1889.] 1^^ [Haupt. 



already well known, wliicli has a useful application in the improvement 

 of our harbors. 



"A copy of the printed paper submitted to the Board by Prof. Haupt is 

 herewith enclosed. Respectfully submitted. 



(Signed by) "Thos. Lincoln Casey, Colonel Corps of Engineers. 

 " Henry L. Abbot, Col. of Engineers, Bvt. Brig. Genl. 

 " C. B. COMSTOCK, Lt. Col. of Engrs., Bvt. Brig. Genl. 

 "D. C.Houston, Lt. Col. of Engrs., Bvt. Col. 

 "W. R. King, Major of Engineers." 



From the above concluding remarks it will be seen that the Board find 

 in the paper submitted "nothing not already well known, etc., "and that 

 the plans "are purely theoretical and unconfirmed by experience." These 

 conclusions appear to me to be contradictory, since if, on the one hand, 

 they are new and untried, they could hardly be expected to be confirmed 

 by experience, or if, on the other hand, they are "well known," they are, 

 by that expression, impliedly recognized as true, and their application 

 should be readily confirmed or denied by the supposed existing precedents. 

 But none have been cited by the Board. 



In the paper of Prof. Hilgard, to which the Board allude in their Report, 

 he describes the, to him, unexpected effects produced during the war by 

 the sinking, on tlie Charleston bar, of the so-called "stone fleet," thus 

 obstructing the entrance to the harbor. 



Prof. Hilgard says : 



"On the accompanying diagram is seen the 'stone fleet' sunk in the 

 main channel, which at that time had twelve feet of water at low tide, 

 where the figure seven indicates the present depth. There was, moreover, 

 another channel, making out more to the southward, with nine feet of 

 water, where the figure three indicates the present depth. The vessels 

 were placed checkerwise, in such a manner as to impede navigation, 

 while interfering least with the discharge of water. The effect, neverthe- 

 less was the formation of a shoal in a short time, and the scouring out of 

 two channels, one on each side of the obstructions, through which twelve 

 and fourteen feet can now (January 27, 1871) be carried at low water. 

 The increased waterway thus given to the ebb tide caused it to abandon 

 the old nine-foot channel on the less direct course to deep water. We 

 have here the total obstruction of a channel, which was of considerable 

 importance to the southward trade, by new conditions introduced at a 

 point four miles distant from where the effect was produced, and we are 

 warned how carefully all the conditions of the hydraulic system of a har- 

 bor must be investigated before undertaking to make any change in its 

 natural conditions, lest totally unlooked-for results be produced at points 

 not taken into consideration." 



So that instead of obstructing the entrance this accidental barrier to the 

 flood actually deepened the water on the bar two feet, and induced the 

 ebb currents to effect an escape in its lee, closing a channel several miles 



