Last week I took my five-year-old s

Last week I took my five-year-old son, Robert, to the Science Museum. He had always enjoyed going to museums, particularly those where you can press buttons to make things work. He did not much like the sort where there are bones and bits of pots in glass cases; but I told him the Science Museum was not like this. When I mentioned to him that we were going to the Science Museum, he looked puzzled. He asked me what there was to see there, and when I replied that there was a collection of cars, trains and airplanes, and an imitation coal-mine that he could walk into, he looked even more puzzled. But there was nothing he liked better than climbing on old railway engines, so he smiled and said he would come. I told him that we would see models of all the world's most famous ships, and of all the most useful machines that men had invented over the years; I told him that there was