Karen Hill

The gross national product, or GNP, is the primary indicator of the pace of economic activity within a nation. It is defined as the sum of the money values of all final goods and services that are produced in a certain period of time, usually a year. The money value of a thing is its … Read more

Astronomers know how many stars are in the universe because they are pretty certain they can tell how big it is. They know how big it is because they think they know how old it is, although there is some disagreement on that point. And estimates of the universe’s age in turn depend on estimates … Read more

It may not settle your queasy stomach to know, but an interconnected network of electronic devices makes the landing of an aircraft in “blind” weather conditions at least as safe as driving home from the airport. The key to your return to the earth from 20,000 feet in a pea soup fog is the instrument … Read more

There are two fundamental methods of tunneling underwater that have enabled engineers to overcome the problem of floods and collapsing walls. The Thames tunnel was built in the mid-nineteenth century by a system that ensured that the air pressure within the tunnel exceeded the water pressure without, thus preventing the inflow of water. First, the … Read more

Shelling peanuts may not seem like a difficult or very interesting task, but when you’re talking about cleaning, sizing, and shelling 100,000 pounds of peanuts an hour (which the Planters plant in Aulander, North Carolina, can do), the process is a major operation. To begin with, peanuts are extremely dirty, for they grow in the … Read more

The airlines seem to compete with one another to make flying at 30,000 or 40,000 feet above the earth as comfortable, homey, and as similar to life on the ground as possible. They boast good food and wine, provide magazines and pillows, and, something we take for granted wherever we are, supply us with air … Read more

As far back as the tenth century the Chinese were making fireworks, using saltpeter, sulfur, and charcoal. With the invention of gunpowder (which is actually composed of those same ingredients), the manufacture and display of fireworks came under military control in Europe until the eighteenth century, when the Italians, notable enthusiasts of fireworks, took the … Read more

In 1883, before fingerprint science was clearly understood as a viable means of criminal identification, Mark Twain was on to the system, a thumbprint leads to the detection of a murderer in Life on the Mississippi. And in Pudd’nhead Wilson, a novel Twain published ten years later, a dramatic court trial highlights the infallibility of … Read more

When an organist strikes the first chord of one of Bach’s majestic chorales and the very arches of the cathedral seem to tremble, it’s incredible to think all that sound is being generated by air. A pipe organ sounds when the column of air enclosed in the pipe is disturbed and set in vibration. Before … Read more

The A. C. Nielsen Company’s Nielsen Television Index (NTI) is one of the most important and powerful rating services in the country, as the entire commercial television industry relies upon the ratings to determine both its programming and its advertising rates. Nielsen, founded in 1923, originally performed surveys for manufacturers of industrial machinery and equipment. … Read more

For centuries dance, magic, invocation of the gods, the lighting of fires, and the ringing of church bells have all been used in one place or another by various cultures in attempts to produce rain. But it wasn’t until 1946 that two pioneering scientists working for General Electric evolved ways to make rain based on … Read more

Next time you’re near a particularly tall high rise building, stand at the base and look up, sighting along a corner. It will undoubtedly surprise you to see that the building really isn’t perfectly vertical; it may even jag in and out in some places. It would be entirely too time consuming and costly for … Read more

When a piano tuner arrives at your house, all he needs is a tuning fork, a crank, a damping wedge, and a finely trained ear. He sounds the fork simply by tapping it and causing it to vibrate. The sound produced is the A above middle C, the first note to be tuned in the … Read more

Charming snakes, though totally alien and perhaps horrific to Westerners, is an ancient and venerated tradition in India, dating from the third century B.C. , and in Egypt, where mention of it appears in the early Book of the Dead. The “snakers” (as they like to be called) in India regard themselves as a distinct … Read more

The controversial question of when humans evolved to a large extent remains shrouded in mystery. To start, we have no clear cut biological definition of a human being, nor do we have a precise behavioral definition. Some of us would like to forget our animal ancestry altogether; others admit the descent from apes but allow … Read more

