by Dale Baker
The history of the word “engineer” gives some understanding of what engineers have been in the past. The original meaning of the word was one who constructs military engines; military engines were devices such as catapults as well as fortifications, roadways, and bridges. This meaning was expanded to mean one who invents or designs. The meaning of engineers as those who plan and execute public works was established in the early 1600s.
In this chapter, we present just a small fraction of all of the historical events related to engineering. Throughout history, society has been affected by the technological advances created by engineers, and engineers and their technology have both been dramatically affected by the societies in which they occurred. Thus, a complete history of engineering would require a complete history of society, which is clearly beyond the scope of this chapter. Also, this chapter focuses primarily on engineering within the western world, including the Roman Empire, Europe, and later North America.
Chapter Learning Objectives
After working through this chapter, you should be able to do the following:
Give examples of how engineers have used creativity and judgment in the application of math, science, and technology to solve societal problems.
Explain why complex engineering problems are usually solved by teams working within broader social structures.
Explain how engineering progress provides new human capabilities, which in turn increases engineering capabilities.
Give examples of how engineering provides society with both intended and desirable consequences as well as unintended and undesirable consequences.
Historical Themes
In this chapter, four themes emerge repeatedly; they have been repeated throughout the history of engineering. Each is related to one of the Chapter learning objectives and will be illustrated several times in this chapter. We briefly introduce these themes before beginning the history.
Engineering requires creativity and judgment in applying math and science to solve problems. You will recognize this theme in almost all of the engineering developments discussed in this chapter. Specific examples of this include development of the steam engine and the electrical light system; in both cases, an understanding of the basic scientific principles associated with steam power and electricity was established before engineers used these principles to develop technology. However, understanding alone did not lead to immediate implementation of the technology; significant effort was often required to make things work.
Complex engineering problems are usually solved by teams working within the broader societal structures. For example, most of history’s large construction projects such as the pyramids in ancient Egypt, the great cathedrals in Medieval Europe, or the large dams in the western United States required extensive materials, labor, and other resources. These resources were provided by governments, corporations, churches, or other organizations. Also, large projects require the organization of large numbers of people. All of this was done within a social structure.
Government is one societal structure that constantly influences engineering advances. Governments have often provided resources for engineering projects, and have spurred development of new technologies, including accurate clocks for measuring longitude, early computers, military aircraft, and rockets and technology for space travel. In addition to providing resources, governments have influenced technology through laws and policies. Some laws may be implemented to protect public safety; for example, explosions of boilers in steam engines in the late 1800s led to government regulation and safety standards. Patents represent another way in which governments use laws to influence technology; a patent gives its holder legal rights to stop others from using a particular technique or design.
As technology has progressed, it has grown more complex. Thus, many early engineering achievements can be attributed to single individuals or small groups. However, most recent engineering achievements have been made by multidisciplinary teams of engineers.
Engineering progress provides new human capabilities, which in turn increase engineering capabilities. Many technological advancements provide a foundation for further technological advancements. For example, the development of affordable printing methods (including movable type and the mechanical printing press) led to wider availability of books and promoted literacy; this in turn led to wide dissemination of scientific knowledge which formed the foundation of the Industrial Revolution. As another example, the development of computers enabled the subsequent development of computer-aided design software, which is now used to create even more powerful computers.
Engineering produces both intended and desirable consequences as well as unintended and undesirable consequences. For example, the development of trucks and cars has allowed people and goods to travel widely. However, these vehicles are a major source of air pollution, particularly in developing nations, and these vehicles have made urban sprawl a major issue in most major American metropolises. In today’s world, engineered systems have become incredibly complex, and no one individual can understand all of the ramifications of a complex technical system; this complexity generates uncertainty, which can lead to problems and even disasters, particularly when circumstances or consequences cannot be foreseen by the engineers developing a system.
As you read this chapter, see if you can identify examples of each of these themes.
Engineering in Ancient Civilizations
This section focuses on major structures created by engineers in ancient civilizations. One of the greatest engineering accomplishments in the ancient world, and certainly one of the best-known, was the construction of the Egyptian pyramids. The Egyptian pyramids were built in the period from approximately 2700 to 2200 BC. Figure 1 shows the pyramids at Giza. Three factors were important to Egyptian engineering. The first was that the Egyptian pharaohs were willing to devote almost unlimited time and resources to the construction of the pyramids. There was an almost unlimited availability of skilled human labor (animals did not provide significant labor in the pyramid construction). Second was the ability to organize all of these workers in a very efficient way. Egyptian laborers worked under the absolute control of a single head engineer and his subordinates. The third was that there were sources of sandstone, limestone, and granite very close to the sites of the pyramids. The pyramids were probably constructed using earth ramps to raise the stones to the level necessary; the ramps were later removed. Egyptian engineers worked from plans drawn on papyrus. Egyptian engineers had an excellent knowledge of geometry and measurement, which is apparent from the accuracy with which the pyramids were constructed. In addition to the pyramids, Egyptian engineers built many temples and other buildings.
