lundi 15 août 2011

“Techniquement parlant, une simple pyramide n’est pas une œuvre d’une grande difficulté” (George Rawlinson - XIXe s.)

Une note de ce blog a déjà été consacrée à l’historien et orientaliste britannique George Rawlinson (1812-1902) : L’extraordinaire “progrès” de la Grande Pyramide, selon George Rawlinson.
Dans son ouvrage History of Ancient Egypt, vol. 1, 1881, il complète sa description des pyramides égyptiennes, sous l’angle de l’évolution architecturale.
On pourra prêter une attention toute particulière aux observations de l’auteur sur le “mérite architectural” des pyramides. Selon George Rawlinson, empiler des blocs de pierre les uns sur les autres ne représentait pas une performance extraordinaire : ce n’est pas dans cette phase du chantier de construction que les bâtisseurs égyptiens démontrèrent l’originalité de leur savoir-faire. Par contre, ce ne fut plus le cas lorsqu’il leur fallut construire des couloirs et des chambres à l’intérieur des monuments. C’est dans cette particularité technique que les pyramides sont des chefs-d’oeuvre “insurpassés et probablement insurpassables”.

“The origin of Architecture, in the proper sense of the term, is different in different countries. In most it springs from the need which man has of shelter, and the desire which he entertains of making his dwelling place not merely comfortable, but handsome. In some this desire seems not to have been early developed ; but in lieu of it, the religious sentiment brought architecture into life, the desire which worked being that of giving to the buildings wherein God was worshipped a grandeur, a dignity, and a permanency worthy of Him.
According to Herodotus, the first Egyptian edifice of any pretension was a temple ; and, could we depend on this statement, it would follow that Egypt was one of the countries in which architecture sprang from religion. The investigations, however, conducted on Egyptian soil by modern inquirers, have led most of them to a different conclusion, and have seemed to them to justify Diodorus in the important place which he assigns, in speaking of Egyptian architecture, to the Tomb. “The inhabitants of this region, says the learned Siceliot, consider the term of man's present life to be utterly insignificant, and devote by far the largest part of their attention to the life after death. They call the habitations of the living ‘places of sojourn’, since we occupy them but for a short time ; but to the sepulchres of the dead they give the name of ‘eternal abodes’, since men will live in the other world for an infinite period. For these reasons they pay little heed to the construction of their houses, while in what concerns burial they place no limit to the extravagance of their efforts.”

Among the sepulchral edifices : the “Three Pyramids”
The early Egyptian remains are in entire harmony with this statement. They consist almost exclusively of sepulchral edifices. While scarcely a vestige is to be found of the ancient capital, Memphis, its necropolis on the adjacent range of hills contains many hundreds of remarkable tombs, and among them the 'Three Pyramids' which, ever since the time of Herodotus, have attracted the attention of the traveller beyond all the other marvels of the country. The art of pyramid building, which culminated in these mighty efforts, must have been practised for a considerable period before it reached the degree of perfection which they exhibit ; and it is an interesting question, whether we cannot to a certain extent trace the progress of the art in the
numerous edifices which cluster around the three giants, and stretch from them in two directions, northward to Abu-Roash, and southward as far as the Fayoum. The latest historian of architecture has indeed conjectured that one, at any rate, of the most interesting of these subordinate buildings is of later date than the Three ; but the best Egyptologists are of a different opinion, and regard it as among the most ancient of existing edifices. It is not improbable that some of the smaller unpretentious tombs are earlier, as they are simpler, than any of the pyramidal ones, and it is therefore with these that we shall commence the present account of
Egyptian sepulchral architecture.

Truncated pyramids (example of Meydoun)
Around the pyramids of Ghizeh, and in other localities also, wherever pyramids exist, are found numerous comparatively insignificant tombs which have as yet been only very partially explored and still more imperfectly described. Their general form is that of a truncated pyramid, low, and looking externally like a house with sloping walls, with only one door leading to the interior, though they may contain several apartments ; and no attempt is made to conceal the entrance.
The body seems to have been preserved from profanation by being hid in a well of considerable depth, the opening into which was concealed in the thickness of the walls. The ground-plan of these tombs is usually an oblong square, the walls are of great thickness, and the roofs of the chambers are in some instances supported by massive square stone piers. There is little external ornamentation ; but the interior is in almost every instance elaborately decorated with coloured bas-reliefs, representing either scenes of daily life or religious and mystic ceremonies.

