Hacker News Reader

Comment by Simon_ORourke | Hacker News Reader

This is one of the most intriguing ancient mysteries, and is sufficiently well grounded in engineering practice that it can be experimentally validated. Things like the hardness of the cutting edge, the RPM required to mimic the drill markings, the shape and progression of the drill bit etc.

So, it's reasonably clear that the bronze-age Egyptians must have had some drilling rig for boring hard stone - one which operated at 1,000 rpm or similar and could make an impression into something like quartz. All the ancient aliens nonsense aside, this rig in itself must have been quite impressive in itself - probably a composite of pulleys and ropes with a tubular emery-embedded cutting bit. Would have loved to have seen it working!

View on HN

If the claims of levitation, ultrasonic resonance, and/or lingam electrical plasma stone masonry methods are valid; perhaps the necessary RPMs for core drilling are lower than 1000 RPM.

Given drilled cores of e.g. (limestone, granite,), which are heavy cylinders that roll, when was the wheel invented in that time and place?

Wheel: https://en.wikipedia.org/wiki/Wheel

"Specific cutting energy reduction of granite using plasma treatment: A feasibility study for future geothermal drilling" https://www.sciencedirect.com/science/article/pii/S235197892... :

> The plasma treatment showed a maximum of 65% and a minimum of 15% reduction in specific cutting energy and was regarded as being dependent on mainly the hardness and size of the samples [and the electrical conductivity of the stone]

E.g. this video identifies electrodes and protrusions in various megalithic projects worldwide: https://youtu.be/n8hRsg8tWXg

Perhaps the redundant doors of the great pyramid were water locks rigged with ropes. There do appear to be inset places to place granite cores for rigging.

Ancient and modern stonemasonry skills; how many times have they been lost and why?

*copper-age

Bronze is a copper alloy, and there are Egyptian bronze objects dating back to the first dynasties of the Old Kingdom.

I'm starting to think we should think of the pre-historic times as the "simple machine age". When I see the artifacts I'm left with the impression that these people had plenty of labor and they were exploiting and learning the use of simple machines.

Everything they did could be explained by mastery of use gravity, ropes, and levers. If the materials used were primarily organic in composition the tooling would be long gone by now.

Always weird when people correct others with something that is wrong. Its bronze age. And if it was the copper age the correct term would be chalcolithic.

Pure copper is too soft and it has never been useful for most tools.

The widespread use of copper for other purposes than jewelry has begun only after it became possible to produce in a reproducible way various alloys of coppers, now known as bronzes.

The tin bronze, i.e. the alloy of copper with tin, has been discovered relatively late, around 5500 years ago, close to the time when writing has been invented, so we have much more historical information about the civilizations that used tin bronze. (The much cheaper brass has been discovered only long after the method of iron extraction, during the Greco-Roman Antiquity.)

Nevertheless, for several thousands of years before, other copper alloys have been used, e.g. arsenical bronze or antimony bronze, so that is still "bronze age", even if it would be useful to differentiate between the ages of iron, of tin bronze and of other "bronzes". The Egyptian state definitely belongs to the age of the tin bronze.

experimental archaeologists (forget the names, sorry) drilling egyptian granite with egyptian sand† found that copper tube drills work better than bronze tube drills, presumably because copper is, as the machinists say, 'gummier'

so while you're right that copper is much less useful than bronze for most tools, here the tool we're talking about is one of the exceptions

they also tried tubular reeds, with and without water. those didn't work at all

the egyptian state seems to predate not just tin bronze or even arsenical bronze but even copper tools, at least in egypt

______

† emery doesn't occur locally and doesn't start appearing in the drilled holes during the first millennium of rock drilling

While you are right about pure copper being the best for such drilling with free abrasive, a few niche use cases for pure copper do not make a "bronze age" into a "copper age".

Even after the much cheaper iron replaced bronze for most uses, bronze remained the best choice for a few purposes, but nonetheless that does not override the transition from the bronze age to the iron age.

While emery does not occur locally, the island of Naxos is closer to Egypt than many other places from which various goods were imported at that time, so that was not a serious obstacle against its use.

The conclusion of the parent article was that emery (with copper cylinders) produced the best matches with the archaeological artifacts, so that was the most probable method used for drilling (the other possible alternatives, like importing diamond dust or corundum dust from India have probabilities far too low to be believable; what we name now as diamonds became known to the Mediterranean world only after the expedition in India of Alexander the Great; the word "diamond" is much older, but it was previously applied to osmium-iridium alloy nuggets, which are found together with gold nuggets in alluvial deposits and which are embedded in the gold of many ancient Egyptian artifacts).

i agree with almost all of your comment. just a few minor points:

- there was a 'chalcolithic' period of copper tools in most places before the advent of bronze, but i believe that bronze tools were already in use in egypt when drilling started

- later investigations did not find emery dust in the oldest drill holes, leading to the conclusion that the abrasive was quartz, so although the egyptians certainly could have been importing abrasives from naxos, they don't seem to have done so until much later

- the identification of plato's 'adamas' with an osmium-iridium alloy is quite dubious; he was certainly talking about a metal, but it could easily have been steel or meteoric iron

- just to clarify, you probably know this, but corundum dust and emery are the same thing (the article was fairly confusing on this point)

Reply on news.ycombinator.com