If you are interested in watchmaking or the repair of old watches, this is a must have book. Henry is very through in his explanations & has a great skill @ illustrations. I am a watchmaker & find this such a great wealth of old school knowledge that has been documented very well. A lot of information & techniques get lost as they are learned on the job or just forgotten when no used, Henry captured a lot of information & put it in this book. In the Preface:..It is intended to serve as a course of study, as a means of reference, & as a textbook or working manual to be used in the school or the library... This is only for mechanical watches a lot on antique watch repair, no quartz. MJR 6 DELTA LS