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Y
- Henry Petroski, Duke University, North Carolina
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Year of Engineering Success (YES). The calendar year 1997 was designated the YES by its British organizers. It was to be a twelve-month celebration of engineering achievement designed to bring public recognition to the profession. Even British engineers, when asked years later if they knew what the acronym stood for, were likely to answer, “NO.”
Bringing public attention to the profession seems to be a constant goal of engineering champions and their organizations, and the syndrome is no less common in America than it is in Britain. There is the oft-stated perception, especially among engineering society leaders and those who aspire to those positions, that their profession does not get proper public credit for its work. In fact, it is often the organization itself that is unrecognized. Unlike the medical and legal professions, which have their very visible and politically savvy umbrella groups of the American Medical Association and the American Bar Association, there is no single group that effectively represents engineers.
Many a layperson is, however, quite aware of engineering and the benefits it brings to daily life. Roads, bridges, buildings, automobiles, airplanes, clean water, electric power, appliances, computers, cell phones, and a virtually endless list of modern conveniences are known to be the works of engineers. That those engineers distinguish themselves as civil, mechanical, aeronautical, environmental, electrical, computer, or more esoteric types is of little significance or consequence in the larger scheme of things.
S
- Henry Petroski, Duke University, North Carolina
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- An Engineer's Alphabet
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- 10 October 2011, pp 270-305
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St. Patrick. Among the tongue-in-cheek stories that have developed to explain why St. Patrick is considered the patron saint of engineers is one that claims that Irish records had long been misinterpreted. According to this theory, St. Patrick did not drive snakes out of Ireland but rather “drove stakes into Ireland” and therefore must have been a surveyor or engineer. According to another story, he had the “honor of being the first engineer, either because of his discovery of the ‘blarney’ stone or because of his reputed development of the first ‘worm drive’.” Some engineers have even claimed that the four-leaf clover design of the emblem of the American Society of Mechanical Engineers was in fact chosen because it resembled a shamrock, which is, of course, the symbol of Ireland.
The connection of St. Patrick to engineering celebrations is believed to have originated at the University of Missouri, in Columbia. According to a brochure that I picked up during a visit to that campus in 2003, it was a hundred years earlier, during the excavation for an engineering annex building, that a stone inscribed in an ancient language was unearthed. Other sources relate that the stone rolled into a crowd of engineering students. None of them could decipher the Gaelic inscription on the stone, until some unknown engineer came forth, announced that the inscription said “St. Patrick was an engineer,” and then faded back into the crowd. The stone came to be enshrined on campus as the “blarney stone.
O
- Henry Petroski, Duke University, North Carolina
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- An Engineer's Alphabet
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- 10 October 2011, pp 226-230
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Order of the Engineer. As early as the 1950s, some Ohio engineers began to look into extending the Canadian Iron Ring Ceremony into the United States; however, it was not until 1970 that the first American ring ceremony was held at Cleveland State University. Local chapters of the Order of the Engineer, known as Links, began to form, first around Ohio, but then increasingly throughout the country. The movement has continued to spread, but the practice of American engineers wearing a stainless steel pinkie ring has not grown to nearly the extent that Canadian engineers wear their iron (now also mostly stainless steel) rings. See Homer T. Borton, “The Order of the Engineer,” The Bent of Tau Beta Pi, Spring 1978, pp. 35–37; “The Iron Ring,” American Scientist, May–June 1995, pp. 229–232; To Forgive Design: Understanding Failure (Cambridge, Mass.: Harvard University Press, forthcoming), chapter 8.
The pledge taken by engineers at the time of their induction into the American Order of the Engineer is known as the “Obligation of an Engineer.” It was modeled after that of the Canadian iron ring tradition and appeared on early membership certificates as follows:
Obligation of an Engineer
I am an Engineer. In my profession I take deep pride. To it I owe solemn obligations.
