EARTH DAMS. 217 



These may be either by covering the face with sods, in 

 case no overflow is permitted, or with masonry or plank- 

 ing. 



The manner of constructing a dam is of the greatest 

 importance. The modern method is to introduce a pud- 

 dle wall in the middle, to place selected materials upon 

 each side of this, and to form the slopes of the most 

 convenient materials to be procured, whether gravel, 

 rubble stone, or waste broken rock. ' But there are many 

 very ancient embankments, still existing, that have been 

 constructed without puddled centers, or any special pre- 

 cautions to make them water-tight. The ancient manner 

 of making these embankments was, to carry the earth in 

 baskets upon the heads of the workmen, and deposit it 

 where it was required, without any particular care as to 

 the disposal of it. The constant treading and the 

 thorough consolidation of the earth, by being thus thrown 

 in small quantities beneath the feet of the workmen, 

 tended to make a well incorporated, homogeneous mass, 

 which would be impenetrable by the water. It would be 

 difficult to discover any better mode of construction than 

 this. A dam constructed by the author upon an uneven 

 rock bottom which furnished an excellent foundation, 

 and of a crumbly, loamy clay earth, which melted down 

 in water to a pasty mass, was made without any puddling, 

 and by simply carting the earth and dumping it into its 

 place ; the stream having been previously confined within 

 a flume of timber where the waste gate was afterwards 

 put in. The treading of the horses and men, and the 

 packing caused by the cart wheels, so perfectly con- 

 solidated the earth that no leak was observable, and the 

 dam is now probably better than it was when first made, 

 15 years ago. This dam was faced upon both sides with 

 waste broken rock, and in one severe freshet, water has 

 poured over the top to a depth of more than two feet, for 

 several days, without any injury. 

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