Karen Hill 
Various kinds of oil have been burned in lamps for thousands of years. Whale oil was once widely used for lighting, and so was kerosene, an oil produced from coal. But the only petroleum available in earlier times was the small amounts that leaked naturally from the ground, or came from wells dug by hand. … Read more
Not the kind of dentists we know today. In ancient times, the only treatment for aching teeth was having them pulled out when they began to hurt. It wasn’t until the Middle Ages that cavities were first filled, usually with wax or gum. Later, soft metals were molded to fit the shape of the cavity. … Read more
Everyone knows that the symbol “&” means “and,” even if they don’t know that the real name of that symbol is ampersand. This symbol was invented by a Roman, Marius Tiro, in ancient times, along with about 5,000 other shorthand symbols. But of all his symbols, only the ampersand has survived. Tiro created the ampersand … Read more
In his early life, Samuel Morse was a painter, and also the first president of the National Academy of Design. In 1832, during a voyage home from Europe where he studied painting, Morse heard about some new discoveries in electricity. Intrigued by its possibilities, Morse soon set to work building a telegraph machine that could … Read more
The skin on the tip of your finger has a network of ridges, and the pattern that these ridges form is called your fingerprint. Everyone has fingerprints, but no two people have ever had the same ones! The idea of using fingerprints to identify people began late in the 19th century, when Francis Galton, an … Read more
The 13 stripes on the American flag stand for the 13 original states of the Union. But all 13 states did not become part of the United States at the same time. The first state to accept the Constitution and thereby become a state was Delaware. Delaware accepted the Constitution on December, 1787, five days … Read more
The world’s first postage stamps appeared in England in 1840, but the first U.S. stamps didn’t appear until 1847. There were two stamps issued at that time: a five-cent and a ten-cent. The five-cent stamp had a picture of Benjamin Franklin, who had been in charge of the mails during the American Revolution. The ten- … Read more
Stock markets, places to buy and sell stocks and bonds, existed before this country was born. A stock exchange in Paris, called the Bourse, grew out of a money-changer’s market that dates back to the 12th century. The first real stock exchange was founded in Holland in 1602, and there was a stock exchange in … Read more
The first large insurance company, and the most famous in the world today, is Lloyd’s of London. This company was founded in 1689 by a group of men who met in Lloyd’s coffee house in London, and originally sold only ship insurance. Today you can buy insurance on almost anything, a house, a car, a … Read more
The first organized mail system in America began before our country was born. In 1639, the city of Boston declared that people who wanted to send mail to or receive mail from England should deposit and pick up their letters at Richard Fairbanks’ tavern. Before that, a person who wanted to send mail to England … Read more
Yes, but not the kind of mail delivery we know today. During ancient times, only government and military officials could use the postal system. Everyone else had to hire their own messengers to deliver a letter to another person. The Egyptians had a mail delivery system by the year 2000 B.C. Its purpose was to … Read more
Before the 17th century, men sometimes wore scarfs around their necks, or large ruffled collars called ruffs, but there was no such thing as the necktie as we know it. Then in 1660, a group of soldiers from Croatia, which is now part of the nation of Yugoslavia, came to Paris to join in a … Read more
Denim is a kind of tough cotton cloth that is used today to make blue jeans. Originally the word was used for a kind of serge cloth made in the French city of Nimes. In French, it was called serge de Nimes. The last two words of the French name, de Nimes, were eventually shortened … Read more
Until the 18th century, men’s pants as we know them today didn’t exist. At that time, well-dressed men wore knee breeches that reached just below their knees, with long hose to cover the rest of their legs. Then in 1789, when the French Revolution began, men who supported the Revolution gave up the knee breeches … Read more
The first living thing to fall to earth with a parachute was a sheep. The animal, attached to a seven-foot-wide umbrella, was dropped from a tower in France late in the 18th century, but the first person to use a parachute was a Frenchman named Andrê Garnerin. In 1797, Garnerin climbed into a basket attached … Read more
In very ancient times, people bathed right in the nearest river or lake. But when cities began to grow, it was no longer possible for everyone to bathe in the same river. So, wash basins came into use for bathing in the house. Most of these ancient vessels were too small to hold a person, … Read more
Portable clocks were invented in Germany around 1500, but no one had the idea of putting a watch around the wrist until very recently. Until around 1900, most watches were carried in a pants or vest pocket, often at the end of a chain. Both the chain and the pocket were called the watch. In … Read more
You might think that the compass has long been used by sailors to navigate on the open seas. The truth is, there was no such thing as the compass in ancient times, and even after the compass was invented, it wasn’t used all that much for marine navigation. Sailors in ancient times charted their course … Read more
