THE VAULT IN EGYPTIAN ARCHITECTURE
From French of Hassan Fathy
Egypt is a country of alluvial deposits where the lack of wood is rare and has been destroyed from the most remote times to the present day. The inhabitants of the Valley of used for their constructions, not only houses but palaces and even temples, brick dried in the sun, made of earth and straw.
(Nature herself offers this mixture to the ingenuity of the builders, when one sees after the harvest the straw mixing with the earth).
If the use of these bricks constitutes a discovery of the greatest importance for civilization, the process of using these same bricks to make a blanket, is a Helonan find, aut even more astonishing ingenuity, because these vaults and domes which were used for the roof were designed to be executed without wooden bends.
To achieve this result, the ancients imagined executing the vault in sections or slightly inclined vertical rings, the first of which rests on a head wall.
This inclination made it possible to support each ring being built on the Nach ring series of bricks previously completed.
Each ring is formed by a series of flat bricks laid in the field and touching at the small
The joint between two bricks therefore happened to be in the shape of an angle because of the curvature of the vault. To fill this gap, the first examples show that they inserted molded and dried earthen corners in advance or they stuffed them with earth mortar with shards of stone.
Later, for larger vaults, these joints were filled with earth mortar and after the completion of each ring, larger stone chips were driven into the joints, part of which remained protruding on the extrados of the vault, which favored the adhesion of the coating. All these vaults have a parabolic or chain layout, which eliminates the bending effect and reduces the thrust to a minimum.
We also find in this necropolis examples of normal voussoir vaults of astonishing perfection which go beyond what is expected of a raw brick construction.The fineness of the joints recalls the improvement of cut stone constructions.This variety of process shows that the builders were completely familiar with the principles of arch construction at a very early date.
From the time of the 18th dynasty (1500 BC), on the site of the tomb of Seneb in Guiza (6th dynasty) we find a spherical dome on a square plan.This dome is undoubtedly the oldest known example in the world. The angles do not have a well-defined architectural character, but they seem to be made up of corbels.The dome itself, of a very spherical shape, is formed of horizontal rings of bricks whose joints converge towards a point higher than the center of the dome.
This technique is found much later at the time of the full development of Byzantine art. Although this is the only known example in Egyptian antiquity, it is not a trial and error, but it shows that the ancient Egyptians knew how to build domes on a square plan.
At Deir el Medina in Thebes, we find an interesting example of a vault made of inclined sections covering the descent of a tomb where the rings are raised as they descend to give the necessary height (Fig . no. 2). The splendid vaults of the Rames-seum stores date from the time of the 19th dynasty (1300 BC) (Fig. no. 3).
These parabolic-shaped vaults have a span of approximately 4 meters and are made up of 4 layers of field brick vaults. They have admirably resisted time and despite the heaps of sand that covered them before they were cleared. There, the large span made it difficult to lay the bricks, making it difficult to reshape each ring. To facilitate the adherence of the bricks, one printed on one of their faces, during the manufacture, of the grooves in hollow which were used as suction cups and which made it possible to hold the bricks in cantilever until the completion of the ring.
In the Greco-Roman period (300 BC), as shown by the ruins of Touna el Gabal, (Necropolis of Hermopolis) directed by Dr. Bami Gabra Bey, cupolas on pendentives (known as Byzantine). The vaults were also used to support stair steps (Fig. no. 4).
In the Christian necropolis of Bagawat, in the Oasis of Kharga (4th century A.D.), we find ourselves in the presence of some 200 tombs built in a way that would seem precarious since the mud brick walls are only 35 cm high, d 'thickness. They are in an astonishing state of preservation, still keeping their vaults and domes and some have even kept their earth rendering and frescoes well. The atmosphere in these streets and house-like tombs is reminiscent of an abandoned city, which is why it has been called the Egyptian Pompeii of the dein (Fig. no. 5).
There appear new combinations of vaults and cupolas covering the same hall. In the square rooms, the domes on pendentives are supported by 4 arches built without arches following the same process by sections as the vaults described above.
For the rectangular-shaped rooms, vaults project from each end and stop towards the middle to give way to a dome on pendentives. The ends of these vaults are left with the inclination the naison intersection of their slices where the cupola occurs, causing the pendentives to taper downwards from their birth. The two eardrums of the dome, on the side faces of the room which remain vertical, make it possible to make windows higher than the birth of the vaults.
It should be noted that to reduce the thickness of the dome above the outer walls, the masons of Bagawat resorted to the following process:
They made bricks of 27cm x 23cm x 7cm, Below the pendants. the thickness of the dome is given by the 27 cm of the length of the bricks and above, it is also given by the 23 cm of the width of these same bricks. which makes it possible to obtain the two different thicknesses by a simple arrangement of the same brick.
During the 10th century, we see in the Fatimite necropolis near Aswan, these same vaults in inclined sections, combined with trumpet domes. These domes have a more elongated shape and sometimes have flutes of varied decorative shapes. They show greater mastery of construction. (Fig. No. 6).
The Kaah of El Dardiri dates from the same period. The 2 Iwans of the Kaah arranged symmetrically on each side of the central Dourkaa have a span of approximately 6 m and approximately 15 m. from above. To avoid bending, the vaults of the iwans were built up to a certain height cantilevered and completed using the inclined slice process. The vaults of this monumental Kâa are built of fired bricks. In the 12th century, there is still a fine example of this construction in the Coptic monastery of Wadi Natroun (Fig. No. 7).
### The arts of the Byzantine and Muslim Orient developed the construction processes for vaults and domes by introducing new elements, such as groined vaults and other intersection vaults, long-span dome, built in fired bricks as well. than in cut stones (Mamluk period). This is no longer the subject of our study which only concerns the construction of vaults and domes executed without bending. These construction methods find their application in our current economic and technical conditions for projects of large extension of peasant and worker housing. This would minimize the cost of construction and use local labor and materials.
These methods of construction are still in use in Upper Egypt and Nubia and are still employed by generations of masons who have passed them on since the highest antiquity. This tradition tends to disappear due to the lack of interest that technicians take in these processes which, however, can solve a large number of problems concerning the coverage
Our efforts tend to reimplement them and to draw from them all the practical and artistic possibilities. Such methods prove to be applicable not only in Egypt, but also in any country in similar conditions.
HASSAN FATHY
