158 Timehri. 



are shown in a pass between Tiger island and the mainland with sound- 

 ings of 20 to 26 feet. In 1888 these were 12 feet. 



In 1802 in the East pass of the Essequebo the depths of the bar are 

 8 feet, in 1888 these are 15 feet and the line of deepest soundings lies 

 south of the Sugar bank, which continues to extend eastwards with a 

 tendency to unite with Dauntless Island and the banks between these 

 two, while the Red banks or Blue Jacket banks are slewing round to the 

 south at their eastern parts. 



All these changes show that the tide comes up from a more easterly 

 direction and that the current entering or leaving the Essequebo flows 

 partly over the Demerara bar and is the cause of this shallowing. 



The deeper water out at sea is the cause of the waves running up 

 higher on the Georgetown seawall than formerly. No information is at 

 hand whether the spring-tides are now higher as shown on the scale at 

 P.W. stelling in 1879. It may be that the seawall laid in 1882 has 

 settled and wants raising. 



As regards the estimate of 1880 this wants revising as the prices of 

 labour and materials have considerably risen. On the other hand new 

 methods of work and better machinery for dredging are obtainable so 

 that in a round sum the estimate of £3,000,000 for a leading dam and 

 channel to the %\ fathom line will not be far out. The general direction 

 of the dam can remain as proposed in 1879, except that the part between 

 the shore and that further out should be laid in a curve of greater radius. 

 Then, it is worth considering whether the use of concrete or fero concrete 

 would be advisable from an economical standpoint. But this requires a 

 serious study and a great deal more information of all sorts than is at 

 present available. 



The better to explain these remarks, a copy of the chart laid over 

 with the report of 1879 is hereto annexed with the changes in the sound- 

 ings obtained from notes made in 1891. On it is marked an amended 

 proposal for the leading dam to be laid in the same direction but a little 

 further to the North-West which will give a better entrance to the river 

 and showing a gap or side opening for traffic to the Essequebo and 

 islands. 



Definitive plans can only be made after a thorough investigation of 

 the present condition, but in principle the scheme of 1879 can be 

 followed. 



H. SICCAMA, 



M. Inst. C.E. 



The Hague, August, 1912. 



