Then I discovered at Basel, the Fair, that not many people knew how escapements worked. And... for example, I had a co-axial escapement there... a model... quite a big model, and a chap came up to me and asked me what was the difference between that and the lever escapement. Well, I thought, well how do you convince these people? And so I tried to explain to him, but I really wasn't interested in explaining to him. I took the view that if he didn't know it wasn't my place to teach him, he can find out first and then come back. But it did occur to me that it would be much better if more people knew how it worked and then they'd see some sense in it and maybe it was that many of the Swiss people didn't believe in it because they didn't know how it worked and they hadn't realised its advantages. I've already explained the advantages, haven't I, about the impulse and all that sort of thing. And so I went home and wrote The Practical Watch Escapement. It's called The Practical Watch Escapement because it includes all those escapements that have been used for practical purposes in watches. Watches haven't always had the best escapement. Sometimes they've had an inferior escapement for very practical reasons like money, for example. You know, you've got to sell the watch, its got an expensive lever escapement you're limited to the number of customers. So, it was a book about practical escapements and it gave a complete analysis of the function of all the escapements so that with that book you can choose any escapement you like and make the whole thing and test it against all the drawings and the figures in the book. And so that book proved to be very useful and it's in its second edition now, and there may be a third edition on that. It gives a full explanation of the co-axial escapement.