The custom of decorating a house with tree leaves or branches in December is actually older than Christmas itself. The ancient Romans celebrated a December feast, called Saturnalia, by giving presents and decorating their houses with green branches. At the same time, pagan people in Germany worshipped a sacred oak tree. Then, when Christian missionaries … Read more
Christmas has been celebrated for many centuries, but the custom of sending greeting cards at Christmas didn’t begin until 1843. That year, an Englishman named Henry Cole wanted to send his friends a note wishing them happiness at Christmas. He hired an artist named John Horsley to design the world’s first Christmas card. This card … Read more
St. Nicholas was a Christian bishop who lived during the fourth century in what is present-day Turkey. Little is known about his life, but he was thought to be the protector of children and travelers. After he died, he was made a saint. According to legend, three daughters of a man who lived in St. … Read more
On December 25, we celebrate the date of Christ’s birth. But no one knows when Christ was really born. When the church decided to mark Christ’s birth with a celebration, it chose December 25 as the date because it was already a holiday in most places in Europe, a holiday called the winter solstice. Since … Read more
Today, Sunday school is a place where young people learn about their religion after they attend church on Sunday. But it didn’t begin like that. The first Sunday school was opened in 1780, in the poor section of Gloucester, England, to teach children reading, writing, and arithmetic. Sunday was the only day these children could … Read more
The Boy Scout movement was founded early this century in England by Sir Robert Baden- Powell. While trying to find his way through the London fog, an American businessman, William D. Boyce, was helped by a British Boy Scout. Boyce then decided to set up a scouting organization in the United States too. In 1910, … Read more
Kindergarten is really a German word. It means “children’s garden.” We use the German word because in 1837, a man named Friedrich Froebel set up a school for children in Germary and called it by that name. Froebel used games, toys, stories, songs, and other playtime things to teach preschool children to exercise their senses … Read more
A toy is anything a child can play with. It might be simply a piece of wood or a spoon or some other common object. But objects made especially for children to play with are as old as history itself. Greek and Roman children played with balls, wagons, and other toys that are still popular … Read more
No, people didn’t always sleep on what we would call a bed, and many people today still have never slept on a bed! Perhaps half of the world sleep on piles of rugs, or on mats or cushions. The beds used by the ancient Egyptians looked very much like couches, and were used during the … Read more
In 1795, the French government offered a prize to anyone who could invent a way to preserve food for the French army. A man named Francois Appert won the prize by devising a way to keep food fresh in sealed glass bottles that were placed in boiling water. But no one knew why the food … Read more
Bile is one of the digestive juices that help the body break down foods into usable elements. It’s a yellowish fluid produced by the liver and stored in a small pouch underneath the liver called the gall bladder. When food enters your small intestine, bile flows out of the gall bladder and into the intestine, … Read more
Your spleen is a large organ inside your body, next to your stomach. But it’s actually attached not to your digestive system, but to your blood stream. Scientists have already discovered some of the spleen’s functions, but they’re not sure they’ve found them all. They do know that the spleen helps make new red blood … Read more
An anesthetic is a drug given to a person before an operation so that he won’t feel pain. Even if you’ve never had a serious operation in a hospital, you probably received an anesthetic at some time in your life. There are two kinds of anesthetic: general and local. A general anesthetic produces unconsciousness, so … Read more
Certain kinds of baldness accompany illnesses. For instance, scarlet fever, pneumonia, and typhoid fever can sometimes result in the loss of hair. Gland problems and an imbalance of certain hormones in the body can lead to baldness. So can poor nutrition, scalp disease, and poor care of the hair and scalp. But the kind of … Read more
The right half of the brain controls the left side of the body, and the left side of the brain controls the right side of the body. In most people, the left side of the brain is better developed, so the right hand is stronger and more controllable than the left hand. But sometimes, the … Read more
Sometimes you might hear someone say: “You eat so much, you must have a tapeworm.” A tapeworm is a kind of flatworm that lives in the digestive tract of another animal or person, and takes in food which its host has partially digested. Many people believe that a person with a tapeworm will eat a … Read more
When you move the muscles in your body, they produce a substance called sarcolactic acid, also called the “acid of fatigue.” When too much of this acid forms around a muscle, the muscle becomes “tired.” The same sarcolactic acid is found in your blood too, as it travels to all parts of your body. So … Read more
The word arthritis means a swelling of the body joints, but not all arthritis involves swelling. In the type of arthritis known as rheumatism, the joints do swell up and eat into the cartilage that surrounds them. Since this cartilage acts as a sort of “shock absorber” around the joint, the loss of cartilage and … Read more
