{"it":{"id":"W21LA01","kind":"artifact","sub":"Authenticated","name":"Petrie core No.7 (7 G)","place":"London","mat":"granite","dims":"height 4.33 in (11 cm)","loc":"Petrie Museum, UCL","acc":"UC16036 (UNVERIFIED against Petrie Museum catalogue; from Dunn caption)","find":"Giza, Petrie collection","flag":"genuine ancient","src":[198],"lat":51.523,"lon":-0.133,"tags":[],"sum":"Wound around a short cylinder of Giza granite is a spiral groove, cut by a drill as it bored down. Flinders Petrie numbered it core No. 7 and called the cutting 'astonishing': the groove drops about .1 inch in 6 inches of circumference, a rate of 1 inch in 60.\n\nPetrie found more. The groove ran deeper through quartz, the hardest mineral in the stone, than through the softer feldspar around it. His drills used tubes from 1/4 inch to 5 inches wide, and the smallest hole he found in granite was 2 inches across. No drill itself has ever been found.\n\nHere is the puzzle. Writing in Analog in August 1984, the engineer Christopher Dunn compared that rate with a modern drill in granite: at 900 rpm, about 1 inch in 5 minutes, or .0002 inch per turn. Against that, the Egyptian figure of .100 inch per turn is 500 times faster. To Dunn, a groove deeper in quartz points to a vibrating drill, an ultrasonic tool working at 19,000 to 25,000 Hz.\n\nPetrie, who first described these marks, put them down to fixed cutting points of a very hard stone, probably corundum, pressed with great force. In a 1999 trial at Aswan, Denys Stocks cut granite with a copper tube 8 cm wide, sand and a bow worked by three people, and got the same kind of horizontal grooves. Petrie's own reading also explains the quartz: a fixed hard point under heavy load bites deepest where the grain resists most, which a free-running modern bit does not.\n\nThe open edge is a single test that matches both the Egyptian rate and the deeper groove in quartz. Until one does, both sides read this cylinder as proof.","why":"The record that started the ancient machining debate, with both sides in their own numbers.","nfacts":4,"nsrc":1,"yt":"Compare groove pitch with experimental drilling.","rel":["W21LA02","GIZ-G1"],"hook":"Petrie said a drill cut 1 inch into granite per 60 turns. Christopher Dunn says that is 500 times too fast."},"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":"W21LA01","alias":[],"ms":[{"a":"Petrie core 7 groove pitch (Petrie JRAI 1884 table, quoted)","v":"mean pitch 0.095 in (turns 0.08-0.12); <1/100 in irregularity","u":"in","unc":"Petrie: \"not 1/100 irregularity\"","by":"W.M.F. Petrie via Dunn","yr":"1884","m":"tracing a normal plane, quarter-turn readings [Dunn 2010 p.312; quote W21LQ039]","b":"S","t":"MEASUREMENT","id":"W21LM039","s":["W21LS01","W21LS04"],"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"},{"a":"Petrie core 7 groove spacing on latex impression (Dunn)","v":"0.050-0.080","u":"in","unc":"from photograph of latex peel","by":"Christopher Dunn","yr":"2003-2008","m":"latex impression flattened, 8 MP photo [Dunn 2010 p.319; quote W21LQ040]","b":"S","t":"MEASUREMENT","id":"W21LM040","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"},{"a":"Petrie core 7 max groove depth on latex (Dunn)","v":"0.0075","u":"in","unc":"instrument not named","by":"Christopher Dunn","yr":"2003-2008","m":"latex impression inspection [Dunn 2010 p.320; quote W21LQ041]","b":"S","t":"MEASUREMENT","id":"W21LM041","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"},{"a":"Petrie core 7 height (UC16036)","v":"4.33","u":"in","unc":"","by":"Petrie Museum via Dunn","yr":"not stated","m":"caption [Dunn 2010 p.302; quote W21LQ042]","b":"S","t":"MEASUREMENT","id":"W21LM042","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":"spiral groove; claimed advanced drilling","mainstream_reading":"tube drilling with copper + abrasive (Stocks)","provenance_flag":"genuine ancient","current_location":"Petrie Museum, UCL","find_circumstances":"Giza, Petrie collection","claimant":"Christopher Dunn","status":"unresolved","dimensions":"height 4.33 in (11 cm)","material":"granite","date":"","culture":"","museum_accession":"UC16036 (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":"VW21LA01-2","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":"VW21LA01-3","t":"Christopher Dunn, GizaPower: Advanced machining in ancient Egypt","u":"http://www.gizapower.com/Advanced/Advanced%20Machining.html"},{"id":"VW21LA01-4","t":"Anarkia333: Aswan 1999 expedition, 8 cm tube (believer page)","u":"https://www.anarkia333data.center/megalithe/exp-dassouan-de-1999-tube-de-8cm"}],"qs":["A feed of 1 inch in 60 turns, in granite. What test would settle whether copper and sand can do it?","Petrie found the groove deeper in quartz than in feldspar. Which explanation fits that detail better?","If the Egyptians had powered drills, where are the machines, workshops and texts?"]},"img":null,"md":{"h":"img/m/W21LA01-16x9.webp","w":1600,"hh":900,"alt":"Illustration: setting associated with Petrie core No.7 (7 G), London","by":"Illustration made for The Nommo","lic":"","lu":"","p":"","g":true,"ct":false,"cap":"","sec":[]},"hh":[{"v":"height 4.33 in","h":"Recorded dimensions: height 4.33 in (11 cm)","s":[269]},{"v":"Granite","h":"Made of","s":[269]},{"v":"Giza","h":"Where it was found: Giza, Petrie collection","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"]}}