|The Architecture of London: Part One – English Romanesque.|
by Stephen Montgomery
Plan of the third floor in the White Tower showing St John’s Chapel
However, following the fall of the Roman Empire, there was a sharp decline in the knowledge of the building arts. Pockets of excellence were to b found only in those places where Byzantine art had survived. The architects of early Church aspired to great buildings but there was a great disparity between these and the means which they used to carry them out. Unlike the Greeks, they did not quarry fine marbles and they had so lost the engineering knowledge of the Romans that they were unable to construct great vaults and domes of concrete. They were compelled to experiment with small stones, loose rubble and bad mortar. However, the experiment and the ceaseless fight to correct the instability of their buildings led, in the end, to that ‘live’ architecture where each part of a building owes its stability to another part which stands ready to counteract its tendency to fall. This is in total contrast to the previous Greek and Roman methods of construction.
The development of the aisled basilica into what was to become the grandeur and beauty of the Romanesque church was achieved by tow or three simple stages. The first concerned the development of the nave. This was often higher than the side aisles and its walls were supported by the two rows of columns which separated the nave and aisles. Very often the columns themselves were taken from the ruins of classical buildings and were placed close together in order to support a continuous entablature in the traditional manner. However, they soon found it easier to construct arches from one column to another to arrive at the structure now know as a nave arcade. That of the Old St Paul’s was a very fine example as can be seen in the drawing by Hollar which was made before the Great Fire of 1666.
The nave from Old St Paul’s
The architects at first hesitated to allow the arches to spring from the capitals of the columns themselves and they were therefore built over the entablature. However, they were soon brought onto the columns which therefore demanded a change in the shape of the capital. This gave birth to the cushion capital which was to become the most characteristic feature of the Romanesque style. It can be seen to excellent effect in St John’s Chapel in the Tower of London.
The south aisle in St John’s Chapel
The next development was to vault the roofs of the nave and aisles. The method adopted was the construction of a semicircular barrel vaults of stone. This worked well for the smaller aisles but was less frequently successful in the nave. St John’s chapel again provides a good example of a successful attempt. The technique involved the construction, beneath the line of the main vault, of walls which were pierced with small round-headed windows. Whenever the height permitted, the wall between them and the nave arcade was again pierced by a second series of openings into the aisle roof. These two ranges of openings are called respectively the clerestory (clear story) and triforium.
The nave and apse of St John’s Chapel
The Nave arcade, clerestory and triforium form the three divisions into which the height of the nave walls were divided into the Gothic period. The external walls of the aisles had to be of a great thickness in order to support the stone vault and whenever there were windows the opening were kept small so as not to reduce the strength of the masonry. The difficult problem of roofing the portion of the church at which the nave and transepts intersected was evaded rather than solved by raising a square tower over the crossing and roofing it with wood and lead. Towers also frequently flanked the main entrance at the west end of the nave.