Engineering

• 1. Introduction

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  Engineering is the practice of systematically applying natural science and mathematics to design and improve systems, devices, or processes that solve problems under constraints. The word itself comes from the Latin ingenium, a term from around 1250 meaning innate quality, especially mental power, and by extension a clever invention. That root hints at something the field rarely advertises about itself. Long before it became a profession of bridges and circuits, the word engineer described a constructor of military engines, someone who built or operated a siege machine like a catapult. How did a word for war machines come to describe the people who build our roads, our power grids, and our spacecraft? What separates an engineer from the scientist whose principles they borrow? And why, after thousands of years of pyramids and aqueducts, did engineering only become a recognized occupation in the middle of the 19th century? The answers run from a step pyramid at Saqqara to a self-proclaimed title coined by a single English physicist.

• 2. From Siege Engines To Civil Works

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  The term engineering descends from engineer, a word dating back to the 14th century, when an engine'er meant a constructor of military engines. In that now-obsolete sense, an engine was a mechanical contraption used in war. Traces of this meaning survive in military engineering corps, such as the U.S. Army Corps of Engineers. As the design of bridges and buildings matured into a technical discipline, a new label was needed. The term civil engineering entered the lexicon to distinguish those who built non-military projects from those engaged in military engineering. That split between civilian and martial work would later branch into the traditional disciplines of civil, mechanical, electrical, and chemical engineering. John Smeaton, an English engineer, became the first person to call himself a civil engineer, a self-applied title that gave the whole civilian profession its name.

• 3. The Ancient Toolkit

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  The six classic simple machines were known in the ancient Near East, and they form the deepest layer of engineering. The wedge and the inclined plane, or ramp, were known since prehistoric times. The wheel, along with the wheel and axle, was invented in Mesopotamia, in what is now Iraq, during the 5th millennium BC. The lever appeared around 5,000 years ago in the Near East, first in a simple balance scale and to move large objects in Egyptian technology. The lever also drove the shadoof, a water-lifting device that became the first crane machine, appearing in Mesopotamia around 3000 BC. The earliest evidence of pulleys dates back to Mesopotamia in the early 2nd millennium BC, and to ancient Egypt during the Twelfth Dynasty, between 1991 and 1802 BC. The screw, the last simple machine to be invented, first appeared in Mesopotamia during the Neo-Assyrian period, between 911 and 609 BC. The Egyptian pyramids were built using three of these machines, the inclined plane, the wedge, and the lever, to raise structures like the Great Pyramid of Giza. The earliest civil engineer known by name is Imhotep, an official of the Pharaoh Djoser, who probably designed and supervised the Step Pyramid at Saqqara around 2630 to 2611 BC.

• 4. Mechanisms Of The Middle World

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  The earliest practical wind-powered machines, the windmill and wind pump, first appeared in the Muslim world during the Islamic Golden Age, by the 9th century AD, in what are now Iran, Afghanistan, and Pakistan. Programmable machines also emerged there. The first music sequencer, an automated flute player, was invented by the Banu Musa brothers and described in their Book of Ingenious Devices in the 9th century. In 1206, Al-Jazari invented programmable automata, describing four automaton musicians that included drummers operated by a programmable drum machine, able to play different rhythms and patterns. Water power had arrived earlier still. The earliest practical water-powered machines, the water wheel and watermill, first appeared in the Persian Empire, in what are now Iraq and Iran, by the early 4th century BC. Far from these centers, Kush developed the Sakia in the 4th century BC, a device that relied on animal power rather than human energy. Kush also built hafirs as reservoirs to store water and boost irrigation, and produced iron in bloomeries and blast furnaces by the 7th century BC. A standard reference for these mechanical arts during the Renaissance is the mining treatise De re metallica of 1556, which remained the standard chemistry reference for the next 180 years.

