Nearly forgot, The manager of the quarry is now on the lookout for a 10 ton piece of limestone similar in shape to the sarsens and is willing to drop it on the spare car park at the museum. The manager of the museum has given his consent to use of the car park subject to approval of the board. I've got to write to the board for this, so, if any of you guys have letters after your names that would help tip the balance. remember all the above is free.

Slippage is undesirable for two reasons. Firstly, the tower needs to be taller to allow for it. Secondly the frictional force can be affected significantly by varying surface roughness, so it makes the outcome less predictable. If we can't eliminate it, then we have to allow for it.

If you have an idea that would eliminate slippage, let's hear it!