THE IMPROVEMENT OF RIVERS. 



and ascending navigation was accordingly undertaken. Here a great obstacle was 

 encountered the mill-dams were difficult to ascend, although sluices had been pro- 

 vided in their construction which could be opened and closed at will by means of small 

 needles, or poutrtUcs. While the opening of these chutes was of great benefit to descend- 

 ing navigation, because of the increased depth and velocity it gave below, the very same 

 causes detained ascending craft. This led to the introduction of locks, which were 

 further beneficial in maintaining a good navigable depth in the pools, because of their 

 economy in water consumption. But even this method, which for a time seemed per- 

 fectly satisf acton', failed to answer to increased commerce and the competition of rail- 

 roads, and finally the introduction of movable in the place of fixed dams followed in 

 France and other parts of Europe, and later in America. 



Choice between Canal and River. England's first engineer of canals, Brindley, who 

 has been dead more than one hundred and twenty-five years, is credited with having 

 said that "Rivers were created for the purpose of feeding canals," and acting on 

 that principle he built a canal lateral to the Irwell and the Mersey. He was not alone 

 in his belief, for many miles of canals were constructed both in Europe and America, 

 along the side of streams which might have been utilized for navigation. The early 

 experience of French engineers led them to believe that where a river was subject to 

 high floods and carried much sediment, its improvement would be of uncertain value, 

 as its bed would be liable to change and the lock entrances would silt up. Besides this, 

 the velocity of the current, which would not exist in a canal, would always be more or 

 less of a hindrance to ascending craft. The invention of movable dams, however, solved 

 many of the problems which confronted engineers of that day, and while not all of them 

 agreed that a lateral canal was preferable to a river, the preponderance of opinion was 

 in that direction. Such canals are accordingly to be found on the Doubs, Scarpe, and 

 other streams. 



Locks. The solution of change of level by locks is believed to have been made in 

 1439. The first one was used to assist in transporting marble to the Milan cathedral 

 and was, according, to Lombardini, built by Philip Visconti. Soon after their intro- 

 duction all European countries made extensive improvements in waterways, and thou- 

 sands of miles of canals were built. The Briare Canal, completed about 1642, and con- 

 necting the Loire and the Seine, in France, was the first summit-level canal, and was 

 rendered possible by the invention of locks. The feasibility of thus connecting two 

 distinct systems of waterways by means of canals and locks added a great impetus to 

 uiternal navigation, and systems were constructed throughout France, Germany, Bel- 

 gium, Russia, and later in England and the United States. There are to-day 3000 miles 

 of canals and 4600 miles of improved rivers in France alone. 



Ancient Canals. It is believed that canals were constructed in China and Egypt 

 long before the time of which we have authentic record. When subject to Rome Egypt 

 furnished to her the necessary supplies, and during the reign of Menes, 2320 B.C., the 

 course of the Nile was diverted by means of canals so as to drain and irrigate the pro- 





