Iron Bridge to Eiffel Tower: Industrial Age Landmarks

The Iron Bridge at Ironbridge Gorge

The Iron Bridge was conceived and erected for the extremely pragmatic purpose of allowing travelers and tradesmen to cross the Severn Gorge, which is part of the River Severn at Ironbridge Gorge. Prior to its construction, the only way to cross this river was by ferry. The Iron Bridge is located in the village of Ironbridge, one of several villages in England's Shropshire. Due to increasing commercial traffic from the village to other parts of England, the construction of the Iron Bridge was viewed as an economic necessity and a herald of the modern period of industrialization.

The original designer of the bridge was Thomas Pritchard, whose construction plans were completed in 1775. The rest of the project was largely overseen by Abraham Darby III; Pritchard's design called for cast iron, which Darby went on to finance after Pritchard's death in 1777 (Ironbridge Gorge Museum).

The Iron Bridge is approximately 60 meters long and rises about 100 feet above water level at its central span (Images of England). It is the first arch bridge in history constructed of cast iron (de Haan). A fortuitous circumstance that enabled construction in this material — previously deemed too costly — was the availability of a nearby blast furnace, which significantly lowered the cost of casting the iron. Darby, an iron master working in nearby Coalbrookdale, oversaw the casting at his foundry. Because this bridge was the first of its kind to utilize cast iron as a construction material, there was no precedent on which to base the design and construction procedures. The smaller pieces of the bridge were cast using wooden patterns, while the larger ribs were cast with excavated moulds in casting sand. The majority of the cast-metal pieces were made individually, giving the separate components a distinct character that fused into the overall form of the bridge.

The Iron Bridge was built over a period spanning from 1775 to 1779. Although the bridge was novel in its construction approach due to its use of iron casting, it also employed more traditional methods appropriate to its pre-industrial era, including conventional masonry abutments. Darby shouldered a cost of £3,000 for the bridge's creation, largely due to the 379 tons of iron required and the fees associated with assembling the individual components.

The construction method was primarily based on carpentry, which required fastening the individually cast iron pieces using woodworking techniques such as blind dovetail joints as well as mortise-and-tenon joints. Altogether, there were 800 iron castings fitted into roughly 12 different cast types. The half-ribs, some of which exceeded five tons, were bolted together at the crown of the arch.

It is noteworthy that after the bridge was completed in 1779 (and opened for use in 1781), several defects in the craftsmanship appeared, such as cracks in the cast iron and in the masonry abutments. Many of these defects are attributed to an excess of cast iron used during construction.

The overarching significance of the Iron Bridge lies in the fact that it was the first arch bridge constructed out of cast iron. As such, the design and construction techniques developed by Darby were novel, and helped to pave the way for future cast-iron work and structures that were able to avoid many of the same mistakes — primarily using too much cast iron — in employing this type of craftsmanship. Despite its obvious defects, the Iron Bridge deserves commendation for its designers' and workers' efforts to advance the construction process by utilizing the latest technological innovations of their time.

Menai Straits Suspension Bridge

In many ways, the history of the Menai Straits Suspension Bridge is the history of its architect, Thomas Telford, who built a number of significant bridges in the United Kingdom, including the Craigellachie Bridge, the Conway Suspension Bridge, and an iron bridge at Buildwas. The construction of the Menai Straits Suspension Bridge was highly utilitarian in purpose, as it connected Wales to the island of Anglesey. There were significant economic reasons for improving transportation from the island to the mainland: the valuable cattle sold in Wales were traditionally transported by ferry, a slow method that could yield considerable profit if updated.

The Menai Straits Suspension Bridge is 98 feet tall, 39 feet wide, and 1,368 feet long. It contains eight arches. One of the principal reasons for its significance is that it is widely regarded as one of the first modern suspension bridges in existence. Several aspects of the bridge's design drew on the previous work of T. F. Pritchard and Abraham Darby, who had composed the Iron Bridge in 1779 by employing five cast-iron ribs to build a single semicircular arch. Telford incorporated this concept into an overall design principle of suspension, hanging a roadbed via wrought-iron chains over towers mired in a foundation of rock at either end.

