The Explainer General
On May 24, 1883, The Brooklyn Bridge was opened to the public. It took 14 years, $15 million and many lives to link Brooklyn and Manhattan.
Before work was begun, its designer, John A. Roebling, was making final surveys of the site. A docking ferryboat nudged a piling near him, driving a dirty nail into his foot. He died of tetanus 24 days later. His son, Washington Roebling took over the engineering project.
To sink the bridge tower foundations down to bedrock, workers excavated river silt inside two open-bottomed 3000 ton iron bases, caissons. High-pressure air pumps kept river water out. As the caissons were dug deeper beneath the river surface, air pressure grew higher; work became more dangerous. When they were digging near seventy feet deep, a few workers walked through the caisson air-lock at the surface, across the street to the tavern, and dropped down dead. The cause: nitrogen embolism—gas dissolved in blood under high pressure expanding rapidly at normal pressure. Scuba divers call it “the bends.” Washington Roebling, himself, was crippled this way but monitored the project through a telescope from his bed upriver. His brilliant wife, Emily Warren Roebling, managed construction on-site. Twenty to 30 bridge workers were killed in construction from nitrogen embolism, being struck by falling material, and by falls from the towers.
It was the longest suspension bridge in the world, with a river-span of 1595.5 feet. Anyone could cross: 1¢ for a pedestrian, 5¢ for a horse and rider, 10¢ for a horse and wagon, 5¢ for cows, 2¢ for sheep or hogs.
Only six days after its opening, the bridge was crowded with walkers when a rumor started that the bridge was collapsing! Strollers stampeded, killing 12, injuring 35 in the panic. Was the great bridge safe?
Months later, May 17, 1884, the great huckster and self-promoter P. T. Barnum set out to prove the solidity of the bridge “in the interest of the dear public.” Across the broad bridge paraded 21 elephants with Barnum’s famous African elephant Jumbo in the rear. They were followed by seven Bactrian camels (two-hump) and ten dromedaries (one-hump). Since elephant and camel fares had never been specified, no tolls were paid. The New York Times reported “…it seemed as if Noah’s Ark were emptying itself over on Long Island.”
If any doubts remained, Barnum’s ballyhoo proof put them to rest.
The story of how Jumbo was brought from Africa to the United States is a fascinating one -- Google it. In the meantime, you might want to have a look at Jan Adkin's fascinating description of how people often have to use brains rather than brawn to move heavy items.
Jan Adkins is a member of iNK's Authors on Call and is available for classroom programs through Field Trip Zoom, a terrific technology that requires only a computer, wifi, and a webcam. Click here to find out more.
MLA 8 Citation
Adkins, Jan. "Proof Positive: Ballyhoo Confirms the Safety of the Brooklyn
Bridge." Nonfiction Minute, iNK Think Tank, 7 June 2018,
celebrating nature, inspiring good writing
This summer, you may be able to observe an amazing event in nature. You can watch a small animal build a structure much bigger than itself, using materials from inside its own body!
This is what happens when a spider spins a web. Inside a spider are glands that can produce seven different kinds of silk. The silk comes out of little spigots, called spinnerets, at the rear of the spider's body.
A strand of spider silk is stronger than a similar strand of steel, and spiders use this amazing material in many ways. If they catch an insect, they may wrap it in silk, to eat later. Female spiders enclose their eggs in a silken sac to protect them. And some spiders—almost always females—make webs that are death traps for insects.
Webs can be in the shape of funnels, sheets, or domes, but the best-known are called orb webs. From an orb web's center, lines of silk radiate out in all directions, like the spokes of a bicycle wheel. After building this basic structure, a spider goes round and round, laying down ever-bigger circles of silk. Some of the silk threads have sticky glue to catch a moth or other prey. A spider can create this whole complex design in an hour or less.
When an orb web is complete, some kinds of spiders wait right in the center. Others hide at an edge. Either way, the builder keeps a front leg in touch with the web. Vibrations from the threads tell a spider whether prey has been caught.
Spiders often have to repair their webs, and some species routinely build a new one every day. And they recycle! They eat most of their old web. After digestion, it becomes brand new silk for the next construction job.
You may be able to watch a spider on the job. Look for webs in a field, park, or backyard. Also look for webs near doors, windows, or on a porch. The nighttime lights from such places attract night-flying insects, and spiders often build webs there. They may or may not be orb webs, but watching any kind of spider at work on its silken insect-trap can be fascinating fun.
And remember: the spider wants nothing to do with you. It is just trying to stay safe and catch some food.