Figure 6.1
The Egyptian pyramids at Giza.
The Romans are also known for their engineering works. These works include road systems, aqueduct systems to provide drinking water, and monuments and buildings. By AD 200, the the Roman road system included 44,000 miles of well-constructed roadway. Roman roads tended to follow a straight line up and down hills, rather than bending to follow level contours. This was because the roads were primarily designed for military use and marching soldiers, not for transportation of cargo.
The Roman aqueducts are famous engineering accomplishments as well. The Romans built aqueducts to move water from its source in springs or rivers to Roman cities. We are familiar with the arched bridges used to carry aqueducts across valleys; the aqueduct shown in Figure 2 is one such bridge.
Figure 6.2
The Pont du Gard is an aqueduct in the south of France constructed by the Roman Empire.
One common theme that runs through these engineering accomplishments is that these projects were very large, especially for the ancient civilizations in which they were pursued. In addition to good engineering, their implementations required large commitments of resources by governments to support large groups of laborers and provide significant amounts of material. Thus, the engineers that led these
projects needed skills far beyond technical ability. They needed to understand and be able to work within the social structures of their times to obtain the resources for their projects. They needed to understand the capabilities of the laborers who would work on the projects.
Engineering in Medieval and Renaissance Europe
The medieval and Renaissance periods in Europe span the time from approximately AD 500 to AD 1600. Life in medieval Europe has often been characterized as the “dark ages,” which gives the impression that there were no advances in technology or engineering. In some aspects, this characterization is correct. For example, the elaborate water works created by the Romans to supply their cities with potable water were not duplicated in medieval European cities. Neither were sanitary sewers. Thus, waterborne disease was a recurring problem in many of these cities. However, in other aspects this characterization is not correct. Several important engineering concepts and techniques were developed during this time which laid the foundation for rapid technological advance during the Industrial Revolution. Engineers developed techniques for constructing astounding buildings, including cathedrals and castles. Engineers also improved the designs of ships, making European exploration of the rest of the world possible. The development of the printing press and associated type technology, as well as the development of linear perspective and engineering drawing techniques, enabled literacy and communication of information. We consider these advances in this section.
Buildings
One area in which engineering made significant advances was the construction of cathedrals, castles, and other large structures. Cathedrals were built across Europe beginning in the fourth century and continuing into the present. In medieval Europe, cathedrals were built in the Romanesque style (in the tenth and eleventh centuries) and later in the Gothic style (in the twelfth through sixteenth centuries). Romanesque buildings are characterized by thick walls, round arches, and large towers. Gothic buildings are characterized by thinner walls with large windows, pointed arches, and flying buttresses. Several technological advances made the Gothic cathedral possible. Flying buttresses transfer the gravitational forces from roofs and upper stories to external pillars; this allowed walls to be thin with large windows. In addition, the use of pointed arches and ribbed vaults transfers forces to columns instead of the walls.
Figure 6.3
The west facade of the cathedral of Notre Dame de Paris.
Figure 6.4
Flying buttresses on the cathedral of Notre Dame de Paris.
Figure 3 shows the west facade of the cathedral of Notre Dame de Paris. Note the pointed arches and the large windows. Figure 4 shows the flying buttresses that help support the roof of the cathedral. Construction on the cathedral was begun in 1163, and the building was not completed until 1345.
Master masons directed the construction of these cathedrals and other buildings. Master masons supervised large groups of workers. They were the structural engineers of their day, and, when working on military projects, were actually called engineers. They had a good understanding of geometry and arithmetic. However, they did not have the engineering theory used by structural engineers today (a mathematical understanding of how loads are transferred in structures as well as the characteristics and strengths of building materials). Instead, they often used rules of thumb, which had been developed from the experience gained by previous generations. Often, these rules of thumb led to mistakes, and plans were often altered to correct these mistakes.
