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A lively controversy has developed over where the first modern traffic signal designed to control automobile traffic was in use. Although Salt Lake City and St. Paul lay claim to the crown, the green-red signal installed on Euclid Avenue in Cleveland, Ohio, in 1914
is generally credited with being the first.
Although the traffic signal’s colors might have been arbitrarily lifted from the railroad’s, there is an important safety reason for the consistency of the configuration today. As recently as the 1950s, many traffic signals, especially in busy urban intersections, were displayed horizontally rather than vertically. The current vertical design with red on top was adopted in order to aid color-blind individuals who might be confused by different layouts. According to Eugene W. Robbins, president of the Texas Good Roads/Transportation Association, the red in traffic signals has some orange in it and the green has some blue in order to make it even easier for the color blind to distinguish them.
Submitted by John Branden, of Davis, California. Thanks also to: Maya Vinarsky, of Los Angeles, California; Sean Gayle, of Slidell, Louisiana; Eddie Haggerty, of Waseca, Minnesota; William De-bovitz, of Bernardsville, New Jersey.
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Why Are Cows Usually Milked from the Right Side?
Although this subject is usually not part of the veterinary school curriculum, we went right to the organization best suited to answer the Imponderable: the American Association of Bovine Practitioners and its officer Dr. Harold E. Amstutz. Although Dr. Amstutz said he had never considered this question before we posed it, he was ready with a sensible explanation:
Since most people are right handed, it is more logical to sit down on the right side of the cow and have more room to maneuver the milk bucket with the right hand between the cow’s front and rear legs. There would not be nearly as much room to maneuver the bucket with the right hand if a right handed person were to sit on the left side.
In general, we think of “right” as correct and “left” as being wrong. Cows have no preference since we milk them from either 128 / DAVID FELDMAN
side in today’s milking parlors. The only ones that would have a preference are those that were trained to be milked on one side and then someone tried to milk them from the other side. The milker would probably be kicked in that case.
Submitted by Marci Perlmutter, of Warren, New Jersey.
Why Do Many Merchants Ask Customers to Put Their Addresses and Phone Numbers on Credit Card Slips?
If Visa or MasterCard or American Express needed your address or phone number, wouldn’t they reserve a spot on their credit-card slips for them? Clearly, it is the stores that want such data.
But why do the stores need this information? If you charge goods on a stolen credit card, it is the creditor, not the merchant, who gets stuck with the bill, as long as the merchant complies with all of the security arrangements (such as verifying all purchases above a certain amount).
The credit-card companies themselves couldn’t think of a good reason for stores to ask for address and phone number. After all, if somebody is going to steal a credit card, he is unlikely to provide accurate instructions on how to locate him. Perhaps, one credit-card executive speculated, the stores make this request in order to compile a mailing list.
So we talked to merchants. Their reasons turned out to be prosaic.
Some of them mentioned that they carry insurance on bad checks, and that part of the agreement with insurance companies is that all customers must supply addresses, phone numbers, and driver’s license or social security number. If they don’t WHY DO CLOCKS RUN CLOCKWISE? / 129
include these data, merchants aren’t reimbursed for bad checks. Although they realize that such precautions are irrelevant when it comes to collecting money from credit cards, some merchants believe that by forcing employees to collect addresses and phone numbers from all noncash customers, clerks would be less likely to forget to ask for the information from people using checks.
All of the merchants in New York City gave one reason, and several mentioned it as the only reason, for asking customers to include address and phone numbers, and this explains why the practice is uncommon in small towns. With the information provided they can contact customers when they leave their credit card at the store by mistake!
Submitted by Mark Schulman of Altamonte Springs, Florida.
On Airplanes, Why Do Our Ears Pop and Bother Us More on Descent Than on Ascent?
The ear is composed of three parts:
1. The outer ear, which includes the part of the ear that is visible, plus the ear canal connected to the eardrum.
2. The middle ear, which includes the eardrum, the ear bones (ossicles), and the air spaces behind the eardrum and in the mastoid cavities.
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3. The inner ear, which contains the nerve endings that facilitate hearing and equilibrium.
The middle ear is what bothers travelers on airplanes because it is, in part, an air pocket vulnerable to changes in air pressure. On the ground, when you swallow, your ears make a little click or popping sound. This noise marks the passage of a small air bubble up from the back of your nose, through the eustachian tube, and into your middle ear. According to the American Council of Otolaryngology, “the air in the middle ear is constantly being absorbed by its membranous lining, but it is frequently re-supplied through the eustachian tube during the process of swallowing. In this manner air pressure on both sides of the eardrum stays about equal. If, and when, the air pressure is not equal, the ear feels blocked.”
If the eustachian tube is blocked, no air can be replenished in the middle ear; any air present absorbs and a vacuum occurs, sucking the eardrum inward. Blocked eustachian tubes can cause a loss of hearing and pain.
