Advances in Construction and Building Design during the Eighteenth Century

Overview

For building design and construction, the eighteenth century represents a period of transition. Engineers and architects, formerly lumped together, assumed separate identities and functions. The increasing complexity of buildings and bridges helped to spur training for architects, engineers, and builders, who until then had little formal instruction. Substituting design and calculation where rule of thumb and practical experience had been the order of the day meant that expert knowledge could be codified and formulated. These developments helped to give substance to Enlightenment notions of progress.

Background

In 1768 John Smeaton (1724-1792) described himself as a civil engineer and began a new vocation. From the earliest times up through the Middle Ages, public works such as the construction of aqueducts and harbors were carried out by armies and their captives. The technology was based on experience of trial and error, passed on by word of mouth. With time, interest in the underlying principles of construction grew, and by the eighteenth century engineering was a developing science in Europe.

In France in 1716, workers trained specifically to work on practical problems set by the government formed the Corps des Ponts et Chaussées. In 1746, a school was formed to supply recruits to the Corps. Toward the end of the century, polytechnic schools specializing in engineering were founded in Paris and Berlin, though it would be two decades before such schools appeared in Britain.

Bernard Forest de Bélidor (1697-1761) began his career as a professor of mathematics. After serving in the War of the Austrian Succession, Bélidor settled in Paris, where he took to writing books for artillery cadets and engineers. However, with La science des ingénieurs ("Engineering Science," 1729) and Architecture hydraulique ("Hydraulic Architecture," 1737-1739), he turned his attention to mechanical problems involving transport, shipbuilding, waterways, water supply, and ornamental fountains. Little in these books was original, but they served as a call to builders to base design and practice on the science of mechanics. Bélidor's volumes influenced generations of architects, builders, and engineers, among them the first two generations of engineers who could also be considered scientists.

Since ancient times, canals have been used to transport passengers and goods inland, and for drainage and irrigation purposes. Locks were most likely invented in Italy, as early as 1440. Knowledge of canal building was brought to France by Italian engineers during the 1600s, and by the end of the 1700s, France had many hundreds of miles of canals for navigation. Some of the greatest French engineers of this period made their names in designing canals and improving rivers. In Sweden, canals made it possible to connect the North Sea with the Baltic by way of several inland lakes, bypassing a long and dangerous sea route.

Throughout the 1700s, road making as a profession was unknown. Daniel Defoe's (1660-1731) A Tour through the Whole Island of Great Britain (1724) does not stint on the sorry state of British roads. France was probably the first country to realize the value of a good system of roads. The engineer Pierre Marie Jérôme Trésaguet (1716-1796) introduced innovations in construction, and revised the system under which French roads were built and maintained. The modern French highway system was completed during this period. The first turnpike in America, connecting Philadelphia to Lancaster, was built between 1792 and 1794.

The first road roller was built and tested in France on the eve of the French Revolution, in 1787, but the machine did not come into practical use until a generation later, and then first in England. Rock asphalt was discovered in Switzerland in 1712, but not used for pavements until the first decades of the nineteenth century.

Until the eighteenth century, bridges were built of stone or, less often, wood. Gradually iron began to be used in combination with wood. In 1739, the young Swiss-born engineer Charles Paul Dangeau Labelye (1705-1781) was the first to use caissons, which are watertight structures, in constructing the foundation for the first pier of Westminster bridge.

French bridges of the era were particularly noted for their elegance and increasing refinement in construction. Advances introduced by the engineer Jean Rodolphe Perronet (1708-1794) included reducing the thickness of piers and using flat arches. The building of the Pont de Neuilly over the Seine River in Paris required 872 workers and 167 horses. This bridge was the first to employ a horse-drawn mortar mixer.

American timber bridges combined arches and trusses in innovative ways. Timber bridges were also built in Europe. A major advance in bridge building was Abraham Darby III's (1750-1791) construction of the first iron bridge in England, between 1775 and 1779. Since the invention of the arch, the only innovation had been the use of timber frames. The bridge was built to replace the ferry over the Severn River, and had an arch of cast iron that spanned more than 100 ft (30 m).

