Hearing aid

The invention: Miniaturized electronic amplifier worn inside the ears of hearing-impaired persons. The organization behind the invention: Bell Labs, the research and development arm of the American Telephone and Telegraph Company Trapped in Silence Until the middle of the twentieth century, people who experienced hearing loss had little hope of being able to hear sounds without the use of large, awkward, heavy appliances. For many years, the only hearing aids available were devices known as ear trumpets. The ear trumpet tried to compensate for hearing loss by increasing the number of sound waves funneled into the ear canal. A wide, bell-like mouth similar to the bell of a musical trumpet narrowed to a tube that the user placed in his or her ear. Ear trumpets helped a little, but they could not truly increase the volume of the sounds heard. Beginning in the nineteenth century, inventors tried to develop electrical devices that would serve as hearing aids. The telephone was actually a by-product of Alexander Graham Bell’s efforts to make a hearing aid. Following the invention of the telephone, electrical engineers designed hearing aids that employed telephone technology, but those hearing aids were only a slight improvement over the old ear trumpets. They required large, heavy battery packs and used a carbon microphone similar to the receiver in a telephone. More sensitive than purely physical devices such as the ear trumpet, they could transmit a wider range of sounds but could not amplify them as effectively as electronic hearing aids now do. Transistors Make Miniaturization Possible Two types of hearing aids exist: body-worn and head-worn. Body-worn hearing aids permit the widest range of sounds to be heard, but because of the devices’ larger size, many hearing impaired persons do not like to wear them. Head-worn hearing aids, especially those worn completely in the ear, are much less conspicuous. In addition to in-ear aids, the category of head-worn hearing aids includes both hearing aids mounted in eyeglass frames and those worn behind the ear. All hearing aids, whether head-worn or body-worn, consist of four parts: a microphone to pick up sounds, an amplifier, a receiver, and a power source. The microphone gathers sound waves and converts them to electrical signals; the amplifier boosts, or increases, those signals; and the receiver then converts the signals back into sound waves. In effect, the hearing aid is a miniature radio. After the receiver converts the signals back to sound waves, those waves are directed into the ear canal through an earpiece or ear mold. The ear mold generally is made of plastic and is custom fitted from an impression taken from the prospective user’s ear. Effective head-worn hearing aids could not be built until the electronic circuit was developed in the early 1950’s. The same invention— the transistor—that led to small portable radios and tape players allowed engineers to create miniaturized, inconspicuous hearing aids. Depending on the degree of amplification required, the amplifier in a hearing aid contains three or more transistors. Transistors first replaced vacuum tubes in devices such as radios and phonographs, and then engineers realized that they could be used in devices for the hearing-impaired. The research at Bell Labs that led to the invention of the transistor rose out of military research duringWorldWar II. The vacuum tubes used in, for example, radar installations to amplify the strength of electronic signals were big, were fragile because they were made of blown glass, and gave off high levels of heat when they were used. Transistors, however, made it possible to build solid-state, integrated circuits. These are made from crystals of metals such as germanium or arsenic alloys and therefore are much less fragile than glass. They are also extremely small (in fact, some integrated circuits are barely visible to the naked eye) and give off no heat during use. The number of transistors in a hearing aid varies depending upon the amount of amplification required. The first transistor is the most important for the listener in terms of the quality of sound heard. If the frequency response is set too high—that is, if the device is too sensitive—the listener will be bothered by distracting background noise. Theoretically, there is no limit on the amount of amplification that a hearing aid can be designed to provide, but there are practical limits. The higher the amplification, the more power is required to operate the hearing aid. This is why body-worn hearing aids can convey a wider range of sounds than head-worn devices can. It is the power source—not the electronic components—that is the limiting factor. A body-worn hearing aid includes a larger battery pack than can be used with a head-worn device. Indeed, despite advances in battery technology, the power requirements of a head-worn hearing aid are such that a 1.4-volt battery that could power a wristwatch for several years will last only a few days in a hearing aid. Consequences The invention of the electronic hearing aid made it possible for many hearing-impaired persons to participate in a hearing world. Prior to the invention of the hearing aid, hearing-impaired children often were unable to participate in routine school activities or function effectively in mainstream society. Instead of being able to live at home with their families and enjoy the same experiences that were available to other children their age, often they were forced to attend special schools operated by the state or by charities. Hearing-impaired people were singled out as being different and were limited in their choice of occupations. Although not every hearing-impaired person can be helped to hear with a hearing aid— particularly in cases of total hearing loss—the electronic hearing aid has ended restrictions for many hearing-impaired people. Hearingimpaired children are now included in public school classes, and hearing-impaired adults can now pursue occupations from which they were once excluded. Today, many deaf and hearing-impaired persons have chosen to live without the help of a hearing aid. They believe that they are not disabled but simply different, and they point out that their “disability” often allows them to appreciate and participate in life in unique and positive ways. For them, the use of hearing aids is a choice, not a necessity. For those who choose, hearing aids make it possible to participate in the hearing world.

Hard disk

The invention: A large-capacity, permanent magnetic storage device built into most personal computers. The people behind the invention: Alan Shugart (1930- ), an engineer who first developed the floppy disk Philip D. Estridge (1938?-1985), the director of IBM’s product development facility Thomas J. Watson, Jr. (1914-1993), the chief executive officer of IBM The Personal Oddity When the International Business Machines (IBM) Corporation introduced its first microcomputer, called simply the IBM PC (for “personal computer”), the occasion was less a dramatic invention than the confirmation of a trend begun some years before. A number of companies had introduced microcomputers before IBM; one of the best known at that time was Apple Corporation’s Apple II, for which software for business and scientific use was quickly developed. Nevertheless, the microcomputer was quite expensive and was often looked upon as an oddity, not as a useful tool. Under the leadership of Thomas J. Watson, Jr., IBM, which had previously focused on giant mainframe computers, decided to develop the PC. A design team headed by Philip D. Estridge was assembled in Boca Raton, Florida, and it quickly developed its first, pacesetting product. It is an irony of history that IBM anticipated selling only one hundred thousand or so of these machines, mostly to scientists and technically inclined hobbyists. Instead, IBM’s product sold exceedingly well, and its design parameters, as well as its operating system, became standards. The earliest microcomputers used a cassette recorder as a means of mass storage; a floppy disk drive capable of storing approximately 160 kilobytes of data was initially offered only as an option. While home hobbyists were accustomed to using a cassette recorder for storage purposes, such a system was far too slow and awkward for use in business and science. As a result, virtually every IBM PC sold was equipped with at least one 5.25-inch floppy disk drive. Memory Requirements All computers require memory of two sorts in order to carry out their tasks. One type of memory is main memory, or random access memory (RAM), which is used by the computer’s central processor to store data it is using while operating. The type of memory used for this function is built typically of silicon-based integrated circuits that have the advantage of speed (to allow the processor to fetch or store the data quickly), but the disadvantage of possibly losing or “forgetting” data when the electric current is turned off. Further, such memory generally is relatively expensive. To reduce costs, another type of memory—long-term storage memory, known also as “mass storage”—was developed. Mass storage devices include magnetic media (tape or disk drives) and optical media (such as the compact disc, read-only memory, or CDROM). While the speed with which data may be retrieved from or stored in such devices is rather slow compared to the central processor’s speed, a disk drive—the most common form of mass storage used in PCs—can store relatively large amounts of data quite inexpensively. Early floppy disk drives (so called because the magnetically treated material on which data are recorded is made of a very flexible plastic) held 160 kilobytes of data using only one side of the magnetically coated disk (about eighty pages of normal, doublespaced, typewritten information). Later developments increased storage capacities to 360 kilobytes by using both sides of the disk and later, with increasing technological ability, 1.44 megabytes (millions of bytes). In contrast, mainframe computers, which are typically connected to large and expensive tape drive storage systems, could store gigabytes (millions of megabytes) of information. While such capacities seem large, the needs of business and scientific users soon outstripped available space. Since even the mailing list of a small business or a scientist’s mathematical model of a chemical reaction easily could require greater storage potential than early PCs allowed, the need arose for a mass storage device that could accommodate very large files of data. The answer was the hard disk drive, also known as a “fixed disk drive,” reflecting the fact that the disk itself is not only rigid but also permanently installed inside the machine. In 1955, IBM had envisioned the notion of a fixed, hard magnetic disk as a means of storing computer data, and, under the direction of Alan Shugart in the 1960’s, the floppy disk was developed as well. As the engineers of IBM’s facility in Boca Raton refined the idea of the original PC to design the new IBM PC XT, it became clear that chief among the needs of users was the availability of large-capability storage devices. The decision was made to add a 10-megabyte hard disk drive to the PC. On March 8, 1983, less than two years after the introduction of its first PC, IBM introduced the PC XT. Like the original, it was an evolutionary design, not a revolutionary one. The inclusion of a hard disk drive, however, signaled that mass storage devices in personal computers had arrived. Consequences Above all else, any computer provides a means for storing, ordering, analyzing, and presenting information. If the personal computer is to become the information appliance some have suggested it will be, the ability to manipulate very large amounts of data will be of paramount concern. Hard disk technology was greeted enthusiastically in the marketplace, and the demand for hard drives has seen their numbers increase as their quality increases and their prices drop. It is easy to understand one reason for such eager acceptance: convenience. Floppy-bound computer users find themselves frequently changing (or “swapping”) their disks in order to allow programs to find the data they need. Moreover, there is a limit to how much data a single floppy disk can hold. The advantage of a hard drive is that it allows users to keep seemingly unlimited amounts of data and programs stored in their machines and readily available. Also, hard disk drives are capable of finding files and transferring their contents to the processor much more quickly than a floppy drive. A user may thus create exceedingly large files, keep them on hand at all times, and manipulate data more quickly than with a floppy. Finally, while a hard drive is a slow substitute for main memory, it allows users to enjoy the benefits of larger memories at significantly lower cost. The introduction of the PC XT with its 10-megabyte hard drive was a milestone in the development of the PC. Over the next two decades, the size of computer hard drives increased dramatically. By 2001, few personal computers were sold with hard drives with less than three gigabytes of storage capacity, and hard drives with more than thirty gigabytes were becoming the standard. Indeed, for less money than a PC XT cost in the mid-1980’s, one could buy a fully equipped computer with a hard drive holding sixty gigabytes—a storage capacity equivalent to six thousand 10-megabyte hard drives.