A clear and properly functioning eustachian tube is the key to problem-free ears on plane flights; if it can open wide enough and often enough, the eustachian tube can moderate changing air-pressure conditions. When you ascend on an airplane, it is to less pressure, so the air expands in the middle ear. The eustachian tube works much like a flutter valve on an automobile. When you ascend, the air in your ear is forced through the tube in a steady stream without any problem.
When you descend, it is to greater air pressure. A vacuum forms even faster in the middle ear, making it harder for the air to go back through the membranous part of the eustachian tube. According to Dr. Andrew F. Horne, in the Office of Aviation Medicine of the Federal Aviation Administration, the ear popping is caused when the valve of the eustachian tube opens and closes. On ascent, the air runs through the eustachian tube in a steady stream; on descent, the air must contend with the membranous part of the eustachian tube. Without the steady air flow,
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it takes longer to equalize air pressure inside and outside your ear.
Airplane pilots are taught how to counteract differences in air pressure. The simple act of swallowing pulls open the eustachian tube, which is why gum chewing or candy sucking has become a takeoff and landing ritual for many passengers. Yawning is even more effective, for it pulls the muscle that opens the eustachian tube even harder than swallowing.
If neither swallowing nor yawning works, the American Council of Otolaryngology recommends this procedure: 1. Pinch your nostrils shut.
2. Take in a mouthful of air.
3. Using your cheek and throat muscles, force the air into the back of your nose as if you were trying to blow your thumb and fingers away from your nostrils.
4. When you hear a loud pop in your ears, you have succeeded, but you may have to repeat the process again during descent.
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Where Do Houseflies Go During the Winter?
To heaven, usually. Some flies survive winter, but only under extremely favorable conditions, when they can take shelter in barns or inside human residences where they can find enough organic matter and warmth to eat
and breed.
Even under the best of circumstances, the normal life-span of a housefly north of the equator is approximately seven to twenty-one days. The most important variable in the longevity of these insects is the ambient temperature—they die off in droves when it falls below freezing or becomes excessively hot.
Although they actually live longest in cool temperatures, because they are less active, flies breed most prolifically when temperatures are warm, food is abundant, and humidity is moderate. Winter tends to deprive them of all of these favorable WHY DO CLOCKS RUN CLOCKWISE? / 133
conditions, so that they not only die off themselves, but do so without having been able to breed successfully. The U.S. Department of Agriculture claims that no housefly has been proved to live from autumn to spring (which answers another Imponderable: why do we see so few houseflies in the spring?).
So how can they regenerate the species? Most people believe that flies hibernate or become dormant, like some other insects, but this theory has proved to be untrue. The few flies that we find in the spring are mainly the descendants of the adult flies that managed to find good hiding places during the previous winter. These spring flies breed their little wings off, just in time to harrass you on your picnics when the weather gets good.
Some of the flies that survive winter are not adults, but rather flies in their earlier developmental stages. Fly eggs are usually deposited in the ground, in crevices, in wood, or in a particular favorite, cow manure. These eggs hatch, literally, in a few hours, and turn into larvae, a phase that can last anywhere from one to four days. Larvae feed on decaying plant or animal matter (such as other insect larvae).
As the fly larva grows, it undergoes pupation, a phase that lasts about five days, in which the fly rests as its larval features are transformed into adult ones. Many entomologists used to answer this Imponderable by speculating that most flies that survive the winter do so in the form of larvae or pupae, but scientists now believe that adult flies have a much better chance of surviving the winter than their younger brethren, who have a hard time coping with cold weather. Still, some larvae and pupae do stay alive during the very end of winter and develop into adults in the spring.
The fecundity of the Musca domestica is truly awesome. One scientist estimated that a single mating pair of houseflies could generate as many as 325,923,200,000,000 offspring in one summer. One-sixth of a cubic foot of soil taken in India revealed 4,024 surviving flies. Maybe the Imponderable should read: why isn’t the entire world overcome with flies?
Any notion that flies migrate south during the winter is easily dispelled. The average flight range of a housefly is a measly 134 / DAVID FELDMAN
one-quarter of a mile. Scientists have tracked the flight of flies: they rarely go beyond a ten-mile radius of their birthplace during their entire lifetime.
Where Does White Pepper Come From?
From black pepper. The most popular of all spices (salt is not a spice) is not related to sweet red, green, or hot peppers, but is the dried berry of a woody, climbing vine known as Piper ni-grum L.
On the vine the peppercorn is neither white nor black. As the fruit ripens, it turns from green to yellow and then to red. To make black pepper, the berries are picked while somewhat immature and then dried. As they dry, their skin turns a dark color. When ground, the pepper contains both light and dark particles—because the whole peppercorn is used—but the general appearance is dark.
White pepper is left on the vine to mature, at which point it is easier to separate the dark skin. The berries are soaked to loosen the skin as much as possible and then rubbed to remove it entirely.
After the dark skin is discarded, the naked white peppercorns are put out in the sun to dry.
Technology has caught up with the spice world. Some white pepper, usually known as “decorticated white pepper,” is now produced by removing the skin of dried black peppercorns by machine.
Decorticated pepper looks like white pepper but tastes more like black pepper.
