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Petrie's Infamous Core #7 |
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Ian Lawton - By email to Chris Dunn 12/6/99 Chris Two things occur to me as a result of your last posting: First, although I am not a trained engineer I am sufficiently intelligent to realise that feeding and cutting are essential and complementary processes in drilling! Nevertheless, you have now amended your explanation of the supposed spiral grooves to suggest that the feedrate was "greater" rather than "faster", and that you do not think the drill bit was rotating rapidly (whichever method was used). I assume that by this you mean that the actual rate of cut (ie the amount of material removed in a specified period of time) must have been phenomenally high in order for the feed rate (as supposedly indicated by the distance apart of the spiral striations) to be so high (neither of which suggest anything about speed of rotation). If this is the case, then I accept that my observations about "feed-not-cut" rates appear to be inaccurate - except with the rider that I did not fully elucidate what I meant and for this omission I apologise. The factor I omitted (albeit that it is one which we bring up in "Giza: The Truth") is the possibility that even IF the striations were spiral (which in Reid and Brownlee's view they are not on this core) and not random horizontal patterns, these would have been caused more likely by the bit continuing to rotate as it was WITHDRAWN from the core. This would render them irrelevant as an indicator of either feed or cut rate. Second, in your posting of 23 Oct you say: "Clyde Treadwell of Sonic Mill described an ultrasonic process where the tool would leave a spiral groove while being drawn out of the hole, but the tool was spinning, and the groove was the result of the eccentric rotation of the tool. I concede that if a spinning tool can create these characteristics, then there is no need to resort to ultrasonic machining. I was persuaded by a variation of the ultrasonic method because of the report that the "spiral" groove was cut deeper through the quartz than the felspar." Then in the more recent one of 25 Oct you say: "I have no argument with Brownlee's observations on the quartz being ripped out of the felspar thereby leaving an indentation. I totally agree with him. A close examination of the core under microscope should determine whether the quartz was ripped or abraded." Although we must await your own report on the drill-core, presumably you are agreeing that if it was ripped then your ultrasonic machining theory becomes Redundant even by your own admission? I trust you will respond to these issues in your next posting. Best, Ian |
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Chris Dunn Ian Lawton Chris Dunn Ian Lawton Chris Dunn Ian Lawton By email to Chris Dunn 12/6/99 Chris Dunn Visit to Petrie Museum Part One - Posted 12/12/1999 Chris Dunn Visit to Petrie Museum Part Two - Posted 12/12/1999 Chris Dunn Visit to Petrie Museum Part Three - Posted 12/12/1999 |
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Text and Photographs © Copyright 1999 Christopher Dunn With Kind Thanks to the Petrie Museum of Egyptian Archaeology, London. |
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posted 10-04-1999 20:54
posted 10-19-1999 00:06