Gyrocompass

The invention: The first practical navigational device that enabled ships and submarines to stay on course without relying on the earth’s unreliable magnetic poles. The people behind the invention: Hermann Anschütz-Kaempfe (1872-1931), a German inventor and manufacturer Jean-Bernard-Léon Foucault (1819-1868), a French experimental physicist and inventor Elmer Ambrose Sperry (1860-1930), an American engineer and inventor From Toys to Tools A gyroscope consists of a rapidly spinning wheel mounted in a frame that enables the wheel to tilt freely in any direction. The amount of momentum allows the wheel to maintain its “attitude” even when the whole device is turned or rotated. These devices have been used to solve problems arising in such areas as sailing and navigation. For example, a gyroscope aboard a ship maintains its orientation even while the ship is rolling. Among other things, this allows the extent of the roll to be measured accurately. Moreover, the spin axis of a free gyroscope can be adjusted to point toward true north. It will (with some exceptions) stay that way despite changes in the direction of a vehicle in which it is mounted. Gyroscopic effects were employed in the design of various objects long before the theory behind them was formally known. A classic example is a child’s top, which balances, seemingly in defiance of gravity, as long as it continues to spin. Boomerangs and flying disks derive stability and accuracy from the spin imparted by the thrower. Likewise, the accuracy of rifles improved when barrels were manufactured with internal spiral grooves that caused the emerging bullet to spin. In 1852, the French inventor Jean-Bernard-Léon Foucault built the first gyroscope, a measuring device consisting of a rapidly spinning wheel mounted within concentric rings that allowed the wheel to move freely about two axes. This device, like the Foucault pendulum, was used to demonstrate the rotation of the earth around its axis, since the spinning wheel, which is not fixed, retains its orientation in space while the earth turns under it. The gyroscope had a related interesting property: As it continued to spin, the force of the earth’s rotation caused its axis to rotate gradually until it was oriented parallel to the earth’s axis, that is, in a north-south direction. It is this property that enables the gyroscope to be used as a compass. When Magnets Fail In 1904, Hermann Anschütz-Kaempfe, a German manufacturer working in the Kiel shipyards, became interested in the navigation problems of submarines used in exploration under the polar ice cap. By 1905, efficient working submarines were a reality, and it was evident to all major naval powers that submarines would play an increasingly important role in naval strategy. Submarine navigation posed problems, however, that could not be solved by instruments designed for surface vessels. Asubmarine needs to orient itself under water in three dimensions; it has no automatic horizon with respect to which it can level itself. Navigation by means of stars or landmarks is impossible when the submarine is submerged. Furthermore, in an enclosed metal hull containing machinery run by electricity, a magnetic compass is worthless. To a lesser extent, increasing use of metal, massive moving parts, and electrical equipment had also rendered the magnetic compass unreliable in conventional surface battleships. It made sense for Anschütz-Kaempfe to use the gyroscopic effect to design an instrument that would enable a ship to maintain its course while under water. Yet producing such a device would not be easy. First, it needed to be suspended in such a way that it was free to turn in any direction with as little mechanical resistance as possible. At the same time, it had to be able to resist the inevitable pitching and rolling of a vessel at sea. Finally, a continuous power supply was required to keep the gyroscopic wheels spinning at high speed. The original Anschütz-Kaempfe gyrocompass consisted of a pair of spinning wheels driven by an electric motor. The device was connected to a compass card visible to the ship’s navigator. Motor, gyroscope, and suspension system were mounted in a frame that allowed the apparatus to remain stable despite the pitch and roll of the ship. In 1906, the German navy installed a prototype of the Anschütz- Kaempfe gyrocompass on the battleship Undine and subjected it to exhaustive tests under simulated battle conditions, sailing the ship under forced draft and suddenly reversing the engines, changing the position of heavy turrets and other mechanisms, and firing heavy guns. In conditions under which a magnetic compass would have been worthless, the gyrocompass proved a satisfactory navigational tool, and the results were impressive enough to convince the German navy to undertake installation of gyrocompasses in submarines and heavy battleships, including the battleship Deutschland. Elmer Ambrose Sperry, a New York inventor intimately associated with pioneer electrical development, was independently working on a design for a gyroscopic compass at about the same time. In 1907, he patented a gyrocompass consisting of a single rotor mounted within two concentric shells, suspended by fine piano wire from a frame mounted on gimbals. The rotor of the Sperry compass operated in a vacuum, which enabled it to rotate more rapidly. The Sperry gyrocompass was in use on larger American battleships and submarines on the eve ofWorldWar I (1914-1918). Impact The ability to navigate submerged submarines was of critical strategic importance in World War I. Initially, the German navy had an advantage both in the number of submarines at its disposal and in their design and maneuverability. The German U-boat fleet declared all-out war on Allied shipping, and, although their efforts to blockade England and France were ultimately unsuccessful, the tremendous toll they inflicted helped maintain the German position and prolong the war. To a submarine fleet operating throughout the Atlantic and in the Caribbean, as well as in near-shore European waters, effective long-distance navigation was critical. Gyrocompasses were standard equipment on submarines and battleships and, increasingly, on larger commercial vessels during World War I, World War II (1939-1945), and the period between the wars. The devices also found their way into aircraft, rockets, and guided missiles. Although the compasses were made more accurate and easier to use, the fundamental design differed little from that invented by Anschütz-Kaempfe.

Geothermal power

The invention: Energy generated from the earth’s natural hot springs. The people behind the invention: Prince Piero Ginori Conti (1865-1939), an Italian nobleman and industrialist Sir Charles Parsons (1854-1931), an English engineer B. C. McCabe, an American businessman Developing a Practical System The first successful use of geothermal energy was at Larderello in northern Italy. The Larderello geothermal field, located near the city of Pisa about 240 kilometers northwest of Rome, contains many hot springs and fumaroles (steam vents). In 1777, these springs were found to be rich in boron, and in 1818, Francesco de Larderel began extracting the useful mineral borax from them. Shortly after 1900, Prince Piero Ginori Conti, director of the Larderello borax works, conceived the idea of using the steam for power production. An experimental electrical power plant was constructed at Larderello in 1904 to provide electric power to the borax plant. After this initial experiment proved successful, a 250-kilowatt generating station was installed in 1913 and commercial power production began. As the Larderello field grew, additional geothermal sites throughout the region were prospected and tapped for power. Power production grew steadily until the 1940’s, when production reached 130 megawatts; however, the Larderello power plants were destroyed late inWorldWar II (1939-1945). After the war, the generating plants were rebuilt, and they were producing more than 400 megawatts by 1980. The Larderello power plants encountered many of the technical problems that were later to concern other geothermal facilities. For example, hydrogen sulfide in the steam was highly corrosive to copper, so the Larderello power plant used aluminum for electrical connections much more than did conventional power plants of the time. Also, the low pressure of the steam in early wells at Larderello presented problems. The first generators simply used steam to drive a generator and vented the spent steam into the atmosphere. Asystem of this sort, called a “noncondensing system,” is useful for small generators but not efficient to produce large amounts of power. Most steam engines derive power not only from the pressure of the steam but also from the vacuum created when the steam is condensed back to water. Geothermal systems that generate power from condensation, as well as direct steam pressure, are called “condensing systems.” Most large geothermal generators are of this type. Condensation of geothermal steam presents special problems not present in ordinary steam engines: There are other gases present that do not condense. Instead of a vacuum, condensation of steam contaminated with other gases would result in only a limited drop in pressure and, consequently, very low efficiency. Initially, the operators of Larderello tried to use the steam to heat boilers that would, in turn, generate pure steam. Eventually, a device was developed that removed most of the contaminating gases from the steam. Although later wells at Larderello and other geothermal fields produced steam at greater pressure, these engineering innovations improved the efficiency of any geothermal power plant. Expanding the Idea In 1913, the English engineer Sir Charles Parsons proposed drilling an extremely deep (12-kilometer) hole to tap the earth’s deep heat. Power from such a deep hole would not come from natural steam as at Larderello but would be generated by pumping fluid into the hole and generating steam (as hot as 500 degrees Celsius) at the bottom. In modern terms, Parsons proposed tapping “hot dryrock” geothermal energy. (No such plant has been commercially operated yet, but research is being actively pursued in several countries.) The first use of geothermal energy in the United States was for direct heating. In 1890, the municipal water company of Boise, Idaho, began supplying hot water from a geothermal well. Water was piped from the well to homes and businesses along appropriately namedWarm Springs Avenue. At its peak, the system served more than four hundred customers, but as cheap natural gas became available, the number declined. Although Larderello was the first successful geothermal electric power plant, the modern era of geothermal electric power began with the opening of the Geysers Geothermal Field in California. Early attempts began in the 1920’s, but it was not until 1955 that B. C. McCabe, a Los Angeles businessman, leased 14.6 square kilometers in the Geysers area and founded the Magma Power Company. The first 12.5-megawatt generator was installed at the Geysers in 1960, and production increased steadily from then on. The Geysers surpassed Larderello as the largest producing geothermal field in the 1970’s, and more than 1,000 megawatts were being generated by 1980. By the end of 1980, geothermal plants had been installed in thirteen countries, with a total capacity of almost 2,600 megawatts, and projects with a total capacity of more than 15,000 megawatts were being planned in more than twenty countries. Impact Geothermal power has many attractive features. Because the steam is naturally heated and under pressure, generating equipment can be simple, inexpensive, and quickly installed. Equipment and installation costs are offset by savings in fuel. It is economically practical to install small generators, a fact that makes geothermal plants attractive in remote or underdeveloped areas. Most important to a world faced with a variety of technical and environmental problems connected with fossil fuels, geothermal power does not deplete fossil fuel reserves, produces little pollution, and contributes little to the greenhouse effect. Despite its attractive features, geothermal power has some limitations. Geologic settings suitable for easy geothermal power production are rare; there must be a hot rock or magma body close to the surface. Although it is technically possible to pump water from an external source into a geothermal well to generate steam, most geothermal sites require a plentiful supply of natural underground water that can be tapped as a source of steam. In contrast, fossil-fuel generating plants can be at any convenient location.

