Lifting 45 ton rocks in the stone age

[Rokcet Scientist]

BBC: Wednesday, 22 August 2007, 05:17 GMT 06:17 UK

Stonehenge building riddle tackled

The question of how Stonehenge was built has never been properly answered.

One suggestion for how the giant rocks which comprise the 5,000-year-old monument were raised into place even involves Merlin the wizard.

But what is known is the first stones - weighing about five tons - were brought from Wales by water in about 2500 BC.

Some 200 years later, they were dug up and rearranged into the familiar 100m-diameter outer circle and inner horseshoe seen today.

'Sheer manpower'

Heavier stones were also brought in - weighing up to 45 tons - which were dragged from the Marlborough Downs.

It is accepted sheer manpower played some part in erecting each upright in holes in the ground.

But the real puzzle is how ancient Britons managed to hoist the massive "crossbars" on to the top of the towering edifices, up to 22ft high.

Engineer Nick Weegenaar, 52, of Bristol, claims simple mechanics and a cunning invention played their part.

[...]

The principle:



Whole article: http://news.bbc.co.uk/1/hi/england/wilt ... 908300.stm

[Minimalist]

I just love it when guys with 65 Engineering degrees figure out how ancient people could have done something?

Why not postulate a beer-powered helicopter?

[Rokcet Scientist]

I just love it when guys with 65 Engineering degrees figure out how ancient people could have done something?

Why not postulate a beer-powered helicopter?

Afaic the the point of this postulation is not that it DID happen that way, but that it COULD have happened that way. And probably in a couple of variants too.

Which method was actually used is not important, imo. (Merely interesting). What is important is that there were ways to do it. And – most importantly – that no 'magic' was involved! This postulation makes a very strong case for that.

[Digit]

When I see this sort of thing I'm aways reminded of the film 'The gun', Sophia Lauren and Frank Sinatra, remember it? The crew is about to lower the gun down an incline and Sinatra informs the world, up hill, down hill, it weighs what it weighs and they the lose the gun.
Yes, I agree that the idea is feasible, though not as shown, but I would not like to try it!

[Minimalist]

Egyptologists have for years postulated that 2.5 million blocks were pushed and pulled one at a time up ramps to build the Great Pyramid using ropes, sleds, manpower and water. They did this around the clock for 20 years, darkness or sandstorms notwithstanding. IIRC it works out to 2 blocks a minute.

Possible? Maybe.

Likely? No.


I seen demonstrations where groups of English engineering students have built a "rail roadway" to "prove" that the big stones at Stonehenge could have been dragged along such rails by teams of about 100. I've seen other demonstrations in which a ramp was constructed and larger teams pulled the lintel stones up the ramp.

There are lots of ways that the fertile mind can come up with to show how things 'could' have been done. No one has as yet showed that any of them are correct.

Still, it does no harm to speculate and experiment. The only danger is, as in Egypt, that one method will be enshrined as "correct" no matter how preposterous it may be!

[Rokcet Scientist]

Sure. But the difference here is that it doesn't sound preposterous . . .

[Digit]

No! Just bloody dangerous!

[Rokcet Scientist]

No! Just bloody dangerous!

So?
Seen the Mohawks building the Empire State building?

[Digit]

Yep! But apart from falling onto somebody below, they can only kill themselves.

[Sam Salmon]

No! Just bloody dangerous!

Not if the wheel is blocked so it can't turn backward.

Simple really.

[Digit]

I'm afraid there is rather more to it than that Sam. The auther suggests, very reasonably, the use of counter weights. Take a closer look at his layout. The lintels are over 10 ft long, the gaps between the uprights just over 3ft.
Just where is he going to attach the weights?
To clear the top of tenons the wheels would need to be at least 17ft in diameter which lift needs to be accomplished with a 180 degree rotation.
This equates to roughly a 1 in 3 incline!
A greased ramp would need less pulling power!
You would need to start your pull from exactly the correct start point and if the weight passed over TDC all hell would break loose.
The inner standing stones and lintels are of course larger and even heavier.
I won't bother you with the rest of the problems that are involved

[daybrown]

It'd be useful to use dendochronology or whatever to nail down the climate and figure out how big the timber in the area was at the time. Access to climax forest timber drives engineering design.

Devereux's "Stone Age Sound Tracks" would also be helpful. We know the acoustic effect of a cathedral had a powerful emotional impact. Structures the size of Stonehenge can do that. But some of the proposed original designs would not provide the correct acoustic experience.

The huge flat stones are very effective reflectors of sound. There are certain points within Stonehenge, where a drumbeat will bounce off a stone to be reflected at another stone, and then in turn a 3rd, but at some point be reflected back to the original source. An echo.

But if you beat a drum in time with an echo, the feedback builds rapidly, like an acoustic amplifier to deafening levels, that will however, only be heard at certain locations within the design.And of course, for it to work, you may need all the stones upright in their correct positions.

Helmholz's formula for the resonant frequency of volumes becomes especially important if the structure has a roof.

[Digit]

There has been quite a lot of debate over here DB as to whether or not SH had a roof. There is no evidence of course but I suspect that IF it had one at some time it would have to have been of timber and thatch, what effect would that have had on the acoustics I wonder?

[kbs2244]

I will have to check my books, but aren’t the various standing stones at SH at differing heights?
Even giving them the knowledge of how to convert a height into diameter, it would mean a different wheel for each lintel stone.

[Digit]

The outer ring are all the same basic height to keep the lintels level. The inner trilithons are taller and heavier, the the wheel system could not have been used on all of them as the gaps between the uprights are in some instances only inches apart.