It originated from the Roman mille passus, or "thousand paces," which measured 5,000 Roman feet.
About the year 1500 the "old London" mile was defined as eight furlongs. At the time, the furlong, measured by a larger northern (German) foot, was 625 feet, and thus the mile equaled 5,000 feet. During the reign of Queen Elizabeth I, the mile gained an additional 280 feet--to 5,280--under a
statute of 1593 that confirmed the use of a shorter foot that made the length of the furlong 660 feet.
Eratosthenes measured the circumference of the earth by the method you described. He paid someone to measure the distance from Alexandria to Aswan. He had been staring down a well there - that fascination with holes in the ground again
- and noticed the shadow thing.
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