Genetically engineered insulin

The invention: Artificially manufactured human insulin (Humulin) as a medication for people suffering from diabetes. The people behind the invention: Irving S. Johnson (1925- ), an American zoologist who was vice president of research at Eli Lilly Research Laboratories Ronald E. Chance (1934- ), an American biochemist at Eli Lilly Research Laboratories What Is Diabetes? Carbohydrates (sugars and related chemicals) are the main food and energy source for humans. In wealthy countries such as the United States, more than 50 percent of the food people eat is made up of carbohydrates, while in poorer countries the carbohydrate content of diets is higher, from 70 to 90 percent. Normally, most carbohydrates that a person eats are used (or metabolized) quickly to produce energy. Carbohydrates not needed for energy are either converted to fat or stored as a glucose polymer called “glycogen.” Most adult humans carry about a pound of body glycogen; this substance is broken down to produce energy when it is needed. Certain diseases prevent the proper metabolism and storage of carbohydrates. The most common of these diseases is diabetes mellitus, usually called simply “diabetes.” It is found in more than seventy million people worldwide. Diabetic people cannot produce or use enough insulin, a hormone secreted by the pancreas. When their condition is not treated, the eyes may deteriorate to the point of blindness. The kidneys may stop working properly, blood vessels may be damaged, and the person may fall into a coma and die. In fact, diabetes is the third most common killer in the United States. Most of the problems surrounding diabetes are caused by high levels of glucose in the blood. Cataracts often form in diabetics, as excess glucose is deposited in the lens of the eye. Important symptoms of diabetes include constant thirst, excessive urination, and large amounts of sugar in the blood and in the urine. The glucose tolerance test (GTT) is the best way to find out whether a person is suffering from diabetes. People given a GTT are first told to fast overnight. In the morning their blood glucose level is measured; then they are asked to drink about a fourth of a pound of glucose dissolved in water. During the next four to six hours, the blood glucose level is measured repeatedly. In nondiabetics, glucose levels do not rise above a certain amount during a GTT, and the level drops quickly as the glucose is assimilated by the body. In diabetics, the blood glucose levels rise much higher and do not drop as quickly. The extra glucose then shows up in the urine. Treating Diabetes Until the 1920’s, diabetes could be controlled only through a diet very low in carbohydrates, and this treatment was not always successful. Then Sir Frederick G. Banting and Charles H. Best found a way to prepare purified insulin from animal pancreases and gave it to patients. This gave diabetics their first chance to live a fairly normal life. Banting and his coworkers won the 1923 Nobel Prize in Physiology or Medicine for their work. The usual treatment for diabetics became regular shots of insulin. Drug companies took the insulin from the pancreases of cattle and pigs slaughtered by the meat-packing industry. Unfortunately, animal insulin has two disadvantages. First, about 5 percent of diabetics are allergic to it and can have severe reactions. Second, the world supply of animal pancreases goes up and down depending on how much meat is being bought. Between 1970 and 1975, the supply of insulin fell sharply as people began to eat less red meat, yet the numbers of diabetics continued to increase. So researchers began to look for a better way to supply insulin. Studying pancreases of people who had donated their bodies to science, researchers found that human insulin did not cause allergic reactions. Scientists realized that it would be best to find a chemical or biological way to prepare human insulin, and pharmaceutical companies worked hard toward this goal. Eli Lilly and Company was the first to succeed, and on May 14, 1982, it filed a new drug application with the Food and Drug Administration (FDA) for the human insulin preparation it named “Humulin.” Humulin is made by genetic engineering. Irving S. Johnson, who worked on the development of Humulin, described Eli Lilly’s method for producing Humulin. The common bacterium Escherichia coli is used. Two strains of the bacterium are produced by genetic engineering: The first strain is used to make a protein called an “A chain,” and the second strain is used to make a “B chain.” After the bacteria are harvested, the Aand B chains are removed and purified separately. Then the two chains are combined chemically. When they are purified once more, the result is Humulin, which has been proved by Ronald E. Chance and his Eli Lilly coworkers to be chemically, biologically, and physically identical to human insulin. Consequences The FDA and other regulatory agencies around the world approved genetically engineered human insulin in 1982. Humulin does not trigger allergic reactions, and its supply does not fluctuate. It has brought an end to the fear that there would be a worldwide shortage of insulin. Humulin is important as well in being the first genetically engineered industrial chemical. It began an era in which such advanced technology could be a source for medical drugs, chemicals used in farming, and other important industrial products. Researchers hope that genetic engineering will help in the understanding of cancer and other diseases, and that it will lead to ways to grow enough food for a world whose population continues to rise.

Genetic “fingerprinting”

