others; the difference lies in the way each mirage is produced.

Refract Up

Although the word mirage is derived from the French verb se mirer, meaning “to be reflected,” a more apt description of a mirage is that it is refracted. As light passes through layers of air with varying densities (density being determined by factors such as pressure and temperature), it bends, or more specifically, refracts, according to each layer’s characteristics.

In the case of inferior mirages, light bends upwards when it moves from a denser layer of cold air into a less dense layer of hot air, like that created above a highway on a hot day. As light hits the surface of the road and bends upwards, it looks to our eyes as if we are seeing a reflection in the road of what is just above it—in this case, the blue sky. This is because we perceive that light travels in a straight line to our eyes, even when that is factually not so.

Lake Superior

A superior mirage is the reverse of this; what we perceive to be higher in the sky is actually lower to the ground. Light is bent downwards when it hits a layer of cold air, making it appear as if what is below our sight line is actually straight ahead or above us because we are seeing the inverted image of what is on the horizon projected above it. This can be further complicated when there are multiple layers of hot and cold air, creating a highly distorted image as the light refracts through them.

Superior mirages occur wherever the surface temperature is colder than the air above it, usually over bodies of water and areas with ice or snow on the ground. The term fata morgana is most often used to describe superior mirages occurring over water. In these instances, objects on the horizon, such as ships, islands, cliffs, or icebergs, appear taller than they are because their inverted image is reflected above or superimposed on them. This elongation of objects on the horizon may make it appear as if there are turrets or towers rising up from the water, leading to the description of fata morganas as castles in the air.

As this effect can occur with ships, making them look higher above the horizon than they are, some have speculated that this is the origin of the Flying Dutchman legend, in which a ghostly ship is doomed to sail the seas for eternity.

There are many other types of superior mirages; one of them, the fata bromosa, or “fairy fog,” is created under the same conditions as the fata morgana, but has a different appearance. It appears as a bank of fog, with varying degrees of brightness, but without the fine detail of the fata morgana.

Fata Complete

Since its introduction into regular usage, the term fata morgana has come to mean more than just an optical phenomenon; although it has kept its original meaning of referring to something that is illusory, its use has been expanded throughout popular culture. It provided the title for a Henry Wadsworth Longfellow poem, an 1868 polka by Johann Strauss, and an Agatha Christie crime novel. It’s the name of a French publishing house, a character in Sergei Prokofiev’s opera, The Love for Three Oranges, and a film by Werner Herzog composed solely of desert landscape images.

The enduring popularity of the term shows how compelling it is as an idea—that there are mysterious phenomena, benign or malevolent, that are beyond our understanding. Or it may be that we continue to be enamored of our castles in the air, despite the knowledge of their illusory nature, as the last stanzas of Longfellow’s poem conclude:

So I wander and wander along,
And forever before me gleams
The shining city of song,
In the beautiful land of dreams.

But when I would enter the gate
Of that golden atmosphere,
It is gone, and I wonder and wait
For the vision to reappear.

Note: This is an updated version of an article that originally appeared on Interesting Thing of the Day on July 24, 2006.

from Interesting Thing of the Day http://bit.ly/2HsKTw1

Take Control of Your Digital Storage

This week, another book just for Mac users! As the amount of data we store continues to grow, figuring out where to put it and how to access it becomes more complicated. Every Mac includes internal storage in the form of a hard drive, SSD, or Fusion drive. But you may also have one or more external devices (such as hard drives, flash drives, SD cards, or RAID devices), not to mention network-attached storage (NAS) devices or cloud storage (like Dropbox or iCloud Drive). Making sense of all your options, managing your stored data, choosing new devices or services when you’re running out of space, or even just figuring out what’s where can drive anyone to distraction.

Jeff Carlson covers all this and much, much more in his book Take Control of Your Digital Storage. For example, the book helps you choose a new (internal or external) hard drive, SSD, or hybrid drive; determine how much storage space you need; understand APFS, Apple’s new filesystem; format, partition, and repair disks using Disk Utility; choose and use a NAS, RAID, flash drive, or SD card for use with your Mac; work with disk images; and decide among local, network, and cloud storage for various types of files.