Between 1759 and 1761, a self-taught mechanic named James Brindley (1716-1772) built the first modern canal in England and earned himself the title of father of the British inland waterways. The canal featured several innovations that were ridiculed at first, including an aqueduct bridge and a mile-long tunnel at one end that penetrated into the Duke of Bridgewater's coal mines at Worsley. In America, where by the end of the eighteenth century the science of civil engineering was still all but unknown, public improvements were slower to appear. A decade after the Revolution, the country could boast only three very short canals.

One of the first applications of the steam engine to supply water to dwellings was undertaken in 1787 in London. In France, until the nineteenth century, availability of water to the public was limited to fountains in public squares. In 1776, two French mechanics formed a company to supply Paris with water pumped from the Seine by steam. They obtained their engine from the English company that made it. Their intent was to supply water to public fountains for the poor and to private residences for those who could afford it. But the company failed in 1787. In America in 1796, water was brought to Boston through wooden pipes from Roxbury. Boston was the first city in America to have a public water supply. The first efforts to pump water for a public supply occurred at the waterworks in Bethlehem, Pennsylvania. The use of steam for pumping water and of cast iron for water mains were introduced in Philadelphia at the close of the century.

Aqueducts built in Lisbon, Montpellier, and Wales during this period were notable mostly for their beauty. Cast iron piping to carry water was used in England early in the eighteenth century, but not extensively. By the middle of the century, such pipes were in use in several French cities. Early innovations in cast-iron piping were introduced by British engineers. These included the first bell-and-spigot water pipes.

By the end of the eighteenth century, Paris had 16 mi (26 km) of sewers. The main beltline sewer was connected to a major aqueduct, which made possible the development of highclass residences and eventually modern Paris. In London, sewers laid in the mid-seventeenth century drained directly or indirectly into the Thames River, with undesirable consequences for public health.

The prevalence of waterways for travel and shipping up to the nineteenth century meant that ships had to be warned of dangerous coastlines and harbors protected from storms. John Smeaton's Eddystone Lighthouse, built between 1757 and 1759, featured interlocking masonry. In 1783, the French engineer Louis Alexandre de Cessart (1719-1806) commenced construction of a breakwater to protect Cherbourg Harbor. Dredges were used to deepen steam channels. In 1796, a four-horse-power Watt steam engine was used to operate a dredge in England for deepening Sunderland Harbor. The engine was designed to operate four "spoon" dredges that each raised a ton of earth 10 ft (3 m) high in one minute.

Up until the middle of the eighteenth century, lime was a standard material used in building. A problem in using it for foundations was that it would not always harden under water. Although various materials were used as hardeners in a process of trial and error, in 1756 John Smeaton found that adding clay in sufficient quantities would cause limestone to harden, although he did not understand why it worked. In 1796 it was discovered that water added to a fine powder of a clay called Sheppy stone generated a material that would harden very rapidly, even under water. The product was patented as "Roman" cement.

The production of cast iron in the sixteenth century led to widespread destruction of forests because of the need for charcoal used in smelting. In 1709, Abraham Darby II (1711-1763) was the first to use coke as fuel in the process, which made possible large-scale production of iron. Wrought iron made its appearance during the Renaissance, but the first rolling mill for iron dates from the early eighteenth century in England.

Impact

The closing years of the eighteenth century saw a move from an approximation of the world to what one scholar has called the "universe of precision." Up to that time, in the world of everyday reality, nature always got the better of man. Builders had exhausted the limits of geometrical reasoning and gauging dimensions by what they could see. There was no systematic body of knowledge to draw on. Technical engineering books were largely based on architectural treatises. Nature and people were at loggerheads.

The move in the 1700s to ground engineering in mathematics freed mathematics as a tool to be used in practical calculations. Moreover, investigations into the forces of nature, and the chemistry of materials, meant that engineers could begin to have a degree of technological control over their constructions. Just as improvements in surveying techniques led to better maps, which made it possible to plan cities, the scientific basis of engineering made it possible to model roads, bridges, and houses before building them. The full impact of these developments, however, was not realized until the nineteenth century.

GISELLE WEISS