The invention: Atechnique for using the unique characteristics of each human being’s DNA to identify individuals, establish connections among relatives, and identify criminals. The people behind the invention: Alec Jeffreys (1950- ), an English geneticist Victoria Wilson (1950- ), an English geneticist Swee Lay Thein (1951- ), a biochemical geneticist Microscopic Fingerprints In 1985, Alec Jeffreys, a geneticist at the University of Leicester in England, developed a method of deoxyribonucleic acid (DNA) analysis that provides a visual representation of the human genetic structure. Jeffreys’s discovery had an immediate, revolutionary impact on problems of human identification, especially the identification of criminals. Whereas earlier techniques, such as conventional blood typing, provide evidence that is merely exclusionary (indicating only whether a suspect could or could not be the perpetrator of a crime), DNA fingerprinting provides positive identification. For example, under favorable conditions, the technique can establish with virtual certainty whether a given individual is a murderer or rapist. The applications are not limited to forensic science; DNA fingerprinting can also establish definitive proof of parenthood (paternity or maternity), and it is invaluable in providing markers for mapping disease-causing genes on chromosomes. In addition, the technique is utilized by animal geneticists to establish paternity and to detect genetic relatedness between social groups. DNAfingerprinting (also referred to as “genetic fingerprinting”) is a sophisticated technique that must be executed carefully to produce valid results. The technical difficulties arise partly from the complex nature of DNA. DNA, the genetic material responsible for heredity in all higher forms of life, is an enormously long, doublestranded molecule composed of four different units called “bases.” The bases on one strand of DNApair with complementary bases on the other strand. A human being contains twenty-three pairs of chromosomes; one member of each chromosome pair is inherited fromthe mother, the other fromthe father. The order, or sequence, of bases forms the genetic message, which is called the “genome.” Scientists did not know the sequence of bases in any sizable stretch of DNA prior to the 1970’s because they lacked the molecular tools to split DNA into fragments that could be analyzed. This situation changed with the advent of biotechnology in the mid-1970’s. The door toDNAanalysis was opened with the discovery of bacterial enzymes called “DNA restriction enzymes.” A restriction enzyme binds to DNA whenever it finds a specific short sequence of base pairs (analogous to a code word), and it splits the DNAat a defined site within that sequence. A single enzyme finds millions of cutting sites in human DNA, and the resulting fragments range in size from tens of base pairs to hundreds or thousands. The fragments are exposed to a radioactive DNA probe, which can bind to specific complementary DNA sequences in the fragments. X-ray film detects the radioactive pattern. The developed film, called an “autoradiograph,” shows a pattern of DNA fragments, which is similar to a bar code and can be compared with patterns from known subjects. The Presence of Minisatellites The uniqueness of a DNA fingerprint depends on the fact that, with the exception of identical twins, no two human beings have identical DNA sequences. Of the three billion base pairs in human DNA, many will differ from one person to another. In 1985, Jeffreys and his coworkers, Victoria Wilson at the University of Leicester and Swee Lay Thein at the John Radcliffe Hospital in Oxford, discovered a way to produce a DNA fingerprint. Jeffreys had found previously that human DNA contains many repeated minisequences called “minisatellites.” Minisatellites consist of sequences of base pairs repeated in tandem, and the number of repeated units varies widely from one individual to another. Every person, with the exception of identical twins, has a different number of tandem repeats and, hence, different lengths of minisatellite DNA. By using two labeled DNA probes to detect two different minisatellite sequences, Jeffreys obtained a unique fragment band pattern that was completely specific for an individual. The power of the technique derives from the law of chance, which indicates that the probability (chance) that two or more unrelated events will occur simultaneously is calculated as the multiplication product of the two separate probabilities. As Jeffreys discovered, the likelihood of two unrelated people having completely identical DNAfingerprints is extremely small—less than one in ten trillion. Given the population of the world, it is clear that the technique can distinguish any one person from everyone else. Jeffreys called his band patterns “DNAfingerprints” because of their ability to individualize. As he stated in his landmark research paper, published in the English scientific journal Nature in 1985, probes to minisatellite regions of human DNA produce “DNA ‘fingerprints’ which are completely specific to an individual (or to his or her identical twin) and can be applied directly to problems of human identification, including parenthood testing.” Consequences In addition to being used in human identification, DNA fingerprinting has found applications in medical genetics. In the search for a cause, a diagnostic test for, and ultimately the treatment of an inherited disease, it is necessary to locate the defective gene on a human chromosome. Gene location is accomplished by a technique called “linkage analysis,” in which geneticists use marker sections of DNA as reference points to pinpoint the position of a defective gene on a chromosome. The minisatellite DNA probes developed by Jeffreys provide a potent and valuable set of markers that are of great value in locating disease-causing genes. Soon after its discovery, DNA fingerprinting was used to locate the defective genes responsible for several diseases, including fetal hemoglobin abnormality and Huntington’s disease. Genetic fingerprinting also has had a major impact on genetic studies of higher animals. BecauseDNAsequences are conserved in evolution, humans and other vertebrates have many sequences in common. This commonality enabled Jeffreys to use his probes to human minisatellites to bind to the DNA of many different vertebrates, ranging from mammals to birds, reptiles, amphibians, and fish; this made it possible for him to produce DNA fingerprints of these vertebrates. In addition, the technique has been used to discern the mating behavior of birds, to determine paternity in zoo primates, and to detect inbreeding in imperiled wildlife. DNA fingerprinting can also be applied to animal breeding problems, such as the identification of stolen animals, the verification of semen samples for artificial insemination, and the determination of pedigree. The technique is not foolproof, however, and results may be far from ideal. Especially in the area of forensic science, there was a rush to use the tremendous power of DNA fingerprinting to identify a purported murderer or rapist, and the need for scientific standards was often neglected. Some problems arose because forensic DNA fingerprinting in the United States is generally conducted in private, unregulated laboratories. In the absence of rigorous scientific controls, the DNA fingerprint bands of two completely unknown samples cannot be matched precisely, and the results may be unreliable.

Geiger counter

The invention: the first electronic device able to detect and measure radioactivity in atomic particles. The people behind the invention: Hans Geiger (1882-1945), a German physicist Ernest Rutherford (1871-1937), a British physicist Sir John Sealy Edward Townsend (1868-1957), an Irish physicist Sir William Crookes (1832-1919), an English physicist Wilhelm Conrad Röntgen (1845-1923), a German physicist Antoine-Henri Becquerel (1852-1908), a French physicist Discovering Natural Radiation When radioactivity was discovered and first studied, the work was done with rather simple devices. In the 1870’s, Sir William Crookes learned how to create a very good vacuum in a glass tube. He placed electrodes in each end of the tube and studied the passage of electricity through the tube. This simple device became known as the “Crookes tube.” In 1895, Wilhelm Conrad Röntgen was experimenting with a Crookes tube. It was known that when electricity went through a Crookes tube, one end of the glass tube might glow. Certain mineral salts placed near the tube would also glow. In order to observe carefully the glowing salts, Röntgen had darkened the room and covered most of the Crookes tube with dark paper. Suddenly, a flash of light caught his eye. It came from a mineral sample placed some distance from the tube and shielded by the dark paper; yet when the tube was switched off, the mineral sample went dark. Experimenting further, Röntgen became convinced that some ray from the Crookes tube had penetrated the mineral and caused it to glow. Since light rays were blocked by the black paper, he called the mystery ray an “X ray,” with “X” standing for unknown. Antoine-Henri Becquerel heard of the discovery of X rays and, in February, 1886, set out to discover if glowing minerals themselves emitted X rays. Some minerals, called “phosphorescent,” begin to glow when activated by sunlight. Becquerel’s experiment involved wrapping photographic film in black paper and setting various phosphorescent minerals on top and leaving them in the sun. He soon learned that phosphorescent minerals containing uranium would expose the film. Aseries of cloudy days, however, brought a great surprise. Anxious to continue his experiments, Becquerel decided to develop film that had not been exposed to sunlight. He was astonished to discover that the film was deeply exposed. Some emanations must be coming from the uranium, he realized, and they had nothing to do with sunlight. Thus, natural radioactivity was discovered by accident with a simple piece of photographic film. Rutherford and Geiger Ernest Rutherford joined the world of international physics at about the same time that radioactivity was discovered. Studying the “Becquerel rays” emitted by uranium, Rutherford eventually distinguished three different types of radiation, which he named “alpha,” “beta,” and “gamma” after the first three letters of the Greek alphabet. He showed that alpha particles, the least penetrating of the three, are the nuclei of helium atoms (a group of two neutrons and a proton tightly bound together). It was later shown that beta particles are electrons. Gamma rays, which are far more penetrating than either alpha or beta particles, were shown to be similar to X rays, but with higher energies. Rutherford became director of the associated research laboratory at Manchester University in 1907. Hans Geiger became an assistant. At this time, Rutherford was trying to prove that alpha particles carry a double positive charge. The best way to do this was to measure the electric charge that a stream of alpha particles would bring to a target. By dividing that charge by the total number of alpha particles that fell on the target, one could calculate the charge of a single alpha particle. The problem lay in counting the particles and in proving that every particle had been counted. Basing their design upon work done by Sir John Sealy Edward Townsend, a former colleague of Rutherford, Geiger and Rutherford constructed an electronic counter. It consisted of a long brass tube sealed at both ends from which most of the air had been pumped. A thin wire, insulated from the brass, was suspended down the middle of the tube. This wire was connected to batteries producing about thirteen hundred volts and to an electrometer, a device that could measure the voltage of the wire. This voltage could be increased until a spark jumped between the wire and the tube. If the voltage was turned down a little, the tube was ready to operate. An alpha particle entering the tube would ionize (knock some electrons away from) at least a few atoms. These electrons would be accelerated by the high voltage and, in turn, would ionize more atoms, freeing more electrons. This process would continue until an avalanche of electrons struck the central wire and the electrometer registered the voltage change. Since the tube was nearly ready to arc because of the high voltage, every alpha particle, even if it had very little energy, would initiate a discharge. The most complex of the early radiation detection devices—the forerunner of the Geiger counter—had just been developed. The two physicists reported their findings in February, 1908. Impact Their first measurements showed that one gram of radium emitted 34 thousand million alpha particles per second. Soon, the number was refined to 32.8 thousand million per second. Next, Geiger and Rutherford measured the amount of charge emitted by radium each second. Dividing this number by the previous number gave them the charge on a single alpha particle. Just as Rutherford had anticipated, the charge was double that of a hydrogen ion (a proton). This proved to be the most accurate determination of the fundamental charge until the American physicist Robert Andrews Millikan conducted his classic oil-drop experiment in 1911. Another fundamental result came froma careful measurement of the volume of helium emitted by radium each second. Using that value, other properties of gases, and the number of helium nuclei emitted each second, they were able to calculate Avogadro’s number more directly and accurately than had previously been possible. (Avogadro’s number enables one to calculate the number of atoms in a given amount of material.)The true Geiger counter evolved when Geiger replaced the central wire of the tube with a needle whose point lay just inside a thin entrance window. This counter was much more sensitive to alpha and beta particles and also to gamma rays. By 1928, with the assistance of Walther Müller, Geiger made his counter much more efficient, responsive, durable, and portable. There are probably few radiation facilities in the world that do not have at least one Geiger counter or one of its compact modern relatives.

Gas-electric car

The invention: 

A hybrid automobile with both an internal combustion engine and an electric motor.

