This book has been written from the point of view of the constructing engineer. It discusses only those features of design which are or may be variable with each particular case, or which, from their nature, are better known and appreciated by the constructor as the work progresses, than by the designer before the work starts.

Many volumes have been written upon the design of masonry dams; the principal features and methods have been reduced to what may be called an accepted, standard practice. It is hoped that the present work will supply the details of construction and supervision which have not been adequately covered heretofore. For a number of years descriptions of particular dams have appeared in the engineering periodicals, but little attention has been given in these articles to the general principles of construction involved.

Within the limitations of this book it was not possible to cover the subject in all of its ramifications. Earth work, rock excavation, cement, pumping and many similar subjects have been passed over entirely either because adequate treatment was impossible in such a work as this, or because they are fully covered in other books. Other subjects, such as power, are touched upon in the most elementary manner and solely from the point of view of the man engaged in dam construction. Thus the material upon source and distribution of power are mere suggestions, while the subjects of power required, cost of power, etc., are treated somewhat more fully.

It is probably true that for one dam actually built, several are projected and more or less thoroughly examined. The inception and promotion of such projects and their examination by financiers, result in a number of engineers being called upon for estimates of cost. Such estimates must often be prepared within a limited time and for a limited expenditure. To facilitate the rapid and reasonably accurate treatment of such estimates, a chapter has been added on this subject, and this, in fact, was one of the chief purposes of the book. It is hoped that the cost figures will prove a reliable and useful guide for estimates. Labor costs, as always, must be used with caution, and only after a careful comparison of conditions. The plant costs should be more generally applicable, as the possible margin of error in them would result in but an insignificant error in the total estimated cost of the work. When time permits, or the plant is especially large, additional figures are advisable, but in the majority of cases the figures presented will, it is hoped, be a useful guide.

New York, December, 1914 c. w. s.