This video was shot by Ingrid Taylor, " I shot this a few minutes after the rain subsided, when the City of Spiders outside the door came to life. Mass web-building and repair going on..." wikimedia commons
.To learn more about the lives of spiders, and see spectacular realistic illustrations, see Laurence Pringle's book:
MLA 8 Citation
Pringle, Laurence. "Watch a Webmaster at Work!" Nonfiction Minute, iNK Think
Tank, 14 June 2018, www.nonfictionminute.org/the-nonfiction-minute/
Sneed B. Collard III
Several years ago, I rode the world’s fastest elevator to the top of one of the world’s tallest buildings—Taipei 101. Shaped like an elegant stalk of bamboo, Taipei 101 soars 1670 feet above the island nation of Taiwan. However, the engineers who designed the building faced two monumental challenges. The first is that dozens of earthquakes shake Taiwan each year. The second is that in an average year, Taiwan gets hammered by three or four hurricanes, or typhoons.
How, engineers wondered, could they keep people comfortable inside Taipei 101 when it swayed back and forth? More important, how could they keep the building from getting damaged or collapsing in a massive earthquake or 100 mile-per-hour winds?
One solution: a damper ball.
Damping devices are weighty objects that can reduce the motion of a bridge, building, or other structure. In the case of Taipei 101, engineers placed the damper ball near the top of the building—the part that sways the most. The ball is hung from thick cables inside the building and rests on giant springs or “dampers.”
One of Isaac Newton’s basic laws of physics is that an object at rest tends to stay at rest—and the damper ball proves it. Every time Taipei 101 starts swaying, the damper ball wants to stay where it is and “pulls back” on the building, reducing how far the building moves. When the building sways in the opposite direction, the process repeats itself—but in the reverse direction. Of course the building also pulls on the damper ball, but the ball’s movements are restricted by the dampers it presses against.
Does the system work? You bet. The damper ball inside of Taipei 101 reduces the building’s movement by 30 to 40 percent!
Of course not just any damping device could protect an enormous building like Taipei 101. Taipei’s damper ball weighs 1.5 million pounds—as much as two fully-loaded jumbo jets. It is composed of 41 circular steel plates that stand taller than a one-story house. In 2008, when a giant earthquake hit mainland China, the people of Taiwan could feel it hundreds of miles away. The damper ball did its job, resisting Taipei 101’s movement, keeping the building safe. During Typhoon Soudelor in 2015, the damper again worked like a charm, protecting the building against 100- to 145-mile-per-hour winds.
Besides protecting Taipei 101, the damper ball has become a major tourist attraction. Each year, thousands of visitors ride to the 89th floor. They take selfies next to the damper ball. They even take “Damper Baby” souvenirs home with them. If you’re ever lucky enough to visit Taiwan, check it out!
The damper ball is visible between the 89th and 91st floor of Taipei 101 and has become an attraction for tourists.
Sneed B. Collard III is author of more than eighty award-winning children’s books as well as a new book for educators, Teaching Nonfiction Revision: A Professional Writer Shares Strategies, Tips, and Lessons.
Sneed is a dynamic speaker and offers school and conference programs that combine science, nature, and literacy. To learn more about him and his talks, visit his website,.
To learn more about the damper ball and watch how it performed during Typhoon Soudelor, check out this article and video: http://www.thorntontomasetti.com/taipei-101s-tmd-explained/
MLA 8 Citation
Collard, Sneed B. "Damping Down Danger." Nonfiction Minute, iNK Think Tank, 10
01 2018, www.nonfictionminute.org/the-nonfiction-minute/
Giving Voice to Children in History
In the late 1800's when homesteaders first located their new claims in the Midwest, some saw nothing in any direction but tall prairie grass. On 160 acres of windswept land, there might not be a single tree. But these settlers were resourceful. They set to work building homes and barns from the one thing they had in abundance: the sod beneath their feet.
Because the soil had never been tilled, roots were tightly packed, and sod could be cut from the earth in three-foot- thick blocks. The sod houses that settlers built stood up well to harsh Midwest weather. Sod was a natural insulator, keeping out cold in winter, and heat in summer, while wood houses, which usually had no insulation, were just the opposite: always too hot or too cold. Another advantage of a soddy was that it offered protection from fire, wind, and tornadoes.
But a soddy also had drawbacks. Dirt constantly sifted down from the ceiling, making it almost impossible to keep clean. Rain or melting snow caused water to work its way through the roof and walls and run in trails along the floor, turning it to mud. Settlers actually used umbrellas or wore jackets—not to mention boots--to keep dry. Heavy rains and snow put the roof at risk of collapsing under the extra weight. If the soddy was built into a hillside and the family cow decided to graze on the roof, the cow could come crashing through the ceiling, especially if it had rained or snowed recently.
