PREFACE. THE present volume is an outgrowth of the needs of the author's own class-room. The matter is essentially that presented to his classes for a number of years past, a considerable part having been used in the form of a blue-print manuscript text-book. It is now published for the greater convenience of his own students, and with the hope that it may be useful to others. The author knows of no work which treats of any considerable part of the field covered by this volume. Nearly all of the matter is believed to be entirely new. The object has been to develop principles and methods and to give such examples as illustrate them, rather than to accumulate details or to describe individual structures. The underlying principles of ordinary practice are explained; and, where needed, ways are pointed out whereby it may be improved. The common theories are compared with the results of actual practice; and only those are recommended which have been verified by experiments or experience, since true theory and good practice are always in accord. The author has had the benefit of suggestions and advice from practical masons and engineers, and believes that the information here presented is reliable, and that the examples cited. represent good practice. The general prices are the average of a large number actually paid; and the special prices are representative. The structures illustrated are actual ones. The accredited illustrations are from well-authenticated copies of working drawings, and are presented without any modification whatever; while those not accredited are representative of practice so common that a single name could not properly be attached. In the preparation of the book the endeavor has been to observe a logical order ar a due proportion between different parts. Great care has been taken in classifying and arranging the matter. It will be helpful to the reader to notice that the volume is divided successively into parts, chapters, articles, sections having small-capital black-face side-heads, sections having lower-case black-face sideheads, sections having lower-case italic side-heads, and sections having simply the serial number. In some cases the major subdivis |