On May 4th 1915 its keepers, probably peering out from the elegant balcony on the seventh floor, saw a German submarine cheekily surface to buy the morning's catch from a local Irish fishing boat.

ECONOMIST: The Fastnet Lighthouse: Light on a lonely rock | The

So it ought to be possible to test for the presence of a certain antigen on a surface by dragging a suitable antibody over it, and seeing if it gets stuck going fishing, in effect, on a molecular scale.

ECONOMIST: Microscopy