This book, like the others in this Part, makes no pretense at originality. The author has studied and compared a considerable number of works by the best authorities on the subject and has endeavored to adapt the best of their contents to the use of printers' apprentices. Every author has his own set of rules. At first sight, each set appears inconsistent with those given by other writers. This inconsistency, however, is generally more apparent than real. It arises from differences in point of view, method of approach, and system of classification.