Exp d'Assouan de 1999 : Scie de 14.5kg

Categorie Mégalithe 1
Categorie Mégalithe 2










Référence - Mégalithe

 


Livre


 

Experiments in Egyptian Archaeology: Stoneworking Technology in Ancient Egypt
129. While the small-scale Manchester tests established the initial sawing and drilling data, it is now instructive to see how the large-scale tests proceeded in Aswan. In March 1999, an opportunity arose to saw and drill the rose granite in a quarry located on the edge of the southern Egyptian town of Aswan. Several Egyptian quarry workers operated a 1.8 m-long copper saw and an 8 cm-diameter copper drill-tube, which was taken to Egypt with its driving bow. These sawing and drilling experiments were undertaken to test two theoretical propositions59: that two- and three-worker teams were required to drive large ancient saws (Figure 4.19) and tubular drills (Figure 4.20) respectively. The saw and the drill-tube were tested upon the rose granite under realistic ancient conditions, and the results compared with those obtained from the previous experiments conducted with the much smaller reconstructed copper saws and drills in Manchester.60 Each Aswan tool used locally obtained sand as the cutting abrasive. The unused 1.8 m-long copper saw blade, stood on its edge, measured 15 cm in depth, 6 mm in thickness and weighed 14.5 kg. The quarry workers had previously, and unnecessarily, fitted a heavy wooden frame to this saw blade, as well as notching it numerous times along the cutting edge with an electric abrasive wheel; no doubt, they understandably were influenced by modern working practices. Nevertheless, for comparison with a completely flat edge acting on dry sand abrasive, it was decided to test the notched edge with very wet, fluid sand along a granite block’s width of 75 cm, its surface initially pounded flat along the line of sawing.

130. Two workers pushed and pulled the saw from opposite sides of the block. The blade rocked from side to side during each forward and backward movement, creating a V-shaped slot.61 At a depth of 8 cm, the V’s cross-sectional shape measured 2.5 cm at the top and 6 mm at the bottom, each side angled at 7° to the vertical. This V-shaped slot is similar to the two partially sawn slots seen in Hordjedef’s rose granite sarcophagus in the Cairo Museum, and saw-slots cut into a basalt pavement block near Khufu’s pyramid at Giza.62 The laterally curved bottoms of these slots are a further consequence of the rocking action of the ancient saw blade, which itself would have assumed a laterally curved shape along its cutting edge. These phenomena occurred in the wet and the dry sand-sawing experiments. Long parallel striations of varying depths and widths, similar to those seen in ancient stone objects, were visible on the sides and the bottom of the slot, and upon the saw’s individual flat edges between the notches. There was extensive pitting to the sides of the saw, also seen in the subsequent dry sawing test. In both the wet and the dry tests, the extra granite abraded to form the V-shape has been disregarded when calculating the cutting rate. It was noticeable that the sand had to be kept fluid; drying-out sand rapidly increased an already significant effort to move the saw. The used sand powder slurry poured over each end of the slot, its copper content largely washed away into the ground below.

For the tests with the dry sand abrasive, the wooden frame was removed and the blade reversed to allow its completely flat top edge to operate on the stone; the granite block’s width at the point of sawing was 95 cm. The blade was now weighted with four stones (see Figure 6.3), two tied on to each end of the blade (first suggested in 1986);63 these four stones, weighing 32 kg, also acted as handles for the sawyers. The saw’s total weight of 45 kg placed a load of nearly 1 kg/cm2 upon the blade’s edge in contact with the granite.

131. Similar parallel striations to ancient ones, and to those obtained in the Manchester sawing tests, were visible on the sides and the bottom of the slot, and upon the saw’s continuous flat edge. The angular crystals embedded into the edge and striated the stone under the blade and along the saw-slot’s walls, sometimes causing new striations, at other times reinstating old ones, as the blade moved backwards and forwards along the stone. The rate of dry cutting was just over 12 cm3/hour, similar to the wet abrasive result. It was noticeable that the effort to reciprocate the saw using the dry sand was easier than for the wet sand abrasive. The used dry sand powder, grey in colour, poured over each end of the slot, its copper content intact.

 


Mégalithe


 

Abrasion - Forage tubulaire et Scie en Cuivre : Exp. d'Assouan