The people behind the invention: 

Victor Wouk -   an American engineer Tom Elliott, executive vice president of
                           American Honda Motor Company
Hiroyuki Yoshino - president and chief executive officer of Honda Motor Company
Fujio Cho              -  president of Toyota Motor Corporation

Fuel cell

The invention: An electrochemical cell that directly converts energy from reactions between oxidants and fuels, such as liquid hydrogen, into electrical energy. The people behind the invention: Francis Thomas Bacon (1904-1992), an English engineer Sir William Robert Grove (1811-1896), an English inventor Georges Leclanché (1839-1882), a French engineer Alessandro Volta (1745-1827), an Italian physicist The Earth’s Resources Because of the earth’s rapidly increasing population and the dwindling of fossil fuels (natural gas, coal, and petroleum), there is a need to design and develop new ways to obtain energy and to encourage its intelligent use. The burning of fossil fuels to create energy causes a slow buildup of carbon dioxide in the atmosphere, creating pollution that poses many problems for all forms of life on this planet. Chemical and electrical studies can be combined to create electrochemical processes that yield clean energy. Because of their very high rate of efficiency and their nonpolluting nature, fuel cells may provide the solution to the problem of finding sufficient energy sources for humans. The simple reaction of hydrogen and oxygen to form water in such a cell can provide an enormous amount of clean (nonpolluting) energy. Moreover, hydrogen and oxygen are readily available. Studies by Alessandro Volta, Georges Leclanché, and William Grove preceded the work of Bacon in the development of the fuel cell. Bacon became interested in the idea of a hydrogen-oxygen fuel cell in about 1932. His original intent was to develop a fuel cell that could be used in commercial applications. The Fuel Cell Emerges In 1800, the Italian physicist Alessandro Volta experimented with solutions of chemicals and metals that were able to conduct electricity. He found that two pieces of metal and such a solution could be arranged in such a way as to produce an electric current. His creation was the first electrochemical battery, a device that produced energy from a chemical reaction. Studies in this area were continued by various people, and in the late nineteenth century, Georges Leclanché invented the dry cell battery, which is now commonly used. The work of William Grove followed that of Leclanché. His first significant contribution was the Grove cell, an improved form of the cells described above, which became very popular. Grove experimented with various forms of batteries and eventually invented the “gas battery,” which was actually the earliest fuel cell. It is worth noting that his design incorporated separate test tubes of hydrogen and oxygen, which he placed over strips of platinum. After studying the design of Grove’s fuel cell, Bacon decided that, for practical purposes, the use of platinum and other precious metals should be avoided. By 1939, he had constructed a cell in which nickel replaced the platinum used. The theory behind the fuel cell can be described in the following way. If a mixture of hydrogen and oxygen is ignited, energy is released in the form of a violent explosion. In a fuel cell, however, the reaction takes place in a controlled manner. Electrons lost by the hydrogen gas flow out of the fuel cell and return to be taken up by the oxygen in the cell. The electron flow provides electricity to any device that is connected to the fuel cell, and the water that the fuel cell produces can be purified and used for drinking. Bacon’s studies were interrupted byWorldWar II. After the war was over, however, Bacon continued his work. Sir Eric Keightley Rideal of Cambridge University in England supported Bacon’s studies; later, others followed suit. In January, 1954, Bacon wrote an article entitled “Research into the Properties of the Hydrogen/ Oxygen Fuel Cell” for a British journal. He was surprised at the speed with which news of the article spread throughout the scientific world, particularly in the United States. After a series of setbacks, Bacon demonstrated a forty-cell unit that had increased power. This advance showed that the fuel cell was not merely an interesting toy; it had the capacity to do useful work. At this point, the General Electric Company (GE), an American corporation, sent a representative to England to offer employment in the United States to senior members of Bacon’s staff. Three scientists accepted the offer. A high point in Bacon’s career was the announcement that the American Pratt and Whitney Aircraft company had obtained an order to build fuel cells for the Apollo project, which ultimately put two men on the Moon in 1969. Toward the end of his career in 1978, Bacon hoped that commercial applications for his fuel cells would be found.Impact Because they are lighter and more efficient than batteries, fuel cells have proved to be useful in the space program. Beginning with the Gemini 5 spacecraft, alkaline fuel cells (in which a water solution of potassium hydroxide, a basic, or alkaline, chemical, is placed) have been used for more than ten thousand hours in space. The fuel cells used aboard the space shuttle deliver the same amount of power as batteries weighing ten times as much. On a typical seven-day mission, the shuttle’s fuel cells consume 680 kilograms (1,500 pounds) of hydrogen and generate 719 liters (190 gallons) of water that can be used for drinking. Major technical and economic problems must be overcome in order to design fuel cells for practical applications, but some important advancements have been made.Afew test vehicles that use fuel cells as a source of power have been constructed. Fuel cells using hydrogen as a fuel and oxygen to burn the fuel have been used in a van built by General Motors Corporation. Thirty-two fuel cells are installed below the floorboards, and tanks of liquid oxygen are carried in the back of the van. A power plant built in New York City contains stacks of hydrogen-oxygen fuel cells, which can be put on line quickly in response to power needs. The Sanyo Electric Company has developed an electric car that is partially powered by a fuel cell. These tremendous technical advances are the result of the singleminded dedication of Francis Thomas Bacon, who struggled all of his life with an experiment he was convinced would be successful.

Freeze-drying

The invention: 

Method for preserving foods and other organic matter by freezing them and using a vacuum to remove their water content without damaging their solid matter.

The people behind the invention:

Earl W. Flosdorf (1904- ), an American physician
Ronald I. N. Greaves (1908- ), an English pathologist
Jacques Arsène d’Arsonval (1851-1940), a French physicist

FORTRAN programming language

The invention: The first major computer programming language, FORTRAN supported programming in a mathematical language that was natural to scientists and engineers and achieved unsurpassed success in scientific computation. The people behind the invention: John Backus (1924- ), an American software engineer and manager John W. Mauchly (1907-1980), an American physicist and engineer Herman Heine Goldstine (1913- ), a mathematician and computer scientist John von Neumann (1903-1957), a Hungarian American mathematician and physicist Talking to Machines Formula Translation, or FORTRAN—the first widely accepted high-level computer language—was completed by John Backus and his coworkers at the International Business Machines (IBM) Corporation in April, 1957. Designed to support programming in a mathematical language that was natural to scientists and engineers, FORTRAN achieved unsurpassed success in scientific computation. Computer languages are means of specifying the instructions that a computer should execute and the order of those instructions. Computer languages can be divided into categories of progressively higher degrees of abstraction. At the lowest level is binary code, or machine code: Binary digits, or “bits,” specify in complete detail every instruction that the machine will execute. This was the only language available in the early days of computers, when such machines as the ENIAC (Electronic Numerical Integrator and Calculator) required hand-operated switches and plugboard connections. All higher levels of language are implemented by having a program translate instructions written in the higher language into binary machine language (also called “object code”). High-level languages (also called “programming languages”) are largely or entirely independent of the underlying machine structure. FORTRAN was the first language of this type to win widespread acceptance. The emergence of machine-independent programming languages was a gradual process that spanned the first decade of electronic computation. One of the earliest developments was the invention of “flowcharts,” or “flow diagrams,” by Herman Heine Goldstine and John von Neumann in 1947. Flowcharting became the most influential software methodology during the first twenty years of computing. Short Code was the first language to be implemented that contained some high-level features, such as the ability to use mathematical equations. The idea came from JohnW. Mauchly, and it was implemented on the BINAC (Binary Automatic Computer) in 1949 with an “interpreter”; later, it was carried over to the UNIVAC (Universal Automatic Computer) I. Interpreters are programs that do not translate commands into a series of object-code instructions; instead, they directly execute (interpret) those commands. Every time the interpreter encounters a command, that command must be interpreted again. “Compilers,” however, convert the entire command into object code before it is executed. Much early effort went into creating ways to handle commonly encountered problems—particularly scientific mathematical calculations. A number of interpretive languages arose to support these features. As long as such complex operations had to be performed by software (computer programs), however, scientific computation would be relatively slow. Therefore, Backus lobbied successfully for a direct hardware implementation of these operations on IBM’s new scientific computer, the 704. Backus then started the Programming Research Group at IBM in order to develop a compiler that would allow programs to be written in a mathematically oriented language rather than a machine-oriented language. In November of 1954, the group defined an initial version of FORTRAN.A More Accessible Language Before FORTRAN was developed, a computer had to perform a whole series of tasks to make certain types of mathematical calculations. FORTRAN made it possible for the same calculations to be performed much more easily. In general, FORTRAN supported constructs with which scientists were already acquainted, such as functions and multidimensional arrays. In defining a powerful notation that was accessible to scientists and engineers, FORTRAN opened up programming to a much wider community. Backus’s success in getting the IBM 704’s hardware to support scientific computation directly, however, posed a major challenge: Because such computation would be much faster, the object code produced by FORTRAN would also have to be much faster. The lower-level compilers preceding FORTRAN produced programs that were usually five to ten times slower than their hand-coded counterparts; therefore, efficiency became the primary design objective for Backus. The highly publicized claims for FORTRAN met with widespread skepticism among programmers. Much of the team’s efforts, therefore, went into discovering ways to produce the most efficient object code. The efficiency of the compiler produced by Backus, combined with its clarity and ease of use, guaranteed the system’s success. By 1959, many IBM 704 users programmed exclusively in FORTRAN. By 1963, virtually every computer manufacturer either had delivered or had promised a version of FORTRAN. Incompatibilities among manufacturers were minimized by the popularity of IBM’s version of FORTRAN; every company wanted to be able to support IBM programs on its own equipment. Nevertheless, there was sufficient interest in obtaining a standard for FORTRAN that the American National Standards Institute adopted a formal standard for it in 1966. Arevised standard was adopted in 1978, yielding FORTRAN 77. Consequences In demonstrating the feasibility of efficient high-level languages, FORTRAN inaugurated a period of great proliferation of programming languages. Most of these languages attempted to provide similar or better high-level programming constructs oriented toward a different, nonscientific programming environment. COBOL, for example, stands for “Common Business Oriented Language.” FORTRAN, while remaining the dominant language for scientific programming, has not found general acceptance among nonscientists. An IBM project established in 1963 to extend FORTRAN found the task too unwieldy and instead ended up producing an entirely different language, PL/I, which was delivered in 1966. In the beginning, Backus and his coworkers believed that their revolutionary language would virtually eliminate the burdens of coding and debugging. Instead, FORTRAN launched software as a field of study and an industry in its own right. In addition to stimulating the introduction of new languages, FORTRAN encouraged the development of operating systems. Programming languages had already grown into simple operating systems called “monitors.” Operating systems since then have been greatly improved so that they support, for example, simultaneously active programs (multiprogramming) and the networking (combining) of multiple computers.

