Abrasion - Forage tubulaire avec Roseau

Categorie Mégalithe 1
Categorie Mégalithe 2





Description - Mégalithe

Expérience de Trou par abrasion sur des pierres tendre avec un tube en roseau et du sable sec et mouillé.






Référence - Mégalithe

 


Livre


 

Experiments in Egyptian Archaeology: Stoneworking Technology in Ancient Egypt
111. Experimental tests41 were made upon the following stones: soft and hard limestone, calcite, hard sandstone (coarse-grained), hard sandstone (fine-grained) and blue granite (close-grained). All of the tests were carried out in Manchester, except for the test upon the fine-grained sandstone, which took place in Aswan, Upper Egypt. Each test utilized a 1 cm-diameter reed tube, which possessed 2 mm-thick walls. The tube was rounded at the top, for the capstone, and driven with a bow (Figure 4.3); a load of approximately 1 kg/cm2 was applied upon the tube.

111. The drill-tubes were tested with dry and wet sand abrasive. Overcutting of the holes, due to the lateral motion imposed by the bow, was allowed for when calculating the cutting rates for each drill-tube. Therefore, the volumes of the reed stem worn off a tube, and the stone drilled out, were used to obtain a ratio between the two materials, rather than measuring a tube’s lost length and a hole’s increased depth. The results are shown in Table 4.1. Dry sand abrasive caused some splintering to the tube, and the stem spread slightly outward. However, the drill retained its tubular shape and effectively drilled the soft and hard limestone and the calcite samples.

112. The reed drill-tube used with wet sand abrasive soon softened and spread outward and inward, thus completely filling the originally hollow interior with softened stem material. Despite this alteration to the tube’s configuration, it performed useful work upon the soft limestone, but performed poorly upon the hard limestone and the calcite. However, because the drill had assumed the shape of a solid stalk, instead of a tube, penetration into the soft limestone was reduced, even though the volumetric rate of drilling remained similar to that of the tube in use with dry sand. The use of the reed tubes upon the coarse-grained hard sandstone and granite, utilizing wet or dry sand abrasive, so badly damaged them that no useful cutting could be achieved.

112. After the introduction of truly smelted and cast copper after ca. 3600 BC, the stone vessel worker was able to imitate the hollow reed by beating thick sheets of cast copper into thinner sheets and rolling them into tubes around wooden, cylindrical formers made from tree branches; larger diameter tubes may have been cast to shape. Possibly, these tubes were cast by creating vertical, open, tubularshaped moulds in damp sand, initially made by a reed tube acting as a pattern.