66 ON THE RECLAMATION 



Occasional reference has been made to drainage, and this is, 

 perhaps, the natural place to say generally, that in all such cases 

 of estuarial reclamation and coast defence as we have been con- 

 sidering, it is essential that the engineering works should embrace 

 a proper system of drainage. Main and cross drains, of suffi- 

 cient capacity and fall, must be formed and led to one or more 

 outlets through the embankments. The outlets of these drains 

 must be provided with self-acting sluices, to close at high tides, 

 but to afford an escape for the drainage at low water. The 

 discharge of such drains, it need hardly be added, must vary in 

 every case with the drainage area and rainfall of the district to 

 be provided for, and their sufficiency to discharge the requisite 

 amount will depend on the fall that may be found available; 

 and whatever that may be, it will regulate the cross sectional 

 area of the drains themselves. The whole of the works of the 

 drainage should be carefully designed, on due consideration of 

 the meteorological, geographical, and engineering features of each 

 separate case, and the offlets, tunnels, pipes, and sluices should 

 be executed under proper supervision. 



Much of the success of such drainage works, I may add, 

 depends on the selection of a favourable site for the discharge of 

 the drainage water, especially on exposed beaches composed of 

 shingle or gravel. The force of this remark may perhaps be 

 well illustrated by a reference to the rivers Findhorn and Lossie, 

 on the Moray Firth, where the shingle is thrown up by the sea 

 in such quantities as completely to overpower them, and con- 

 sequently these rivers discharge into the sea at points very 

 distant from what might be regarded as the natural position of 

 their outlets. Fig. 11 shows this action at the Findhorn; and fig. 



