The author believes the following features of his work adapt it to the purpose for which it was designed:
1. It contains no more than can be mastered by the average engineer and those associated with him, such as millwrights, machinists, superintendents of motor power, electric stations, water works, etc.
2. It is thoroughly systematized. The order and development of subjects is thought to be logical, and the arrangement of topics especially adapted to the needs of those who aspire to do the best service in their every day responsibilities.
3. The work is written in accordance with modern theories and practice; no exertion has been spared in the attempt to make it fairly represent the latest state of the science of hydraulics and its adaptation to the needs of modern mechanical advancement, _i.e._, in the line of practical hydraulics.
NOTE.—The preface is almost invariably made after the book itself is finished, for an author never knows with much exactness whither his researches will lead him. The book he begins is not always the book he finished; this is especially the case with books relating to modern sciences and industry. As an instance of this, it may be told that at the commencement of this work it was generally agreed that the easy “lift” of the centrifugal pump was some sixty or eighty feet, and not much more, but the appropriate section relating to centrifugal pumps has reached a lift of two thousand feet had been practically assured by recent discoveries. This important difference demanded a change in the writing although—as it happened—not in the printing. This, to explain why here, the author gives generous praise to others who have assisted in the long task of making these volumes.
4. It has been made by “men who know for men who care,” for the whole circle of the sciences consists of principles deduced from the discoveries of different individuals, in different ages, thrown into common stock; this is especially so of the science of hydraulics; thus it may be truthfully owned that the work contains the gathered wisdom of the ages, utilized wherever the author has found that it would increase the usefulness of the volumes.
5. It is a work of reference minutely indexed. We are warned by Prof. Karl Pearson that “education can only develope; it cannot create. If a man has not inherited ability to learn, education cannot make him learn,” but in a well indexed book, simply and plainly written, both classes referred to are equally benefited.