26 Transactions Texas Academy of Science. [72] 
the height of a little over sixty feet on the city side of the river and 125 
or more on the other side. The spillway was 1091 feet long between the 
bulkheads at each end, which extended to the natural rock. The upper 
face of the dam was vertical and sixty feet high, measured from an 
assumed low water. The down stream face was a reverse curve of ogee 
form, which, at the toe of the dam, was horizontal. The width of the 
dam at the base was sixty-six feet. The rotten and loose rock excavation 
over the area covered by the dam was comparatively slight, being only a 
few feet im depth. It was designed to have two trenches, about four feet 
wide and somewhat greater depth, extending lengthwise along the upper 
and lower edges of the dam and filled with masonry to increase frictional 
resistance. The total exposed surface of the dam was constructed of 
squared granite and the interior of limestone rubble masonry, Portland 
cement being used throughout. As was afterwards proved, this granite 
facing was not sufficiently tied into the interior rubble, as in its case of 
great trial it acted like- a coating of veneering. 
The original cross-section of the dam, as recommended by Mr. Prizell, 
is shown in Fig. 8 (left half). The cross-section as adopted (Fig. 8 — 
right half) was recommended by Mr. Fanning, who in his report to the 
Board of Public Works said: 
“The profile (Fig. 8, left half) as shown to me seems not to fulfill the 
required conditions for passing the floods, because of the slightly rounded 
or nearly angular form at the front of its crest. Another ‘diagram (Fig. 
8, right half) presented shows an advised modification of the profile of 
the upper part of the dam, which is better adapted to pass the flood in a 
gliding sheet down the face of the dam and to deliver it to the lower level 
without a direct blow, and so that its velocity will be expended chiefly in 
• Figure 8. 
Cross-sections of Austin Dam; Left Half as Proposed by Prizell; Bight Half as Modified 
by Fanning, 
