Purdom, Charles "Watchmaster watchmakers" (200 pp, ill, the author, 1949) Like Purdom and Hagans “Scientific timing”, this book is meaningless rubbish. Much of it is simply wrong. Three examples are the description of the lever escapement (the diagrams are wrong and the explanation borders on ludicrous), balance poising (Purdom has no idea of static and dynamic poising), and detecting mainspring power variations (which are not visible from the instantaneous rates produced by timing machines). In addition, the basic principle, of “center lines” is irrational. Some of it might contain correct statements, but the approach is superficial, largely unintelligible and of no practical use. In particular, the few timing machine charts shown are meaningless because the principles of timing machines are not discussed and no explanation of chart analysis is given. The most interesting feature of the book is that balance spring needling, prominent two years earlier in “Scientific timing”, has disappeared; presumably enough ridicule was directed at it to force Purdom to dump the idea. As it is impossible to understand his books, I wondered if it might be possible to understand Purdom. This book gives us a few hints. First, he was an employee of American Time Products, the company which manufactured the Watchmaster rate recorder and the book suggests he was a travelling salesman. Second, he wrote “If it were not for the Watchmaster, in all probability I would know less about all of this than any other person”. So we can reasonably conclude that he never trained as a watchmaker and his knowledge of watch repair was picked up from visits to watchmakers as he tried to flog timing machines. Third “The only reason that I write books is to make money”, a rather startling admission. So it is likely that Purdom’s ideas are the result of listening to watchmakers and reading a book or two on adjusting; and, not surprisingly, failing to understand any of it. Then, with this background and the need to glorify the product he was selling, he produced a couple of books which try to explain what he did not comprehend by utterly incorrect pseudo-science. The result is bare-faced, incompetent advertiing. In one respect this book is better than “Scientific timing”; it does not contain Hagans’ incredibly stupid statement.