In 1973 the National Academy of Sciences Ocean Affairs Board reported that each year 5 to 10 million metric tons of crude oil and its byproducts (fuel oil, kerosene, gasoline, and lubricants) go into the sea. Sources range from expended ocean transport fuel to the much publicized and controversial oil spills. Although big spills near … Read more

A phone bugging detection service (or, as it’s known in the trade, “intelligence sweeping”) is one of the most secretive businesses in the world, topped, perhaps, only by the phone bugging business itself. Phone bugging detection equipment is usually changed by the service every three months, and often sooner, but then, so are the phone … Read more

The motive force for cable cars is provided by a moving cable generated from a power station. The system was conceived in 1867 by the American mechanic Andrew S. Hallidie. By 1873 the first cable railroad, built by the Clay Street Hill Railroad Company, was in operation in San Francisco. This remarkable system, which aroused … Read more

When Galileo turned the first telescope toward the heavens, he recorded that the Milky Way (the galaxy in which Earth spins) is a stretch of innumerable stars grouped together in clusters. Those star clusters are, in fact, groupings of solar systems, composed of many suns, some with planets revolving around them. Webbing all the clusters … Read more

According to Dr. Michael Greenwald, one of the nation’s leading hair and skin specialists, hair transplantation was developed in the early 1950’s by New York dermatologist Dr. Norman Orentreich, and his technique remains today the only safe and permanent way to replace hair: a minor surgical office procedure in which hair plugs from normal areas … Read more

In 1879, when Ivory soap was first developed by Procter and Gamble, it sank just like any other brand. It had never entered anyone’s head to make it float. The soap’s “floatability” actually came about by accident. According to Procter and Gamble, one day, in the early days of Ivory soap manufacture, a worker went … Read more

As the company slogan says, “It takes a tough man to make a tender chicken,” and Frank Perdue prides itself on the efficiency with which it processes all those chickens, slaughters them, and prepares them for the marketplace in a matter of hours. If a chicken passes the examination for quality, it is lucky enough … Read more

Ailurophiles around the world would have protested long ago if catgut were truly from cats. Although the ancient Egyptians, Babylonians, and later the Greeks and Romans made the tough cords we call catgut, it is doubtful that cats were ever the source. Today, at any rate, catgut is actually sheepgut. The intestines of a sheep … Read more

The Chief Medical Examiner’s Office in New York City operates twenty four hours a day to determine how people die. Twenty four percent of the 72,079 deaths in the city in 1979 were not certified by a private physician and were referred to the Medical Examiner’s Office. Most of those were caused by criminal violence, … Read more

Using strands made of 100,000 hair like glass fibers drawn into a bundle, medical scientists can see around corners and even take pictures in the darkest reaches of the human body. The technology is called fiber optic endoscopy, and with it doctors can photograph the inner surfaces of the esophagus, stomach, intestines, lungs, arteries, and … Read more

There may be more than one way to tell if a string of pearls is real, but the great Arthur Barry, a big time thief in the twenties who averaged half a million dollars in thefts per year, had a unique and quick technique. In the Plaza Hotel robbery of 1925, Barry made off with … Read more

Billboard painters make pictures big enough to put on billboards, with brushes and oil paint. “We’re probably the fresco painters of the modern era. In the Renaissance, the Church had the money; now it’s the ad agencies. Our stuff isn’t as creative as other art, but it’s real craftsmanship that goes into these signs,” says … Read more

Many of us are unaware that modern paintings as well as those of the Old Masters must be cared for periodically. If you have an oil painting in your home that has been subjected to smoke or intense light from a southern exposure for 10 or 20 years, the colors may have darkened gradually, the … Read more

Skating rinks maintain their frozen surfaces even in warm air because the temperature beneath the ice is so cold that the ice is not affected significantly by moderate temperatures above it. Thus a burst of sunshine over an outdoor rink, which allows skaters to shed their sweaters, cannot succeed in melting the ice. In a … Read more

Although modern suspension bridges dazzle the eye as awesome feats of technology, the engineering form is nearly as old as man himself. Vines were the source of cables on the earliest suspension bridges. In the fourth century A.D. plaited bamboo and iron cables were used on bridges in India. The first truly modern suspension bridge … Read more

