For the flute, "a stream of air [is] directed against a sharp edge" which separates into eddies. The tone and sound are controlled by the placement of the fingers over the flute's holes. The flute in our illustration is known as a recorder, fipple flute, or whistle flute. The recorder was produced during the fourteenth century; today, it is often used in schools as the students' introduction to playing a musical instrument... Read more
Radio waves were first discovered in 1886. By 1894, Italian inventor Guglielmo Marconi had devised a way to transmit telegraph signals via radio waves. Radio was being used commercially by 1920, and... Read more
Fruitcake is both lauded as a holiday gift-giving tradition and loathed as the butt of jokes and as a synonym for "crazy." What is a fruitcake? It is a very heavy spice cake filled with candied or dried and sugared fruits and nuts. Some recipes also contain alcohol. Fruitcake is known for lasting many years due to the preserving qualities of the sugar and alcohol... Read more
New Year festivals are celebrated around the world. According to the Encyclopedia Britannica, they are "among the oldest and the most universally observed."... Read more
Catwoman is the supervillain alias of the fictional character Selina Kyle, and occasionally of other female characters. She first appeared as "the Cat" in DC Comics Batman #1 in 1940. She is a burglar in Gotham city, and her preferred weapon is a bullwhip. She wears a tight black suit and is often outfitted with spy gear... Read more
Lions are one of the world's most iconic mammals. Female lions are called lionesses... Read more
A firefighter, fireman, or firewoman is a person employed in firefighting - putting out dangerous fires and keeping them from spreading. This may involve rescuing people from a burning building... Read more
A troll or trow is a legendary creature from Scandinavian folklore. The troll was thought to be a "giant, monstrous being, sometimes possessing magic powers." They were said to live in castles and patrol the surrounding areas at night - never did they venture forth in the day, lest they burst or turn into stone. This type of troll was depicted in the animated series The Gummy Bears... Read more
Gravity Falls is an animated series from Disney Channel. It stars twin siblings Mabel and Dipper Pines, "who are in for an unexpected adventure when they spend the summer with their great uncle in the mysterious town of Gravity Falls, Oregon."... Read more
Earthworms are invertebrates that live in the soil around the world. There are over 1,800 distinct species. Most are only a few inches in length, but one Australian species can reach a length of 3.3 meters, or about 11 feet!... Read more
The beard is the facial hair grown on a man's chin and cheeks. The Encyclopaedia Britannica calls the beard a "badge of manhood," as it appears only when a young male becomes physically mature... Read more
An axe or ax is a chopping or cutting tool that has been used by humans since the Stone Age. The first axes were, not surprisingly, made from sharpened blocks of stone. Later, wooden handles were added and the blades were made from copper, bronze, or iron... Read more
Red roses have long been used to symbolize love. But a wilted, dead, or dying rose can mean a fading of hope and love or even the end of life. The most memorable depiction may be the enchanted rose from Beauty and the Beast. It was kept beneath glass to ensure that the last petal would not fall a moment too soon... Read more
In German, dachshund means "badger dog." It traces its ancestry to hounds and terriers used to pursue badgers into their burrows. This iconic dog is famous for its short legs and elongated body. Dachshunds were developed in two sizes, standard and miniature, and stand up to 10 inches (25 centimeters) tall. They may have long or short fur classed as smooth, longhaired, and wirehaired... Read more
A comet is an object made of rock and ice that orbits the Sun. When the comet's orbit brings it close to the Sun, it undergoes a process known as sublimation - its particles go directly from the solid state to a gaseous state, creating a magnificent tail... Read more
Pelicans are seafaring birds famous for their extendable throat pouch that they use as a fishing net. They are large birds; many have wingspans of more than 10 ft or 3 meters. The name "pelican" comes from an ancient Greek word meaning "ax."... Read more
Camping is a "recreational activity in which participants take up temporary residence in the outdoors." Camping first took a recreational turn around 1908, with the publication of The Camper's Handbook... Read more
The firefly, also called a glow worm or lightning bug, is a beetle that has a special light-producing organ on its abdomen. The largest can reach 1 inch in length. The bioluminescent light is... Read more
Glass has been used to make man-made objects since ancient times. In fact, the earliest specimens date to around 3500 B.C. and were discovered in Egypt and Mesopotamia. Glass is made by heating materials such as sand and cooling it in such a way that crystals do not form... Read more
Geckos are small lizards. There are more than 1,000 species of this reptile around the world, native to every continent but Antartica. Geckos range in size from less than half an inch to 14 inches; a 24-inch specimen of a possibly extinct species from New Zealand is held in one European museum... Read more