Since the Stone Age, human progress has been spurred by the engineering genius. Engineers have made usable Nature's vast resources of material and energy for Mankind's benefit. Engineers have vitalized and turned to practical use the principles of science and the means of technology. […]
Q
- Henry Petroski, Duke University, North Carolina
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- An Engineer's Alphabet
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- 10 October 2011, pp 263-264
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Quebec Bridge. This steel cantilever bridge across the St. Lawrence River at Quebec collapsed during construction in 1907. After an inquiry by a royal commission, which found that the bridge was inadequately designed and its construction improperly supervised, the structure was redesigned and construction begun anew. A second accident befell the bridge in 1916, when because of the failure of a casting, the central suspended span that was being hoisted into place fell into the water and was destroyed.
The Quebec Bridge was finally completed in 1917 and now stands as a symbol of Canadian resolve. It also serves as the entranceway to Canada for ships coming up the St. Lawrence River. The structure, which at 1,800 feet between piers has remained for almost a century the longest spanning cantilever bridge in the world, demonstrates the chilling effect on technology that a failure can have.
The bridge was the subject of Willa Cather's first novel, Alexander's Bridge, which was published in 1912; has appeared on Canadian commemorative postage stamps; and is said to have provided inspiration for the country's iron-ring tradition. Although the belief persists that the wreckage of the original structure was the source of the iron for the first rings adopted by Canadian engineers as a symbol of their professionalism, this is belied by the fact that the material of the failed bridge was not iron but steel.
List of Illustrations and Credits
- Henry Petroski, Duke University, North Carolina
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- Henry Petroski, Duke University, North Carolina
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- 10 October 2011, pp 135-149
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hairy-eared engineer. This jocular term has been applied to engineers who are advanced enough in age to have hirsute ears. More importantly, but no less jocularly, hairy-eared engineers are believed to have worked on enough projects over the course of their career to have made every imaginable mistake. This makes such an engineer invaluable to a project where the participants do not wish to repeat past failures. In other words, as the hairy-eared engineer Marvin B. Davis has been quoted as saying, “Every project needs at least one hairy-eared engineer.”
However, since the term “hairy-eared engineer” is most likely to evoke a male image, its usage is open to being termed sexist. Since the 1970s, significant numbers of female engineers have been entering the profession, and enough time has passed that some of them, too, have made their share of mistakes. Perhaps the term “hairy-eared” should be replaced by “gray-haired.” Whatever called, every project can benefit from having one of these experienced engineers aboard.
half-life of technical skills. Half-life is a term used in physics to describe the time required for half of a substance to undergo a process, such as radioactive decay. The term has come to designate the period of usefulness that precedes obsolescence. In the mid-1980s it was estimated that the half-life of an engineer's technical skills was as little as 2.5 years for a software engineer; electrical engineers were estimated to have half-lives of 5 years, and mechanical engineers 7.5 years.
U
- Henry Petroski, Duke University, North Carolina
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- 10 October 2011, pp 320-326
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U.S. Army Corps of Engineers. A Corps of Engineers in the Continental Army was established by the Second Continental Congress in 1775 and came to be organized, trained, and led by French-trained military engineers. With the coming of peace in 1783, the Corps was dissolved with respect to the Army. Coastal fortifications continued to be necessary for defense, however, and there was a clear need for a permanent corps of engineers and for a means of training engineers for it. In 1794, Congress authorized the creation of a Corps of Artillerists and Engineers, which was garrisoned atop cliffs overlooking a strategic stretch of the Hudson River at West Point, New York, located about 50 miles north of New York City. From this group the Corps of Engineers was created in 1802, the same year that the U.S. Military Academy was established at West Point. The location came to be used as the name for the institution itself.
Considered the first engineering school in America, West Point did not have a focused system of instruction or examination until 1817, when Colonel Sylvanus Thayer (1785–1872) was appointed superintendent. He enlisted the help of Claudius Crozet (1790–1864), an 1809 graduate of Paris's Ecole Polytechnique, and the French system of educating engineers became a model for the U.S. Military Academy. Because the engineers and cadets of the Academy were at the service of the President, they were available for assignment to civilian as well as military engineering projects, and the Corps of Engineers became an important force in developing the young nation's infrastructure.
