Caligula

The Roman Emperor Caligula commissioned a number of royal yachts, each more than 200 feet long. The boats included reception chambers, exercise rooms, baths, a grape arbor, and in at least one case, a brothel.

Safety

Warren G. Harding was the first U.S. president who knew how to drive a car when he entered the nation's top office. For the sake of the president's safety, however, the Secret Service did not allow Harding to drive while in office.

Love

When Alexander Graham Bell realized he had fallen in love with the young Mabel Hubbard, he wrote her a 17-page letter, expressing his feelings. But he did not ask her to marry him. She was too young. Mabel thought otherwise, and on her 18th birthday, she surprised Bell, telling him she had grown to love him more than anyone except for her mother. She added that they could be engaged as soon as he liked. The two were married 18 months later.

Babieca

One of Spain's national heroes, Rodrigo Diaz de Bivar (a.k.a. El Cid), affectionately named his horse babieca, which means dumbbell or idiot. According to legend, when Bivar chose this scraggly colt, his father called him a babieca. Bivar applied the term to his horse, claiming that it would be a reminder of his father's doubts.

Finley

When growing up, Samuel Finley Breese Morse, inventor of the electromagnetic telegraph, didn't go by his first name. His parents, Jedediah and Elizabeth, simply called their oldest child Finley.

Navigate

While at sea, a navigator, standing on deck at five feet above sea level, has a view of 2.5 nautical miles in all directions. The curvature of the earth is such, however, that if that same navigator is elevated 15 feet above sea level, the horizon will be 4.44 miles away.

Unmarried

When the Wright brothers made their first flight, Wilbur was 36 and his brother, Orville, 32. Neither was married, and they still lived at home with their 74-year-old father, Milton, and 29-year-old sister, Katharine. Working as a high school teacher, Katharine also was unmarried.

CFCs

Although CFCs have been banned in the United States, there are two exceptions to the rule: their use in asthma inhalers and in the making of methyl chloroform, which is used to clean O-ring seals in NASA's space shuttles.

Cortes

When Hernando Cortes began his conquest of Mexico, he rode a chestnut horse. But he soon replaced the mount with a black stallion named El Morzillo, meaning the Black One. When El Morzillo developed a limp, Cortes left him in the custody of a Mayan chief. The chief and his people renamed the horse Tziminchac, after the Mayan god of thunder and lightning, and housed the steed in their temple. When El Morzillo died, the Mayans carved a stone statue of him.

Coffee

In 17th-century Constantinople (now Istanbul), tradition required that the groom provide his bride with coffee and promise always to do so. A failure to supply his wife with the enervating drink was legal grounds for divorce.

Doorbell

Marion Donavan, inventor of the disposable diaper, also created the Turtling-a-ling. The brass turtle, with bells on its head and tail, simulated a doorbell. Donavan pitched the device as a means of cutting short an unwanted phone call by making it clear to the caller that other priorities demanded attention.

Horses

Historians record that Napoleon Bonaparte was not a good rider, so he needed especially stable horses in battle. He owned 60 or more white horses. Each of them was trained to stand steady - not to rear or shy - when guns were fired from nearby.

Membership

The National Geographic Society rarely removed its members in the organization's early years. But the society made an exception in 1932, striking Al Capone's name from the membership list when he entered federal prison. Capone continued to receive copies of "National Geographic" as a paying subscriber.

Chickens

Ornithologists report that chickens are capable of deception. If a rooster, for instance, judges that a hen has wandered too far, he will use a food call to get her attention, even when no food is present.

Margaritologia

The physician Malachias Geiger published a protection against the Black Death in his 1637 book, "Margaritologia." Geiger recommended baking pulverized pearls with antlers and cinnamon as well as other ingredients.

Everest

Norman G. Dyhrenfurth's well-equipped climb of Mt. Everest in 1963 required 1,000 porters and sherpas to carry the almost 30 tons of gear. Supplies included 12,000 cigarettes, 216 bottles of oxygen, waterproof diaries, seven movie cameras, and freeze-dried foods, including crab imperial, pork chops and chicken tetrazzini.

Man o' War

In his two-year racing career, the famous horse, Man o' War, earned prizes of $249,465. He raced 21 times and took second place in only one contest. He won all the rest.

Wild Ducks

Charles Darwin reported that wild ducks are monogamous, at least for a season. But such is not the case for their much-more promiscuous, domesticated relatives.

Tarsier

The tarsier, a primate found in southeastern Asia, has an eyeball that is larger and weighs more than its brain. While seizing its prey, the tarsier closes its eyes tightly to protect them from the victim's struggles.

Dresses

After Orville and Wilbur Wright had finished their first experiment with a homemade glider at Kitty Hawk, N.C., they left the machine behind. Local citizens didn't approve of the work, claiming that God didn't intend for man to fly. So they left the contraption to rot in the sand. But flight was one thing, and waste was another. Local resident Addie Tate used the glider's white sateen fabric to make dresses for her daughters.

Underground

Harriet Tubman personally freed at least 300 slaves by guiding them along the Underground Railroad. But Tubman's work didn't end there. During the Civil War, she served Union forces as a cook and as a spy.

Yacht

America's first luxury yacht, launched in 1816 from Salem, Mass., was named "Cleopatra's Barge." At the time, Salem had the highest per-capita income of any town in the country.

Hair and Nails

It has long been believed that a person's hair and nails continue to grow after death. But experts claim that, in reality, the skin of the deceased recedes, causing more of the hair and nails to be exposed.

Diet

About 20 percent of a robin's diet is made up of earthworms, and the red-breasted birds are quite adept at getting a meal. Ornithologists have observed robins that successfully captured earthworms at the rate of 20 per hour.

Boats

During the reign of England's King Charles II, the cost of a merchant vessel was about 8 per ton. A warship cost about 15 per ton. Construction of the king's yachts, however, required silk ceremonial flags, crimson damask, rich mahogany and other luxuries, which brought construction costs up to about 33 per ton.

Pauline

Pauline, the last cow to live on White House grounds, moved to the neighborhood of 19th and B streets in 1911. But she retained special privileges at the president's home, visiting there each morning to graze the White House lawn. She was returned home each day at twilight.