THE IMPROVEMENT OF RIVERS. 



PART I. 



GENERAL CHARACTERISTICSPRELIMINARIES TO 

 IMPROVEMENT SURVEYS. 



CHAPTER I. 



INTRODUCTION. 



Progress of Navigation. The utilization and improvement of watercourses is as 

 old as history. The ancients improved and utilized streams and constructed canals, 

 at first for irrigation, and later for navigation. Successive improvements have followed 

 each other in the methods of navigation in order to keep pace with the requirements of 

 commerce, and the methods of one hundred years ago would fail to satisfy the demands 

 of the present, and one hundred years hence the methods now seemingly satisfactory 

 will probably be considered wholly insufficient. 



In early navigation trees were cut in the forest and rolled into the streams and floated 

 singly to the point required for use. This was followed by assembling the logs in rafts 

 held together by tie-poles pinned to the logs. Later, various kinds of merchandise and 

 farm products were placed upon these rafts and transported, and this led to the intro- 

 duction of small boats in which the merchandise could be more safely carried, and which 

 were tied to the rafts. Finally, larger boats were built and floated independently, car- 

 rying considerable loads. In America a large amount of coal, farm products, tanbark, 

 staves, etc., was taken to market in this manner. The boats were sold or wrecked for 

 the material, upon arrival at destination, no ascending navigation being attempted. 



Many of the rivers, however, afforded sufficient water for navigation only during 

 the wet season, and this, together with the necessity of having power to turn the mills 

 for grinding grain, carding wool, manufacturing lumber, etc., led to the construction 

 of dams. These provided pools which were easy of ascent, and rivermen soon found 

 that it was more advantageous to bring back their boats than to sell or cut them up, 



