More Rocking and Rolling (3)

 The Merlin Wheel or Merlinwheel

A few years ago there was an interesting web site with fantastic graphics explaining how another fine invention, the Merlin Wheel, worked.    It was, as I recall, really a pair of wheels joined together not by a central axle but by parallel beams joining the two rims.  This would then create a "cage" within which a heavy elongated stone could be either slung or packed in to the position that would otherwise be occupied by the axle.

The web site has sadly disappeared, and I can find none of those splendid graphics on the web.  Does anybody know where they went?

How stable such a structure might have been is anybody's guess,  and I suppose the connecting beams would have acted as obstacles to the effective rolling of the wheels, in effect turning the whole thing into a gigantic roller, with much more frictional drag etc. 

When is a wheel not a wheel?  All of the archaeologists say that when Stonehenge was built, the wheel had not been invented.  But as Nigel Molesworth might have said, "any fule kno that the best way to move a heavy log is to roll it."  So rollers of one sort and another must have been known in the Neolithic.  The question is -- did they know about the axle?