The Menai Suspension Bridge was built over a period of six years in the early part of the nineteenth century. Telford utilized several ingenious techniques to erect this structure, not least his practice of rust-proofing the construction links by pre-treating them in warm linseed oil and drying them by stove. Furthermore, Telford made use of wrought iron as a construction material, a technique he had previously employed, as the following quotation from Colvin attests: "…as a bridge-builder he was not slow to realize the possibilities of iron, already demonstrated by T. F. Pritchard at Coalbrookdale, and his iron bridge at Buildwas was one of the pioneer structures of its kind" (970).

Additionally, Telford sought to imbue the Menai Suspension Bridge with a distinct aesthetic flair that was also highly utilitarian. The metal reinforcements were decorated with a variety of designs, and the masonry abutments reflected an artistic sensibility. In addition to combining iron with the principle of suspension, Telford's construction techniques were renowned for their picturesque appeal, prompting Kostof to remark that "Telford's distinction was to endow metal bridges with architectural grace" (599).

The primary significance attributed to Telford and his work on the Menai Suspension Bridge pertains to his merging of the relatively new principle of suspension with iron construction. Works of iron were becoming increasingly popular at the time the bridge was erected, yet this particular structure represented iron building on a larger scale than anything previously attempted — particularly with suspension techniques. Other significant aspects of Telford's work allude to the grandeur he brought to wrought-iron construction using suspension, as the following quotation from Kostof makes clear: "Telford's contribution, again, was to approach this as an architectural problem, making it feasible on a large scale" (599). It is significant that subsequent to Telford's work on the Menai Suspension Bridge, his technique of supporting structures with metal was refined into the practice of supporting structures with cables or wire ropes. The Menai Suspension Bridge can therefore be considered a forerunner of this technique.

Originally, the Crystal Palace was constructed to host the Great Exhibition of 1851, a glorified showcase of novel products from countries around the globe. To that end, a number of aspects of the building's design and construction served aesthetic as well as utilitarian purposes. Queen Victoria's husband, Prince Albert, worked in tandem with Henry Cole to organize the exhibit and to facilitate the construction of the building that would house it. The Great Exhibition was conceived for commercial purposes, so that the Crystal Palace was essentially designed as an economic tool. More importantly, the exhibit was a testament to humanity's achievements in the industrial age. The Crystal Palace was therefore created as a structure modern enough to be demonstrative of that age and of the developing construction techniques of the time, primarily the use of iron and plate glass.

The Crystal Palace was designed by Joseph Paxton, whose design was largely influenced by the greenhouses he had encountered during his previous work as a gardener at Chatsworth House. During his tenure there he first worked with the technology he would later use on the Crystal Palace: cast plate glass supporting the structure of greenhouses in combination with iron supports. Paxton was selected as the designer after the selection committee had rejected all entries from an international competition. His design was chosen in part due to the affordability and expedience with which the proposed materials — iron and glass — could be assembled. Notably, Paxton was one of only a few designers to submit a proposal based on iron and glass construction (Hitchcock 184). The engineer was Sir William Cubitt; Sir Charles Fox, who founded the engineering company Fox and Henderson, was contracted for the ironwork.

The Crystal Palace (1850–1851)

The height of the Crystal Palace's interior was approximately 39 meters; its length was approximately 564 meters and its width approximately 139 meters. The palace encompassed 990,000 square feet, with the ground floor alone covering 71,794 square meters (Hunt et al. 685).

The most significant aspect of the Crystal Palace's design is that it was built using prefabricated materials, most of which were iron. Prefabricated materials are those that can readily be disassembled and moved elsewhere, which allowed for a new mobility and flexibility in the construction process. It was also due to the use of prefabricated materials — which were relatively easy to assemble — that the construction process took less than two years. Kostof writes: "the casting process was geared to prefabrication in bulk, so that members could be shipped to the site ready-made and assembled with ease" (594). The lightness of the parts used allowed for expedient transportation of the materials, which could then be put together in a variety of configurations to suit construction purposes, a fact to which Nuttgens alludes: "there was no reason why it should not be made bigger or smaller, longer or wider" (246).

Another practical innovation credited to Paxton was his employment of an internal skeleton consisting of wrought- and cast-iron beams and stanchions. This use of iron materials helped to usher in the iron age of construction and was widely replicated by architects in the ensuing years. Iron structures were used to make the framework and columns that supported the Crystal Palace.

