Civil engineering, like military engineering, emerged in large part from the employments of Renaissance architects. Many Renaissance cities and regional princes engaged an architect-engineer to oversee the construction of all public works, including defensive structures, bridges, and maintenance of roads and waterways. Well into the eighteenth century, a number of engineers maintained versatile skills in both military and civil engineering, although men of more specialized backgrounds, such as surveyors, millwrights, and drainage engineers, always added expertise in the construction of public works and often fashioned themselves more broadly as engineers. Mathematicians, too, consulted on engineering works and helped develop the relationship between engineering and the emerging sciences of mechanics and hydrology. The rise of absolutism combined with growing capital interests to fund a broad range of city-planning, communication, and, above all, water-management programs. Civil engineers were those experts who rose to the challenges and the perquisites these projects offered.
CITIES AND VILLAS
The vision of the Renaissance city developed out of new conceptions of the role cities played and an idealized notion of classical urbanism. Building programs to reshape major capitals or plan new military strongholds created cityscapes that demonstrated the power of the rulers, but also served pedestrian traffic, the easy transport of goods (or munitions), water-supply needs, and public theaters and hospitals. The work of Domenico Fontana (1543–1607) for Sixtus V is emblematic: Fontana not only designed new, more convenient, traffic patterns for Rome, but he was involved in the vaulting of St. Peter's cupola and is best known for his direction of the removal of a giant Egyptian obelisk from the site of the Circus Maximus and its reerection in the center of St. Peter's piazza. The latter was itself a theatrical technological feat that involved massive scaffolding and numerous windlasses, tackles, and pulleys. It drew a huge audience of spectators, reportedly hushed under threat of death so that workers could hear the bell prompts.
Expertise with materials was largely a tacit knowledge among Renaissance architects and engineers. The astounding heights achieved by the domes and basilicas of the period tested artisanal acumen in the analysis of tensional stress and outward thrust. Filippo Brunelleschi's (1377–1446) pioneering octagonal duomo atop Santa Maria dei Fiori in Florence featured a double-shelled dome, tapered walls that distributed stress to the thicker walls at the base, and a wooden chain that fortified the structure precisely at the point where tensional strain was greatest. A number of engineers consulted on the challenges posed by the even larger and higher circular dome of St. Peter's in Rome, finally completed under Michelangelo Buonarroti (1475–1564). In designing St. Paul's Cathedral in London, Christopher Wren (1632–1723) drew on structural ideas provided by the Royal Society's curator, Robert Hooke (1635–1703). By the beginning of the eighteenth century, rules for the proportioning of a masonry dome were available through the Swiss architect Carlo Fontana (1634–1714), and an easy geometrical construction for determining the thickness of abutments known as "Blondel's Rule" widely applied. The French mathematician Philippe de la Hire (1640–1718) investigated dome equilibrium from the point of view of theoretical statics. Three mathematicians, hired to analyze the cracks in St. Peter's dome in 1742–1743, partially employed de la Hire's work, but it seems to have been little utilized by practicing engineers.
Arched bridges were also a favorite form for experimentation by early modern engineers. Their construction was detailed by technical experts from Leon Battista Alberti (1404–1472) to Jean Rodolphe Perronet (1708–1794). Some of the most acclaimed examples of early modern engineering are bridges, such as the Rialto Bridge in Venice (Antonio da Ponte, begun 1588), Santa Trinità in Florence (Bartolomeo Ammannati, begun 1567), and the Pont Neuf in Paris (Jacques Androuet and Guillaume Marchand, begun 1578).
Galileo Galilei (1564–1642), himself trained as a military engineer, attempted to address some of the problems posed by structural engineering mathematically in the first half of his Discourses on Two New Sciences, devoted to material strength. The "new" science presented ways of determining the tensile strength of beams and ways of proportioning machines in larger scales. Galileo also discussed the subject of centers of gravity, a subject that had been developed by mathematicians Luca Valerio (1552–1618) and Federico Commandino (1509–1575), as a key to determining the equilibrium of rigid systems. This approach, rooted both in engineering practice and the Archimedean revival so influential to Renaissance engineers, contrasted dramatically with the prevalent Aristotelian approach to materials.
Water supply and fountains. Water was supplied to city residents through aqueducts or pipes. Raising enough water from nearby river sources with pumps was a constant occupation of engineers. One of the most ingenious pumping stations was constructed in 1602 by the Flemish hydraulic engineer Jean Lintlaer, whose water-wheel-driven pump, constructed under the Pont Neuf, could rise and fall with the level of the river.
Lintlaer had been hired by Henry IV (ruled 1589–1610) not only on behalf of Paris, but because the king wanted to improve his gardens. The baroque fountains that engineers designed for the gardens of very wealthy houses across Europe were largely inspired by the work of the ancient engineer Hero of Alexandria. Hero had used the natural flow of water, the effects of air pressure and steam, and the creation of a vacuum to achieve delightful effects, such as the playing of music or operation of mechanical birds. Hero's Pneumatica was translated numerous times between 1575 and 1700, many vernacular editions brought out by engineers. The book not only inspired technological marvels, but set out a newly revived matter theory. Hero maintained that the air was elastic, and was composed of tiny bits of matter separated by vacua, a theory discounted by traditional Aristotelians.
