Science

Core Number Seven

UC16036, Petrie Museum
The pink granite drill core Flinders Petrie pulled from Giza rubble in 1881, now accession UC16036 at the Petrie Museum, University College London, carrying a spiral groove that has been argued about for 140 years.
Documented

The museum object

The core is documented museum property: found by Petrie at Giza in 1881-82, published in The Pyramids and Temples of Gizeh (1883), plate VII, entry 7, held by the Petrie Museum as UC16036. Petrie's text records the spiral cut sinking .100 inch in a circumference of 6 inches, a rate of ploughing out of the quartz and feldspar which is astonishing, and concludes only fixed jewel points could have cut such grooves.

Assessment: Documented: the object, the accession number, the published measurement. Petrie's astonishment is on the page.
Stories

Dunn's re-examination

Machinist Christopher Dunn examined Core 7 at the Petrie Museum in 1999 with depth gauges and a cotton thread, and reported Petrie was wrong in detail and right in kind: not one spiral groove but a double helix, pitch .110 to .120 inch, running the full length of the tapered core. Dunn's conclusion: a feed rate hundreds of times faster than modern diamond drilling implies powered, possibly ultrasonic, machinery.

Assessment: Interesting: the double helix finding is documented in Dunn's own visit report. The inference to powered machinery is interpretation, not measurement.
Interesting claims

The dental-school experiment

The counterweight: Gorelick and Gwinnett (SUNY Stony Brook) replicated ancient-style granite drilling and reported that loose sand produced no lines at all, but emery or corundum in a water slurry produced exactly the concentric cutting lines at issue, partly vindicating Petrie on the abrasive and Lucas on the method, with no exotic machinery required. What remains unexplained is the feed rate Petrie measured, which nobody has replicated.

Assessment: Interesting: the lines are reproducible by ancient means; the speed is not, yet. The honest gap is one number.
Sources and further reading
  1. Flinders Petrie, The Pyramids and Temples of Gizeh, 1883, p.77 and plate VII.7 (primary source)
  2. Petrie Museum, UCL, accession UC16036, Core 7 catalogue record
  3. Christopher Dunn, Petrie Museum examination report, 1999 (double-helix finding, claim source)
  4. Gorelick and Gwinnett, 'Ancient Egyptian Stone-Drilling', Expedition Magazine, Penn Museum (experimental counterweight)
Worth asking

When the father of scientific archaeology finds a tool mark he cannot explain, who inherits the problem?

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GR8YFILES · competing origin stories, labeled by the strength of their evidence · readers 14+