Academy of Sciences of Heroesland

Well, there's actually another awesome method.
Take VERY accurate clocks.
Measure the distance VERY accurately.
Have an object run the distance.
Record the time.
Divide the distance by the time.

Well, maybe that's how they did it. But, as I see it, there's just a terrible margin of error here. Although, 15,000 experiments...
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Lord, I want proof. Preferably with an explanation of the physical principle.