Re: The hole for stone 56 | Forum — The Modern Antiquarian

Stonehenge 180

Image by The Eternal

Stone Shifting 3

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Steve Gray Sep 5, 2003 23:41:53

Replying to GordonP

I have to say, Gordon, I'm impressed by your style. You bounce back like a trampoline.

I have calculated a few figures for you to ponder. The first set shows the pulling force needed to raise a stone from various angles assuming that a rope is attached to the top of the stone and is pulling at an angle of 10 degrees below horizontal:

Angle Pulling force (tons)
70 7.9
75 5.7
80 3.7
85 1.8

The second set shows how the pulling force can be reduced if a simple A-frame is used just to change the direction of pull so that it is perpendicular to the stone:

Angle Pulling force (tons)
70 6.8
75 5.2
80 3.5
85 1.7

You will notice that the A-frame is more effective at low angles, but becomes less so as the stone gets close to being upright.

A person pullling on a horizontal rope and leaning back at an angle of 45 degrees exerts a pulling force of half his own weight. So to exert a force of say 8 tons would need 16 tons of people, a little over 200 at 12 stones each.

There are other possibilities we could consider:

1. Use props and wedges behind the stone to raise it up.

2. Use another stone to load the middle of a tensioned rope. This would amplify the weight of the secondary stone considerably. We could lever it up like the big one, attach it to the rope and then allow its weight to do the work. We would need a damned good ground anchor like another sarsen block. If the erection is not achieved in a single pull we just prop the back of the stone, retension the rope and do it again. I reckon the secondary stone may only need to be a couple of tons. I can work out the numbers if you think it's worth it.

GordonP Sep 6, 2003 07:40:52

Replying to Steve Gray

The BBC used an "A" frame as a form of gearing, the rope from the top of the stone was attached to the "A" frame about one third from the bottom of the "A"frame and the pulling rope was attached to the top, giving an advantage of about 3 to 1.

I instantly saw this as cheating because it assumes the builders had a knowledge of gearing, a sophisticated concept.

I know a lever is a form of gearing but to use it, it is not necessary to understand it.

Try this, image the stone is in the hole lying at say 70 degrees. continue to build up the tower until it is level with the top of the stone. Place some men on top of the tower holding levers vertically between the stone and the tower using the tower as a fulcrum. Trail ropes from the ends of these levers to men at ground level. If the levers were about 10 or 12 foot long the men on the ground would gain an advantage of 10 to 1. We would still only need a few men and we would still be using levers perhaps without knowing how they worked.

FourWinds Sep 6, 2003 09:40:59

Replying to Steve Gray

"... another stone to load the middle of a tensioned rope. "

Would it be possible to place a basket/box in the centre of the rope and slowly load it with smaller stones? Would this allow a controlled lift?

Also, as a golden rule in these sort of things:

Never associate yourself with Stonehenge, unless you are 100% certain. That way madness lies ... or at least being labelled 'a nutter'. :-)

It's the quickest way to attract the 'New Age' tag and not be taken seriously.