Dedication
- Henry Petroski, Duke University, North Carolina
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- Henry Petroski, Duke University, North Carolina
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railroads and engineers. It is a pet peeve of many engineers that their profession is confused with the occupation of railroad engine operator. They consider it a stale joke at best, after they identify themselves to be an engineer, to have someone ask if they drive a locomotive. Historically, the word engineer designated someone who designed engines before it did someone who drove or operated them; however, to some laypeople the latter definition is the one that comes first to mind.
The locomotive engineer's cap, made out of the tightly woven and strong cotton upholstery fabric known as ticking, has also been annoyingly associated with engineers who have no connection to trains. Next to cartoon depictions of engineers in hard hats are those caricaturing them in the railroader's cap. I was conflicted at my university's commencement ceremony one year when the graduates receiving engineering degrees were handed blue-and-white striped caps as they marched to their seats. The idea was that at the end of the ceremony they would doff their mortarboards and put on the caps. The well-intended but ill-advised act of camaraderie nevertheless bothered some other engineering faculty members, who had also fought the misdirected stereotype of engineers as train drivers. Fortunately, the attempt to establish a commencement “tradition” lasted only a year or two before being forgotten.
E
- Henry Petroski, Duke University, North Carolina
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economics and engineering. Engineering and economics are inseparable. Indeed, they are linked in one of the most quoted and paraphrased definitions of engineering, which comes from the self-made engineer Arthur Mellen Wellington (1847–1895). In 1876 he published a series of articles on railroad layout in the Railroad Gazette, which the next year were published as a book. A decade later, a greatly expanded and revised edition was published as The Economic Theory of the Location of Railways: An Analysis of the Conditions Controlling the Laying Out of Railways to Effect the Most Judicious Expenditure of Capital (New York: Wiley, Engineering News, 1887). The now-classic definition reads:
It would be well if engineering were less generally thought of, and even defined, as the art of constructing. In a certain important sense it is rather the art of not constructing: or, to define it rudely, but not inaptly, it is the art of doing well with one dollar, which any bungler can do with two after a fashion.
This is often found paraphrased in a shorter version to serve as a definition of an engineer: “An engineer is someone who can do for one dollar what anyone can do for two.” The definition has become so familiar that it is frequently cited, in various modified forms, without association with Wellington. Thus, Nevil Shute used it as an epigraph for his posthumously published novel, Trustee from the Toolroom (New York: Morrow, 1960): “An engineer is a man who can do for five bob what any bloody fool can do for a quid.
A
- Henry Petroski, Duke University, North Carolina
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abbreviations. As frequently as engineers find themselves using the words engineer and engineering, they do not appear to have agreed on any single standard or official shorthand for the words. Among the abbreviations I have seen used are egr., eng., engr., eng'r., and engng. – none of which is especially mellifluous or, in isolation, unambiguous. Abbreviations are not meant to be pronounced as such, however, and as long as the context is clear there should be little need to worry about them being misunderstood. Even so, the arrangement of the letters in these abbreviations is not especially typographically graceful, and situations can arise where confusion might result, as in a university setting when a course number is designated Eng. 101. Is this Engineering 101 or English 101 or Energy 101? Engineers dislike ambiguity, and so the imprecision of an abbreviation for our own profession is annoying, to say the least.
It is apparently this aversion to ambiguity that has led engineers to introduce less-than-logical abbreviations for themselves. And it may well have been the potential confusion over what “eng.” designates (engine, engineer, engineering, English, engrave, etc.) that led to the introduction of the unconventional, unpronounceable, and ungraceful abbreviation egr. for engineer, and sometimes its natural extension egrg. or egrng. for engineering. Although many common abbreviations have multiple meanings, the context can be expected to make clear which one is intended. Unfortunately, the words engine, engineer, and engineering often occur in the very same context.
T
- Henry Petroski, Duke University, North Carolina
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- An Engineer's Alphabet
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Tacoma Narrows Bridge. This bridge, constructed across the stretch of Puget Sound known as the Narrows, between Tacoma, Washington, and the Olympic Peninsula, was torn apart in the wind on November 7, 1940, only four months after it was opened.