This book, like all Take Control titles, comes as an ebook, and you can download any combination of formats—PDF, EPUB, and/or Kindle’s Mobipocket format—so you can read it on pretty much any computer, smartphone, tablet, or ebook reader. The cover price is $14.99, but as an Interesting Thing of the Day reader, you can buy it this week for 30% off, or just $10.49.

from Interesting Thing of the Day http://bit.ly/2YC0TS6

___-of-the-Month Clubs

Old marketing gimmicks never die

Hark back with me to the Dark Years (or the Good Old Days, depending on your point of view)—the time before any object a person desired could be delivered to one’s door within days (if not hours), with no more effort than a few taps on a smartphone screen. I’m old enough to remember a time before Amazon.com—indeed, before the internet itself—when discovering, locating, and procuring a variety of any particular type of merchandise actually presented a challenge. Way back in the days when we had to wait for checks to clear and then allow 6–8 weeks for delivery, the notion that a previously unknown specimen of one of our favorite things would arrive automagically on our doorstep once a month was quite compelling.

I had experienced, and then long forgotten about, thing-of-the-month clubs when, in the early 2000s, my Christmas gift from my mother was a subscription to the Fruit of the Month Club. Once each month, Airborne Express arrived at our door with a box of fresh fruit. The selection changed each month. In December, for example, it was Mandarin oranges; in April it was kiwi and pineapple. The fruit was always of good quality, and the shipments were just infrequent enough that I was always slightly surprised when each package arrived. Although the shipments were fairly small, they were always a welcome treat that didn’t require a trip to the market—and the subscription was something I never would have thought to purchase for myself.

They Deliver for Me

Before my fruit started arriving, I had heard of the Book-of-the-Month Club but had only a vague notion that other kinds of things were available on a monthly subscription plan. Now, however, I seem to find ___-of-the-month clubs every time I turn around. In most cases, the general idea is the same: for a fixed fee, you get a six- or twelve-month subscription, with a different selection of your chosen product arriving each month. This can be an easy way to experience new tastes and broaden your horizons a bit. (You can also, of course, have Amazon or another retailer automatically send you refills of exactly the same staple items on the schedule of your choice, but that’s different from having someone select a different item in a given category for a monthly surprise.)

What other sorts of ___-of-the-month clubs are there? A quick web search turned up hundreds, ranging from the delightful to the bizarre. Things you can receive by monthly subscription include: candles, chocolate, coffee, cookies, craft beer, fruit, gourmet cheese, hot sauce, jam, leggings, oysters, pasta, pastries, pickles, potato chips, socks, tea, trout flies, wine…well, I could go on, but you get the idea. I haven’t seen armchair-of-the-month or vaccine-of-the-month clubs, but with very few exceptions, it appears one can now receive a curated monthly example of virtually any item needed for survival or leisure by subscription.

Reader’s Dozen

And then, of course, there are books, the item-of-the-month that started it all. The original Book-of-the-Month Club was founded in 1926, designed as a way to get new books into the hands of people living in rural areas without easy access to bookstores or libraries. A panel of judges selected a new volume each month, sent at a respectable discount to subscribers. The following year, The Literary Guild—another variation on the same theme—started business. Many decades later, after a series of mergers and acquisitions, both clubs still exist. If you enjoy reading the types of books the book-of-the-month club offers, it can be a convenient way to stay on top of the latest bestsellers and keep your library well-stocked at a reasonable price. As for me, I already accumulate books far faster than I can read them, so I’m more likely to subscribe to consumable products.

Notwithstanding the fact that I write a ___-of-the-day column, I find the notion of monthly subscription clubs strangely appealing—in an endearingly retro sort of way. Since it’s easy to purchase almost anything instantly online these days, this type of subscription program is a bit of an anachronism. My suspicion is that clubs like these continue to thrive not so much for the convenience they provide but because people like novelty…and they like getting packages. If you can justify a subscription by convincing yourself that you’re saving money, all the better—but when you get right down to it, there’s just nothing like opening a box of goodies.

Note: This is an updated version of an article that originally appeared on Interesting Thing of the Day on May 11, 2003, and again in a slightly revised form on October 24, 2004.

from Interesting Thing of the Day http://bit.ly/2Qn2Z5v

Oil from Garbage

Modern-day alchemy

Well, I’ve got some good news and some bad news. The good news is that there may be an elegant solution on the horizon to the gigantic problem of garbage—and not just the kind that gets dumped in landfills, but hard-to-recycle plastics, too, along with agricultural wastes, used tires, and just about everything else. More good news: we might get to reduce dependence on foreign oil and pay less for gasoline in the process. The bad news? More cheap oil to burn means more carbon dioxide going into the atmosphere, perpetuating the already dire problem of global warming.

