The blue whale, who swims all of the world’s oceans, in the largest mammal. The largest blue whale cited was at least 110 feet (33.5 meters) long and weighed 209 tons (189,604 kilograms). The average length is about 82 feet (25 meters) for the males, and 85 feet (26 meters) for the females. A newborn blue whale can weigh anywhere from 2.5 to 4 tons (2,268 to 3,628 kilograms), and can reach 100 to 120 tons in adulthood. Whale calves drink 50 to 150 gallons of its mother’s milk per day, adding about 8 pounds (3.6 kilograms) of weight per hour, or 200 pounds (90.7 kilograms) per day.
At about eight months of age, when the calf is weaned, it measures close to 50 feet (15.2 meters) long and weighs about 25 tons (22,679 kilograms). Blue whales do not have teeth. Instead, in their upper jaw they have rows of hundreds of baleen plates—flat, flexible plates with frayed edges, arranged in two parallel rows that look like combs of thick hair. The blue whale feeds on a small shrimp-like animal called krill. Scientists believe that large marine mammals, like whales and dolphins, have brains much like those of humans. They are able to communicate, follow instructions, and adapt to new environments. Throughout history, these gentle giants have been hunted for their baleen and blubber (fat), and are today considered an endangered species. Scientists believe there are about 4,000 or so of them left in the world.
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.
As a boy, Benjamin Franklin was sharpening tools in his father’s yard when a stranger carrying an axe came by and praised the boy on how good he was with the grindstone. He then asked Franklin if he would show him how it would work on his own axe. Once his axe was sharpened, the stranger simply laughed and walked away, giving young Franklin a valuable lesson about people with “an axe to grind.”
The custom of dressing baby boys in blue clothes began around 1400. Blue was the colour of the sky and therefore Heaven, so it was believed that the colour warded off evil spirits. Male children were considered a greater blessing than females, so it was assumed that demons had no interest in girls.
It was another hundred years before girls were given red as a colour, which was later softened to pink.
“Hanging out” usually means getting together for no particular reason other than to pass time and see what’s happening. The expression comes from a time before commercial signs, when English shopkeepers set up poles in front of their stores from which they would hang flags describing their goods. These flags were called hangouts, and they became a place where people would stop to linger and gossip with their friends.
Cellular, or cell, phones first became available to consumers in the early 1980s, but the technology that made them small and truly portable evolved gradually over the next 10 years or so. By the beginning of the twenty-first century, millions and millions of people in countries all over the world were using cell phones on a daily basis. And it isn’t just adults who enjoy the benefits of completely mobile phone capabilities: in the United States alone, more than 20 percent of teenagers have a cell phone. That translates to at least one in five American teens. The cellular system divides each city into many small cells (a large city can have hundreds). Each cell has its own tower (which contains an antenna as well as transmitters and receivers that send and receive signals). Each tower can handle numerous callers at a given time, and their small size and weaker signal (compared to the radio antennae) means that their signals don’t interfere with those of nearby towers. When you call someone using a cellular phone, your phone is sending and receiving signals via radio waves, invisible bands of energy that work like light rays. In other words, your cell phone is a fancy, high-tech radio. After you dial a friend’s number, your phone must find the closest tower by searching for the strongest signal. Once that signal is located, your phone transmits certain information—like your cell phone number and serial number—that help your service provider make sure you are one of their customers.
Then the mobile telephone switching office (MTSO) finds an available channel where your conversation can take place. The MTSO then completes the connection (all of this happening in a few short seconds) and you are chatting with your friend, without wires or cords to hold you down. If you are sitting in the back seat of the car while talking, and your mom is driving you from one end of town to the other, your call will be switched automatically from one cell tower to the next without any pause in your conversation.