Food freezing

The invention: It was long known that low temperatures helped to protect food against spoiling; the invention that made frozen food practical was a method of freezing items quickly. Clarence Birdseye’s quick-freezing technique made possible a revolution in food preparation, storage, and distribution. The people behind the invention: Clarence Birdseye (1886-1956), a scientist and inventor Donald K. Tressler (1894-1981), a researcher at Cornell University Amanda Theodosia Jones (1835-1914), a food-preservation pioneer Feeding the Family In 1917, Clarence Birdseye developed a means of quick-freezing meat, fish, vegetables, and fruit without substantially changing their original taste. His system of freezing was called by Fortune magazine “one of the most exciting and revolutionary ideas in the history of food.” Birdseye went on to refine and perfect his method and to promote the frozen foods industry until it became a commercial success nationwide. It was during a trip to Labrador, where he worked as a fur trader, that Birdseye was inspired by this idea. Birdseye’s new wife and five-week-old baby had accompanied him there. In order to keep his family well fed, he placed barrels of fresh cabbages in salt water and then exposed the vegetables to freezing winds. Successful at preserving vegetables, he went on to freeze a winter’s supply of ducks, caribou, and rabbit meat. In the following years, Birdseye experimented with many freezing techniques. His equipment was crude: an electric fan, ice, and salt water. His earliest experiments were on fish and rabbits, which he froze and packed in old candy boxes. By 1924, he had borrowed money against his life insurance and was lucky enough to find three partners willing to invest in his new General Seafoods Company (later renamed General Foods), located in Gloucester, Massachusetts. Although it was Birdseye’s genius that put the principles of quick-freezing to work, he did not actually invent quick-freezing. The scientific principles involved had been known for some time. As early as 1842, a patent for freezing fish had been issued in England. Nevertheless, the commercial exploitation of the freezing process could not have happened until the end of the 1800’s, when mechanical refrigeration was invented. Even then, Birdseye had to overcome major obstacles. Finding a Niche By the 1920’s, there still were few mechanical refrigerators in American homes. It would take years before adequate facilities for food freezing and retail distribution would be established across the United States. By the late 1930’s, frozen foods had, indeed, found its role in commerce but still could not compete with canned or fresh foods. Birdseye had to work tirelessly to promote the industry, writing and delivering numerous lectures and articles to advance its popularity. His efforts were helped by scientific research conducted at Cornell University by Donald K. Tressler and by C. R. Fellers of what was then Massachusetts State College. Also, during World War II (1939-1945), more Americans began to accept the idea: Rationing, combined with a shortage of canned foods, contributed to the demand for frozen foods. The armed forces made large purchases of these items as well. General Foods was the first to use a system of extremely rapid freezing of perishable foods in packages. Under the Birdseye system, fresh foods, such as berries or lobster, were packaged snugly in convenient square containers. Then, the packages were pressed between refrigerated metal plates under pressure at 50 degrees below zero. Two types of freezing machines were used. The “double belt” freezer consisted of two metal belts that moved through a 15-meter freezing tunnel, while a special salt solution was sprayed on the surfaces of the belts. This double-belt freezer was used only in permanent installations and was soon replaced by the “multiplate” freezer, which was portable and required only 11.5 square meters of floor space compared to the double belt’s 152 square meters.The multiplate freezer also made it possible to apply the technique of quick-freezing to seasonal crops. People were able to transport these freezers easily from one harvesting field to another, where they were used to freeze crops such as peas fresh off the vine. The handy multiplate freezer consisted of an insulated cabinet equipped with refrigerated metal plates. Stacked one above the other, these plates were capable of being opened and closed to receive food products and to compress them with evenly distributed pressure. Each aluminum plate had internal passages through which ammonia flowed and expanded at a temperature of -3.8 degrees Celsius, thus causing the foods to freeze. A major benefit of the new frozen foods was that their taste and vitamin content were not lost. Ordinarily, when food is frozen slowly, ice crystals form, which slowly rupture food cells, thus altering the taste of the food. With quick-freezing, however, the food looks, tastes, and smells like fresh food. Quick-freezing also cuts down on bacteria. Impact During the months between one food harvest and the next, humankind requires trillions of pounds of food to survive. In many parts of the world, an adequate supply of food is available; elsewhere, much food goes to waste and many go hungry. Methods of food preservation such as those developed by Birdseye have done much to help those who cannot obtain proper fresh foods. Preserving perishable foods also means that they will be available in greater quantity and variety all year-round. In all parts of the world, both tropical and arctic delicacies can be eaten in any season of the year. With the rise in popularity of frozen “fast” foods, nutritionists began to study their effect on the human body. Research has shown that fresh is the most beneficial. In an industrial nation with many people, the distribution of fresh commodities is, however, difficult. It may be many decades before scientists know the long-term effects on generations raised primarily on frozen foods.

FM radio

The invention: A method of broadcasting radio signals by modulating the frequency, rather than the amplitude, of radio waves, FM radio greatly improved the quality of sound transmission. The people behind the invention: Edwin H. Armstrong (1890-1954), the inventor of FM radio broadcasting David Sarnoff (1891-1971), the founder of RCA An Entirely New System Because early radio broadcasts used amplitude modulation (AM) to transmit their sounds, they were subject to a sizable amount of interference and static. Since goodAMreception relies on the amount of energy transmitted, energy sources in the atmosphere between the station and the receiver can distort or weaken the original signal. This is particularly irritating for the transmission of music. Edwin H. Armstrong provided a solution to this technological constraint. A graduate of Columbia University, Armstrong made a significant contribution to the development of radio with his basic inventions for circuits for AM receivers. (Indeed, the monies Armstrong received from his earlier inventions financed the development of the frequency modulation, or FM, system.) Armstrong was one among many contributors to AM radio. For FM broadcasting, however, Armstrong must be ranked as the most important inventor. During the 1920’s, Armstrong established his own research laboratory in Alpine, New Jersey, across the Hudson River from New York City. With a small staff of dedicated assistants, he carried out research on radio circuitry and systems for nearly three decades. At that time, Armstrong also began to teach electrical engineering at Columbia University. From 1928 to 1933, Armstrong worked diligently at his private laboratory at Columbia University to construct a working model of an FM radio broadcasting system. With the primitive limitations then imposed on the state of vacuum tube technology, a number of Armstrong’s experimental circuits required as many as one hundred tubes. Between July, 1930, and January, 1933, Armstrong filed four basic FM patent applications. All were granted simultaneously on December 26, 1933. Armstrong sought to perfectFMradio broadcasting, not to offer radio listeners better musical reception but to create an entirely new radio broadcasting system. On November 5, 1935, Armstrong made his first public demonstration of FM broadcasting in New York City to an audience of radio engineers. An amateur station based in suburban Yonkers, New York, transmitted these first signals. The scientific world began to consider the advantages and disadvantages of Armstrong’s system; other laboratories began to craft their own FM systems. Corporate Conniving Because Armstrong had no desire to become a manufacturer or broadcaster, he approached David Sarnoff, head of the Radio Corporation of America (RCA). As the owner of the top manufacturer of radio sets and the top radio broadcasting network, Sarnoff was interested in all advances of radio technology. Armstrong first demonstrated FM radio broadcasting for Sarnoff in December, 1933. This was followed by visits from RCA engineers, who were sufficiently impressed to recommend to Sarnoff that the company conduct field tests of the Armstrong system. In 1934, Armstrong, with the cooperation of RCA, set up a test transmitter at the top of the Empire State Building, sharing facilities with the experimental RCAtelevision transmitter. From 1934 through 1935, tests were conducted using the Empire State facility, to mixed reactions of RCA’s best engineers. AM radio broadcasting already had a performance record of nearly two decades. The engineers wondered if this new technology could replace something that had worked so well. This less-than-enthusiastic evaluation fueled the skepticism of RCA lawyers and salespeople. RCA had too much invested in the AM system, both as a leading manufacturer and as the dominant owner of the major radio network of the time, the National Broadcasting Company (NBC). Sarnoff was in no rush to adopt FM. To change systems would risk the millions of dollars RCAwas making as America emerged from the Great Depression. In 1935, Sarnoff advised Armstrong that RCA would cease any further research and development activity in FM radio broadcasting. (Still, engineers at RCA laboratories continued to work on FM to protect the corporate patent position.) Sarnoff declared to the press that his company would push the frontiers of broadcasting by concentrating on research and development of radio with pictures, that is, television. As a tangible sign, Sarnoff ordered that Armstrong’s FM radio broadcasting tower be removed from the top of the Empire State Building. Armstrong was outraged. By the mid-1930’s, the development of FM radio broadcasting had become a mission for Armstrong. For the remainder of his life, Armstrong devoted his considerable talents to the promotion of FM radio broadcasting. Impact After the break with Sarnoff, Armstrong proceeded with plans to develop his own FM operation. Allied with two of RCA’s biggest manufacturing competitors, Zenith and General Electric, Armstrong pressed ahead. In June of 1936, at a Federal Communications Commission (FCC) hearing, Armstrong proclaimed that FM broadcasting was the only static-free, noise-free, and uniform system—both day and night—available. He argued, correctly, thatAMradio broadcasting had none of these qualities. During World War II (1939-1945), Armstrong gave the military permission to use FM with no compensation. That patriotic gesture cost Armstrong millions of dollars when the military soon became all FM. It did, however, expand interest in FM radio broadcasting. World War II had provided a field test of equipment and use. By the 1970’s, FM radio broadcasting had grown tremendously. By 1972, one in three radio listeners tuned into an FM station some time during the day. Advertisers began to use FM radio stations to reach the young and affluent audiences that were turning to FM stations in greater numbers. By the late 1970’s, FM radio stations were outnumberingAMstations. By 1980, nearly half of radio listeners tuned into FM stations on a regular basis. Adecade later, FM radio listening accounted for more than two-thirds of audience time. Armstrong’s predictions that listeners would prefer the clear, static-free sounds offered by FM radio broadcasting had come to pass by the mid-1980’s, nearly fifty years after Armstrong had commenced his struggle to make FM radio broadcasting a part of commercial radio.

