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Stone Shifting 2

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Steve Gray S
Steve Gray Aug 30, 2003 22:18:40
Replying to GordonP

> We now seem to be assuming the cutaway was to allow the bottom of the stone to clear the far edge of the hole as it rotated from a low launching tower. this could just as easily apply to a low launch from the other side if the setup was designed for the stone to begin its entry into the hole at less than vertical.

No, I was playing around with this idea, but your 4 ton demonstration convinced me that the stone has to enter the hole at a fairly steep angle. A shallow angle would require a very large build up of momentum to take it to the vertical, and to achieve this requires a large overhang and a correspondingly higher tower. As you pointed out to me, the load on the A-frame is considerable if the overhang is large.

> Without computors perhaps they didn't have the confidence to launch the stone towards a slopeing side but relied on the vertical side to deal with the extra momentum they had purposely built in to the system.

I really need to do some more work to determine just how much momentum the stone can have and yet still be arrested by the hole.

I think it would be useful to know more about what the excavations revealed of the angle of the slope and also how much of the hole was sloping. There are three possiblilities that seem plausible:

1. A small slope (say the top couple of feet) at a shallow angle (45 degrees or less) is what my theory predicts.

2. A steep slope (say 70 degrees or more) supports your theory.

3. A deep slope at a shallow angle suggests that they just pivoted the stones into the hole and then either hauled them to vertical with ropes and A frames, or pushed them up with props and wedges.

4. Any other configurations do not support any theory that I can think of.

S Steve Gray
Steve Gray Aug 30, 2003 22:40:03
Replying to Steve Gray

Actually, Nigel's idea of erecting buttressing on the far side of the hole has some merit. I was thinking that it would just be in the way of the rotating stone, but we could have a couple of long (40') logs set into the ground at an angle so that their top ends are just below where the top of the block will be when erected. Support logs set back far enough from the hole to allow the block to swing freely would carry the weight of the long logs and a short timber would join their top ends together and form an impact plate for the block. Another log would be fastened to the top of the block either by rope lashing or your wooden collar, just above the point at which it will make contact with the impact plate. This would prevent the buttress logs from rising up the block and would result in a considerable braking force being exerted on the block.