It was no great advance on these truncated pyramids to conceive the idea of adding to their height and solidity by the superimposition of some further storeys, constructed on a similar principle, but without internal chambers.
An example of this stage of construction seems to remain in the curious monument at Meydoun, called by some a 'pyramid’, by others a ‘tower’ (...) This monument, which is emplaced upon a rocky knoll, has a square base, about 200 feet each way, and rises at an angle of 74° 10', in three distinct stages, to an elevation of nearly 125 feet. The first stage is by far the loftiest of the three, being little short of seventy feet ; the second somewhat exceeds thirty-two feet, while the third (which, however, may originally have been higher) is at present no more than twenty-two feet six inches.
The material is a compact limestone, and must have been brought from a considerable distance. The blocks, which vary in length, have a thickness of about two feet, and have been worked and put together with great skill.  
No interior passages or chambers have as yet been discovered in this edifice, which has, however, up to the present date, been examined very insufficiently.

Great Pyramid of Saccarah
After the idea of obtaining elevation, and so grandeur, by means of stages had been once conceived, it was easy to carry out the notion to a much greater extent than that which had approved itself to the architect of the Pyramid of Meydoun. Accordingly we find at Saccarah an edifice similar in general character to the Meydoun pile, but built in six instead of three stages. The proportions are also enlarged considerably, the circumference measuring 1,490 feet
instead of 800, and the height extending to 200 feet instead of 125. The stages still diminish in height as they rise ; but the diminution is only slight, the topmost stage of all falling short of the basement one by no more than eight feet and a half. The sides of the several stages have a uniform slope, which is nearly at the same angle with that of the Meydoun building - viz. 73° 30' instead of 74° 10'. The core of the Saccarah pyramid is of rubble ; but
this poor nucleus is covered and protected on all sides with a thick casing of limestone, somewhat roughly hewn and apparently quarried on the spot.
In the rock beneath the pyramid, and almost under its apex, is a sepulchral chamber paved with granite blocks, which, when discovered, contained a sarcophagus, and was connected with the external world by passages carefully concealed. A doorway leading into another smaller chamber, a low and narrow opening, was ornamented at the sides by green cubes of baked clay, enamelled on the surface, alternating with small limestone blocks ; and the limestone lintel, which covered in the doorway at the top, was adorned with hieroglyphics.
Among other peculiarities of this pyramid are its departure from correct orientation, and its oblong-square shape. It is said to be the only pyramid in Egypt the sides of which do not exactly face the cardinal points
The departure is as much as 4° 35', and can therefore scarcely have been unintentional. To intention must also be ascribed the other peculiarity (which is not unexampled), since the length by which the eastern and western sides exceeded the northern and southern was certainly as much as forty-three feet. According to a conjecture of the principal explorer, the original difference was even greater, amounting to sixty-three feet, or more than one-fifth of the length of the shorter sides.

Multiplication of the stages
When multiplication of the stages had once been conceived of as possible, it became a mere question of taste for the designer or the orderer of a monument how numerous the stages should be. It was as easy to make them sixty as six, or two hundred as two. Evidence is wanting as to intermediate experiments ; but it seems soon to have suggested itself to the Egyptian builders that the natural limit was that furnished by the thickness of the stones with which they built, each layer of stones conveniently forming a distinct and separate stage. Finally, when a quasi-pyramid was in this way produced, it wouId naturally occur to an artistic mind to give a perfect finish to the whole by smoothing the exterior, which could be done in two ways : either by
planing down the projecting angles of the several stages to a uniform level, or by filling up the triangular spaces between the top of each step and the side of the succeeding one.
There are from sixty to seventy pyramids remaining in Egypt, which appear to have been constructed on these principles. Agreeing in form and in general method of construction, they differ greatly in size, and so in dignity and grandeur. As it would be wearisome to the reader if we were to describe more than a few of these works, and as it has been usual from the most ancient times to distinguish three above all the rest, we shall be content to follow the example of most previous historians of Egypt, and to conclude our account of this branch of Egyptian architecture with a brief description of the Three Great Pyramids of Ghizeh. 