• 5. Steam And The Birth Of A Profession

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  Applied science led to the development of the steam engine through a sequence of careful steps. It began with the invention of the barometer and Evangelista Torricelli's measurement of atmospheric pressure in 1643. Otto von Guericke demonstrated the force of that pressure using the Magdeburg hemispheres in 1656. Denis Papin built experimental model steam engines and demonstrated the use of a piston, publishing his work in 1707. Thomas Savery built a steam pump in 1698 called The Miner's Friend, which used both vacuum and pressure. The iron merchant Thomas Newcomen built the first commercial piston steam engine in 1712, and was not known to have any scientific training. John Smeaton, often regarded as the father of civil engineering, designed bridges, canals, harbors, and lighthouses. Using a model water wheel, Smeaton ran experiments for seven years to increase efficiency, and he introduced iron axles and gears to water wheels. He designed the third Eddystone Lighthouse, built between 1755 and 1759, pioneering the use of hydraulic lime, a mortar that sets under water. His search for hydraulicity in lime led ultimately to the invention of Portland cement. Among the most famous engineers of the mid-19th century was Isambard Kingdom Brunel, who built railroads, dockyards, and steamships. The 1850 United States Census listed the occupation of engineer for the first time, counting just 2,000 of them.

• 6. New Branches Take Root

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  Fewer than 50 engineering graduates existed in the United States before 1865. The first PhD in engineering awarded in the country went to Josiah Willard Gibbs at Yale University in 1863, which was also the second science PhD awarded in the U.S. In 1870 there were a dozen American mechanical engineering graduates; by 1875 that number had risen to 43 per year. By 1890, there were 6,000 engineers across civil, mining, mechanical, and electrical fields. Cambridge had no chair of applied mechanics until 1875, and Oxford had no chair of engineering until 1907, while Germany established technical universities earlier. Electrical engineering grew from the 1800s experiments of Alessandro Volta, Michael Faraday, and Georg Ohm, the electric telegraph invented in 1816, and the electric motor in 1872. The theoretical work of James Maxwell and Heinrich Hertz in the late 19th century gave rise to electronics, and the later vacuum tube and transistor accelerated it so far that electrical and electronics engineers now outnumber every other specialty. Chemical engineering developed in the late 19th century, as by 1880 the need for large-scale chemical production created a whole new industry of industrial plants. Aerospace engineering traces to the aviation pioneers around the start of the 20th century. Only a decade after the Wright brothers' flights, military aircraft used in World War I drove extensive development of the field.

• 7. How Engineers Decide

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  In the engineering design process, engineers apply mathematics and the physical sciences to find novel solutions or improve existing ones. When more than one solution exists, they weigh each design choice on its merits and choose the one that best matches the requirements. Constraints may include the fundamental laws of physics and chemistry, available resources, and demands for cost, safety, marketability, productivity, and serviceability. Genrich Altshuller, after gathering statistics on a large number of patents, suggested that compromises lie at the heart of low-level engineering designs, while the best high-level design eliminates the core contradiction causing the problem. Engineers try to predict how well their designs will perform before full-scale production, using prototypes, scale models, simulations, destructive tests, nondestructive tests, and stress tests. They typically build in a factor of safety to reduce the risk of unexpected failure. This philosophy is embodied by Cicero's Creed, considered the original engineer's code of ethics, whose slogan salus populi suprema lex esto translates as the health, safety, or welfare of the people shall be the supreme law. When a product fails, forensic engineering attempts to identify the cause and allow a redesign. The consequences of failure range from the minor cost of a machine breakdown to large loss of life in accidents involving aircraft, buildings, and dams.

• 8. Where Engineering Meets Everything Else

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  Scientists study the world as it is; engineers create the world that has never been. That contrast runs through engineering's relationships with neighboring fields. In the book What Engineers Know and How They Know It, Walter Vincenti argues that engineering research often deals with areas where the basic physics or chemistry are well understood, but the problems themselves are too complex to solve exactly. The revision to the text Foundations of Solid Mechanics, attributed to Fung and others, puts it plainly: scientists try to understand nature, while engineers try to make things that do not exist in nature. The human body provides a common link between medicine and engineering, since the heart functions much like a pump and the skeleton resembles a linked structure with levers. These parallels led to biomedical engineering, drawing concepts from both disciplines. Engineering also touches art. Leonardo da Vinci stands as a prime example of the nexus between art and engineering, and Robert Maillart's bridge design is seen by some as deliberately artistic. The term has even been borrowed elsewhere, appearing in social engineering, political engineering, marketing engineering, and financial engineering. In Canada, engineers wear the Iron Ring as a symbol and reminder of the obligations and ethics tied to their profession.