Radiation works on cancer because it damages cells; by and large, normal cells recover from the bombardment better than malignant ones. “Radiation” in this case refers to ionizing radiation, a flow of energy that tends to split the molecule it strikes into ions, or particles with an electrical charge. For example, when a water molecule … Read more

This strange substance, ice so cold it burns, is an excellent refrigerant, of course, and also a useful source for the ghoulish vapors in vampire and mystery movies. Dry ice is actually composed of carbon dioxide, which at normal temperatures sublimes, or becomes a gas. The carbon dioxide is stored and shipped as a liquid … Read more

The ice in a hockey rink ranges in thickness from 3 inches to a mere 5/8 inch in places such as Madison Square Garden, where ice must be made and taken up in a matter of hours. This thin ice is a trial to professional players who make abrupt turns or screeching stops and sometimes … Read more

When people wrote checks in England as early as 1762, the banks hired delivery clerks to run back and forth between banks to collect the money. To expedite matters, banks developed clearinghouses, organizations in the bank’s locality through which checks were exchanged and net balances settled. Woodrow Wilson organized this system on a nationwide basis … Read more

Gene splicing, a truly revolutionary feat of molecular biologists in recent years, has the potential to make new life forms from different organisms and to synthesize cheaply the scarce substances needed to cure disease. Among those is the potent antiviral protein interferon, which may at last cure the common cold and may provide effective treatment … Read more

The range of eye problems is vast, and the methods of correction are highly refined and complex, but the basic principle behind the correction of nearsightedness or farsightedness is quite simple. If you have either of these conditions, the purpose of your glasses is to converge or diverge the light that enters your eyes so … Read more

Thermostat means, literally, “heat constant.” Temperature changes have a great effect on matter, including the matter human beings are made of; being too hot or cold can do the body great damage. A thermostat keeps the temperature of a house constant by using the response of matter to temperature change to throw switches in a … Read more

An X ray photograph of the leg you broke skiing down the expert slope with intermediate skill shows your bones most brightly because bone is dense and stops more X ray particles than the flesh around it. An X ray camera fires electrons at a plate covered with silver halide crystals, which are sensitive to … Read more

When you flick on your gas stove to make a cup of coffee, you may be at the receiving end of a delivery system reaching more than 1,000 miles. Natural gas, created by the decomposition of organic matter, becomes trapped in pockets hundreds of feet below the earth’s surface. Shafts are drilled into those pockets … Read more

If the rubble always contained the secret of why a building collapsed, the work of investigating engineers would be greatly facilitated. As it is, digging through and photographing the rubble is only a part of the work entailed. Thorough examination must be made of the building’s history from the time it was conceived by an … Read more

The transmission of photographs over telephone wires was extremely useful, especially for newspapers and magazines which required photographs instantly, and it is not as complicated as one might think. First, a positive photographic image is illuminated with a small light. The whiter the image, the greater the reflection; darker images reflect less light. A photocell … Read more

All slot machines are built to take in more than they give back, but buyers of the machine can request (within limits) that the machine always retain a certain percentage. In other words, when ordering a particular model, the operator can request a “tight” or a “liberal” machine. There is a recent trend toward liberal … Read more

Whether out of curiosity, vanity, or a motive as yet unexplored, people throughout the ages have wanted to see their own reflection. As early as 2500 B.C. the Egyptians had mirrors of highly polished metal, usually of bronze, occasionally of silver or gold. The first commercial glass mirrors were made in Venice in 1564; these … Read more

The notion that camels can go without water completely is a myth, nor do they use their extraordinary humps as storage tanks for water. The fact is, camels are able to make long, burdened treks across blazing deserts where oases are few and far between because of their uncommonly economical use of water. They are … Read more

The anxious high school student faced with taking the dreaded Scholastic Aptitude Test (SAT) on a Saturday morning has every reason to wonder just who writes those tests and how. For in many cases the tests are the single largest factor in determining where, or even whether, a student will go on to college. Although … Read more

