40 Transactions Texas Academy of Science. [86] 
to estimate otherwise, as it is probable that if not washed out, at least 
that much would have to be removed before rebuilding. This break-up 
of the bed rock I have assumed to be from a point six feet above the 
upper face of the dam a line twenty feet below the toe. This, then, 
will make a pit 483 feet long by ninety-two feet wide by four and eight- 
tenths feet deep, which must be filled with masonry or concrete before 
reaching the base of the original dam. 
(5) It seems to me imperatively necessary tjiat the toe of the dam 
its entire length should be protected by an apron of masonry or concrete 
to prevent undermining. This I have estimated as 1100 feet long, aver- 
age width twenty feet, average depth three feet. 
(6) In my estimate I assumed that the up-stream face wall will 
be built of limestone to a height fourteen feet below the crest of the 
dam, and will have a slope or batter of three inches to one foot vertical. 
This will add 442 feet to the original sectional area of the dam, making 
it 2642 feet. The upper fourteen feet of the up-stream face, the coping, 
and the down-stream face all to be of granite as in original plans. . All 
this will be shown more fully by the- sketch (Fig. 17) which I herewith 
enclose, showing suggested profile. It is suggested that the entire filling' 
or interior shall consist of concrete made of American Portland cement. 
(7) The cost of the contractors plant or outfit under conditions 
like these is quite as great for the construction of a dam 600 feet long 
ns for the original length of 1091 feet. 
With the above explanations I submit the following estimate of cost : 
Earth excavation, wet and dry, 21,000 cubic yards, 30 cents. $6,300, 
Eock excavation, 2000 cubic yards, $1.60, $3,200. 
