220 J, E. Macnellan, C.E.— On [Oct. 26, 



called on me and said lie had just entered into a contract for the 

 construction of a reservoir bank on his property for a certain sum, 

 and now wished to know how much earthwork would be required to 

 fiuish the work, insisting, in spite of my remonstrances, on only 

 giving such slopes as the material would stand at when first tipped. 

 The slopes were not to be pitched, owing to the scarcity of stones. 

 It will scarcely be a matter of surprise, if this dam, so constructed, 

 should be washed away by the first heavy rain. 



Another fault in many of these dams is that too little attention is 

 paid to their overflows, and this is a very serious one, for the existence 

 of the bank depends almost always on a proper provision being made 

 to carry ofi the surplus water after the dam is full. If this point 

 is neglected the water will rise till it reaches the crest of the dam, 

 when it then only becomes a question of time for it to share the fate of 

 many others whose safety valves have been omitted or made too small. 



It is scarcely a matter of wonder to hear of so many dams having 

 given way after a heavy rainfall, Avhen they are made in this 

 haphazard style by men who have little knowledge how to construct 

 a bank able to withstand the denudation caused by alternate filling 

 and emptying as well as by the insidious percolation of standing water. 



Outlets should, where practicable, be placed some distance from the 

 bank, a natural 'nek' being best, but where such is not to be found, the 

 overflow may be formed by making a cutting, or by leaving a sufficient 

 opening ac the end of the bank. In the event of the latter plan being 

 adopted, the bottom, and side next the embankment, should be 

 protected from scour by substantial stone pitching. A training wall 

 or bank must also be made to lead the water clear away from the 

 outside slope, and protected with stones or bushes where necessary. 



Front slopes should always be pitched, if there are suitable stones 

 to be procured in the neighbourhood, to prevent damage from burrow- 

 ing of crabs and trampling of cattle. 



From the foregoing remarks it is not to be understood that all the 

 dams in the country are badly made, far from it, for there are many 

 excellent ones, which have stood firm for years, proving a source of 

 wealth to their owners, and showing them that substantial work pays 

 the extra outlay in the long run. But althou h some grave errors 

 have been pointed out in the general construction of dams, the farmers 

 .are not altogether to be blamed, for they have to contend with many 

 difficulties and troubles which most people in the large towns know 

 little or nothing of. What they have chiefly to struggle against are 



