Today we are not talking about the rulers of empires, but measuring rulers.
We have at some point used a tool to measure distance in various units and we owe this to an invention that dates back to 2650 BC.
This tool of measure took a different form as a rod of copper, discovered by Eckhard Unger. Since then, a number of other measuring tools have been invented and used throughout history, taking various forms and calibration measurements.
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