Designed to accommodate just two lanes of traffic in a then sparsely populated area, the bridge deck was narrow as well as shallow, being supported, for reasons of economy and aesthetics, by plate girders rather than a more conventional deep truss. This meant that the deck's resistance to bending and twisting was uncommonly low. When the wind blew in a certain way, the roadway undulated up and down, thus earning the bridge the nickname Galloping Gertie. After about four months, torsional oscillations began when there was the dislocation of a cable at mid-span. The amplitude of the oscillations was magnified by a phenomenon known as wind-structure interaction, and eventually the aerodynamic forces on the deck were of such a magnitude that its center span broke up and fell into the water.
Because the Tacoma Narrows Bridge had demonstrated unexpectedly large motions from the outset, it had already been the subject of study. When the rhythmic twisting began, cameras were set up and thus the failure of the bridge that occurred only hours later was captured on film. This footage, along with other made under the direction of Frederick Burt Farquharson (1895–1970), a professor in the University of Washington's Department of Civil Engineering who had been studying the behavior of the bridge, soon became a classic.
Frontmatter
- Henry Petroski, Duke University, North Carolina
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- Henry Petroski, Duke University, North Carolina
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factor of safety. In structural engineering, a factor of safety is effectively the ratio of the theoretical failure load of a beam, column, or other component to the largest actual load it is designed to carry. A factor of safety provides assurance against such uncertainties as the design load being exceeded in service, the statistical variation in the strength of materials, and the occurrence of detrimental effects during the construction and life of a structure. Factors of safety have historically varied from only slightly greater than unity, in structures where excess strength (which generally equates to excess weight) cannot be tolerated, as in spacecraft, to as high as 6, 7, 8, or even more in civilian structures whose behavior is not completely understood or whose failure would have life-threatening or severe economic consequences, as in mid-nineteenth century railroad bridges. By extension to non-structural applications, employing a factor of safety implies being conservative in design, the structure or component having reserve capability for unusual situations. The factor of safety is sometimes referred to as a “factor of ignorance” because it is intended to take into account unknown contingencies. Euphemisms such as “design factor” and “design margin,” which are sometimes used, mask the life-protecting implications of the term factor of safety.
Factors of safety in living organisms have been discussed in an article by the physiologist and biogeographer Jared Diamond.
P
- Henry Petroski, Duke University, North Carolina
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patent system. The American patent system has its foundation in the U.S. Constitution. According to Article I, Section 8, the Congress has the power “to promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries.”
During much of the nineteenth century, physical models of inventions were submitted with patent applications. A fire in the Patent Office destroyed all such models submitted prior to 1836, and more were lost in a second fire, in 1877. Those that have survived are scattered in collections ranging from that of the Smithsonian Institution to those of private collectors. As engineer-turned-historian-of-technology Eugene Ferguson pointed out, patent models are useful for dating the state of the art of such things as screws and other fasteners. Patent models were no longer required after about 1880, except to accompany patent applications for perpetual-motion machines. See American Enterprise: Nineteenth-Century Patent Models (New York: Cooper-Hewitt Museum, 1984).
Almost ten thousand U.S. patents were issued before the present serial numbering system was initiated with U.S. Patent No. 1, which was issued on July 13, 1836. By the end of the nineteenth century, the number of U.S. Patents exceeded 600,000. Patents continued to grow exponentially, and by the end of the twentieth century the number exceeded 6,000,000. The 7,000,000 mark was reached in 2006, and patent number 8,000,000 was expected to be granted in 2011.
D
- Henry Petroski, Duke University, North Carolina
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definitions of engineering. See economics and engineering; engineer; engineering
design. Arguably, it is design that is the central activity of engineering, with all other engineering pursuits following from and in service to design. Design is a process of synthesis, as opposed to analysis, which is more akin to what scientists do. Thus, design is the aspect of engineering that distinguishes it from science. According to Joel Moses, once dean of engineering at MIT, “Design is the soul of engineering.”