In addition to the networks of highways, railroads, and telephone wires that connect the farthest sections of the country, another, less visible system exists by which elevations of towns, cities, mountains, and lakes have been determined. Points of reference are marked by thousands of bench marks from coast to coast, the work of state surveys, … Read more

There are two answers to this question, depending on the definition of “the universe.” One answer is that the universe is infinite, that it consists of simply everything: all matter, dust, planets, stars, energy, time, and space. Nothing could lie beyond the boundaries of “everything”; so, by simple semantics, we know the universe is infinite. … Read more

Vending machines are equipped with a coin testing device that not only measures the diameter and thickness of your coin, but checks its weight, alloy composition, and magnetic properties. The coin enters a slot, which has been carefully measured to accommodate the required coin or coins, and rolls down a chute to two hook shaped … Read more

The universe is blowing up. Earth is but a particle of debris hurtling through space from an awesome explosion that took place 20 billion years ago, which generated temperatures of trillions of degrees, and marked the Beginning. Ever since the “Big Bang”, stars, planets, gases, and intergalactic dust have been moving away from one another … Read more

This question is debatable. Ripe bananas, for instance, have more than 150 taste components; it is highly unlikely, therefore, that a synthetic banana flavor could really duplicate the ripe banana flavor. Furthermore, the cheap synthetic flavors that consumers have been fed in recent years have made them so accustomed to an artificial taste that often … Read more

The hunt for New York’s infamous “Son of Sam” killer ended when ballistics experts at the city’s Police Academy Crime Laboratory examined the .44 caliber Charter Arms “Bulldog” revolver they had turned up in the car of suspect David Berkowitz. The bullets found in the bodies of the victims had all been fired from that … Read more

The first known clock humans used was a sundial of some kind, which told us the time with as much precision as we needed: how high is the sun in the sky, and how long will it be till dark? A sundial tells more exactly than the eye alone where our real clock, the sun, … Read more

In 1945 Edison General Electric introduced the first microwave oven for popular consumption. Since then the commercial and domestic use of these ovens has been steadily increasing, largely because of the speed with which they cook food. Microwave ovens cook food by friction: the oven emits short radio waves (microwaves range from 1 millimeter to … Read more

All transactions on the New York Stock Exchange take place in one of three rooms, which are known collectively as “the floor,” at 11 Wall Street in New York. The largest of the rooms, built in 1903, contains twelve numbered U shaped booths or “posts.” Adjacent to this room is “the garage,” built in 1911, … Read more

When a hovercraft moves across water, it is literally floating on air, for a high pressure air cushion is maintained beneath the hull that provides lift and allows even large vessels to whiz along at high speeds. First developed in 1959, air cushion vehicles (AVCs) are sometimes amphibious, capable of traveling both on land and … Read more

Neon is a colorless, odorless, inert gas, first discovered in 1898 by the British physical chemists Sir William Ramsay and Morris W. Travers, who named the gas after the Greek word meaning “new.” About that time physicists were experimenting with generating radiation by striking an arc between electrodes in an evacuated tube containing only small … Read more

If you ever pull out more Scotch tape than you need, you might as well forget trying to save it by rolling it back onto the roll. It’ll twist and stick to itself, your fingers, and the dispenser, and if it does actually get back on the roll it’s bound to be crooked and overlap … Read more

Each frame in a pack of Polaroid film is a self contained unit that serves as film, darkroom, and finished print. It works its sorcery in the seventeen chemical layers crammed with great precision under the surface of a square image area less than .002 inch thick. Migrating among these layers are the dyes that … Read more

Movie ratings are determined by a board of seven, six members and a chairman, within the Classification and Rating Administration (CARA), under the auspices of the Motion Picture Association of America (MPAA). The six board members are full time, paid employees based in Hollywood, where they watch movies nearly all day long. “The members are … Read more

Perhaps you have watched the impeccable movements of George Szell, the nuances of Seiji Ozawa, the romantic drama of Leonard Bernstein, who flails his arms and occasionally leaves the ground, and been at a loss to see how any musician really knows what the conductor wants him to do, and further, how any musician could … Read more