The smallest of the “Three Great Pyramids of Ghizeh”
The smallest of these constructions, which is usually regarded as being the latest, was
nearly of the same general dimensions as the stepped pyramid of Saccarah recently described. It a little exceeded the Saccarah building in height, while it a little fell short of it in circumference. The base was a square, exact or nearly so, each side measuring 354 feet and a few inches. The perpendicular height was 218 feet, and the angle of the slope fifty-one degrees. The pyramid covered an area of two acres three roods and twenty-one poles, and contained above nine millions of cubic feet of solid masonry, calculated to have weighed 702,400 tons.
Originally it was built in steps or stages, like the Saccarah monument ; the stages, however, were perpendicular, and not sloping ; they seem to have been five in number, and were not intended to be seen, the angles formed by the steps being at once filled in with masonry.
Externally the lower half of the pyramid was covered with several layers of a beautiful red granite, bevelled at the joints, while the casing of the upper half as well as the main bulk of the interior was of limestone.
Nearly below the apex, sunk deep in the native rock on which the pyramid stands, is a sepulchral chamber, or rather
series of chambers, in one of which was found the sarcophagus of the monarch whom tradition had long pointed out as the builder of the monument. The chamber in question, which measures twenty-one feet eight inches in length, eight feet seven inches in breadth, and eleven feet three inches in its greatest height, runs in a direction which is exactly north and south, and is composed entirely of granite. The floor was originally formed of large masses well put together, but had been disturbed before any modern explorer entered the room ; the sides and ends were lined with slabs two and a half feet thick ; while the roof was composed of huge blocks set obliquely, and extending from the side walls, on which they rested, to the centre, where they met at an obtuse angle. Internally these blocks had been caved out after being put in place, and the roof of the chamber was thus a pointed arch of a depressed character. The slabs covering the sides had been fastened to the rock and to each other by means of iron cramps, two of which were found in situ.
The sarcophagus which the chamber contained was extremely remarkable. Formed, with the exception of the lid, of a single mass of blue-black basalt, and the apex ; this was carved out of the solid rock, but covered in by the basement stones of the edifice, which were here sloped at an angle. The length of the chamber from east to west was forty six feet, its breadth from north to south a little more than sixteen feet, its greatest height twenty-two feet.  It contained a plain
granite sarcophagus, without inscription of any kind, which was sunk into the floor, and measured in length eight feet seven inches, in breadth three feet six inches, and in depth three feet.The chamber was connected with the world without by two passages, one of which, commencing in the north side of the pyramid, at the height of fifty feet above the base, descended to the level of the base at an angle of 25° 55', after which it became horizontal ; while the other, beginning outside the pyramid in the pavement at its foot, descended at an angle of 21° 40' for a hundred feet, was horizontal for sixty feet, and then, ascending for ninety-six feet, joined the upper passage halfway between the outer air and the central chamber. Connected with the horizontal part of the lower passage were two other smaller chambers, which did not appear to have been sepulchral. These measured respectively eleven feet by six and thirty-four feet by ten. They were entirely hewn out of the solid rock, and had no lining of any kind. The passages were in part lined with granite ; and granite seems to have been used for the outer casing of the two lower tiers of the pyramid, thus extending to a height of between seven and eight feet ; but otherwise the material employed was either the limestone of the vicinity, or the better quality of the same substance which is furnished by the Mokattam range. The construction is inferior to that of either the First or the Third Pyramid ; it is loose and irregular, in places a sort of gigantic rubble-work, composed of large blocks of stone intermixed with mortar, and seems scarcely worthy of builders who were acquainted with such far superior methods.

