{"it":{"id":"W21LA03","kind":"artifact","sub":"Authenticated","name":"Petrie diorite potsherd with cusp and lip (15 D)","place":"London","mat":"diorite","dims":"2.5 x 2.3 in","loc":"Petrie Museum, UCL","acc":"UC43197 (UNVERIFIED against Petrie Museum catalogue; from Dunn caption)","find":"Giza, Petrie","flag":"genuine ancient","src":[198],"lat":51.523,"lon":-0.133,"tags":[],"sum":"Some of the finest lines on Egyptian hard-stone vessels are about 1/150 inch wide, cut into diorite, a stone that steel struggles to scratch. Flinders Petrie found such pieces at Giza, broken bowls of diorite that became central to the question of how Egyptians worked hard stone.\n\nPetrie described them closely. On one fragment, No. 14, the bowl had been turned, then re-centred, leaving a small cusp where the two curves meet. On another, No. 15, the curve was spherical, and the tool's pivot had been shifted to cut the lip. He dated the lathe to the fourth dynasty. No tool has been found.\n\nWhat is hard to explain is the evenness. Curves on the best pieces look regular enough that an engineer's eye reads them as made by a machine.\n\nThe engineer Christopher Dunn sees exactly that. He writes of diorite pieces with 'true turning' and of Egyptian work flat and even to fractions of a thousandth of an inch, and reads it as proof of powered machine tools. Petrie's answer comes from the same fragments: lines this fine, he wrote, were cut with fixed points of very hard stone, probably corundum, and the cusp and the shifted pivot are the marks of a lathe set up and reset by hand. Skill built over generations, with abrasives harder than diorite, can reach precision that looks mechanical to us.\n\nWhat would settle it is a modern scan of these fragments, set beside bowls known to be hand-made. Until then, the question is how much precision a trained hand can reach.","why":"Diorite bowl fragments at the centre of the hand-versus-machine question, known mainly through Petrie's own notes (single source).","nfacts":1,"nsrc":1,"yt":"Check edge profile data.","rel":["W21LA02"],"hook":"Lines 1/150 inch wide in diorite. Christopher Dunn sees machine work; Petrie saw a skilled hand."},"S":{"198":["Christopher Dunn, Lost Technologies of Ancient Egypt: Advanced Engineering in the Temples of the Pharaohs (Bear & Co 2010, ISBN 978-1-59143-102-2); printed-page refs","file:books/upload5.pdf"]},"rec":{"id":"W21LA03","alias":[],"ms":[{"a":"Petrie potsherd UC43197 (his 15 D per caption) size","v":"2.5 x 2.3","u":"in","unc":"","by":"Petrie Museum via Dunn","yr":"not stated","m":"caption [Dunn 2010 p.299; quote W21LQ044]","b":"S","t":"MEASUREMENT","id":"W21LM044","s":["W21LS01"],"c":"Christopher Dunn, Lost Technologies of Ancient Egypt: Advanced Engineering in the Temples of the Pharaohs (Bear & Co 2010, ISBN 978-1-59143-102-2); printed-page refs","url":"file:books/upload5.pdf"}],"lab":[],"eng":[],"ori":[],"gaps":[],"dat":[],"aa":[],"ac":[],"me":[],"ci":[],"cq":[],"sd":[],"art":{"claimed_anomaly":"cusp from re-centred lathe pivot","mainstream_reading":"Petrie: true turning","provenance_flag":"genuine ancient","current_location":"Petrie Museum, UCL","find_circumstances":"Giza, Petrie","claimant":"Christopher Dunn","status":"unresolved","dimensions":"2.5 x 2.3 in","material":"diorite","date":"","culture":"","museum_accession":"UC43197 (UNVERIFIED against Petrie Museum catalogue; from Dunn caption)","b":"S","s":["W21LS01"]},"sub":[],"src":[{"id":"W21LS01","t":"Christopher Dunn, Lost Technologies of Ancient Egypt: Advanced Engineering in the Temples of the Pharaohs (Bear & Co 2010, ISBN 978-1-59143-102-2); printed-page refs","u":"file:books/upload5.pdf"},{"id":"VW21LA03-2","t":"Petrie 1883, Pyramids and Temples of Gizeh, ch. 19: mechanical methods of the pyramid builders","u":"https://www.ronaldbirdsall.com/gizeh/petrie/c19.html"},{"id":"VW21LA03-3","t":"Christopher Dunn, GizaPower: Advanced machining in ancient Egypt","u":"http://www.gizapower.com/Advanced/Advanced%20Machining.html"}],"qs":["Lines 1/150 inch wide in diorite. Could a lifetime of training produce this, or does it need a machine?","A cusp where a bowl was re-centred: does that look like a machine to you, or a person resetting a lathe?","If advanced tools shaped these bowls, why did no trace of them survive?"]},"img":null,"md":{"h":"img/m/W21LA03-16x9.webp","w":1600,"hh":900,"alt":"Illustration: setting associated with Petrie diorite potsherd with cusp and lip (15 D), London","by":"Illustration made for The Nommo","lic":"","lu":"","p":"","g":true,"ct":false,"cap":"","sec":[]},"hh":[{"v":"2.5 x 2.3 in","h":"Recorded dimensions","s":[269]},{"v":"Diorite","h":"Made of","s":[269]},{"v":"Giza, Petrie","h":"Where it was found","s":[269]},{"v":"Petrie Museum, UCL","h":"Held at","s":[269]}],"hs":{"269":["Christopher Dunn, Lost Technologies of Ancient Egypt: Advanced Engineering in the Temples of the Pharaohs (Bear & Co 2010, ISBN 978-1-59143-102-2); printed-page refs","file:books/upload5.pdf"]}}