If you’ve ever actually noted how long one can of shaving cream lasts, you’ll know that a lot of foam is somehow packed into a small 11 ounce can. The fact is, the soapy solution expands as it comes out of the can because it contains hydrocarbon propellant, which vaporizes as it hits the air. … Read more

When you drop off two or three shirts at a laundry, they generally go into a machine with at least a dozen others. To keep track of whose shirt belongs to whom, laundry workers actually write on each shirt, sometimes you can see it, sometimes you can’t. One method of differentiating shirts involves writing a … Read more

When truckloads of freshly picked corn arrive at a processing plant, the ears are dumped onto a conveyor belt that transports them to a husking machine. Rotating rollers with fluted surfaces strip the foliage and stalk from the randomly fed corn and send it on for inspection. Immature or diseased corn is removed by hand; … Read more

A simple combination of motion and magnetism underlies the creation of electricity by turbine generators. In the mid nineteenth century scientists found that an electric conductor passed near a magnet and through its magnetic field picks up an electric current. In generators today, the magnet is a huge electromagnet bolted to the shaft of a … Read more

Although the sun is 93 million miles away, we can tell what the temperature is on its surface because we can measure the frequencies of the light waves it sends us. Things at high temperatures generate a lot of light of very high frequency (or short wavelength); the frequencies sent out by the sun are … Read more

The velocity of light and how to go about measuring it evaded Galileo in the early part of the seventeenth century when, after experimenting with lanterns, all he could deduce was that light goes fast. The problem with his efforts was that light travels far too rapidly for its speed to be detected over the … Read more

In the late 1950’s and throughout the 1960’s, new knowledge was acquired and new methods developed for the storage and preservation of human sperm. The 1970’s saw the natural consequence: the advent of sperm banks and sperm as a salable commodity. Today there are nearly a dozen sperm banks scattered across the country, and the … Read more

A Xerox machine seems a miraculous thing: it makes a clear, permanent copy of a document on ordinary paper in about 5 seconds and the copy is sometimes easier to read than the original. Like many modern inventions, the Xerox copier should not be possible under the classical laws of physics laid down by Isaac … Read more

In the late 1940’s Don MacDonnell of Smith Kline & French, a pharmaceutical company, went into his local grocery store and lighted upon a jar of “petites”, tiny candy beads used for decorating pastry. Scientists at the time were searching for a form of medication that would release slowly, and the candy provided MacDonnell with … Read more

It would be nice if hens were systematically grouped into jumbo, large, and medium sizes, just as their eggs are classified. But even though tall people often have tall children, big hens don’t necessarily lay big eggs. In a standard coop all the hens, large side by side with small, are kept in cages of … Read more

If roads were always dry, tire manufacture would be a simple operation: all tires would be completely smooth, like racing tires; for the greater the amount of tire in contact with the road, the greater the amount of traction. Our changeable climate creates another set of problems, however, for smooth tires (especially wide ones) speeding … Read more

Tools help, as do various specific techniques, but rock climbers depend mostly on sound judgment, careful analysis, and astonishing nerve. The physical mechanics of rock climbing involve not only the feet, knees, hands, arms, and body. Pressure of the body against the rock, for example, lends support. If a very steep rock affords no hand … Read more

Artificial insemination has been popular among cattle breeders for more than fifty years, for it enables a champion bull to sire 50,000 prize offspring in one year. Although this is not exactly the goal among human beings, artificial insemination has been used with increasing frequency since 1953 for a variety of reasons. The ability to … Read more

The people at Infinetics, Inc., the manufacturer of “Friskem” detectors, which comprise over 90 percent of the worldwide market for airport metal detectors, are fearful of releasing any secrets about how their detectors operate. According to the management (who seem to assume guilt on the part of the questioner until proof of innocence is established), … Read more

A very small mammal or insect endemic to a particular area might be considered endangered while several million are still known to be alive, but a lesser number of another species, spread out over a broad area, would not give rise to concern. Determining whether or not a species is endangered is a complex task … Read more

