Page:The Columbia River - Its History, Its Myths, Its Scenery Its Commerce.djvu/575

this method of deepening river mouths. The jetty consists of a double line of piling, filled with rock and mattresses of woven willows. This constitutes a solid core against which the current of the River on one side piles the silt, while on the other the ocean waves pound the sand into a permanent barrier-reef. The philosophy of it is so to narrow the entrance that the accelerated current of the River will scour out the channel to an increased depth. Piles have been set in place by an ingenious system of pneumatic pipes by which compressed air bores a hole in the sand. Into this hole the pile is dropped, and the sea-waves in a moment fill in and tamp the sand around it. Thus the ocean is made to fence itself out. Upon the jetty a railroad has been built, and a train, loaded with rock and willows, runs out on this every eleven minutes for dumping material into the space between the piles. Very gratifying results have already been secured. There is now a depth of twenty-six feet on the Bar at low water. The crest of the Bar has been cut much deeper at several narrow points, and this indicates the progress that may be expected. It is hoped that the completed jetty will maintain a permanent channel of forty feet at low water. In stormy weather the work on the jetty is difficult and dangerous. The impact of the Pacific waves when lashed by a sixty-mile "sou'-wester" is something terrific. Large sections of piling have been torn out, and much loss has resulted. But patience and money triumph over all obstacles, and the work goes steadily on. Some conception of the magnitude of the commerce to be accommodated by this great work may be formed from