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If I had to build something like this in 1000 BC, I'd use a cart with wheels that did not turn at all and put a heavy statue on top. Then, whenever it came time to change direction, I'd get a few guys to hoist the statue up, while someone else rotated the cart independently. (And there are easily mechanical ways to make this process simpler.) You could recalibrate using the sun or stars.

A differential gear would automate all of this, but would be unmaintainable, expensive, would barely work for more than a few hundred yards, and all this in an era where labor is slave-cheap.

EDIT:

Another way would be to use multiple carts, only move one at a time, and calibrate it from the others, survey style. Cumulative error should be far smaller this way, and you would have fewer terrain problems.




I think you're assuming their roads were straight. This wouldn't work at all on a winding road/trail where turns are constant.


It would be a massive annoyance, but would still work better than a differential gear made with the materials science of the time. I personally think that the story is fantasy.


There's nothing particularly difficult or expensive about a wooden differential.

edit: no seriously, zoom in on this pic here https://upload.wikimedia.org/wikipedia/commons/d/d6/South-po...


At some point, a massive annoyance asymptotically approaches physical impossibility.


Or to have two statues on the same cart, or to keep some sort of a more discrete and orientable object on the same cart to keep track.


> cart with wheels that did not turn at all

Huh? What kind of wheels don't turn? That's literally the definition of a wheel.


Rotate about the axle, but not turn from side to side.


You can still rotate the entire chariot. There’s a vertical axis of rotation through each wheel. Think about how you can rotate a wheelbarrow by rotating the entire thing at once. The tire doesn’t spin, but you’re still rotating.


Perhaps he meant a fixed axle, so both wheels have to turn at the exact same rate. Still doesn’t make much sense though, it would be incredibly inefficient to have to lift up the statue every time the road changes direction ever so slightly.


Harder to do that with a 4 wheeled cart.


The object we're discussing is a two-wheeled cart.


Not in the earliest record, presumably the only eyewitness account.




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