The professions of water management assumed ever greater attention in the early modern period. Hydraulic engineering was necessary not only to raise water for drinking and fountains, but to drain and reclaim wetlands, dredge ports and harbors, build canals, and turn mills for industry. In Venice, a sea-empire into which several rivers flowed, nine out of ten patents were requested by inventors of machines that could control or utilize water. The various demands on waterways could also conflict. Too many mills constructed on a river would hinder commercial traffic, or even drinking water delivery. A river diverted to serve the needs of one town might render another town's waterways unnavigable.
The leaders in hydraulic engineering were the Dutch, who had developed their expertise through long experience maintaining their below-sea-level landscape with dykes, dredging machines, and canals. Regarding the interrelation of hydraulic works and Dutch government, the English poet Andrew Marvel quipped, "To make a bank, was a great plot of state/Invent a shov'l and be a Magistrate." Indeed, administrative skills were often an indispensable requisite for engineers who directed the huge labor force that large water management schemes demanded.
Land reclamation. Europeans began to drain the wetlands of alluvial plains beginning at least in the twelfth century. In the sixteenth century, the desire to create productive land from the swampy river valleys was translated into capital investment. Olivier de Serres (1539–1619) gave full attention to the conversion of marshlands into arable rents in his Théâtre d'Agriculture. Sixteenth- and seventeenth-century land improvement schemes were carried out from Andalusia through Italy, the Languedoc, the lower Rhône, and the fens of England. The latter was a favorite project of James I (ruled 1603–1625) for which he hired the Dutch engineer Cornelius Vermuyden (1595?–1683). The reclaimed land fell to the control of regional noblemen and investors, and head engineers were sometimes given grants from them.
Ports, rivers, and canals. Rivers and tidal ports prone to silting required periodic dredging. This was usually accomplished with bucket or scraper dredgers. Ports often needed seawalls or the installation of locks. Salvage operations were also a matter of import to the state and to entrepreneurs, as wrecked ships blocked harbors. Sometimes, inventive but ultimately inefficacious schemes were conducted, such as the attempt of Bartolomeo Campi (1525–1573) to raise a sunken ship in the Venetian lagoon with a machine built on two caissons, on Archimedean hydrostatic principles suggested by the mathematician Niccolò Tartaglia (1500–1557). However, the use of diving bells and diving suits, such as those developed by the mathematicians Giovanni Alfonso Borelli (1608–1679) and Edmond Halley (1656–1742), were the more promising means of removing wreckage.
Rivers and their tributaries were constantly diverted, channeled, or dammed in order to irrigate land, avoid flood, or improve navigation. Engineers reinforced banks with piers and the planting of trees and straightened and deepened numerous tributaries. The greatest boon to intracontinental navigation was the development of canal locks.
The invention of the lock was of signal importance to commerce and communication. The construction of intercity turnpikes and well-drained roads did not accelerate until the second half of the eighteenth century. Systems of canals, however, greatly extended alluvial navigation beyond the paths of naturally navigable rivers, and made possible commercial transport between many more cities. Canal waters were also employed to turn the water wheels that powered numerous mills.
While single gates had been employed in regulating water flow, the first lock, with gates at either end of a short section of the canal, appears to have been constructed by Bertola da Novate in the mid 1450s. Bertola, commissioned by the Duke of Milan, Francesco Sforza (ruled 1450–1466), to enlarge the Berguardo Canal, devised the scheme by which boats could ascend or descend the elevation of the waterway in a step-wise way by lifting one gate to fill or empty to the level of the subsequent section of canal. In seventeenth-century Netherlands, where canals had defined the landscape since the Middle Ages, new intercity canals were dug that carried passenger traffic on horse-drawn boats. England almost doubled its river navigation in the second half of the century, from 685 miles to 1160 miles. In France, the ambitious project to connect the Mediterranean with the Atlantic by canal, originally promoted by Leonardo da Vinci in the service of Francis I, was half completed with the Canal du Midi in 1681. Beginning in 1642, the foodstuffs of the Loire Valley could be carried to Paris via a canal that included thirty-five locks, and featured a seven-rise staircase of consecutive locks. The fortifications chief, Sébastien le Prestre de Vauban (1633–1707), extended the canal system through Belgium.
