Calibration History

Outsourcing the Great Pyramid
The cubit is one of the most ancient of all measurements. Though it is no longer in existence, the firm historical documentation of the unit provides some essential insights into the importance of traceability. 
A cubit is a unit of length equal to the distance from the elbow to the tip of the middle finger. We can already see the problem with this unit of measurement. Who's arm are we talking about? How do we even agree on who's arm we should use?

The Egyptian Royal Cubit
The Egyptian Royal Cubit appears to have dated back to at least 2700 BC. Today we have several existing artifacts spanning a range of 20.61 to 20.83 inches in length, that date to several periods throughout ancient Egypt. To me, this represents some precision. A difference of less than 1/4 of an inch, or 6 millimeters in ancient times seems remarkable considering the methods & materials that were used at the time. The existing cubits span over 2,000 years of Egyptian history with this exceptional accuracy.

 An Ancient Egyptian Cubit - Source Wiki-Bakha

An Ancient Egyptian Cubit - Source Wiki-Bakha

The Mesopotamian Cubit
We have only a single copper alloy artifact of this cubit dated to 2650 BC exists and it is referred to as the Sumerian cubit at a length of 20.42 inches. This measurement is amazingly close to that of its contemporary Egyptian Royal Cubit.

 The Sumerian Cubit - Source Wiki

The Sumerian Cubit - Source Wiki

The Biblical Cubit
The biblical cubit is estimated at 18 inches. This is quite a bit different from the Egyptian and Sumerian cubits. Unfortunately, we don't have any cubit artifacts to know for sure, so the estimation is based on comparisons of surviving artifacts to structures described in the bible.

The Roman Cubit
In ancient Rome, according to Vitruvius, a cubit was equal to 1⁄2 Roman feet approximately 17.5 inches.

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Outsourcing the Great Pyramid
Now that we know some of the different cubits that existed all at about the same time, we can think about traceability in measurements. The critical component of traceability is the idea of measures have a common ancestor, so to speak, that allows them to relate to one and another. Let's look at what we end up with if, depending on who built the Great Pyramid.

  • 280 Egyptian Cubits 481 Feet
  • 280 Mesopotamian Cubits 476 feet
  • 280 Biblical Cubits 420 feet
  • 280 Roman Cubits 408 feet

So as we can see we end up with a vast array of potential sizes for the Great Pyramid depending on who built the thing. 

To Make Matters Worse
What if the Egyptians wanted the Great Pyramid built more quickly and decided to outsource three of the sides while they produced the first side. Now we can see the real problem with a lack of traceability. We would have one very crooked looking Great Pyramid if we were lucky enough to have one at all.