The Science Museum in London is currently showing an exhibition about Alan Turing. Kate and I wandered up there on Saturday. I found the exhibition itself a little superficial - which isn't so surprising given the breadth of material the curators had to draw on between his personal life and death, contributions to computing, the war effort and Bletchley park, and his work on morphogenesis.

But there were two little gems in there which I focused on: the first, one of the tortoises of W. Grey Walter: beautiful and tremendously simplistic devices which exhibit eerily animalistic behaviours. And secondly, a bombsight computer from a Lancaster bomber, on which I was chuffed to discover the manufacturer's mark of Sperry. For it was a Sperry machine which D P Henry used to create his spirograph...