I’m off to Ireland for a few days to attend the wedding of my good colleague, Dr. Marie O’Shea, in County Cork, and to team up with my old mate, Dr. Robert Pogue, in Limerick.

Whilst there I intend to conduct a meticulous scientific evaluation of the relative merits of Guinness, Murphy’s and Beamish. Dirty work, but someone has to do it.

In the meantime, have a look at this. I have a problem with it; I don’t understand; can anyone help?