Several special features within the Crystal Palace alluded to Paxton's gardening background. An eight-meter-tall crystal fountain was located near the central exhibition hall; the hall also quartered a number of fully grown elm trees in a spacious park. The palace housed several cascading fountains and a pair of jets approximately 76 meters high to maintain the irrigation system. Water towers were located at opposite ends of the structure — on the south and north sides, respectively — and three reservoirs supplied the palace's cascades and foliage.

Other design innovations attributed to the Crystal Palace included the installation of public toilets for a facility of this size, which undoubtedly added to the demand for the building's water supply.

As a final tribute to the usefulness of the design principles Paxton introduced, it is noteworthy that the entire structure was dismantled following the six-month Great Exhibition and moved to Penge Place atop Sydenham Hill, where it was promptly reconstructed. It continued to host an assortment of festivals and exhibitions until it was eventually destroyed by fire in 1936.

The absence of conventional masonry techniques was readily apparent in the Crystal Palace. The building's roof was glazed and the floor was tiled with clay. Additionally, wood-framed glass sheets (Hobhouse 34) were supported by iron latticework, which typified the construction technique of this epoch. The glass was largely provided by a Smethwick, Birmingham company known as Chance Brothers, which utilized sources of labor as far away as France to fulfill what has been estimated at approximately 84,000 square meters of glass.

By utilizing the new technology of prefabricated parts, the Crystal Palace was built in roughly six months with the help of 5,000 navvies. Significantly, no more than 2,000 navvies were employed at the construction site at any one time, which further indicates the degree of efficiency Paxton achieved in his design. The original construction cost £150,000, estimated at £13.1 million by contemporary standards. After the palace was subsequently rebuilt in Sydenham, construction costs amounted to an additional £1,300,000 — roughly equivalent to almost £100 million today — due in no small part to the expanded scale of the palace. Despite the fact that many of the same construction materials were used in the updated version, rebuilt in 1854, there were definite modifications, including significantly expanded dimensions.

The erection of the Crystal Palace helped to usher in the age of iron in construction. Its liberal use of glass also served to distinguish this structure, and the epoch in construction it heralded, from the Victorian age — a fact attested to by Middleton and Watkin, who wrote that "iron and glass were not generally applicable to Victorian architectural needs" (359).

Another highly noteworthy aspect of the Crystal Palace is that it was one of the first structures of this magnitude to utilize prefabricated parts. This innovative construction technique proved instrumental in accelerating the pace at which projects could be carried out, and revolutionized the building process by allowing prefabricated parts to be disassembled and transported to erect the same structure in a different location. Worksites became more efficiently mechanized, which directly resulted in large contractors replacing the work typically done by craft guilds. Prefabricated parts also allowed for the implementation of novel internal systems, which Nuttgens addresses by stating: "the needs of industry led to the development of new technical services in heating, ventilation and sanitation, which began to be applied to domestic architecture as well" (245).

Lastly, there was a rippling effect from Paxton's innovation of internal skeletons — consisting of cast- and wrought-iron beams and stanchions — that immensely benefitted Western civilization, as his technique of creating columns out of iron would be consistently utilized by future builders. These three facets of the Crystal Palace helped to issue a revival in the field of construction following the Gothic Age, "when mass production was beginning to alter the age-old habits of the building industry" (Kostof 594).

Most significantly, however, the design, construction materials, and even the initial purpose of the Crystal Palace — to host the World's Exhibition of Industry and Commerce and a plethora of new tools utilizing cutting-edge technology — signaled a transition from the remnants of the Gothic era into the Industrial Revolution, which was a definite precursor to the twentieth century. Although considered passé by today's standards, the innovations of iron and plate glass that Paxton utilized were regarded by many as the most radical advance in building material technology since the Roman practice of using concrete in construction (Kostof 595). During the 1850s the world was definitively changing, and one of the most tangible markers of that fact was the transportable construction materials of the Crystal Palace. Although the technique for plate glass was developed in the 1840s, it was not until the 1850s that glass glazing — such as that found on the Crystal Palace roof — was made possible alongside other modern innovations such as highway construction, railroad expansion, and the proliferation of steam engine use, all of which typified the industrial age.