18?9.] A^^ [Ilaupt. 



of a single detached jetty made up of elliptical curves presenting their 

 cusps to oppose the supposed advancing component of the tidal wave, 

 and of an in-sliore extension to concentrate the tiood current upon a 

 secondary or 'beach' channel, which it is proposed to keep open. At 

 New York and Galveston 'detached breakwaters' are indicated, to pre- 

 vent the ebb from being diverted from its course, and to train it upon a 

 point where, according to his theoretical deductions, 'the bar-building 

 forces are weakest. ' 



" Without going into any general discussion of this typical plan, it will 

 be sufficient to point out : (I) That since no provision is made to close the 

 'beach' channel during ebb tide, it will carry oft water which might be 

 more usefully applied to scouring out the main or 'ebb' channel, and that 

 one good channel is certainly better than two bad ones ; (2) that this pro- 

 posed main channel, in the case of Charleston, is so lengthened by its loca- 

 tion, that the working energy, due to the difference of head between the 

 harbor and the outer ocean, is frittered away by being distributed over a 

 path needlessly long ; and (3) that the degree of contraction on the bar is 

 ill-defined, uncertain and altogether insufficient." 



To any one at all familiar with the original plans of the Government 

 engineers for both Galveston and Charleston, the above criticism of my 

 methods must appear as singularly inconsistent. If there are serious ob- 

 jections in the plans which I have submitted, they must apply with much 

 greater force to those now being executed at so great expense to the Gov- 

 ernment. 



The whole merit of the submerged jetty plan, as adopted, was based 

 upon the theory that the flood would be admitted freely over the jetties at 

 their shore ends, and be, at ebb, trailed by them out across the bar, where 

 the jetties were to be raised to or above the surface of the water. If the 

 loss of ebb energy throvigh the comparatively small lateral opening left 

 in my plans be of serious amount, it would be far more so when the lateral 

 openings amount to nearly four hundred per cent of the section at the 

 mouth of the jetties, as is at present the case at Charleston. 



As to my proposed channel being so lengthened as to fritter away the 

 working energy due to difference of head, it is only necessary to say that 

 the point of escape for the ebb at all these sites is, in my plans, nearer the 

 gorge, giving a greater slope and more rapid discharge than in the plans 

 now under construction. At Charleston, the most unfavorable case for 

 me, it is but two and seven-eighths miles distant from the gorge, while 

 the mouth of the Government jetties is about three and one-eighth miles 

 distant. 



"ONE GOOD CHANNEL verSUS TWO BAD ONES." 



There is no doubt that one good channel is to be preferred to two bad 

 ones, but the counter.proposilion that "two bad ones" are better than no 

 good one is likewise true, and when it is remembered that the forces relied 

 upon to create and maintain the two channels are distinct, are operating 



PROG. AMER. PHIIiOS. SOC. XXVI. 129. U. PRINTED APRIL 1, 1J8D. 



