1901.1 HAUPT — METHODS OF IMPROVING OCEAN BARS. 79 



signed to rise only to half-tide, but both were subsequently raised 

 above high water to make them, if possible, effective. It is not the 

 purpose of this paper to review the results of works of this class, but 

 their sequel shows that they have not fulfilled the expectations of 

 their designers and that they have not arrested the advance of the bar 

 seaward nor have they given '■he anticipated depths, with the excep- 

 tion of South Pass. This, however, has caused a rapid shoaling in 

 the entire channel above the jetties in consequence of over-contrac- 

 tion, and necessitates the maintenance of the depths by dredging for 

 a distance of many miles because of the elevation of the flood plane 

 and bed of the stream by sedimentation. 



Hence the necessity for an early removal of the bar at the South- 

 west Pass. 



But to return to the discussion. The author suggests that to 

 arrest sand movements entirely, high tide jetties are requisite, and 

 cites those at Yakina Bay as a type, as having " increased the depth 

 from seven to fifteen feet at mean low water, and, so far as the 

 records show, without as yet producing any new bar seaward of the 

 jetties." It may suffice to state, on the contrary, that while the 

 original depths at low water were seven to nine feet, the latest 

 annual report of the Chief of Engineers for 1900 says on p. 4298 : 

 "There is at present, about one-half mile from the end of the 

 jetties, a crescent-shaped bar almost enclosing the entrance and 

 having from eight to twelve feet of water over it at low water.. 

 Around the south end of this shoal there is a channel having a 

 least depth of thirteen feet 1 at low tide. This bar has apparently 

 shoaled somewhat since the survey of 1895." The report of 1887, 

 when only a portion of the south jetty was built, also shows a low 

 tide channel of thirteen feet, and the officer then in charge calls 

 attention to the movement of the bar seaward toward a reef of 

 rocks. 



These official statements would appear to discredit the asser- 

 tions of the author as to an increase of depths to fifteen feet 

 and no advance of the bar seaward. 



In commenting further upon twin jetties, the author remarks : 

 " Jetties built to a height sufficient to stop the sand flow from both 

 sides and also high enough to control the tidal flow should be ex- 

 pected to reproduce at the bar the depths at the gorge." Experi- 

 ence does not seem to confirm this expectation, since nature fur- 



1 The chart shows but ten feet. This may be an error, however. 



