The granite drill core Flinders Petrie recovered at Giza in 1881 to 1882 and numbered seven, now UC16036 in the Petrie Museum, University College London. Petrie recorded a groove sinking .1 inch in a circumference of 6 inches, and noted that it runs as deep in the quartz as in the adjacent feldspar “and even rather deeper”, the reverse of what an abrasive process should do. Christopher Dunn reads the groove as a single continuous spiral and derives from it a feed rate far beyond anything hand drilling could reach, which is the showpiece of the Ancient Machining argument. The reading is contested at the premise rather than the arithmetic: Gorelick and Gwinnett’s electron microscopy of Egyptian drilled surfaces (Expedition, 1983) argued for loose abrasive rather than Petrie’s fixed cutting point, and whether the groove on core seven is one helix or overlapping concentric scoring has never been settled in peer-reviewed print.
Connections
Flinders Petrie · Christopher Dunn · Ancient Machining · Denys Stocks · Great Pyramid of Giza