[Mike Cecil]

..... and a few more spanners, since we are continuing on this topic, from the Encyclopedia Britannica:

'Derrick, a type of crane; the name is derived from that of a famous early 17th century Tyburn hangman, and was originally applied as a synonym (see Cranes). The derrick of the petroleum industry is a skeleton framework or tower of wood or steel for hoisting or lowering from a fixed point. It is used to raise or drop the drilling tools and also to insert and remove the well casing or pipe.'

And from the Shorter Oxford: the original definition was simply 'A hangman; hanging; the gallows' . And on that note, I think I've 'hanged about' in this thread long enough.... I'm off to the Town Hall to meet up with Lang!

Mike C