This book makes possible the accurate geometrical solution of all problems of pattern development normally encountered, by giving examples arranged according to a systematic plan which progressively illustrates the underlying principles.  In the five ¿courses¿ into which the book is divided, the three basic methods of Radial Line, Parallel Line and Triangulation are applied in more and more complex examples, culminating in the solution of difficult problems of pipe intersection, twisted surfaces and spiral chutes.  Each stage in the solution of the problem is clearly explained and shown in detailed drawings, and the superiority of the accurate geometrical method, in terms of time and material saved, is effectively demonstrated.  All sheet metal workers will find this book invaluable.