Saturday, January 28

How medieval cathedrals were built


The tallest building on the planet today and since 2010 is the Burj Khalifa, in Dubai, United Arab Emirates, with 828 meters. The building that held the title for the longest time, no less than 3,800 years, is the Pyramid of Cheops. Its 138 meters in height were not surpassed until 1311: the achievement was achieved by the Gothic cathedral of Lincoln (England), which had begun to be built in 1185 and reached 159 meters in height, but its spire collapsed in 1594. The next building The tallest was Strasbourg Cathedral in France, completed in 1439 and with its 142 meter bell tower it held the record until 1874.

In the two and a half centuries that elapsed between the beginning of the cathedral works in Lincoln and the end in Strasbourg, there was an intense competition throughout Europe: cities and even towns sought to make the tallest, most voluminous cathedral (like that of Amiens , designed in 1220 to house the 20,000 inhabitants that the city then had), the largest, the most impressive and the one that best displayed divine glory.

In the construction of medieval cathedrals, which has also been the subject of various myths and fantasies, the engineering heritage of Greece and Rome converged, on the one hand, innovation in theoretical and practical procedures, access to suitable materials and an abundant labor force. and qualified in the various disciplines involved. And, of course, the favorable disposition of the entire population that could wait decades, sometimes centuries, to see the finished cathedral that would give glory to the deity… and to the city, thus exhibiting true feats of engineering that to this day cause the astonishment of the visitor and the interest of engineers, architects and scientists from different areas.

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Cranes from Greece

The creators of the cranes as a way of lifting heavy weights were the Greek architects. Although the
wooden cranes they have not left remains that can be studied, around 515 BC. There were already large stones with holes made to use systems such as ‘lewissons’, a kind of metal clamps that use the weight of the stone to secure it and lift it with a crane. These machines then replaced the ramps used to move large stones. The documents of the time speak of the use of winches and pulleys on the cranes, operated by men or animals, such as donkeys and oxen. The cranes placed on rollers, could also move horizontally, a system that was used for the construction of the Parthenon. These machines were improved and evolved by the Romans for their buildings and perfected in the Middle Ages, especially in their drive, by animal or human traction using large squirrel wheels as well as windlasses and levers.

A 14th-century wheeled crane has survived to this day in the bell tower of Chesterfield Church, which was completed around this time. It is currently in a city museum.

Reconstruction in Bonn (Germany) of a Roman wheel crane.

A key element in the progress of the cranes was the use of sets or groups of pulleys called ‘hoists’, which are until today the best way to multiply the lifting effort. From the single to the double, triple and quintuple pulley, the load capacity of the cranes really depended only on the resistance of its wooden structure.

The arch and the wall

The pillars and beams of the Greeks, which supported their buildings, were replaced in Roman engineering by
Round arches, semicircles that distribute the weight they support towards their pillars. The Middle Ages developed an ingenious solution, the pointed arch, with two wider circle segments meeting at the top at an angle. They are the typical arches of Gothic architecture and, being more resistant and better distributing the weight, they allowed the construction of vaults much higher than their predecessors. As in the case of Roman arches, these were raised on wooden falsework that allowed the stones or voussoirs of the arch to be placed. When these were fixed, the falsework was removed.

Pointed arches in the Cathedral of Santa María de Vitoria. /

QUINTAS / CATHEDRAL FOUNDATION

A clear objective of the cathedral builders was to have narrower walls than those that had been used in Romanesque architecture or that were common in other buildings such as castles. Light walls that could be supported by the new arches and in which wonderful stained glass windows were integrated that illuminated the temple only with sunlight. But it was seen that these walls, however, tended to give way under their own weight, and the builders developed the buttresses, columns attached to the wall by inclined elements called flying buttresses that directed the effort of the weight away from the temple and prevented the walls from collapsing. they won

stone and glass

Since the Greeks, cranes have facilitated the transition from using large stones to using smaller ones and in larger quantities. These stones came from both older buildings and quarries, often located far from the cathedrals under construction. To facilitate the work, in the quarries the stone was not only cut, but also roughly shaped or carved into its final shape as it was to be used according to the builder’s instructions.

The
colored glass, which the Greeks and Romans were already producing in small quantities, suffered a true technological explosion with the need to illuminate the interior of the cathedrals. The glass was produced with sand, potash from burned wood and different metals that gave different colors. A curious detail is that the glass is naturally green. To make it transparent, manganese had to be added. Other metals used, in oxide form, were copper for a bluish green, cobalt for a deep blue, gold for red or violet, silver for shades from yellow to deep orange, and various mixtures to complete the color palette. of the glass.

The Notre Dame fire

On April 15, 2019, a fire broke out in the iconic 12th-14th century Parisian Notre-Dame cathedral, destroying its oak and lead roof and its 93-meter-high spire, which dated from 1859. Despite how fierce the fire was, the walls, the arches and its famous stained glass windows survived without damage, as a testimony to the skill of its builders.

The triumphs and resounding failures in the construction of medieval cathedrals were the basis of what would later be the engineering and numerous knowledge with which today we make taller, safer and more efficient buildings… but probably not as beautiful as the cathedrals of the past. medieval


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