66 HAUPT— METHODS OF IMPROVING OCEAN BARS., [May 3. 



the theory," although admitting that beneficial results have fol- 

 lowed its construction. In the large space which he devotes 

 to its discussion, he unwittingly shows that the theory and its 

 application are entirely misunderstood by himself and others 

 who have attempted to apply it at other places, and that great waste 

 to the Government has resulted from a misconception of local 

 physical conditions. 



2. The Single Jetty. 



It is generally believed that to protect an area from material mov- 

 ing in a given direction it is necessary to place a barrier on the 

 near side of the area, or between it and the source of the drift, to 

 arrest it on the "windward" side. This is the common practice 

 on our western prairies to defend the railroads from prevailing winds 

 and snowdrifts, or along our seashore drives to keep the sand out. 

 To place the barricade on the far side would result in rendering 

 such thoroughfares impassable or greatly increase the cost of main- 

 taining traffic. Precisely the same laws obtain in sand driven by 

 ocean currents or waves, and yet it appears that almost invariably 

 and with numerous precedents as a guide the jetty is placed on the 

 far or wrong side of the channel to be created, where it invariably 

 chokes it up and results in pushing the bar seaward, giving no bene- 

 ficial result from the natural energy and adding greatly to the cost. 



For example, this report says that a single jetty projecting from 

 shore to fix the channel and prevent a considerable escape of the 

 tidal flow should be placed on the leeward of the channel, or 

 "upon that side of the channel toward which the latter is being 

 driven by the drifting sands," and it adds, "This principle of 

 construction was first suggested by Major Thomas W. Symons, 

 Corps of Engineers, U. S. Army." 



The Major will hardly claim the honor of so serious a fallacy, 

 since a jetty so located was suggested by a former Chief of Engi- 

 neers, now deceased, for the improvement of Aransas Pass and 

 was partially built by the district engineer in the years 1885-90, 

 but it merely intercepted the littoral drift moving southerly, 

 dropped it in the channel which it obstructed and pushed the bar 

 seaward with a consequent loss of depth. It cost nearly half a 

 million dollars and was an acknowledged failure. It furnished a 

 complete demonstration of the falsity of the theory of attempting 

 to create a channel by placing a jetty to " leeward of the channel." 