The technology that makes it possible to do this is called the thermal depolymerization process, or TDP for short. It was developed for commercial use a couple of decades ago by a company called Changing World Technologies (now owned by Canadian firm Ridgeline Energy Services), and its first full-scale plant operated for a number of years in Carthage, Missouri. Now various other firms are taking the same technology in other directions. In any case, the idea behind TDP is not new—in fact, it’s millions of years old. Take organic matter, subject it to heat and pressure, and eventually you get oil. Of course in nature, “eventually” is usually an inconvenient number of millennia; TDP shortens that time to hours, if you can believe that.

A Well-Oiled Machine

TDP is a surprisingly straightforward five-step process. First, raw materials are fed into an industrial-grade grinder where they’re chopped up into extremely small bits and mixed with water. The mixture is then subjected to heat and pressure, breaking molecular bonds and reducing the material to simpler components in as little as 15 minutes. The next step is reducing the pressure dramatically to drive off the water; in the process, some useful minerals such as calcium and magnesium settle out as valuable byproducts. The remaining slurry is sent into a second reactor, which uses even higher temperatures to produce a hydrocarbon mixture. Finally, a distillation step divides the hydrocarbons into vaporous gas (a mixture of methane, propane, and butane), liquid oil (similar to a mixture of gasoline and motor oil), and powdered carbon.

All that to say: garbage in, (black) gold out. The process itself produces no waste materials, unless you count water, which can be recycled in the system. The gas can be used to produce heat for the machine itself; oil can be sent to refineries to be made into a variety of useful products; carbon can be turned into everything from water filters to toner cartridges; and the remaining minerals can be used as fertilizer.

Virtually any organic material can be fed into a TDP apparatus. By making adjustments to the combinations of temperature, pressure, and cooking times, various input products (referred to as feedstock) can produce a wide range of output products; the proportions of, say, gas to oil to carbon will depend on the composition of the feedstock. The first fully operational TDP system was used to recycle the waste at a turkey processing plant. All the turkey parts that weren’t used as meat—skin, bones, feathers, and so on—were fed into the machine, thus solving a serious waste problem (up to 200 tons per day) while creating commercially valuable products. But TDP can also process discarded computers, tires (even steel-belted radials), plastic bottles, agricultural waste, municipal garbage…you name it.

Almost nothing is too messy or too scary for TDP to handle. It can make clean, safe materials out of sewage, medical wastes, dioxins, and other biohazardous materials. Even anthrax, for crying out loud. Apparently the only kind of material this system can’t handle is nuclear waste—I guess you can’t have everything.

Pouring Oil on Troubled Water

Thermal depolymerization is still finding its footing for commercial use, though similar processes have been known for many years. The problem was that they were always too expensive to operate; it cost more for the fuel to decompose the garbage than the resulting materials were worth. The inventors of TDP claim that it is highly energy-efficient—better than 85% in most cases. If that is true, if it continues to be true on a large scale, and if demand is sufficiently high, then TDP may eventually be able to produce oil more cheaply than drilling, and get rid of garbage as a convenient side-effect—or vice-versa, if you prefer.

As fantastic as TDP sounds, the process does have its critics. Some engineers have expressed skepticism that the energy efficiency could be even close to what proponents claim. Even supposing that it were, the oil needs of the United States are currently so massive that if all the agricultural waste in the country were processed into oil, it would still be just a drop in the bucket (so to speak). In other words, so the argument goes, the process holds more promise as a method of recycling and waste reduction than it does as a source of fuel.

The more optimistic viewpoint is that if TDP comes into widespread use, we won’t run out of oil as long as we have garbage. But that also means there will be less incentive to reduce oil consumption or seek out cleaner alternative power sources. Ah, but I suppose every silver lining must have its cloud.

Note: This is an updated version of an article that originally appeared on Interesting Thing of the Day on August 3, 2003, and again in a slightly revised form on June 4, 2004.

from Interesting Thing of the Day http://bit.ly/2W0pL9i