The worst drawback was insects and critters. Blocks of sod were home to fleas, ticks, mice, worms, and even snakes. One settler reported a snake dropping down from the rafters right onto the table at dinnertime. And a young mother never got over finding a snake curled up with her baby. Before getting up in the morning, folks learned to look under the bed first--because you just never knew.
In spite of this, lots of settlers loved their soddies and stuck with them even after they could afford to have wood shipped in to build what most people considered to be a proper house. They added on rooms, plastered all the walls, and installed wood floors and ceilings to keep the critters out. With that done, living in a soddy suited them just fine. And when the soddy needed repairs, they merely stepped outside, looked down—and there was their building material.
You can learn more about what it was like to live in a sod house in Andrea Warren's nonfiction book for young readers,Pioneer Girl: A True Story of Growing Up on the Prairie.
Andrea Warren is a member of iNK's Authors on Call and is available for classroom programs through Field Trip Zoom, a terrific technology that requires only a computer, wifi, and a webcam. Click here to find out more.
MLA 8 Citation
Warren, Andrea. "Snakes on the Dinner Table! Life in a Sod House." Nonfiction
Minute, iNK Think Tank, 9 Mar. 2018, www.nonfictionminute.org/
The great Paris tower was underway. From each corner of a broad base the size of a football field, four spidery iron structures rose, curving inward in one majestic sweep toward the middle. The construction – a web of connecting girders – called for 300 workers to assemble some 15,000 pieces of iron and snap 2.5 million rivets into place. This would be the world’s tallest man-made structure, reaching a height of 300 meters (934 feet). A glorious demonstration of engineering, it was conceived by Gustave Eiffel, the most illustrious engineer of nineteenth-century France.
The tower was to be the focal point of the International Exhibition of Paris in 1889, commemorating the 100th birthday of the French Revolution. After that, since it had no practical use, it was to be torn down.
It took two years, two months, and three days to build the Eiffel Tower. Eiffel used wrought iron, which was a relatively new building material at the time, used primarily for bridges and aqueducts. As the tower rose, becoming the city’s most prominent feature, not everyone approved. “Useless and monstrous,” one newspaper called it. Another described it as an “odious column of bolted metal.”
Called the Magician of Iron, Eiffel’s mathematical prowess and attention to detail was legendary. To put the tower project on paper took 30 draftsmen working full time for 18 months. Every rivet of the 2.5 million needed for the structure had its designated place, down to a fraction of a millimeter.
The Tower became the hit of the International Exhibition, with nearly two million people visiting it. Still, not everyone loved this prodigious web of steel girders. A famous writer was once asked why he ate lunch there every day, since he was known to hate the sight of it. He replied, “Because it’s the only place in Paris where I can’t see the damn thing.”
So why wasn’t the Eiffel Tower torn down? It almost was. What saved it was the radio broadcasting center and the weather station that Eiffel installed at the top.
Now France’s most famous landmark, it is not the only national symbol that Eiffel was involved with. He also built the iron skeleton of a lady we’re all familiar with: The Statue of Liberty.
As for the Eiffel Tower, “I ought to be jealous of that tower,” he once said. “She is more famous than I am.”
The Eiffel Tower under construction highlights the intricacy of the design as well as the massive size of the project in relation to the city of Paris. Art by Roxie Munro
Eiffel's most famous works are still major tourist attractions in the 21st century. The Eiffel Tower is the most-visited paid monument in the world. An average of 25,000 people ascend the tower every day. Approximately four million people visit New York's Statue of Liberty National Monument and Ellis Island each year. Photo Benh Lieu Song viia Wikimedia Commons. Art by Roxie Munro
One of Roxie's most recent, Masterpiece Mix, is a book about art. As an artist searches for inspiration, she explores thirty-seven paintings of different genres, and comes up with a grand finale, using all of them. The book has "smart, concise, marvelously amplifying backmatter" (Kirkus), a dedicated web page, and free downloads.
MLA 8 Citation
Munro, Roxie. "The Magician of Iron." Nonfiction Minute, iNK Think Tank, 7 Mar.
For Vicki Cobb's BLOG (nonfiction book reviews, info on education, more), click here: Vicki's Blog
The NCSS-CBC Notable Social Studies Committee is pleased to inform you
that 30 People Who Changed the World has been selected for Notable Social Studies Trade Books for Young People 2018, a cooperative project of the National Council for the Social Studies (NCSS) & the Children’s Book Council