Why bother with white pepper? Often it is used solely for aesthetic purposes, such as in light-colored sauces and soups where little black specks may upset the chef’s carefully orches WHY DO CLOCKS RUN CLOCKWISE? / 135
trated balance (or be misconstrued as little black insect fragments).
Some spice wimps also prefer white pepper for its milder taste and smell.
Ted Turner does not have a monopoly on colorization. Go into any gourmet store and you will encounter green peppercorns. These immature berries are not left out in the sun but either packed in liquid (usually wine vinegar or brine) or freeze-dried in order to retain the distinctive green color. Because green peppercorns are harvested at an early stage of the berry’s development, they are quite mild, but they do have a distinctive taste, which is prized by nouvelle cuisine restaurateurs.
Submitted by Kathy Cripe, of South Bend, Indiana.
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What Purpose Do Wisdom Teeth Serve?
They serve a powerful purpose for dentists, who are paid to extract them. Otherwise, wisdom teeth are commonly regarded as being useless to modern man. But because nature rarely provides us with useless body parts, a little investigation yields a more satisfying answer.
Primitive man ate meats so tough that they make beef jerky feel like mashed potatoes in comparison. The extra molars in the back of the mouth, now known as wisdom teeth, undoubtedly aided in our ancestors’ mastication.
As humans have evolved, their brains have gotten progressively larger and the face position has moved farther downward and inward. About the time that primitive man started walking in an up-right position, other changes in the facial structure occurred. The protruding jawbones of early man gradually moved backward, making the jaw itself shorter and leaving no room for the wisdom teeth (also known as third molars). Most people’s jaws no longer have the capacity to accommodate these four, now superfluous, teeth.
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Why Are Ancient Cities Buried in Layers? And Where Did the Dirt Come From?
This Imponderable assumes two facts that aren’t always true. First, not all ruins are the remains of cities. Many other ancient sites—such as forts, camping sites, cave dwellings, cemeteries, and quarries—are also frequently buried. Second, not all ancient cities are buried; once in a while, archaeologists are given a break and find relics close to or at the surface of the ground.
Still, the questions are fascinating, and we went to two experts for the answers: George Rapp, Jr., dean and professor of geology and archaeology of the University of Minnesota, Duluth, and coed-itor of Archaeological Geology; and Boston University’s Al B.
Wesolowsky, managing editor of the Journal of Field Archaeology.
Both stressed that most buried ruins were caused by a combination of factors. Here are some of the most common: 138 / DAVID FELDMAN
1. Wind-borne dust (known to archaeologists as “Aeolian dust”) accumulates and eventually buries artifacts. Aeolian dust can vary from wind-blown volcanic dust to ordinary dirt and house dust.
2. Water-borne sediment accumulates and eventually buries artifacts. Rain carrying sediment from a high point to a lower spot is often the culprit, but sand or clay formed by flowing waters, such as riverine deposits gathered during floods, can literally bury a riverside community. Often, water collects and carries what are technically Aeolian deposits to a lower part of a site.
3. Catastrophic natural events can cause burials in one fell swoop, though this is exceedingly rare, and as Dr. Rapp adds, “In these circumstances the site must be in a topographic situation where erosion is absent or at least considerably slower than deposition.”
Even when a city is buried after one catastrophe, the burial can be caused by more than one factor. Dr. Wesolowsky notes that although both Pompeii and Herculaneum were buried by the eruption of Mt.
Vesuvius in A.D. 79, one was buried by mudflow and the other by ashflow.
4. Manmade structures ca
n collapse, contributing to the burial.
Sometimes this destruction is accidental (such as floods, earthquakes, fires), and sometimes intentional (bombings, demolitions). Humans seem incapable of leaving behind no trace of their activities. Says Rapp: “Even cities as young as New York City have accumulated a considerable depth of such debris. Early New York is now buried many feet below the current surface.”
5. Occasionally, ancient civilizations did their own burying.
Wesolowsky’s example:
When Constantine wanted to build Old St. Peter’s on the side of the Vatican Hill in the early fourth century, his engineers had to cut off part of the slope and dump it into a Roman cemetery (thereby preserving the lower part of the cemetery, including what has been identified as the tomb of Peter himself) to provide a platform for the basilica. When Old St. Peter’s was demolished in
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the sixteenth century to make way for the current church, parts of the old church were used as fill in low areas in the locale.
Rapp’s example:
This phenomenon is best seen in the tels of the Near East. Often they are tens of feet high. Each “civilization” is built over the debris of the preceding one. The houses were mostly of mud brick, which had a lifetime of perhaps sixty years. When they collapsed the earth was just spread around. In two thousand or three thousand years these great habitation mounds (tels) grew to great heights and now rise above the surrounding plains. Each layer encloses archaeological remains of the period of occupation.
While we self-consciously bury time capsules to give future generations an inkling of what our generation is like, the gesture is unne-cessary. With an assist from Mother Nature, we are unwittingly burying revealing artifacts—everything from candy wrappers to beer cans—every day.
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