The First Pyramid

The First Pyramid of Ghizeh - the 'Great Pyramid’, as it is commonly called - the largest and loftiest building which the world contains, is situated almost due north-east of the Second Pyramid, at the distance of about 200 yards. It was placed on a lower level than that occupied by the Second Pyramid, and did not reach to as great an elevation above the plain. In height from the base, however, it exceeded that pyramid by twenty-six feet six inches, in the length of the base line by fifty-six feet, and in the extent of the area by one acre three roods and twenty-four poles. Its original perpendicular height is variously estimated, at 480, 484, and 485 feet. The length of its side was 704 feet, and its area thirteen acres one rood and twenty-two poles.
It has been familiarly described as a building more elevated than the Cathedral of St. Paul's, on an area about that of Lincoln's Inn Fields. The solid masonry which it contained is estimated at more than 89,000,000 cubic feet, and the weight of the mass at 6,848,000 tons. The basement stones are many of them thirty feet in length and nearly five feet high. Altogether, the edifice is the largest and most massive building in the world and not only so, but by far the largest and most massive - the building which approaches it the nearest being the Second Pyramid, which contains 17,000,000 cubic feet less, and is very much inferior in the method of its construction. The internal arrangement of chambers and passages in the Great Pyramid is peculiar and complicated. A single entrance in the middle of the northern front, opening from the thirteenth step or stage from the base, conducts by a gradual incline, at an angle of 26° 41', to a subterranean chamber, deep in the rock, and nearly under the apex of the building, which measures forty-six feet by twenty-seven, and is eleven feet high. The passage itself is low and narrow, varying from four to three feet only in height, and in width from three feet six inches to two feet nine. It is necessary to creep along the whole of it in a stooping posture. The sides, which are perpendicular, are formed of blocks of Mokattam limestone, and the passage is roofed in by flat masses of the same.
Above two such masses are seen, at the entrance, two stones, and then two more placed at an angle, and meeting so that they support each other, and act as an arch, taking off the pressure of the superincumbent masonry. It is supposed that the same construction has been employed along the whole passage until it enters the rock. This it does at the distance of about forty yards from the outer air, after which it is carried through the rock in the same line for about seventy yards, nearly to the subterranean chamber, with which it is joined by a horizontal passage nine yards in length. No sarcophagus was found in this chamber, which must, however, it is thought, have originally contained one.
At the distance of twenty-one yards from the entrance to the pyramid an ascending passage goes off from the descending one, at an angle which is nearly similar, and this passage is carried through the heart of the pyramid, with the same height and width as the other, for the distance of 124 feet. At this point it divides. A low horizontal gallery, 110 feet long, conducts to a chamber, which has been called 'the Queen's’, a room about nineteen feet long by seventeen feet broad, roofed in with sloping blocks, and having a height of twenty feet in the centre.
Another longer and much loftier gallery or corridor continues on in the line of the ascending passage for 150 feet, and is then joined by a short passage to the central or main chamber - that in which was found the sarcophagus of Cheops, or Khufu. The great gallery is of very curious construction. It is five feet two inches wide at the base, and is formed of seven layers of stones, each layer projecting a little beyond the one below it, so that the gallery contracts as it ascends ; and the ceiling, which measures only about four feet, is formed of flat stones laid across this space, and resting on the two uppermost layers or tiers.

The central chamber, into which this gallery leads, has a length (from east to west) of thirty-four feet, a width of seventeen feet, and a height of nineteen. It is composed wholly of granite, beautifully polished, and is roofed in a manner which shows great ingenuity and extreme care. In the first place, nine enormous granite blocks, each of them measuring nearly nineteen feet long, are laid across the room to form the ceiling ; then above these there is a low chamber, roofed in similarly ; this is followed by a second chamber, a third, and a fourth ; finally, above the fourth, is a triangular opening, roofed in by blocks that slope at an angle and support each other, like those over the entrance.
Further, from the great chamber are carried, northwards and southwards,
two ventilators or air-passages, which open on the outer surface of the pyramid, and are respectively 233 and 174 feet long. These passages are square, or nearly so, and have a diameter varying between six and nine inches.
Finally, it must be noted that from the subterranean chamber a passage is continued towards the south, which is horizontal, and extends a distance of fifty-three feet, where it abruptly terminates without leading to anything.