Fluorescent lighting

lighting The invention: A form of electrical lighting that uses a glass tube coated with phosphor that gives off a cool bluish light and emits ultraviolet radiation. The people behind the invention: Vincenzo Cascariolo (1571-1624), an Italian alchemist and shoemaker Heinrich Geissler (1814-1879), a German glassblower Peter Cooper Hewitt (1861-1921), an American electrical engineer Celebrating the “Twelve Greatest Inventors” On the night of November 23, 1936, more than one thousand industrialists, patent attorneys, and scientists assembled in the main ballroom of the Mayflower Hotel in Washington, D.C., to celebrate the one hundredth anniversary of the U.S. Patent Office.Atransport liner over the city radioed the names chosen by the Patent Office as America’s “Twelve Greatest Inventors,” and, as the distinguished group strained to hear those names, “the room was flooded for a moment by the most brilliant light yet used to illuminate a space that size.” Thus did The New York Times summarize the commercial introduction of the fluorescent lamp. The twelve inventors present were Thomas Alva Edison, Robert Fulton, Charles Goodyear, Charles Hall, Elias Howe, Cyrus Hall McCormick, Ottmar Mergenthaler, Samuel F. B. Morse, George Westinghouse, Wilbur Wright, and Eli Whitney. There was, however, no name to bear the honor for inventing fluorescent lighting. That honor is shared by many who participated in a very long series of discoveries. The fluorescent lamp operates as a low-pressure, electric discharge inside a glass tube that contains a droplet of mercury and a gas, commonly argon. The inside of the glass tube is coated with fine particles of phosphor. When electricity is applied to the gas, the mercury gives off a bluish light and emits ultraviolet radiation.When bathed in the strong ultraviolet radiation emitted by the mercury, the phosphor fluoresces (emits light). The setting for the introduction of the fluorescent lamp began at the beginning of the 1600’s, when Vincenzo Cascariolo, an Italian shoemaker and alchemist, discovered a substance that gave off a bluish glow in the dark after exposure to strong sunlight. The fluorescent substance was apparently barium sulfide and was so unusual for that time and so valuable that its formulation was kept secret for a long time. Gradually, however, scholars became aware of the preparation secrets of the substance and studied it and other luminescent materials. Further studies in fluorescent lighting were made by the German physicist Johann Wilhelm Ritter. He observed the luminescence of phosphors that were exposed to various “exciting” lights. In 1801, he noted that some phosphors shone brightly when illuminated by light that the eye could not see (ultraviolet light). Ritter thus discovered the ultraviolet region of the light spectrum. The use of phosphors to transform ultraviolet light into visible light was an important step in the continuing development of the fluorescent lamp. Further studies in fluorescent lighting were made by the German physicist Johann Wilhelm Ritter. He observed the luminescence of phosphors that were exposed to various “exciting” lights. In 1801, he noted that some phosphors shone brightly when illuminated by light that the eye could not see (ultraviolet light). Ritter thus discovered the ultraviolet region of the light spectrum. The use of phosphors to transform ultraviolet light into visible light was an important step in the continuing development of the fluorescent lamp. The British mathematician and physicist Sir George Gabriel Stokes studied the phenomenon as well. It was he who, in 1852, termed the afterglow “fluorescence.” Geissler Tubes While these advances were being made, other workers were trying to produce a practical form of electric light. In 1706, the English physicist Francis Hauksbee devised an electrostatic generator, which is used to accelerate charged particles to very high levels of electrical energy. He then connected the device to a glass “jar,” used a vacuum pump to evacuate the jar to a low pressure, and tested his generator. In so doing, Hauksbee obtained the first human-made electrical glow discharge by “capturing lightning” in a jar. In 1854, Heinrich Geissler, a glassblower and apparatus maker, opened his shop in Bonn, Germany, to make scientific instruments; in 1855, he produced a vacuum pump that used liquid mercury as an evacuation fluid. That same year, Geissler made the first gaseous conduction lamps while working in collaboration with the German scientist Julius Plücker. Plücker referred to these lamps as “Geissler tubes.” Geissler was able to create red light with neon gas filling a lamp and light of nearly all colors by using certain types of gas within each of the lamps. Thus, both the neon sign business and the science of spectroscopy were born. Geissler tubes were studied extensively by a variety of workers. At the beginning of the twentieth century, the practical American engineer Peter Cooper Hewitt put these studies to use by marketing the first low-pressure mercury vapor lamps. The lamps were quite successful, although they required high voltage for operation, emitted an eerie blue-green, and shone dimly by comparison with their eventual successor, the fluorescent lamp. At about the same time, systematic studies of phosphors had finally begun. By the 1920’s, a number of investigators had discovered that the low-pressure mercury vapor discharge marketed by Hewitt was an extremely efficient method for producing ultraviolet light, if the mercury and rare gas pressures were properly adjusted. With a phosphor to convert the ultraviolet light back to visible light, the Hewitt lamp made an excellent light source. Impact The introduction of fluorescent lighting in 1936 presented the public with a completely new form of lighting that had enormous advantages of high efficiency, long life, and relatively low cost. By 1938, production of fluorescent lamps was well under way. By April, 1938, four sizes of fluorescent lamps in various colors had been offered to the public and more than two hundred thousand lamps had been sold. During 1939 and 1940, two great expositions—the New York World’s Fair and the San Francisco International Exposition— helped popularize fluorescent lighting. Thousands of tubular fluorescent lamps formed a great spiral in the “motor display salon,” the car showroom of the General Motors exhibit at the New York World’s Fair. Fluorescent lamps lit the Polish Restaurant and hung in vertical clusters on the flagpoles along theAvenue of the Flags at the fair, while two-meter-long, upright fluorescent tubes illuminated buildings at the San Francisco International Exposition. When the United States entered World War II (1939-1945), the demand for efficient factory lighting soared. In 1941, more than twenty-one million fluorescent lamps were sold. Technical advances continued to improve the fluorescent lamp. By the 1990’s, this type of lamp supplied most of the world’s artificial lighting.

