Mechanics

It is bewildering the pace of change.
Occasionally when seated in deep thought I have been startled by the sound of a runaway marble rolling down a metal tray. It turns out to be the last 4 or 5 feet of the toilet roll spontaneously making a last desperate run for freedom leaving the inner cardboard tube bare.
Several times I have tried with pencil and paper to work out the mechanics of this phenomenon, unsuccessfully.
Let me digress. When I was doing my degree with the OU one of the great memories is of the time when we all constructed our own mass spectrometers out of a razor blade, a small lens and the cardboard tube of a toilet roll. To see the spectral line of sodium with an instrument two thirds of which could be found in our bathroom really was a proper use of the word amazing.
Anyway this morning as I retracted the last couple of pieces of paper I suddenly saw that there was no cardboard tube !
My first thought was could I get another 24 rolls of toilet paper out of Morrisons for this obvious product defect. But then the sad truth dawned It was intentional.
It was part of the same process that causes chocolate bars to shrink.
This does not advance the cause of civilisation.