Many speculations

Many speculations have been indulged in, and various most ingenious theories have been framed, as to the object or objects for which the pyramids were constructed, and as to their perfect adaptation to their ends. It has been supposed that the Great Pyramid embodies revelations as to the earth's diameter and circumference, the true  length of an arc of the meridian, and the proper universal unit of measure. It has been conjectured that it was an observatory, and that its sides and its various passages had their inclinations determined by the position of certain stars at certain seasons. But the fact seems to be, as remarked by the first of living English Egyptologers, that these ideas do not appear to have entered into the minds of the constructors of the pyramids, who employed the measures known to them for their symmetrical construction, but had no theories as to measure itself, and sloped their passages at such angles as were most convenient, without any thought of the part of the heavens whereto they would happen to point.
The most sound and sober view seems to be, that the pyramids were intended simply to be tombs. The Egyptians had a profound belief in the reality of the life beyond the grave, and a conviction that that life was, somehow or other, connected with the continuance of the body. They embalmed the bodies of the dead in a most scientific way ; and having thus, so far as was possible, secured them against the results of natural decay, they desired to secure them also against accidents and against the malice of enemies. With this view they placed them in chambers, rock-cut, or constructed of huge blocks of stone, and then piled over these chambers a mass that would, they thought, make it almost impossible that they should be violated.
The leading idea which governed the forms of their constructions was that of durability, and the pyramid appearing to them to be, as it is, the most durable of architectural forms, they accordingly adopted it.
The passages with which the pyramids are penetrated were required by the circumstance that kings built their sepulchres for themselves, instead of trusting to the piety of a successor, and thus it was necessary to leave a way of access to the sepulchral chamber. No sooner was the body deposited than the passage or passages were blocked. Huge portcullises, great masses of granite or other hard stone, were placed across them, and these so effectually obstructed the ways that moderns have in several instances had to leave them where they were put by the builders, and to quarry a path round them.
The entrances to the passages were undoubtedly intended to be concealed, and were, we may be sure, concealed in every case, excepting the rare one of the accession, before the tomb was finished, of a new and hostile dynasty. As for the angles of the passages, whereof so much has been said, they were determined by the engineering consideration, at what slope a heavy body like a sarcophagus could be lowered or raised to most advantage, resting without slipping when required to rest, and moving readily when required to move.
The ventilating passages of the Great Pyramid were simply intended to run in the line of shortest distance between the central chamber and the external air. This line they did not exactly attain, the northern passage reaching the surface of the pyramid about fifteen feet lower, and the southern one about the same distance higher than it ought, results arising probably from slight errors in the calculations of the builders. 

The architectural merit of the pyramids
In considering the architectural merit of the pyramids, two points require to be kept distinct : first their technic, and secondly their artistic or aesthetic value.
Technically speaking, a simple pyramid is not a work of much difficulty. To place masses of stone in layers one upon another, each layer receding from the last, and the whole rising in steps until a single stone crowns the summit ; then to proceed downwards and smooth the faces, either by cutting away the projections or by filling up the angles of the steps, is a process requiring little constructive art and no very remarkable engineering skill.
If the stones are massive, then, of course, a certain amount of engineering proficiency will be implied in their quarrying, their transport, and their elevation into place ; but this last will be much facilitated by the steps, since they afford a resting-place for the block which is being raised, at each interval of two or three feet.
Had the Egyptian pyramids been nothing more than this  - had they been merely solid masses of stone - the technic art displayed in them would not have been great. We should have had to notice for approval only the proper arrangement of the steps in a gradually diminishing series, the prudent employment of the largest blocks for the basement and of smaller and still smaller ones above, and the neat cutting and exact fitting of the stones that form the outer casing.  As it is, however, the pyramid-builders are deserving of very much higher praise. Their constructions were not solid, but had to contain passages and chambers - chambers which it was essential should remain intact, and passages which must not be allowed to cause any settlement or subsidence of the building. It is in the formation of these passages and chambers that the architects of the pyramids exhibited their technic powers. (...)
Still, the great pyramids of Egypt, having this disadvantage to struggle against, must be said to have overcome it. By the vastness of their mass, by the impression of solidity and durability which they produce, partly also perhaps by the symmetry and harmony of their lines and their perfect simplicity and freedom from ornament, they do convey to the beholder a sense of grandeur and majesty, they do produce within him a feeling of astonishment and awe, such as is scarcely caused by any other of the erections of man

In all ages travellers have felt and expressed the warmest and strongest admiration for them. They impressed Herodotus as no works that he had seen elsewhere, except perhaps the Babylonian. They astonished Germanicus, familiar as he was with the great constructions of Rome. They stirred the spirit of Napoleon, and furnished him with one of his most telling phrases. Greece and Rome reckoned them among the Seven Wonders of the world. Moderns have doubted whether they could really be the work of human hands. If they possess one only of the elements of architectural excellence, they possess that element to so great an extent that in respect of it they are unsurpassed, and probably unsurpassable.”

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