In America, it has been traditional for separate contracts to be let for the design and the building phases of large construction projects. In contrast, in the design-build concept, the same firm is responsible for both the design and the construction phases. Proponents of this system, which has been more common in Europe, argue that design-build contracts are more economical and efficient and result in better quality design and construction. Opponents argue that separate contracts better ensure the benefits of competition. The proponents prevailed in late-twentieth century America, where design-build contracts went from about 3 percent of contracts negotiated in 1987 to more than 33 percent in 1997.
When a new building, bridge, or other structure is desired, a design competition can be held to which entries are invited from a select group, resulting in a closed competition, or from anyone who cares to enter, resulting in an open competition.
J
- Henry Petroski, Duke University, North Carolina
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jokes about engineers. The words of an imagined recent engineering graduate, “Once I couldn't even spell injunear, and now I are one,” is a familiar commentary that engineers make about themselves, perhaps reflecting what they think the rest of the world thinks of them. Then there is what is perhaps one of the most popular self-characterizations of the engineer, which takes the form of a question-answer interchange: “How can you tell an introverted engineer? He looks at his shoes when he is talking to you. How can you tell an extroverted engineer? She looks at your shoes when she is talking to you.”
Another engineer joke might go as follows: A lawyer, a priest, and an engineer were scheduled to be guillotined. First the lawyer's neck was placed in the device, but when the executioner pulled on the latch, the blade got stuck and did not fall. The lawyer was told that it must have been a sign of a higher form of justice and that his life was spared. He walked away saying justice had indeed been served. Next the priest's neck was locked in place. When the executioner pulled the latch, the blade also got stuck. Higher powers were again assumed to have intervened. The priest was released, and he walked away praising the Lord. Then the engineer was locked in place, and as he waited for the blade to drop, he craned his neck to inspect the mechanism of the guillotine.
Preface
- Henry Petroski, Duke University, North Carolina
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This abecedarian is one engineer's collection of thoughts, quotations, anecdotes, facts, trivia, arcana, and miscellanea relating to the practice, history, culture, and traditions of his profession. The entries, which represent the distillation of decades of reading, writing, talking, and thinking about engineers and engineering, range from brief essays on concepts and practices that are central to the profession to lists of its great achievements. This book is at the same time an anthology, a commonplace book, and a reference volume.
My approach in composing the entries has generally been to convey as much information in as little space as possible, to create more of a dictionary-like than an encyclopedia-like sense of the topic under discussion. In no case is an entry meant to be definitive or exhaustive, and so references to further information are provided freely. However, I have included no references to the World Wide Web, not only because web sites can come, go, and change so unpredictably, but also because it can be easier to query a reliable search engine than to type in correctly a long web address.
This volume is not intended to be read from first page to last, but rather is meant to be dipped into here and there as the mood strikes the reader, with the alphabetical arrangement promoting serendipity. In time, it is hoped, this book will become the source to which readers come first when they encounter a vague or obscure reference to something related to the softer side of engineering.
Index of Proper Names
- Henry Petroski, Duke University, North Carolina
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Z
- Henry Petroski, Duke University, North Carolina
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Zen and the Art of Motorcycle Maintenance. Subtitled An Inquiry into Values, this book was written by Robert M. Pirsig (born in 1928) and first published in 1974. It has been widely assigned in engineering design courses for its insights into the nature of design and the idea of quality. A tenth-anniversary edition of the book, published by William Morrow and Company in 1984, included a new introduction by the author in which he reflected on the astounding success of a book that had been turned down by 121 other publishers and also on the tragic death of his son, who played a prominent role in the book's narrative. Pirsig, a biochemist by education who became disillusioned with science and eventually came to be identified as a philosopher, has been quoted as believing that “traditional scientific method has always been at the very best, 20-20 hindsight. It's good for seeing where you've been. It's good for testing the truth of what you think you know, but it can't tell you where you ought to go.” That responsibility, at least in the material world, rests more squarely on enlightened and responsible engineering infused with the values of its softer side.