The following are the principal additions or alterations that have been made in this edition.

Chapters on Riveting, Centres, Built-up Beams, and Plate Girders have been revised, and transferred to this Volume from Part II.

The remaining chapters have also been revised and added to; much of that upon Iron Roofs has been rewritten, and 7 Plates have been added to it, giving reduced copies of the cod tract drawings for some recently constructed roofs. A Plate has also been added to Chapter VII (Iron Roofs). giving the contract drawings for a plate girder to support a workshop floor.