The amazing answer is, simply, hot air balloon pilots don’t steer balloons. Control over ascent and descent is vital, and possible, but when it comes to velocity and direction, the huge balloon and its crew are utterly at the mercy of capricious winds. It is only by the use of these winds that a balloonist … Read more

Swayed by the high esteem in which youthful minds and youthful bodies are held these days, many people are turning to cosmetic surgery to smooth their furrowed brows and lift their sagging jowls. Although face lifts were first performed in Europe and the United States at the turn of the century, the process remained cloaked … Read more

A seedless grapevine is grown from a bit of stem cut from a mature seedless vine. But where do we get seedless grapevines? They originated thousands of years ago in the Middle East, in the area of present day Iran or Afghanistan, no one knows exactly when or where. Raisins from seedless grapes are mentioned … Read more

It isn’t easy to shrink the Statue of Liberty so that it fits into the hand of a tourist from Cedar Rapids, Iowa, or to make thousands of copies of a famous bust of Abraham Lincoln, each with the same wise, somber expression. The entire process calls for specialized teams of sculptors, working from the … Read more

As anyone can read in the back of The New York Times Book Review each Sunday, the best seller lists reflect the sales of books in 1,400 bookstores across the country. Each week those stores submit sales figures of the most popular titles, and this information is fed into a computer, which comes up with … Read more

Although it’s intriguing to imagine the peppermint stripes neatly wound inside the tube of toothpaste, actually the stripes don’t go onto the paste until it’s on its way out. A small hollow tube, with slots running lengthwise, extends from the neck of the toothpaste tube back into the interior a short distance. When the toothpaste … Read more

The plain fact is truth serum doesn’t work, at least not well or consistently enough to be accepted by our legal system as a reliable means of extracting the truth from unwilling subjects. Most courts of law do not admit information produced by drug analysis as legal evidence. The catchy phrase truth serum appears to … Read more

Visions of auditors and interminable interrogations may rattle your nerves as you mail in your tax return each year, wondering whether an inscrutable Big Brother will select you as the lucky host to an IRS agent. There is no surefire answer to the question of who will be audited, but you can be aware of … Read more

Humans are the only beasts who use telephones or permanent addresses, or fill out census forms. How are the other animals counted? How can anyone tell that the timber wolf and the California condor are rare and “endangered”? How do we know how many robins chirp every spring? The task of taking a census of … Read more

The first step is to chart the subway precisely, taking note of all underground utilities, existing subways, foundations, and soil and rock conditions. If the route happens to coincide with the path of a street, or if it lies beneath clear areas above ground, a “cut and cover” method of digging trenches at the surface … Read more

Submarines dive and resurface simply as a result of changes in the amount of weight on board. It’s essential, then, that the captain keep careful track of the number of crew members and the amount of food, batteries, torpedoes, and so on. When the submarine’s weight is equal to the weight of water it displaces, … Read more

Bees know how to build honeycombs in their hives by accident, that’s the biological answer to the question. The dazzling geometric perfection of the honeycomb, with its perfectly flat surfaces made of straight rows of elegant hexagons, compact, yet capacious enough inside to support a population of 80,000, is the product of blind instinct, the … Read more

Nothing seems more random than the haphazard looking zigs and zags of a bee as it buzzes along on a summer afternoon. Yet nothing is more deliberate in all of nature. That bee has been flying a distance of up to 6 miles in a literal “beeline” from its hive to the place where it … Read more

An act of Congress in 1962 designated the Secretary of the Treasury as the one responsible for choosing who will have the honor of appearing on our money. In most cases the secretary consults other Treasury officials, the Director of the Bureau of Engraving and Printing, and sometimes the President before making a final decision. … Read more

The Director of the Mint, with the approval of the Secretary of the Treasury, has the prerogative of choosing new coin designs, though changes cannot be made on any coin more than once every twenty five years, according to an act of Congress, Title 31, Section 276, enacted in 1890. It wasn’t until the one … Read more