Mortimer was Walt Disney’s original name for a cartoon mouse in the historic 1928 cartoon “Plane Crazy.” When Walt came home and told his wife about the little mouse, she didn’t like the name “Mortimer” and suggested that “Mickey” was more pleasant-sounding.
Walt thought about it for a while and then grudgingly gave in, and that’s How Mickey, and not Mortimer, went on to become the foundation of an entertainment empire.
Around 2400 BC, the ancient Sumarians, who used six as their mathematical base, divided a circle into 360 degrees, with each degree subdivided into another 60 parts, and so on. The Romans called these units minute prima, or first small part, and secunda minuta, or second small part. This system was perfect for round clock faces, and that’s why we use minutes and seconds as divisions of time.
Dogs bark to communicate with other dogs and with humans. Dogs are descendants of wolves, which are social animals that live in packs, and they share many of the behaviors that define the complex relationships that exist within such animal groups. Few domestic dogs live together in packs (though they often consider their human family their group), but they still use complicated behaviors that involve smell, sight, and hearing to communicate. A dog has many scent-producing glands that it uses to communicate. The scent that a dog leaves behind (in its urine, feces, and paw prints) can reveal its sex, age, and even its mood to other dogs that come sniffing by.
A dog uses its posture, facial expression, and ear and tail position to communicate with other dogs, too. And it uses its voice to communicate by whining, growling, howling, or barking. A dog usually whines or whimpers when it is in distress: when it is hungry, cold, or in pain. Growls indicate that a dog is angry and ready to fight. Barks usually show excitement.
Early in human history, people used anything that they could find to keep their teeth clean. Usually a thin, sharp object, like a stick, was used to pick out food left between teeth. Chewing on the end of certain sticks would fray the wood, making a kind of brush, which could then be rubbed across the teeth. (Even today, members of primitive tribes chew sticks to keep their teeth clean. The constant chewing produces more saliva than usual, which helps wash food away.) Later, people found that if they rubbed abrasive elements, like salt or chalk, across their teeth, they could get rid of grime. They also used water and pieces of rough cloth to clean their teeth. Toothpicks made of all kinds of materials also became popular. Rich people had jeweled toothpicks made of gold and silver. Toothbrushes for the wealthy, with fancy handles and hog bristles, came into use in the eighteenth century.
Only much later, when cheaper, woodenhandled toothbrushes were made, and the importance of good dental hygiene became known, did most people start to regularly use them.
Often it is a group of people with something in common, whose members identify with one another, that makes up a country. It may be a shared race, religion, language, history, or culture that makes people feel that they belong together as a nation. Because of its uniqueness, the group feels that it should govern itself as an independent country. This feeling of shared identity and loyalty to the group is frequently behind the rise of nations. Some countries are so large and have such complicated histories of war and conquest that they are home to many different groups of people who have their own separate beliefs, languages, and customs.
The differences between these groups sometimes make it difficult for them to get along. A nation is weakened by such groups if they put their own interests ahead of those of their country. But a population of many different groups can also enrich a country with diverse ideas and cultures if a spirit of acceptance and cooperation exists.
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.
In the early days of theatre, the players were lit by gas lamps hidden across the front of the stage. Early in the twentieth century, it was discovered that if a stick of lime was added to the gas, the light became more intense, and so they began to use the “limelight” to illuminate the spot on stage where the most important part of the play took place. Later called the “spotlight,” the “limelight” was where all actors fought to be.
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.
Since ancient times, soldiers have worn special clothing or armor to protect themselves during warfare. Hard materials like leather, wood, shells, and even woven reeds were used to give soldiers extra protection against enemy arrows. Metal started to be used for armor about 3,500 years ago, by warriors in the Middle East. By the time of the ancient Greeks, about 1,000 years later, soldiers were well protected, wearing large pieces of metal on their chests and backs, shin guards, and metal helmets, and they carried metal shields. Soon armored clothing, garments with metal strips and plates attached, began to be made for soldiers. Then chain mail, a type of metal cloth, was developed. Made of small metal rings linked together, chain mail was much more flexible than metal plates, but could not withstand the force of larger weapons, like lances. So full suits of armor made of steel plates, hinged at the knees and the elbows, came into use around the fourteenth century. Soldiers were covered with steel from head to toe, with heavy metal helmets covering their faces, heads, and necks. A warrior could see and breathe through small slits or openings in the helmet’s visor, a movable metal flap that could be lifted up.
(Only important or wealthy warriors could afford this kind of elaborate armor.) Suits of armor weighed so much that the soldiers or knights who wore them usually could not move around in them very well; they wore such armor mostly when they fought on horseback. Even the horses sometimes wore armor. As the methods and weapons of warfare changed, clumsy personal armor was no longer useful. It became far more important for soldiers to be able to move quickly and easily. Today’s soldiers usually wear cloth uniforms, body armor, and steel helmets. But armor is used on war vehicles like tanks, naval vessels, and aircraft. The bulletproof vests that police officers use are also a type of armor.
Scientists have conflicting opinions about whether dinosaurs were warm-blooded or cold-blooded. Some paleontologists think that all dinosaurs were “warm-blooded” in the same way that modern birds and mammals are, with a high rate of metabolism (body chemistry). Some scientists think they were “cold-blooded,” much like modern reptiles. Some scientists think that very big dinosaurs could have had warm bodies because of their large body size, just as some sea turtles do today. It may be that some dinosaurs were warm-blooded—the problem is that it is hard to find evidence that shows with certainty what dinosaur metabolisms were like. An understanding of dinosaur metabolism helps paleontologists understand the behavior of dinosaurs. If they were cold-blooded, they were most probably sluggish, with only occasional bursts of quickness.
In addition, they probably would not have been very smart creatures. Like modern crocodiles, they probably spent most of their time basking in the sun, moving only to get more food. On the other hand, if dinosaurs were warm-blooded, then they were probably active, social animals. They would have been quick, alert, and intelligent. They would have spent much of their time actively grazing, like the modern antelope, or hunting in packs, like the lion.