True Arch: A Quantum leap in architecture

In the two earlier pieces we have tried to trace the journey of one element of architecture — the technique of spanning space — from its earliest incarnations in forest dwellings to its evolution into the Trabeate and then into the Corbelled arch. We have also tried to connect the evolution of these elements to the techniques of building that were in use when these architectural devices evolved.

We now come to a time when everything suddenly, well almost, suddenly changed. This change was heralded by the arrival of the True Arch. In architecture, as in all evolutionary developments, what appears sudden is a qualitative transformation resulting from slow and gradual quantitative changes that have been accreting gradually. So, the appearance of the True Arch is in fact the result of a series of developments and changes that eventually lead to an almost revolutionary transformation, not only in techniques of construction but in adoption of absolutely new materials and devices and the repositioning of age-old materials from playing a fringe role in construction to assuming centre stage.

Among the earliest users of the True Arch were the Romans and it is commonly believed that the arch evolved during the time of the expansion of the Roman Empire. Among the most common early use of the True Arch was as the base of Roman Aqueducts.

Perhaps the earliest evidence of the arch in Asia will be found in areas of Greek influence that were later captured by the Romans. One of these is the picturesque site of Ephesus, the Greek City, dating back to 10th century BCE, located within 3 kilometres of Seljuk in the Turkish district of Izmir and 30 km from the popular Turkish Cruise Ship Port of Kusadasi. Ephesus reached its maximum expansion during its control by Romans more than 100 years before the start of the Common Era and it is here that one finds several True Arches that were perhaps added to earlier structures during the time of Roman control.

Before proceeding any further, it might be a good idea to explain the difference between a True Arch and its immediate predecessor the corbelled arch. The corbelled arch as we had mentioned in the piece last week consisted of a series of large blocks of stone between the post and the lintel of the Trabeate, in such a way that the projecting slabs extended closer and closer to the opposite post while supporting the lintel from below. The corbelled technique relied on building with large blocks of stone fitted into each other and believing that the weight of massive blocks gave strength to structures. This style made minimal or almost no use of binding materials.

The True Arch drew strength from the fact that the central or Key stone took the load of the superstructure and shifted it sideways and gradually the load was transferred onto the post. The new technique used smaller pieces of stone and relied on limestone or brick and limestone mortar, the stones that formed the arch were not wedged inside the wall as in the case of the corbelled arch but were stand-alone wedges that sprung from the posts and were held together because of the Key stone.

The first use of the True Arch in India is perhaps in the mausoleum of the last slave king Ghiyas-ud-din Balban in 1287. The Turks were familiar with the True Arch for much longer, in fact Emperor Septimius Severus rebuilt the provincial city of Byzantium in 203 CE and endowed it with a Hippodrome — a course for horse racing, I have seen a fully preserved True Arch in one of the walls of the Hippodrome and there will be more. The True Arch existed in Ephesus from at least the 1st century of the Common Era and at the capital city from 200 years earlier and the Turks could not have been unaware of the form.

The presence of Turks in India dates back to 1192 and yet the first arch is used only 95 years later in 1287. Was it because the indigenous builder and mason were reluctant to use this new form and the technique of building with rubble and cementing the entire thing together with this new plaster of slaked lime and crushed bricks that the Turks had introduced? It would appear so and it is this that explains the false arches of the Jami Masjid at Qutub, the arches at the Mausoleum of Nasir-ud-Din Mehmood — the elder son of Iltutmish and at the mausoleum of Iltutmish. The shape of the True Arch is there, but the builders have cleverly shaped corbelled arches to make them look like a True Arch.

How did the True Arch and the Corbelled Arch coexist over the next few centuries? The emergence of the Dome and the transformation that the Arch and the Dome brought about in the way we built will be discussed in the concluding part of this mini-series.

The author is a historian, and organises the Delhi Heritage Walk for children and adults