This, the Fifth Edition of the Practical Petroleum Engineers' Handbook, offers additions to and revisions, up to 1967, of the text presented in the preceding Fourth Edition of this book, published in 1956. The original, basic concept of the book has been retained in this new Edition. This concept was to compile a handbook which, under one cover, would provide information and data which an operating engineer or an operations' man needs in his everyday work in oil drilling and producing practices. However, some innovations have been added. For instance, for those who want to make a broad study of a subject, or subjects, presented briefly in this book, a rather detailed bibliography has been furnished for some of the Chapters.