A few years ago I was talking to a friend of mine in our club. It was obvious that he had, as we say, something on his mind. ‘Do you realize’, he said, ‘that in this technological age we still have no comprehensive history of technology?’ I paused for a moment, but before I could speak he had answered my thoughts. ‘I don't mean economic history—there are plenty of books about that; technology and economics are quite different’. I asked him to expand this. ‘Well, take any farm you know. An economic survey of it would cover everything on the farm—field-workers and their wages, birds, animals, dung, crops, carts, ploughs, reaping-machines, dairy utensils. But if it's to be a technological survey you concentrate on the carts and ploughs, how they're made, and how they work. What you are then concerned with is how things on the farm are done and made’. When he thus explained it the distinction became obvious. Seeing what was in his mind I murmured : ‘A History of Technology is going to be a big thing’. ‘It is’, he said, ‘for the world is my farm, the human race my farmers and field-workers, and the farm has been a going concern for many millennia’.