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Numbering System “Arabic” When Arabs Don’t Use Arabic Numbers Themselves?
     
    The first numbering system was probably developed by the Egyptians, but ancient Sumeria, Babylonia, and India used numerals in business transactions. All of the earliest number systems used some variation of 1 to denote one, probably because the numeral resembled a single finger. Historians suggest that our Arabic 2 and 3 are corruptions of two and three slash marks written hurriedly.
    Most students in Europe, Australia, and the Americas learn to calculate with Arabic numbers, even though these numerals were never used by Arabs . Arabic numbers were actually developed in India, long before the invention of the printing press (probably in the tenth century), but were subsequently translated into Arabic. European merchants who brought back treatises to their continent mistakenly assumed that Arabs had invented the system, and proceeded to translate the texts from Arabic.
    True Arabic numerals look little like ours. From one to ten, this is how they look:
     

     
     
Submitted by Dr. Bruce Carter of Fort Ord, California .
     
     

     
     
    When You Are Driving Your Car at Night and Look Up at the Sky, Why Does It Seem that the Moon Is Following You Around?
     
    If you, like every other literate human being, have read Why Do Clocks Run Clockwise? and Other Imponderables , then you know why the moon looks larger on the horizon than up in the sky, even though the moon remains the same size. Clearly, our eyes can play tricks on us.
    Without reference points to guide us, the moon doesn’t seem to be far away. When you are driving on a highway, the objects closest to your car go whirring by. Barriers dividing the lanes become a blur. You can discern individual houses or trees by the side of the road, but, depending upon your speed, it might be painful to watch them go by. Distant trees and houses move by much more slowly, even though you are driving at the same speed. And distant mountains seem mammoth and motionless. Eventually, as you travel far enough down the highway, you will pass the mountains, and they will appear smaller.
    If you think the mountain range off the highway is large or far away, consider the moon, which is 240,000 miles away and bigger than any mountain range (more than 2,100 miles in diameter). We already know that our eyes are playing tricks with our perception of how big and far away the moon is. You would have to be traveling awfully far to make the moon appear to move at all. Astronomy editor Jeff Kanipe concludes that without a highway or expanse of landscape to give us reference points “this illusion of nearness coupled with its actual size and distance makes the moon appear to follow us wherever we go.”
    This phenomenon, much discussed in physics and astronomy textbooks, is called the parallax and is used to determine how the apparent change in the position of an object or heavenly body may be influenced by the changing position of the observer. Astronomers can determine the distance between a body in space and the observer by measuring the magnitude of the parallax effect.
    And then again, Elizabeth, maybe the moon really is following you.
     
Submitted by Elizabeth Bogart of Glenview, Illinois .
     
     
    When Does a Calf Become a Cow?
     
    The calf’s equivalent of a bar mitzvah occurs after it stops nursing, usually at about seven to eight months of age. After they are weaned and/or when they reach twelve months, they are referred to as yearling bulls or yearling calves.
    According to Richard L. Spader, executive vice president of the American Angus Association, “calves don’t achieve full-fledged bullhood or cowhood until they’re in production. We normally refer to a first calf heifer at, say, twenty-four months of age or older, as just that, and after her second calf as a three-year-old, she becomes a cow.”
    Bulls don’t usually reach maturity until they are three. After they wean from their mothers,