Early railroads had only a single track between destinations. Problems arose when a train was met by another going in the opposite direction or was about to be overtaken by a faster one. This dilemma was solved with the creation of sidings, short lengths of track built parallel to the main line where one train could pull over while the other went by. The train had been “sidetracked,” meaning that, for a time at least, it wasn’t going anywhere.
Like many inventions, the development of the modern zipper can be traced to a series of events. In 1893, Whitcomb Judson patented and marketed a “clasp locker,” a complicated hook-and-eye shoe fastener. Together with businessman Colonel Lewis Walker, Whitcomb launched the Universal Fastener Company to manufacture the new device. He did not use the word “zipper,” although many people often credit him as the zipper’s creator. Instead, it was Swedish-born Gideon Sundback, an electrical engineer who was hired to work for the Universal Fastener Company, Who gets the credit.
He was responsible for improving Judson’s fastener, and by December 1913, he had designed the modern zipper. Sundback increased the number of fastening elements from four per inch to ten or eleven, had two facing-rows of teeth that pulled into a single piece by a slider, and increased the opening for the teeth guided by the slider. Sundback also created a machine that was able to manufacture the zipper.
Much of what you need to know to live successfully as an adult does not come naturally— it has to be learned and studied and memorized. Children learn to speak nathandy urally, for example, by listening to those around them, but reading and writing must be specifically taught. The complicated process of learning the alphabet and the sounds it represents, putting letter sounds together to make words, and learning the meaning of words in order to read and write are skills that only come with special effort. Knowing how to figure out problems that involve numbers, and learning how the world is run or how nature works are important things to learn, too. Although your parents might be able to teach you these things, they would need many hours each day to do it. Most parents work outside the home and wouldn’t have the time to give proper instruction (although some kids are “home schooled” by their parents instead of going to school).
In the United States, a public school system provides years of free education for all children. Teachers, who are specially trained to know what children should learn, and how, and when, are the people who do the job. To ensure that children learn what they need to, state governments now require that all children go to school for a certain number of years (usually until age 16). Kids who skip school a lot can find themselves in court. (Children who go to private schools or whose parents have received special permission to teach them at home are exceptions.)
The Industrial Revolution was an era of sweeping change, as the focus in different societies changed from agricultural to mass-producing and industrial. It began in Great Britain in the 1700s. By the early 1800s it had spread to western Europe and the United States. It was brought about by the introduction of steam-power-driven machinery to manufacturing.
As inventors made new machines that could take over manual labor, sweeping changes in agriculture, textile and metal manufacture, transportation, economic policies, and social structures took place. By the end of the eighteenth century, most finished goods—which had once been made by hand or by simple machines—were produced in quantity by technologically advanced machinery. Factories were built to house the new machines, causing a population shift from rural areas to urban ones.
The great Shawnee Chief Tecumseh, who died fighting with Canada against the United States’ invasion in the War of 1812, placed a curse on the American presidency. He proclaimed that every president elected in a year that ends in a zero would die during his term. Since then, every president elected in such a year has died in office, with the exception of Ronald Reagan, who was shot, but survived. Here is a complete list of presidents affected by the curse:
- William Henry Harrison, elected in 1840, died of pneumonia one month into his presidency.
- Abraham Lincoln, elected in 1860, was assassinated in 1865 at the beginning of his second term.
- James A. Garfield, elected in 1880, was assassinated in 1881.
- William McKinley, elected for his second term in 1900, was assassinated in 1901.
- Warren G. Harding, elected in 1920, died of Ptomaine poisoning in 1923.
- Franklin D. Roosevelt, elected for his third term in 1940, died of a cerebral hemorrhage in 1945 at the beginning of his fourth term.
- John F. Kennedy, elected in 1960, was assassinated in 1963.
- Ronald Reagan, elected in 1980, survived an assassination attempt while in office. Some say that by surviving he broke the curse.
The ancient Greeks believed a blessing might prevent evil from entering your body during its unguarded state while you sneeze. Our tradition comes from the black plague of 1665, when sneezing was believed to be one of the first symptoms of the disease. Infection meant certain death, and so the symptom was greeted with the prayer, “God bless you,” which through time has been shortened to “Bless you!”
The fluid in your inner ear is responsible for dizziness. After you spin around, your ear fluid keeps spinning, sending conflicting messages to your brain.
These mixed signals cause dizziness, lack of balance, and lightheadedness. After a few seconds, the liquid levels out and the dizziness goes away.
Comets are solar system bodies that orbit the Sun, just as planets do, except a comet usually has a very elongated orbit. Part of its orbit is very, very far from the Sun and part is quite close to the Sun. They are sometimes nicknamed dirty “cosmic snowballs,” because they are small, irregularly shaped chunks of rock, various ices, and dust.
As the comet gets closer to the Sun, some of the ice starts to melt and boil off, along with particles of dust. These particles and gases make a cloud around the nucleus, called a coma. The coma is lit by the Sun. The sunlight also pushes this material into the brightly lit “tail” of the comet.
Any group of birds, goats, or sheep can be referred to as a flock, but each feathered breed has its own proper title. Hawks travel in casts, while it’s a bevy of quail, a host of sparrows, and a covey of partridges.
Swans move in herds, and peacocks in musters, while a flock of herons is called a siege. A group of geese is properly called a gaggle, but only When they’re on the ground. In the air they are a skein.
Glow-in-the-dark stickers, stars, toys, and clothes, all work by absorbing light and emitting it later. These items contain phosphors, substances such as zinc sulfide that radiate visible light after being energized by natural light. Phosphorescent materials continue to glow after the energizing light is removed. They have electrons that are easily excited to higher energy levels when they absorb light energy.
In phosphorescent materials—such as glow-in-the-dark objects—the excited electrons drop to a lower, but still excited intermediate level and stay there for a period of time before returning to their ground state (original energy level) and emitting the excess energy as visible light.