Sawing the joints of blocks in ancient Egypt
December 3, 2016
| Here I refer to an article published on December 31, 2013 in the BIFAO, the Bulletin of the French Institute of Oriental Archaeology, signed by Etienne Laroze and Antoine Garric. This work answers the question: - How, in antiquity, did workers manage to fit massive blocks with such precision? The answer is extremely clever. It had already been suggested more than a century earlier, but it took my friend Antoine to demonstrate it himself on his worksite at the Open-Air Museum of Karnak. In fact the blocks are intimately joined only at the periphery of the faces, over a depth of 5-7 cm. The center of the faces is slightly hollowed out with a pick (the specialized term is "démaigri"), by a few millimeters of depth. The fitting is therefore achieved by sawing this joint-band using a small saw, which is a simple metal blade (in Egypt, of copper) that incorporates quartz particles (either added, or automatically present in the sandstone, which is a "secondary rock," naturally contains abrasive particles and is thus naturally "self-abrasive"). The saw operates a back-and-forth motion and abrades the joint. Very few original tools have been found (metal was a precious element, systematically recovered). Moreover the tools found in tombs are simulacra, symbolic and non-functional. Here is what the authors indicate in their article: These saws abrade the facing joints, without wearing down much. They in fact serve to set the abrasive in motion: the quartz powder. Antoine Garric on his worksite. He adjusts horizontality using a plumb-line level, from the Old Kingdom Garric sawing the vertical joint The drawings below illustrate this technique of sawing blocks (fast, one centimeter/minute!) The sawings follow one after another: The jointing of the blocks can be completed by injecting through a vertical channel a very fluid plaster grout, which then forms a lens a few millimeters thick, in contact with the "démaigri" faces. The resistance to seismic shocks is then maximal. The photo below demonstrates the proven existence of grout injection channels: Channels for injecting the very fluid plaster grout. These channels also ensure the rigid jointing of the vertical faces. One can distinguish horizontal grooves facilitating the flow of the plaster and ensuring ultra-rigid jointing of the horizontal faces. The photos refer to excavations of elements dating from the New Kingdom (1500 BC). This study should be applied to the oldest elements. But already a conclusion emerges: there is no need for these blocks to be "laser-cut" and transported by "antigravity." Extremely simple techniques make it possible to carry out operations that until now appeared incomprehensible. Moreover the copper extracted from Egyptian mines, containing a high proportion of arsenic had mechanical properties close to those of bronze, which takes us away from this image of Egyptian workers working with tools of pure, soft copper. That being said, this does not answer all the questions. For example the way the blocks were joined at South American sites where metals were unknown. Nor does it exclude the fact that these civilizations of a very ancient past possessed knowledge that would have been lost. The presence of a "multi-vernier" technology on the pharaonic cubits, three thousand years before Vernier rediscovered this technique in 1631, is an undeniable, troubling fact, for which to this day there is no explanation. |