There are two measurement systems used in the world today: the imperial system (also known as the English system) and the metric system.

The imperial system was developed in England hundreds of years ago and was brought to the the United States by the colonists. The metric system is the accepted measurement system used in most countries of the world. It is a system based on multiples of 10. The metric system was developed in France around 1790 and has been revised several times. Its official name today is the International System of Units or SI Units for short.

Both systems have come a long way since their conception. Here are some noteworthy facts about both, which may have been "lost" in history, but are still worth mentioning today.

Base u ...

1)  Roman Numeral IV

Although the Roman numeral for the number 4 has always been taught to have been "IV," according to historians, the ancient Romans probably used "IIII" most of the time. This is partially backed up by the fact that early grandfather clocks displayed IIII for the number 4 instead of IV. Early clockmakers apparently thought that the IIII balanced out the VIII (used for the number 8) on the clock face and that it just looked better.

2)  Base 60

The Babylonians wrote numbers in a system that used 60 as the base value rather than the number 10. They did not have a symbol for "zero."

3)  Fraction Bar

The Romans did not use numerals to indicate fractions but instead used words to indicate parts of a whole. It wasn't until later in h ...

Some mammals, such as camels, polar bears, and seals, have full nictitating membranes. That is the transparent or translucent third eyelid that can be drawn across the eye for protection and to moisten it while maintaining visibility.

In humans, the plica semilunaris (also known as the semilunar fold) and its associated muscles are thought to be homologous to the nictitating membranes seen in other animals. In most primate species, a plica semilunaris is present, but a fully developed nictitating membranes still exists in lemurs and lorisiform primates.

Unlike the upper and lower eyelids, the nictitating membrane moves horizontally across the eyeball (shown below). In some diving animals, such as beavers and manatees, it moves across the e ...

Regardless of your size, men and women, big or small, all pee at the same average rate — between 1/3 and ½ ounces per second (10 ml to 15 ml per second). Since the mean urine quantity ranges between 1 to 2 quarts a day (1.4 L, on average), we are condemned to spend one to two full minutes peeing daily.

The average lifespan in the United States today is 27,375 days. If we multiplying 27,375 days by 2 minutes per day peeing, that's 54,750 minutes, or 912.5 hours of your lifetime urinating. That also translates into roughly 38 days of your lifetime ...

Summer is officially over, and fall has arrived. With this season comes runny noses and doctor visits. Save yourself the time and money, because it's either the common cold or the flu, both of which have no cure other than to rest and endure the discomfort. Luckily, you can be immunized for the flu, but not the cold. In fact, many people battle the cold several times a year, rather than developing a natural immunity towards it, why is that? 

The primary reason that immunity generally does not develop against the common cold is that there is not a single cause of the disease. Over 200 serotypes of viruses, including enteroviruses (previously called rhinoviruses), coronaviruses, and adenoviruses, can cause the symptoms of the common cold. Ther ...

Rodents are mammals characterized by a pair of broad, sharp-edged, chisel-like incisor teeth that are firmly inserted in both jaws and are used in gnawing vegetation. The front surface of each incisor tooth is composed of enamel, and the hind surface is of soft dentine wears away during the process of gnawing so that the teeth are constantly kept sharp. Shown above is a beaver sporting bright orange teeth; the reason they are orange is because of an unusually high concentration of iron in the enamel.

Unlike human teeth, the incisors of rodents don't have roots, and they never stop growing! To keep these teeth from growing into their brains, rodents grind their teeth against each other. This friction is similar to using a grindstone to sharp ...

Did you know that the Moon's rotation is locked to its orbit around Earth by a bulge of material under the Moon's surface? This material is denser than the rest of the Moon's surface material, and Earth's gravity pulls on it especially strongly. The side of the Moon containing the bulge always faces Earth. We call it the near side and we call the other side, which we never see from Earth, the far side. People often mistakenly use the term "dark side" when referring to the far side of the Moon, forgetting that the far side is fully illuminated by the Sun whenever we see a new moon from Earth.

If we were to look from high above the Earth-Moon system, we would see the Moon rotate once per month with respect to the stars. This is its sidereal ro ...