Journey from the arch to the dome

We have already seen that it was the Romans who first began to use the true arch to make a wall-like structure. The arches were built next to each other, the curves of adjacent arches were filled up to get a flat surface upon which were built the aqueducts to carry water from the source to the point of consumption. The next stage in the use of the arch was perhaps the innovation of placing them face to face, and we had the vaulted roof

Imagine slicing out vertical sections of this long hall and you would get a number of arches of equal size, put them together and you get a covered space that can accommodate a large number of people and all of them would see anyone who stands on a raised platform at one end. And you had the ideal location for a Church The arch made it possible to create long halls for the assembly of many people under one roof and there were no pillars, because the pillars were placed in two continuous rows to become the walls of this large hall. The weight of the roof was now placed on this continuous series of Posts, you could insert lintels to create doors and windows or you could just have one or two large doors at one or both ends. You could now build tunnels as well. Imagine standing under a vaulted roof and looking up at the ceiling. You would see a huge boat placed upside down on two very long and high walls.

The idea of a large roof without pillars might well have occurred to someone who took shelter under an inverted boat a long time ago and thus was born the idea of copying this form. In fact, the ceilings of many of Chaitya Grihas and Viharas at Ajanta are shaped like inverted boats, complete with ribs and fastening planks.

This does not, however, mean that, like plastic surgery, we invented the arch as well because we did not. The Ajanta Caves have been carved out of one huge mass of rock and there are no joints and therefore despite the shape, these are not true arches, just as the arches at the Jami Masjid of Qutub-ud-Din Aibak are only corbelled arches masquerading as true arches.

Coming back to the true arch and to the last part of this mini-series, the true arch is first used in Aqueducts, then in making vaulted roofs and tunnels, but the true arch has not exhausted its potential to surprise us by morphing into new shapes and its next incarnation was to truly transform the language of architecture.

In its conception, the change was so simple that once it happened, everyone involved would have said, “Oh but why did I not think of it” let us deconstruct the next incarnation and you would see what I am getting at.

Imagine a plastic ball, made with a slightly stiff sheet so that it would not lose its shape if it were to be cut into two halves. If you were to take one half and were to cut it into thin vertical slices, beginning at one end and carrying on till the other end, you will notice that you have arches of different sizes, put them together beginning with the smallest and gradually going up to the largest and then going through step by step to the smallest and you have constructed a dome. The dome is an agglomeration of arches of different sizes, each made of wedge-shaped stones and each with its own keystone as opposed to the vaulted roof, where each arch is of the same size.

The dome is radically different from the arch in one more aspect; each true arch has one Keystone, but in a dome, each stone is a Keystone and that is why dome builders are able to make holes at the top of the dome or to make windows on its side walls to let in light. They are able to do so because even after removing some of the stones the others hold the rest of the structure together. That is why even half broken domes are able to stand for centuries.

Incidentally, the first dome was probably built by the Romans; it was built for a secular purpose, for the meetings of the Roman Senate. This was a covered space, uncluttered with pillars, where each senator could see all the others. Judaism, a congregational religion that predates the Roman Empire, saw the potential in the architectural form. This was a form ideally suited to collective worship where one priest led the prayers and the congregation followed. The Christians and Muslims also used the dome for the same reason. One needs to remember that the dome is not Islamic, it is, in fact, pre-Christian and so all this talk of Islamic architecture is the product of Anglo-Saxon scholarship and nothing else. The largest dome in the world is at the Vatican. The Basilica of St Peter and the dome at the Capitol Hill in Washington DC too have nothing to do with Islam.

Architecture all over Europe is described as Classic, Gothic, Renaissance, Baroque, Neo-Classical or as Scottish, Irish, Welsh, French, Prussian, Slavic, Italian or Hispanic but never Christian. Strangely though, the domes and arches in Central Asia and India have always been described as Islamic architecture? The reasons for this distortion are obvious.

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