Very interesting - I also have similar experience as rosbriagha above -
Extra point is that the article mentions how other methods are not very efficient, but sometimes this is because of lack of experience - often the experiments on TV have asked engineers who immediately plonk for Oak for sledges and sliders, whereas holly or blackthorn are far better. Holly in particular seems to self polish and is the first choice of fishermen for timbers to move their boats on Beer Beach.
Another programme I watched about moving a Viking longship across Orkney (I think) had no one chanting to get everyone to push, pull and tug in unison - A very important part of moving a heavy object. Once again this is employed by the Beer Fishermen.
Anyway I like the ball bearing idea and think it fits in (in Scotland in particular) with their other love of carving the platonic solids (circa 2,000BCE)
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