Some years ago the author of this book contributed to "Architecture and Building" and the Architects' and Builders' Magazine a series of articles on "Trussed Roofs," which were so well received that he has been led to prepare a book which would treat the subject of trussed roofs and roof trusses in a more complete and comprehensive manner than has ever before been attempted.

Starting with the articles above mentioned as a nucleus, they have been revised and rearranged and a great amount of additional matter added.

The aim of the author has been to describe nearly every type of roof construction commonly met with in buildings such as architects have occasion to design, to point out the advantages of the different types of wooden and steel trusses for different spans and building requirements and to explain the process of computing the loads, drawing the stress diagram and proportioning the members and joints to the stresses. Special pains have been taken to make the mechanical principles involved as plain as possible and to describe the method of obtaining the stresses so that any intelligent person can apply them and that without violating any scientific principle. The author has had in mind the needs of architects, draughtsmen and builders rather than those of the engineer and hence more space has been given to the description of wooden trusses and the common types of steel trusses than to intricate engineering problems; the object being to make the book of practical value to the greatest number of persons.

The author desires to express his thanks to the publishers of the Engineering Record for the use of many illustrations from that excellent journal, and also to the several architects and manufacturers who have furnished him with working drawings from which many of the illustrations have been made.

The preparation of this book has involved an immense amount of labor, and the author hopes that its value to the persons for whom it is intended may be in some slight degree commensurate to the labor and expense involved. F, E. KIDDER.