PREFACE .My experience in the construction of such buildings having been largely obtained in America, I have naturally found it convenient to my purpose to give a preponderance of illustrations of typical American factories : at the same time, some noteworthy English examples are included, and with respect to several of these I wish to express my indebtedness to Mr. Thomas Wallis, M.S.A., of the firm of Wallis, Gilbert & Partners, Architects.A treatise explaining and illustrating modern principles and practice in the design and construction of industrial buildings has therefore a valuable function to perform, especially at a time when professional and business men are anxiously preparing for a period of unparalleled commercial and industrial expansion, in which factory building must play an important part."National efficiency " is clearly recognised as a condition of vital consequence to the Empire ; and it is my aim to show how to build efficient factories.Caxton House, Westminster.