Sources of information have been acknowledged in the text, but special mention may be made of lectures given by Professor Unwin at Coopers Hill College, of Harcourt’s large work on _Rivers and Canals_, of the papers[1] by Binnie on rainfall, by Shaw on the closing of the river Tista, by Harcourt on movable weirs and on estuaries, by Strange on reservoirs, and by Ottley and Brightmore, Gore and Wilson, and Hill on the stresses in masonry dams; of the articles by Bligh[2] on weirs with porous foundations and by Deacon[3] on reservoir capacity, of the Indian Government paper by Spring on “River Control on the Guide Bank System,” and of the Punjab Government paper containing Kennedy’s remarks on silting and scour in the Sirhind Canal. The two papers last mentioned are not easily accessible, and they contain matter of great interest. The important points, often obscured by masses of detail or figures, have been extracted.[4] Silting and scour (CHAP. IV.) had already been dealt with in _Hydraulics_,[5] but some further information has since come to light and the subject has been treated afresh and the matter re-written. E. S. B. CHELTENHAM, _1st May 1913_. RIVER AND CANAL ENGINEERING CHAPTER I INTRODUCTION 1. =Preliminary Remarks.=--River and Canal Engineering is that branch of engineering science which deals with the characteristics of streams flowing in open channels, and with the principles and methods which should be followed in dealing with, altering, and controlling them. It is not necessary to make a general distinction between natural and artificial streams; some irrigation canals or other artificial channels are as large as rivers and have many of the same characteristics. Any special remarks applicable to either class will be given as occasion requires. 2. =Résumé of the Subject.=--CHAP. II. of this book deals with the collection of information concerning streams, a procedure which is necessary before any considerable work in connection with a stream can be undertaken, and often before it can even be decided whether or not it is to be undertaken. CHAP. III. deals with rainfall, and describes how rainfall figures and statistics can be utilised by the engineer in dealing with streams. CHAP. IV. explains the laws of silting and scouring action, a subject of great importance and one to which the attention ordinarily given is insufficient. The general characteristics of streams, being due entirely to silting or scouring tendencies, are included in this chapter. CHAP. V. describes how silting or scouring may be, under some circumstances, artificially induced or retarded. CHAP. VI. deals with various methods of protecting banks against erosion or damage. CHAP. VII. treats of diversions or the opening out of new channels, and with the opposite of this, viz. the closing of channels, a feat which, when the stream is flowing, is sometimes very difficult to achieve. This chapter also deals with dredging and excavation.