Floppy disk

The invention: Inexpensive magnetic medium for storing and moving computer data. The people behind the invention: Andrew D. Booth (1918- ), an English inventor who developed paper disks as a storage medium Reynold B. Johnson (1906-1998), a design engineer at IBM’s research facility who oversaw development of magnetic disk storage devices Alan Shugart (1930- ), an engineer at IBM’s research laboratory who first developed the floppy disk as a means of mass storage for mainframe computers First Tries When the International Business Machines (IBM) Corporation decided to concentrate on the development of computers for business use in the 1950’s, it faced a problem that had troubled the earliest computer designers: how to store data reliably and inexpensively. In the early days of computers (the early 1940’s), a number of ideas were tried. The English inventor Andrew D. Booth produced spinning paper disks on which he stored data by means of punched holes, only to abandon the idea because of the insurmountable engineering problems he foresaw. The next step was “punched” cards, an idea first used when the French inventor Joseph-Marie Jacquard invented an automatic weaving loom for which patterns were stored in pasteboard cards. The idea was refined by the English mathematician and inventor Charles Babbage for use in his “analytical engine,” an attempt to build a kind of computing machine. Although it was simple and reliable, it was not fast enough, nor did it store enough data, to be truly practical. The Ampex Corporation demonstrated its first magnetic audiotape recorder after World War II (1939-1945). Shortly after that, the Binary Automatic Computer (BINAC) was introduced with a storage device that appeared to be a large tape recorder. A more advanced machine, the Universal Automatic Computer (UNIVAC), used metal tape instead of plastic (plastic was easily stretched or even broken). Unfortunately, metal tape was considerably heavier, and its edges were razor-sharp and thus dangerous. Improvements in plastic tape eventually produced sturdy media, and magnetic tape became (and remains) a practical medium for storage of computer data. Still later designs combined Booth’s spinning paper disks with magnetic technology to produce rapidly rotating “drums.” Whereas a tape might have to be fast-forwarded nearly to its end to locate a specific piece of data, a drum rotating at speeds up to 12,500 revolutions per minute (rpm) could retrieve data very quickly and could store more than 1 million bits (or approximately 125 kilobytes) of data. In May, 1955, these drums evolved, under the direction of Reynold B. Johnson, into IBM’s hard disk unit. The hard disk unit consisted of fifty platters, each 2 feet in diameter, rotating at 1,200 rpm. Both sides of the disk could be used to store information. When the operator wished to access the disk, at his or her command a read/write head was moved to the right disk and to the side of the disk that held the desired data. The operator could then read data from or record data onto the disk. To speed things even more, the next version of the device, similar in design, employed one hundred read/write heads—one for each of its fifty double-sided disks. The only remaining disadvantage was its size, which earned IBM’s first commercial unit the nickname “jukebox.” The First Floppy The floppy disk drive developed directly from hard disk technology. It did not take shape until the late 1960’s under the direction of Alan Shugart (it was announced by IBM as a ready product in 1970). First created to help restart the operating systems of mainframe computers that had gone dead, the floppy seemed in some ways to be a step back, for it operated more slowly than a hard disk drive and did not store as much data. Initially, it consisted of a single thin plastic disk eight inches in diameter and was developed without the protective envelope in which it is now universally encased. The addition of that jacket gave the floppy its single greatest advantage over the hard disk: portability with reliability. Another advantage soon became apparent: The floppy is resilient to damage. In a hard disk drive, the read/write heads must hover thousandths of a centimeter over the disk surface in order to attain maximum performance. Should even a small particle of dust get in the way, or should the drive unit be bumped too hard, the head may “crash” into the surface of the disk and ruin its magnetic coating; the result is a permanent loss of data. Because the floppy operates with the read-write head in contact with the flexible plastic disk surface, individual particles of dust or other contaminants are not nearly as likely to cause disaster. As a result of its advantages, the floppy disk was the logical choice for mass storage in personal computers (PCs), which were developed a few years after the floppy disk’s introduction. The floppy is still an important storage device even though hard disk drives for PCs have become less expensive. Moreover, manufacturers continually are developing new floppy formats and new floppy disks that can hold more data.Consequences Personal computing would have developed very differently were it not for the availability of inexpensive floppy disk drives. When IBM introduced its PC in 1981, the machine provided as standard equipment a connection for a cassette tape recorder as a storage device; a floppy disk was only an option (though an option few did not take). The awkwardness of tape drives—their slow speed and sequential nature of storing data—presented clear obstacles to the acceptance of the personal computer as a basic information tool. By contrast, the floppy drive gives computer users relatively fast storage at low cost. Floppy disks provided more than merely economical data storage. Since they are built to be removable (unlike hard drives), they represented a basic means of transferring data between machines. Indeed, prior to the popularization of local area networks (LANs), the floppy was known as a “sneaker” network: One merely carried the disk by foot to another computer. Floppy disks were long the primary means of distributing new software to users. Even the very flexible floppy showed itself to be quite resilient to the wear and tear of postal delivery. Later, the 3.5- inch disk improved upon the design of the original 8-inch and 5.25- inch floppies by protecting the disk medium within a hard plastic shell and by using a sliding metal door to protect the area where the read/write heads contact the disk. By the late 1990’s, floppy disks were giving way to new datastorage media, particularly CD-ROMs—durable laser-encoded disks that hold more than 700 megabytes of data. As the price of blank CDs dropped dramatically, floppy disks tended to be used mainly for short-term storage of small amounts of data. Floppy disks were also being used less and less for data distribution and transfer, as computer users turned increasingly to sending files via e-mail on the Internet, and software providers made their products available for downloading on Web sites.

Field ion microscope

The invention:Amicroscope that uses ions formed in high-voltage electric fields to view atoms on metal surfaces. The people behind the invention: Erwin Wilhelm Müller (1911-1977), a physicist, engineer, and research professor J. Robert Oppenheimer (1904-1967), an American physicist To See Beneath the Surface In the early twentieth century, developments in physics, especially quantum mechanics, paved the way for the application of new theoretical and experimental knowledge to the problem of viewing the atomic structure of metal surfaces. Of primary importance were American physicist George Gamow’s 1928 theoretical explanation of the field emission of electrons by quantum mechanical means and J. Robert Oppenheimer’s 1928 prediction of the quantum mechanical ionization of hydrogen in a strong electric field. In 1936, ErwinWilhelm Müller developed his field emission microscope, the first in a series of instruments that would exploit these developments. It was to be the first instrument to view atomic structures—although not the individual atoms themselves— directly. Müller’s subsequent field ion microscope utilized the same basic concepts used in the field emission microscope yet proved to be a much more powerful and versatile instrument. By 1956, Müller’s invention allowed him to view the crystal lattice structure of metals in atomic detail; it actually showed the constituent atoms. The field emission and field ion microscopes make it possible to view the atomic surface structures of metals on fluorescent screens. The field ion microscope is the direct descendant of the field emission microscope. In the case of the field emission microscope, the images are projected by electrons emitted directly from the tip of a metal needle, which constitutes the specimen under investigation.These electrons produce an image of the atomic lattice structure of the needle’s surface. The needle serves as the electron-donating electrode in a vacuum tube, also known as the “cathode.” Afluorescent screen that serves as the electron-receiving electrode, or “anode,” is placed opposite the needle. When sufficient electrical voltage is applied across the cathode and anode, the needle tip emits electrons, which strike the screen. The image produced on the screen is a projection of the electron source—the needle surface’s atomic lattice structure. Müller studied the effect of needle shape on the performance of the microscope throughout much of 1937. When the needles had been properly shaped, Müller was able to realize magnifications of up to 1 million times. This magnification allowed Müller to view what he called “maps” of the atomic crystal structure of metals, since the needles were so small that they were often composed of only one simple crystal of the material. While the magnification may have been great, however, the resolution of the instrument was severely limited by the physics of emitted electrons, which caused the images Müller obtained to be blurred. Improving the View In 1943, while working in Berlin, Müller realized that the resolution of the field emission microscope was limited by two factors. The electron velocity, a particle property, was extremely high and uncontrollably random, causing the micrographic images to be blurred. In addition, the electrons had an unsatisfactorily high wavelength. When Müller combined these two factors, he was able to determine that the field emission microscope could never depict single atoms; it was a physical impossibility for it to distinguish one atom from another. By 1951, this limitation led him to develop the technology behind the field ion microscope. In 1952, Müller moved to the United States and founded the Pennsylvania State University Field Emission Laboratory. He perfected the field ion microscope between 1952 and 1956. The field ion microscope utilized positive ions instead of electrons to create the atomic surface images on the fluorescent screen.When an easily ionized gas—at first hydrogen, but usually helium, neon, or argon—was introduced into the evacuated tube, the emitted electrons ionized the gas atoms, creating a stream of positively charged particles, much as Oppenheimer had predicted in 1928. Müller’s use of positive ions circumvented one of the resolution problems inherent in the use of imaging electrons. Like the electrons, however, the positive ions traversed the tube with unpredictably random velocities. Müller eliminated this problem by cryogenically cooling the needle tip with a supercooled liquefied gas such as nitrogen or hydrogen. By 1956, Müller had perfected the means of supplying imaging positive ions by filling the vacuum tube with an extremely small quantity of an inert gas such as helium, neon, or argon. By using such a gas, Müller was assured that no chemical reaction would occur between the needle tip and the gas; any such reaction would alter the surface atomic structure of the needle and thus alter the resulting microscopic image. The imaging ions allowed the field ion microscope to image the emitter surface to a resolution of between two and three angstroms, making it ten times more accurate than its close relative, the field emission microscope. Consequences The immediate impact of the field ion microscope was its influence on the study of metallic surfaces. It is a well-known fact of materials science that the physical properties of metals are influenced by the imperfections in their constituent lattice structures. It was not possible to view the atomic structure of the lattice, and thus the finest detail of any imperfection, until the field ion microscope was developed. The field ion microscope is the only instrument powerful enough to view the structural flaws of metal specimens in atomic detail. Although the instrument may be extremely powerful, the extremely large electrical fields required in the imaging process preclude the instrument’s application to all but the heartiest of metallic specimens. The field strength of 500 million volts per centimeter exerts an average stress on metal specimens in the range of almost 1 ton per square millimeter. Metals such as iron and platinum can withstand this strain because of the shape of the needles into which they are formed. Yet this limitation of the instrument makes it extremely difficult to examine biological materials, which cannot withstand the amount of stress that metals can. Apractical by-product in the study of field ionization—field evaporation—eventually permitted scientists to view large biological molecules. Field evaporation also allowed surface scientists to view the atomic structures of biological molecules. By embedding molecules such as phthalocyanine within the metal needle, scientists have been able to view the atomic structures of large biological molecules by field evaporating much of the surrounding metal until the biological material remains at the needle’s surface.