Ships
Another aspect in which engineering made significant progress in medieval Europe was the design and construction of sailing vessels. In Scandinavia, the Viking longship reached the height of its development during the Middle Ages. These ships were very fast; they were used to carry cargo as well as transport Viking raiding expeditions over long distances. Longships had a single mass that was rigged with a square sail.
Progress on sailing vessels in medieval Europe, particularly by Spain and Portugal, set the stage for European exploration and colonization in North and South America and Africa. The two types of sailing vessels that had the largest impact on this exploration were the caravel and the carrack. A caravel is a small, highly maneuverable ship with two or three masts as shown in Figure 5. A carrack is a larger ship with three or four masts and square sails; it was large enough to carry a significant amount of cargo and to be stable on long ocean voyages. Figure 6 shows a carrack. Christopher Columbus’ (1451–1506) small fleet that sailed to the New World consisted of one carrack (the Santa Maria) and two caravels (Pinta and Nina).
Figure 6.5
A caravel is a small highly maneuverable ship with two or three masts.
Figure 6.6
, a painting of the Santa Maria by Andries van Eertvelt about 1628; the Santa Maria was a carrack.
Moveable Type
A third advance in the Middle Ages, which may not at first be recognized as engineering, was the development of a printing system that used movable type. The technology to print books and make them available at a price that a large segment of the population can afford is one of the most significant advances ever. The development of this technology has been called “the technical advance which facilitated every technological advance that followed it” (Derry and Williams, 1961). Johannes Gutenberg (about 1400–1468) is often credited with the development of movable type; however, this development, similar to many engineering advances before and after, was not made by a single person working in isolation. Rather, Gutenberg combined several processes that had already been developed in a novel way to print books; his methods were further improved by those who followed him. His genius was to combine type casting, ink, and a printing press into a system that could mass produce books.
Before the development of movable type in the fifteenth century, almost all books were copied by hand. A scribe toiled laboriously to create a copy of a book, often requiring a whole year to create one. These handwritten books were so expensive that only the very wealthy could afford them. Movable type was probably first invented in Asia. Bronze type was in use in Korea and China in the early fifteenth century. In Europe, copper plates were engraved to produce playing cards and illustrations; this practice was well established by the mid-fifteenth century. Wooden type was used in the 1420s in the Netherlands.
Johannes Gutenberg was a silversmith in Mainz, Germany. He was probably aware of these previous advances in printing and typography. In 1426, Gutenberg began printing with individually cast metal letters; each letter was on the surface of a block. He cast these letters using type metal, an alloy of lead, tin, and antimony. It has long been thought that letter blocks were formed using dies (molds) of soft metal, so that in all blocks of a given letter, the letter form would be identical. However, modern analysis suggests that the form for each letter was individually inscribed in clay and then cast, so that each block for a given letter was subtly different. To typeset a page of text, the letter blocks were arranged in rows of text, and the rows were then arranged into pages. This process is illustrated in Figure 7. Once the page was typeset (a laborious process that could take a whole day for a single page), it could be inked and printed as many times as necessary to create copies of a particular page in a book.
Note that the creation of books and other material required both technology for typesetting and technology for printing. Typesetting is the process of arranging letters and other content (e.g., illustrations and drawings) into the desired pattern, while printing is the process of getting the ink on the paper in the desired pattern.
Figure 6.7
Type blocks arranged into rows.
In 1455, Gutenberg used this system to print the Bible. It is believed that he printed about 180 copies. Figures 8 and 9 and show this Bible.
Figure 6.8
A Gutenberg bible.
Figure 6.9
A close view of a page from the Gutenberg bible. The black text was printed using the printing press; then, the red decorations were added by
hand.
Gutenberg’s methods were immensely successful, and were widely copied and improved. By 1480, almost every large European city had at least one printing press. Venice emerged as the printing capital of Europe. These early printers designed many fonts that are very similar to those used today.
Perspective and Technical Drawing
One of the primary engineering advances of the Renaissance was the development of linear perspective and the invention of several methods of technical drawing, including cutaway drawings, exploded drawings, and rotated views. It may not be clear why these techniques are such significant advances. However, these drawing techniques made it possible for engineers to study mechanical systems and buildings without the need for three-dimensional models; since a two-dimensional drawing can typically be created much more quickly than a three-dimensional model, new drawing capabilities greatly accelerated the pace at which engineering work could be accomplished. These capabilities also improved the ability of engineers and scientists to communicate ideas and concepts. Thus, they helped drive the transformation of engineering from using rules of thumb and accumulated experience to a discipline based on scientific principles and theory.