A scoutmaster was teaching his scouts about survival. "What are the three most important things", he asked, "that you should bring with you in case you get stranded alone in the desert?" Hands were raised to suggest food, matches, distress flares and so on, but one boy said: "A compass, a canteen of water and a deck of playing cards." "Why those items?" asked the scoutmaster. The boy replied: "The compass is to find direction, and the water is to prevent dehydration." "Yes, I understand that," said the scoutmaster, "but why would a deck of playing cards be of any use if you were stranded alone in the desert?" "Well, you know how it is," said the boy. "As soon as you start playing solitaire, someone is bound to come up behind you and say, 'Put that red six on top of the black seven.'" I phoned the local ramblers' club today, but the bloke who answered just went on and on. Tim Vine