Tetanus is a disease caused by bacteria that secrete poisons. These bacteria usually enter the body through cuts or scratches. You may believe that tetanus can be caused only by cuts from old or rusty metal, but actually, a cut from any object can cause tetanus. That’s why when you get a serious cut, your … Read more
Sometimes when your body is very tired, your lungs and the rest of your respiratory system may slow down until there’s too little air in your lungs. As soon as this happens, your body sets off a quick movement, or spasm, in the muscles of your mouth, throat, and chest. This spasm forces you to … Read more
For people who suffer from hay fever and certain other allergies, it’s important to know how much pollen is in the air. Some people who are very sensitive to pollen go away during peak pollen seasons, and they want to know what the pollen count is before they return home. A pollen count is, quite … Read more
Most plants produce pollen, which is carried by insects or the air to other plants to pollinate them and produce seeds. Many people are allergic to the pollen of certain plants, and the sickness they suffer from this pollen is called hay fever. Most hay fever is caused by the pollen from ragweed and goldenrod. … Read more
The pupil, the black spot in the middle of your eye, is actually a hole that allows light to enter the eye. Around this hole is the colored part of the eye, the iris, which regulates the size of the pupil and how much light is allowed into the eye. The iris has pigment in … Read more
About one in every 12 males and one in every 200 females suffer from some form of colorblindness. But there are many different kinds of colorblindness. In one common form, a person cannot tell the difference between yellow and pale green. In another common form, a person cannot tell red and green apart. These colors … Read more
Your eyes are probably the most sensitive optical instruments ever invented, by man or by nature. In good light, your eyes can tell the difference between some 10 million colors! The best machines can recognize only four million. From ten inches away, you could see an object just 4/1000 of an inch long. And in … Read more
When you have allergies, certain things don’t “agree” with your body. These things may be foods, animal hairs, plant pollen, chemicals, or almost anything else, and may enter the body when you eat or inhale. When they do, you feel uncomfortable or even sick. Although millions of people have this problem, scientists still aren’t sure … Read more
Your body is constantly burning up sugar and other food substances to provide energy. Normally, this burning produces a body temperature of 98.6° F. But when you’re sick, your body tries to fight the sickness by working faster and harder. More blood cells and hormones are produced, your blood circulates faster, and your lungs breathe … Read more
Sometimes when your fingers or ears get very cold, even numb, you might say that they’re frostbitten. But frostbite is really very serious, and requires a doctor’s care. In very cold weather, the skin on your fingers, toes, or ears may become so cold that blood stops flowing to it. This is your body’s way … Read more
Saliva, or “spit,” helps you swallow and digest food. As soon as you start to eat, glands in your mouth begin to secrete saliva, moistening and softening food to make it easier to swallow. Saliva also contains an enzyme called ptyalin, which digests food the same way that the digestive juices in your stomach do. … Read more
By the age of 13, most people have 28 permanent teeth, including two sets of molars. Then, at age 18 or later, a third set of molars begins to come in. These molars are called wisdom teeth, because they appear later in a person’s life, when he is “supposedly” wiser. Often, wisdom teeth don’t come … Read more
The air is only one-fifth oxygen. When you take a breath, your lungs inhale oxygen from the air, and you exhale the rest, which is mostly nitrogen. But when a diver is in the water and breathing through an aqualung, there’s no way he can get rid of all this nitrogen, and some of it … Read more
Seasickness may feel like it begins in the stomach, but it actually starts in the ears! Your sense of balance is controlled by canals filled with lymph inside the ears. Now, when you’re on a ship that is rocking back and forth, the lymph rocks back and forth too, sending messages to the brain that … Read more
The organs that control your sense of balance are actually inside your ears. Three arched tubes, called semicircular canals, are inside each ear, filled with a liquid called lymph. Each tube helps to control your sense of balance in one dimension: width, height, and depth. Inside these canals are stiff hairs attached to nerve cells. … Read more
Have you ever wondered why, when you cut yourself, all the blood in your body doesn’t flow out of that cut? What stops the blood from flowing is a process called clotting. As soon as a blood vessel is cut, the blood begins to produce tiny threads of protein that form a sort of net, … Read more
A doctor takes your pulse by squeezing a blood vessel in your wrist and counting the number of beats, or pulses, he feels in one minute. But the pulse rate can be taken by feeling the beats in many other parts of your body too. Each time your heart beats, it sends a pulsation through … Read more
