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Stone Shifting 2

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Steve Gray S
Steve Gray Aug 30, 2003 12:34:03
Replying to nigelswift

I typed a long reply to your posting, Nigel. Then I clicked "Post Message" and it disappeared into oblivion. I will try to summarise what I said:

Originally I thought the pivot log would work like an axle, but your idea of notched logs strapped to the back of the block is probably better. The pivot log could be fixed and the notches rotate around it until they reach some angle at which they slip off.

I also mentioned the unfinished obelisk at Aswan which was abandoned because it cracked while being quarried. The Egyptians were obviously confident that they could erect this 1100 ton stick of granite otherwise they would not have gone to all the trouble of quarrying it. Several attempts have been made to raise obelisks and one that I saw on TV some years ago used a pivot log lashed to the stone. The attempt was almost a disaster since the log slid on its track as well as rolling. Also, as the stone pivots, its centre of gravity moves beyond the pivot point and makes the descent much more difficult to control.

I am rapidly coming to the conclusion that we should keep things simple and just allow for slippage.

N nigelswift
nigelswift Aug 30, 2003 13:49:23
Replying to Steve Gray

“I am rapidly coming to the conclusion that we should keep things simple and just allow for slippage.”

Supposing, for now, that Gordon and everyone agrees with that (and of course they may not, and experimentation may prove them right).
So where do we go from there? We have a number of variables to tweak, and many combinations can achieve the same result, as I mentioned, but what should we be aiming at?

I think the height variable can be ignored, as I mentioned, since it can simply be thought of as the lowest possible elevation at which the finished system will work, so it’ll become abundantly clear from our experiments or your model.

So that leaves offset (and perhaps tilting the stone) to play with to determine the rotation.

Plus, now: slippage.
I’m thinking slippage in itself is no problem, if you can predict or measure it, but variability of slippage is the difficulty. To me, that spells grease. (On the grounds that a low coefficient of friction will be subject to less variance than a high one? You’re moving closer to having a perfectly smooth stone?).

If that’s right, you can have reliable and predictable control over all your variables, and it’ll work the same every time. (The slippage would obviously be very severe but you’d have the scope to allow for this by tilting the stone’s starting position so it builds up rotational speed.)