How long is a fortnight?

The word fortnight is a unit of time that equals fourteen days. It comes from the Old English word feorwertyne niht, meaning “fourteen nights.” The term is used in Great Britain, where salaries and most social security benefits are paid on a fortnightly basis, but in the United States people use the term “two weeks.”

In many languages, there is no single word for a two-week period and the equivalent of “fourteen days” has to be used. In Spanish, Italian, French, and Portuguese, the terms quince días, quindicina, quinzaine, and quinzena—all meaning “fifteen days”—are used.

Why are rain clouds gray?

Rain clouds are generally dark gray because light cannot penetrate them due to the deep and densely packed water droplets and ice inside the cloud. Generally, the color of a cloud depends on the cloud’s relationship to the sunlight: Clouds appear gray when they block sunlight.

The thicker the cloud, the more light it blocks. When a cloud is about 3,000 feet (914 meters) thick, hardly any sunlight will make its way through the cloud.

How does a cat’s tail help keep the animal balanced?

Almost 10 percent of a cat’s bones are in its tail, and the tail is used to maintain the animal’s balance. A cat’s tail plays a vital part in its “righting reflex” that allows it to land on its feet after falling from a height. Cats often survive a long fall based on their agility and balance, which they develop as kittens. When falling, the fluid in the inner ear shifts and the cat rotates its head until it equalizes and the fluid is level.

The body automatically shifts to follow the head, and the cat lands on its feet. A cat also uses its tail to communicate. A cat’s tail held high means that it is happy. A twitching tail is a warning sign that it may be angry or on guard, and a tail tucked in close to the body is a sign of insecurity or fearfulness.

Why are barns usually painted red?

Paint coats wood, protecting it from sunlight and rain damage and making it last longer. When early farmers had enough money to paint their barns, they usually used inexpensive paint because the structures were so large. Ferrous oxide, a chemical powder that gives paint its red color, was readily available and cost little. Thrifty farmers in New England, New York, and the upper Midwest region painted their barns red. In those places, red barns remain a tradition. But there are plenty of barns in other parts of the country that are not red. Early farmers that were poor—especially in regions like Appalachia and the South—left their barns unpainted because they did not have the money to do the job.

Unpainted wood usually weathers to a soft gray color. And in places like Pennsylvania, Maryland, and some southern Midwestern states, the most frequently seen barn color is white. Some people think that white barns grew popular when dairy farming became more important after the Civil War; white suggests cleanliness and purity, desirable qualities to be associated with milk production. Special farms where fancy horses or prize livestock were raised sometimes had barns painted unusual colors, like yellow, green, or black.

What is e-mail?

People can use the Internet to send electronic mail, known as e-mail, to one another in just a few seconds. Once you type a message into your computer to send to your cousin, let’s say, who lives miles from you across the country, it travels through the wires of your phone line as a series of electrical signals (or, for some people, the signals travel through the same cables that bring them cable television). These signals travel to a station run by your service provider, where a big computer sends them to an Internet routing center. Located all over the world, routing centers, which are linked to organizations and Internet providers, send the countless computer communications that come to them each second along the quickest possible routes to their destinations.

A giant computer there reads the address on your e-mail and sends it farther: depending on the distance it must travel, it may continue along phone lines, be changed into light signals that can travel with great speed along thin glass strands called fiber-optic cables, or be converted into equally speedy invisible bands of energy known as radio waves and transmitted to a communications satellite that will bounce it back to Earth, to a ground station located close to where your cousin lives. Once your message reaches the routing center nearest your cousin, it will be sent to the station of his or her service provider. From there it will be sent along regular phone lines to his or her computer. And all of this happens in a matter of moments.

Why do certain items glow-in-the-dark?

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.

How is steel used in skyscrapers?

Tall, multistory structures called skyscrapers are made of steel, which is sturdier and lighter in weight than other building materials, such as brick and stone. In the late 1800s, when steel production became common, architects experimented with steel, forming it into long, thin pieces called girders. The first skyscrapers, built in the United States in the 1880s, were constructed using vertical columns and horizontal beams made from steel girders. This supporting skeleton allowed buildings to rise to 10 or more stories. Skyscrapers grew taller when designers began using bundled steel tubes instead of heavy girders.

Tube buildings, like Chicago’s Sears Tower, get most of their support from a stiff grid of steel columns and beams in their outer walls. The lighter weight pieces need less support, and so architects can 144 add more height. Additional beams can be placed diagonally for additional support while adding little extra weight. The girders and beams are bolted together and welded on all sides so that the building will not sway from side to side as a unit when there is wind.

Which city is the largest?

There are many cities around the world that are “big,” meaning they have more than 10 million people living in them. Tokyo, Japan, ranks the largest, since it has 33.2 million people living in the city, according to 2005 estimates. The next biggest cities in order of size are São Paulo, Brazil (17.7 million), Seoul-Incheon, South Korea (17.5 million), Mexico City, Mexico (17.4 million), Osaka-Kobe-Kyoto, Japan (16.4 million), and New York City (about 8 million people).

Most of these cities are located in different places around the globe. In the United States, after New York, Los Angeles is the biggest city (with almost 4 million people), and then Chicago (with almost three million people). Populations of cities are constantly changing as people move in and out of them, according to the U.S. Census Bureau, a government organization that estimates how big or small cities are based on their populations, or the number of people living in them.

Which was the smallest dinosaur?

The smallest dinosaurs were just slightly larger than a chicken. Compsognathus (meaning “pretty jaw”) was 3 feet (1 meter) long and probably weighed about 6.5 pounds (2.5 kilograms). At one time, scientists thought that Mussaurus (meaning “mouse lizard”) was the smallest dinosaur, but it is now known to be the hatchling of a dinosaur type that was much larger than Compsognathus when fully grown.

If birds are advanced dinosaurs, as some scientists believe, then the smallest dinosaur would be the hummingbird!

Why is some extreme behaviour called “beyond the pale”?

The expression dates back to the English Crown’s first efforts to control the Irish by outlawing their language and customs. But the unruly Irish were just that, and by the fifteenth century the English still controlled only a small area around Dublin, protected by a fortification called “The Pale,” meaning sharp sticks (i.e., impaled). To the British, to go “beyond The Pale” meant that you were entering the uncivilized realm of the wild Irish.