Water rushing through a hose exerts pressure on the hose, and in the same way, blood surging through your blood vessels exerts pressure on the vessels. It’s important for a doctor to know your blood pressure, because this tells him the strength of your heart, the condition of your arteries, and other important things about … Read more
When a doctor describes your blood type, he’ll probably not only indicate its type, 0, A, B, or AB, but also if it’s “positive” or “negative.” This refers to your Rh factor. If your blood is positive, you have the Rh factor; if it’s negative, you don’t. A person with the Rh factor has certain … Read more
The heart is a muscular organ that serves as a pump, sending blood to every part of the body. The heart is always at work, even while you sleep. If your heart were to stop for any length of time, you couldn’t live, but that doesn’t mean the heart never rests. Each “heartbeat” consists of … Read more
People need to drink water because water is a major part of every cell in our bodies. A person who doesn’t get enough water will suffer from dehydration, a lack of water in the body’s cells to allow them to work properly. If a person aboard a ship is suffering from thirst, he may be … Read more
Protein is quite different from vitamins. Our bodies take vitamins from food, use them to aid in certain chemical processes, and then discard the vitamins. But our bodies take the protein from foods and keep it, using it to make new body cells or repair old ones. Proteins are made up of substances called amino … Read more
At a certain age, your brain stops growing. You stay alive, but some of your brain cells die, and are not replaced. In fact, after the age of 18, a person may lose more than a thousand brain cells each day! But there’s no danger of your brain ever “burning out,” for the number of … Read more
The amount of food energy you need each day depends on how old you are, how big you are, and whether you’re a girl or a boy. Children from 6 to 9 years old require at least 2,100 calories a day to maintain good body health. By the age of 12, the body requires about … Read more
Not unless you include water as a food. Only water and club soda have absolutely no calories. Coffee and tea have almost none, just one or two calories for every 100 grams, or about 31/2 ounces. Among vegetables, artichokes have the least calories, about seven per 100 grams. A sour or dill pickle has 10 … Read more
Yes, all animals need vitamins, and some plants do too. But the need for a certain vitamin varies from one animal to another. Some animals can make all the vitamins they need right in their own bodies, and don’t have to take in vitamins with their food. For instance, people need to take Vitamin C … Read more
The calorie is often used to measure the fattening qualities of foods. But the calorie is not a measure of weight or of the sugar in foods or of the fat. It’s actually a measure of heat! One calorie is the amount of heat needed to raise a. gram of water one degree Centigrade. A … Read more
During the 19th century, an English doctor found that eating lemons or limes could prevent a disease known as scurvy, which had been common among sailors and soldiers for thousands of years. Beginning in 1800, all English Navy ships carried lime juice, and every sailor had to drink a ration of lime juice daily. That, … Read more
In the 1920s, scientists believed that only two vitamins existed. One was fat-soluble, which means it could dissolve in oil or fat. This vitamin the scientists called Vitamin A. The other vitamin was water-soluble; it could dissolve only in water. This, they called Vitamin B. The fat-soluble vitamins were given letters of their own. But … Read more
A vitamin is a chemical substance found mostly in foods. It is necessary for the proper working and growth of the body. Vitamins take part in chemical reactions that help bring food energy to the body’s cells. In these reactions, vitamins serve as catalysts, substances which speed up or aid reactions, but which are not … Read more
Many woodland mammals eat plants during the warm months. When winter comes, these plants die or are covered with snow, and the animals have nothing to eat. But nature has provided them with a way to survive the I winter. It’s called hibernation, from the Latin word that means “winter.” Animals that hibernate eat much … Read more
There are many animals without teeth, but almost every animal has some kind of jaws it can open and close to take in food. Except the anteater! This strange-looking creature from South America appears to have no mouth, for his snout is shaped like a tube and contains neither teeth nor jaws. Then how does … Read more
We eat every day, but some animals can go for so long without a meal that it might seem they never eat. A snake often eats only once in two weeks or longer, penguins sometimes go a month without eating, salmon don’t eat for long periods of their life, and snails have been known to … Read more
This animal is known to most people because aardvark is the first word in many dictionaries. But do you know what an aardvark actually is? The aardvark is a strange creature indeed. It’s about the size of a hog, with a long, pig-like snout and thick, gray-brown hair. It has long ears like a rabbit, … Read more
It’s almost impossible for you to fall asleep while standing. The moment you began to doze, you’re likely to fall down. But horses often seem to sleep while they’re standing up, and they do! When a horse stands perfectly still and relaxes, joints in his legs lock into position, holding the horse up even if … Read more
The average dog lives for about 15 years. Some dogs show signs of age at six years old, while others remain active and youthful until they are ten or more. The oldest dog on record was a Labrador who died in 1963, at the age of 27 years and three months. However, some people have … Read more
