[TheForge] Mechanics of Stonehenge

[Peter Hirst]

Go to the guy's website and you will find that he added I think 5 tons of 
framing to stiffen up the building.  Having done that, however, he and his 
son were able to move the building 300 feet by hand.


----- Original Message ----- 
From: "GRAF" <adveniam at att.net>
To: "Blacksmithing List Sponsored by ABANA" <theforge at mailman.qth.net>
Sent: Monday, March 30, 2009 11:52 AM
Subject: Re: [TheForge] Mechanics of Stonehenge


>
>
> Bruce Freeman wrote:
>> The one flaw I saw in this video was that he moves monoliths on a
>> cement surface by placing a couple pebbles under the monolith and
>> rotating first on one, then on the other to get net linear motion.  It
>> is not clear how he could apply this technique over soft earth, though
>> the demo of the barn moving might have been one such.  (Not clear how
>> that barn was constructed to enable to be moved like a monolith.)
>>
>
> I'll bet that there was a fair amount of skeletal work done before
> jacking it up.
> Concrete on soft earth or flat stones set in flat earth or on movable
> sledges would be my guess. Stepping stones if you will.
>
>> I just went through my collection of "ancient engineering" books to
>> find a technique I've read about.  Unsuccessfully.  So I can't give
>> you a source, but I can give you another hypothesis, apparently based
>> upon relics from Egypt, IIRC.  Apparently, excavations found what
>> could be described as large (6'+) millstones that were not quite
>> millstones.  So the hypothesis was that these stones were placed one
>> over another and could then pivot fairly easily around a center shaft
>> because they touched only near the shaft.  It continued that two booms
>> projected away from the center shaft in such a manner that they'd
>> rotate with the upper stone (I don't recall details).  These two booms
>> were held at an angle above the stone (like, 60+ degrees to
>> horizontal) and connected at the top with a rope, from the center of
>> which rope a rope was dropped to the top stone.  Call this the "center
>> rope".  From the end of each boom, a rope was dropped.  One of these
>> held the load, the other the counterweight sling.
>>
>> So you get a rope around your monolith and hook it up to one of the
>> boom ropes.  Now load small stones up in the counterweight sling until
>> you have an equal mass on both booms.  Pull down on (or hang a weight
>> from) the center rope and the load and counterweight both are lifted
>> from the ground a small amount.  At this point, using oxen hitched to
>> a beam extended radially from the 'millstones', rotate the upper stone
>> on the lower 180* and you've moved your load by the distance between
>> the tops of the two booms.  If you have a chain of these cranes in a
>> series, you can move loads continuously and the counterweights
>> oppositely.
>>
>> Note that since the counterweights are smaller stones, they could, if
>> necessary, be loaded up on a sledge and moved back for reuse.
>>
>> One neat thing was that you could take the two "millstones", stand
>> them on edges and put a beam between them and you've got wheels.
>> Place the other beams across them, hitch up the oxen, and you can move
>> your crane to the next work site.
>>
>>
> Something on this order might have application for a temporary crane for
> moving things around the yard or shop.
> Gotta go get the sketch pad, now.
>
> Mike Graf
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