Hydraulics and mathematicians. Attempts to systematize the artisanal knowledge of hydraulic engineering within a more learned framework were available by the seventeenth centuries in the work of Alvise Cornaro (1484–1566) and Simon Stevin (1548–1620). Although Stevin was a preeminent mathematician, his hydraulics did not significantly depart from contemporary engineering practices. The work of Galileo's pupil Benedetto Castelli (1577–1644), in response to Papal plans to (re)divert the Reno into the Po flowing past Ferrara, extended the geometrical study of motion to waters. While Renaissance engineers like Leonardo had grappled with questions of water velocity, Castelli carved out new territory in his 1628 On the Measurement of Running Waters (Della misura dell'acque correnti). Castelli articulated the law of constant flow, that a river discharges equal quantities of water in equal times, regardless of the size of the cross-section. While this work had little direct effect on practice, the science of fluids was studied intensively over the next century. Fluid mechanics was developed experimentally by the French physicist Edme Mariotte (1620–1684), and the mathematician Daniel Bernoulli (1700–1782) formulated the relationship between the density of fluid in a pipe, its speed and pressure. By the eighteenth century, figures such as the mathematical professor and hydraulic engineer/government administrator Giovanni Poleni (1683–1761) were not rare.
Early modern engineers constantly designed and redesigned the wheeled machines that lifted stones for building; pumps that drained mines and swamps and raised water for drinking or ornamental fountains; and a vast array of machines that milled wheat, crushed minerals, lifted hammers, beat cloth, and operated the bellows of the new iron blast furnaces. Until the employment of the steam engine in the eighteenth century, the power of these machines was either a water wheel, a human-turned treadmill, winch, capstan, or crank, or an animal-turned device such as the horse whim. The cam, which translated rotational motion into vertical motion, was greatly developed by sixteenth-century engineers and was of huge industrial import. Printed machine books produced by Agostino Ramelli (1531–c. 1600), Jacques Besson (1540–1576), and Vittorio Zonca (b. c. 1580) demonstrate how combinations of toothed wheels, worm gears, crown gears, and lanterns might redirect motion in various ways. The treadmill that powered a sixteenth-century crane employed several men running on the inside of a huge wheel; due to gearing and other improvements, eighteenth-century cranes were smaller and could be turned externally with a crank.
With the mutually reinforcing developments of mining, metallurgy, and steam engines, the mechanical engineer had, literally, to retool. The new steam engines were first used in the drainage of mines; the new product of cast iron found one of its premier uses in the cylinders used on the steam engine. While engineers had increasingly employed metal in eighteenth-century machines, its wide adoption in the final years of the eighteenth century not only added strength, but also made precision, industrial tooling possible. The circle around the steam-engine moguls James Watt (1736–1819) and Matthew Boulton (1728–1809) procured watchmakers and other artisans skilled in machining gears. With the invention of the industrial lathe in 1716 by Christopher Polhem (1661–1751) of Sweden, its development by Jacques de Vaucanson (1709–1782) and others, and the 1776 cylinder-boring machine of the ironmaster John Wilkinson (1728–1808), it became possible to produce machines that produced machines.
ENGINEERS, SCIENCE, AND PROFESSIONALISM
Throughout the early modern period, civil engineers were artisans of more and less learning, or mathematicians of more and less experience. The relationship between the practices of engineering and the new mathematical sciences of mechanics and hydraulics, however, was never unidirectional or static, nor was it easy to generalize. The engineer and machine book author Agostino Ramelli wrote an elaborate preface insisting on the necessity of mathematics as the foundation for machine design. On the other hand, practicing engineers often resisted the advice of mathematicians employed as consultants and sneered at theoreticians. In both cases, the relationship seems rhetorically constructed. Only in the eighteenth century did a more stable professional identity for engineers emerge, as technical education was formally organized and the social role of the technical expert more clearly defined. By that time, the sciences of rational mechanics and hydrology had developed within the framework of engineering problems.
John Smeaton (1724–1792) was the first Englishman to adopt the title "civil engineer." Although he was trained, as were many engineers, as a millwright, Smeaton performed systematic experimentation on the superior efficiency of overshot waterwheels, engaged in investigations regarding Leibnizian and Newtonian mechanics, and advocated a more rigorous technical education. The leaders in the establishment of the latter were the French.
In keeping with the rational systematization of absolutist, Enlightenment France, the Corps de Ponts et Chaussées was founded in 1719 to organize the network of roads and waterways throughout the country. Members of the corps tested the bending of various materials and invented machines for compression tests on stone and mortar; Henri de Pitot (1695–1771) invented the Pitot tube, by which the velocity of a current could be taken. The corps also founded a school. Cadets would have available to them the textbooks of Bernard Forest de Belidor (1697–1761), books reprinted so often that the copper plates wore out and had to be reengraved in the early nineteenth century. There was nothing new or cutting-edge in these handbooks, but they offered both traditional guidelines of practice and the possibility of applying static and dynamic theorems to practical problems. The French engineering organizations were the apotheosis and production line for engineers who could combine knowledge, machines, and the organization of human labor in order to fulfill corporate demands for huge undertakings.
See also Architecture ; Cities and Urban Life ; City Planning ; Communication and Transportation ; Galileo Galilei ; Henry IV (France) ; Hooke, Robert ; James I and VI (England and Scotland) ; Leonardo da Vinci ; Mathematics ; Mechanism ; Michelangelo Buonarroti ; Newton, Isaac ; Technology ; Wren, Christopher .
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