20 ON THE RECLAMATION 



fill it with clay puddle. The ordinary dimensions for such 

 embankments are that they rise about 2 feet above flood level, 

 that they have a top width of 3 feet, with a slope of 3 to I 

 towards the river, and 2 to 1 towards the land ; it will hardly 

 be desirable to attempt to construct such defence flood embank- 

 ments when they are likely to be exposed to a greater pressure 

 than 4, or at most 5 feet, as their cost will then become too 

 great, and the difficulty and risk of construction too formidable 

 for private enterprise. 



As the effect of all such embankments is to prevent the 

 river from spreading over flat tracts of country, so their tendency 

 is to cause a greater discharge and higher velocity through 

 the natural channel of the river, and to increase the abrading 

 power of the current on the bed and banks. Again, if the 

 works of protection include only one side of the river, the 

 result may be to increase flooding on the opposite bank, if it 

 be not similarly protected. Hence such operations on the part 

 of proprietors have led to serious legal proceedings, which 

 renders it advisable not to embark in the formation of such 

 works without careful consideration of the consequences. 



The remarks I have offered refer, it will be seen, to works 

 made purely in the interests of agriculture. But the beneficial 

 effects which have followed extensive navigation improvements 

 in lessening the floods in some of our large rivers are highly 

 important and deserving of notice. 



The works executed in improving the navigation of the lower 

 reaches of the Tay, the Clyde, and the Tees, have lowered the 

 level of the low-water line, and the power of discharging flood 

 waters with an ebbing tide ; and, accordingly, we find ample 