It may be hard to believe, but the largest dogs on earth are almost 300 times as Davy as the smallest dogs! The breed of dog with the largest average size is the St. Bernard. Full-grown St. Bernards may weigh more than 250 pounds, and the heaviest St. Bernard, the heaviest dog of kind ever … Read more
If you thought yes, you’re way off. The most common domesticated animal on earth is, by a long shot, the chicken. Although this familiar bird is the descendant of a jungle fowl from Asia that wasn’t domesticated until about 1500 B.C., there are now some four billion chickens on earth, about the same number as … Read more
If we use the word “cattle” not only for the cow and steer, but for other members of the cattle family, such as the yak and buffalo, then cattle are by far the most important domesticated animals on earth. This single creature provides man with his number one work animal, half of all his meat, … Read more
Because many people think that lions and tigers both live in Africa, they may wonder which of these giant cats proves the strongest when they tangle. But there isn’t a single wild tiger in Africa! Tigers are native to Asia, with one kind living in the hot regions of India, and another kind inhabiting the … Read more
All tamed animals are not domesticated animals; it takes many centuries after an animal that has been taken from its wild state and tamed before it changes completely into a domesticated animal, one that has been tamed by man and raised to provide him with food, clothing, transportation, or friendship. Once an animal is domesticated, … Read more
Dogs often whimper and whine, and appear to be crying, while hyenas and some birds can sound as if they’re laughing. But no creature besides man is capable of really crying or laughing. Dogs and other animals have tear ducts, but their tears are used only to moisten their eyes, not to express sadness. And … Read more
If you were to guess what an animal called the camelopard might look like, you’d probably say it resembled a camel and a leopard. And you’d be right! A camelopard has a long neck like a camel, and spots like a leopard. You say you’ve never seen such a beast? Sure you have. Camelopard is … Read more
The koala is a small mammal that looks something like a cute little teddy bear. It lives only in Australia, and even if a few of these animals were brought to America, they wouldn’t live very long. The koala can eat only the leaves of the eucalyptus tree, which grows almost entirely in Australia. The … Read more
We really should call the flying squirrel the “gliding squirrel,” as no mammal except the bat is really capable of flying. The flying squirrel doesn’t have wings, but it does have thin flaps between its front and back legs. When a flying squirrel wants to move from one tree to another, it spreads its legs … Read more
The jackal is a member of the dog family that lives in parts of Africa, Europe, and Asia. Because it can eat rotting meat, the jackal is known as a scavenger. But the jackal prefers to eat animals it has killed itself, and so hunts at night for small mammals and birds. Sometimes, a pack … Read more
The chimpanzee, the most intelligent of all animals besides man, is even more clever than scientists had once thought. Trained chimps have shown that they can be taught to use a form of silent language to “speak” with their trainers. First, the chimps learned symbols for a number of simple words. These symbols were contained … Read more
The hippopotamus, the second largest land animal after the elephant, spends most of its time partly submerged in a river. When the hippo does climb out of the water, its skin often secretes drops of a bright red liquid that looks just like blood. Some circuses used to claim that they had “blood-sweating hippos” on … Read more
Some mammals utter sounds so rarely that people used to think they had no voices. Scientist once believed that giraffes, rabbits, and mice had no voices, but they now know that these creatures do have voices and occasionally utter sounds. Giraffes and rabbits make a variety of sounds. We don’t hear a lot of mouse … Read more
The mouse is a rodent, and most rodents prefer a diet of vegetables and grains. But mice and many other rodents will also eat insects and animal flesh. In fact, a hungry mouse will eat just about anything, including cheese.
You may have heard the expression “ferret out,” meaning to chase something out of hiding. But did you know that this word comes directly from an animal? The ferret is a relative of the weasel, and most ferrets are about the size of a cat. Before modern rat poisons and traps were invented, ferrets were … Read more
A donkey and an ass aren’t quite the same thing. An ass is a smaller relative of the horse, with longer ears and a shorter mane. A donkey is a domesticated ass. So all donkeys are asses, but not all asses are donkeys. The word “ass” is much older than the word “donkey.” The Latin … Read more
The creature called the mongoose isn’t a goose, but a mammal that looks something like a mink or weasel. The animal, a native of India, gets it confusing name from an Indian word that sounds like “mongoose.” Although only about two feet long when fully grown, and gentle enough to serve as a pet in … Read more
The mouse deer is closer in size to a mouse than to a deer, but it’s actually a deer! This tiny resident of Southeast Asia has the shape and all the markings of an ordinary deer, but it rarely grows more than one foot high. Imagine a full-grown deer that you can hold in the … Read more
