Appendix TTT 157 



For the present a width of 250 feet is deemed sufficient. The 

 channel in the improved Mississippi South Pass was at first stipulated 

 to be 300 feet wide and 30 feet deep under ordinary high water, but 

 since the contractors have been bound to 250 feet only, as this was 

 considered enough. 



Should, however, the outlay to obtain 20 feet be too great, and a 

 depth at low water of 15 feet be thought enough, a training dam on the 

 same principle as above described should be laid to that depth at sea. The 

 direction of this dam should, however, be more northerly, as in the 15 

 feet depth the current sets more southerly than further out, and the full 

 advantage would not be taken, splitting the stream instead of intercept- 

 ing it, by laying the dam, too parallel to the direction of the current. 



It is estimated that this work will amount to about 81,700,000 with 

 a total length of dam of 16,000 yards, and the same width of 250 feet 

 for the channel. 



The works at present being carried out in the Mississippi and at 

 Charleston may give experience to cheapen the work here proposed, and 

 it is thought advisable not to enter into further details till investigations 

 have shown whether the knowledge gained on the latest hydraulic works 

 in the United States can lead to an improved and a simpler mode of 

 construction. 



H. SICCAMA, 

 M. Inst. C.E. Govt. Hydr. Engr 



Georgetown, Demerara, 31st December, 1879. 



Since the foregoing report was made many changes are noticeable. 

 On Bouchenroeder's map of 1802, the centre line of the fairway from the 

 Demerara river lies in a direction 8 degs. East of True North, with 

 depths on the bar of from 9 to 11 feet. On the chart of 1872 the fairway 

 over the bar lies in a direction 39 degs. East of North, with greatest 

 depths of 8 to 8| feet. On the chart as amended in 1888 the line of 

 deepest soundings of 8 feet lies 58 degs. East of North. 



On the chart of 1872 the position of the Lightship is shown due 

 North of Cumings Lodge on the Demerara East Coast ; on that of 1888 

 this position lies due North of Montrose, a mile and a quarter further 

 East ; while in 1891 the Lightship had been again moved in an easterly 

 direction but a little further inshore as the 3 fathom line had approached 

 the mainland. 



These changes are related to similar changes in the Essequebo 

 River. On Bouchenroeder's map the greatest depths to enter the river 



