mardi 1 février 2011

Le chadouf des bâtisseurs égyptiens, selon Thomas Ewbank (XIXe s.)

Dans son ouvrage A descriptive and historical account of hydraulic and other machines for raising water, ancient and modern, with observations on various subjects connected with the mechanic arts, publié en 1842, l’écrivain anglo-américain Thomas Ewbank (1792-1870) s’est intéressé à l’utilisation du chadouf au cours des âges, dans différentes civilisations : Chine, Inde, Égypte..., et même dans des usines anglaises.
Généralisé (jusqu’à nos jours) dans les campagnes égyptiennes pour les travaux d’irrigation, cet outil semble avoir trouvé une autre utilisation toute naturelle pour l’élévation des matériaux de construction, d’une assise à l’autre, sur le chantier des pyramides. Ce fut, on le sait, la théorie retenue par Hérodote. Thomas Ewbank y souscrit sans hésitation, tant lui semble évident et constant ce savoir-faire des Égyptiens. Pourquoi se seraient-ils ingéniés à chercher une autre technique de construction, alors qu’elle leur était transmise de génération en génération et qu’elle n’avait plus besoin de donner des preuves à la fois de sa simplicité et de son efficacité ?
Aussi logique soit-elle, cette analyse ne fait pas, est-il besoin de le souligner ?, l’unanimité. Elle a toutefois retenu l’attention de nombreuses générations de chercheurs et a toujours ses adeptes. À ce titre, elle a sa place dans notre inventaire.

“Of machines for raising water, the Swape has been more extensively used in all ages, and by all nations, than any other. Like most implements for the same purpose, its application is confined within certain limits ; but these are such as to render it of general utility. (...)
In Egypt, this machine is named the Shadoof, and in no country has it been more extensively employed. In modern days, more persons are there engaged in raising water by it (...), than are to be found in any other class of Egyptian laborers. They raise the liquid at each lift about seven feet, and where it is required higher, series of swapes are placed at proper distances above each other (...). The lowermost laborer empties his vessel into a cavity or basin formed in the rock, or in soil rendered impervious to water, three or four feet above him, and into which the next one plunges his bucket, who raises it into another, and so on till it reaches the required elevation. M. Jomard says it is not uncommon to see from thirty to fifty shadoofs at one place, raising water one above another. At Esne, he saw twenty-seven Arabs on one tier of stages, working fourteen double swapes, i. e. two on each frame, the bucket of one descending as the other rises. They were relieved every hour, so that fifty-four men were required to keep the machines constantly in motion. The overseer or task-master measured the time by the sun, and sometimes by a simple clepsydra or water-clock.
It is impossible to pass up the Nile in certain states of the river, without being surprised at the myriads of these levers, and at their unceasing movements ; for by relays of men, they are often worked without intermission, both night and day. In Upper Egypt especially, where from the elevation of the banks they are more necessary, and of course more numerous, the spectacle is animating in a high degree, and cannot but recall to reflecting minds similar scenes in the very same places in past ages, when the population was greatly more dense than at present, and the country furnished grain for surrounding nations. In some parts, the banks appear alive with men raising water by swapes and the effect is rendered still more impressive by the songs and measured chantings of the laborers, and the incessant groans and creakings of the machines themselves.(...)
The Arabs have a tradition that the shadoof was used in the times of the Pharaohs, and a proof that such was the fact, has recently been furnished by Mr. Wilkinson, who found the remains of one in an ancient tomb at Thebes ; in addition to which they are represented in sculptures which date from 1532 to 1550 B. C. a period extending beyond the Exodus. (...)

The swape is one of the ancient and modern implements of China, where it is used, as in Egypt and India, for the irrigation of land. It is frequently made to turn in a socket (or the post itself moves round), in addition to the ordinary vibratory motion. In several situations, this is a decided improvement, as the vessel of water when raised above the edge of a tank or river, can, if desirable, be swung round to any part of the circle which it describes. (...) When thus constructed, it is according to Goguet (*) identical with the engines mentioned by Herodotus (...) as employed in the erection of the Egyptian pyramids ; these, he supposes were portable swapes, or levers of the first order, with a rotary movement like those of the Chinese. A number of these being placed on the lowest tier of stones which formed the basis of the pyramids, were used to raise those which form the second tier ; after which, other swapes were placed on the latter and materials raised by them for the third range, and in like manner to the top. This was the process which Herodotus says was adopted. M. Goguet, supposes that two swapes were employed in raising every stone, one at each end, and that the levers were depressed by a number of men laying hold of short ropes attached to them for that purpose. This mode appears to accord with the meagre description of the machines used in the erection of the pyramids, which the father of history has given.”
(*) Sur cet auteur, consulter la note qui lui a été consacrée dans Pyramidales : ICI

Aucun commentaire: