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.
The custom of proclaiming wedding banns began in 800 AD when Roman Emperor Charlemagne became alarmed by the high rate of interbreeding throughout his empire.
He ordered that all marriages be publicly announced at least seven days prior to the ceremony and that anyone knowing that the bride and groom were related must come forward. The practice proved so successful that it was widely endorsed by all faiths.
When the time came to honour the patron saint of Ireland’s birthday, church officials gathered solemnly to choose a day, then realized that most of St. Patrick’s life was a mystery. They finally narrowed his birthdate down to either March 8 or 9, but because they couldn’t agree which was correct, they decided to add the two together and declared March 17 to be St. Patrick’s Day.
Humans are credited with five senses: sight, hearing, touch, taste, and smell. So someone with a “sixth sense” is gifted with an unexplained perception outside of the common five.
The expression sixth sense comes from a study of blind people reported in 1903 in which it was found that, although deprived of sight, some of the subjects could perceive or sense certain objects in a room in a way that defied scientific understanding.
Approximately 2,500 years ago the Pythagoreans defined a “perfect” number as one for whom the sum of its divisors, excluding itself, equals the number itself. For example, 6 can be divided by 1, 2, 3, and 6. If you add these numbers together, excluding 6 itself, the total is 6. Therefore 6 is a perfect number. Over the centuries, many mathematicians from all over the world have contributed to finding and defining perfect numbers.
Governor William Penn established Pennsylvania’s first post office in 1683. Central postal organization came to the colonies after 1692, when Thomas Neale received a 21-year grant from the British Crown, whose settlements dominated the Atlantic seaboard, for a North American postal system. It wasn’t until 1774, however, that William Goddard, a newspaper publisher and former postmaster, set up the Constitutional Post for intercolonial mail service.
Colonies funded it by subscription, and net revenues were used to improve mail service rather than to pay back to the subscribers. By 1775, when the Continental Congress met in Philadelphia, Goddard’s post was flourishing, and thirty post offices operated between Williamsburg, Virginia, and Portsmouth, New Hampshire. The Constitutional Post provided security for colonial messages and created a communication line that played a vital role in bringing about American independence during the Revolutionary War.