36 Transactions Texas Academy of Science. [ 82 ] 
and replaced, became so saturated with water that upward pressure from 
the pond was transferred to the underside of the dam in sufficient amount 
to neutralize a considerable part of the weight pressure of ^he masonry 
resting upon that soft rock and, furthermore, that this saturated stratum 
became like a lubricant on which that part of the dam had but moderate 
resistance against sliding. 
“The parted sections constituted nearly one-half the length of the dam. 
It is probable that the section of the dam resting on the formation on 
which it had not sufficient frictional resistance was held as a part of a 
beam until a vertical cross-crack came at the central part of the soft sec- 
tion at B (Fig. 12), and also that then the two parts adjacent to B were 
held briefly as cantilevers until they cracked at C and A, after which 
they slid, moving slightly fastest at B, the point of first crack, until they 
rested eighty feet forward of their original positions. The erosion in 
front of the toe of the dam was not so wide but that the two parted sec- 
tions of the dam slid over the erosion without tilting and stood erect in 
their new position, as shown in Fig. 10. 
“In such constructions it is usual to countersink the toe of the dam 
flush into the bed rock, giving it an abutment, which makes sliding 
impossible. 
“Power House Foundations . — The injury to the power house was a 
remarkable and unprecedented accident. 
“The foundations remain now uninjured, as' is indicated in Fig, 11. 
The basement windows were placed above the forty foot backwater level, 
and the river wall was trussed to resist the inward pressure of forty feet 
of backwater. The wave of water from the broken dam rose above the 
windows and broke them in and then flooded the basement where the 
turbines were located. As the flood receded the basement held this watery 
as a tank, up to the forty foot level. When the backwater outside had 
next day (twelve hours after break in dam) fallen below the level of the 
basement floor the enclosed water pressed a part of the basement wall 
outward and permitted a part of the floors and roof to fall. 
“Site of Power House . — Someone has stated that the power house was 
in more danger from the flow over the dam than it would have been if 
located one hundred feet further down stream. Its position as con- 
structed was adopted as the one of greatest safety and stability, and also 
in part because the extension of the abutment and steel penstocks one 
hundred feet further would have added $20,000 to their cost. The rela- 
tive location of the dam and power house are approximately shown in 
Fig, 16. In this sketch GF is the face of the east abutment, but with 
exaggerated curve. This easy curve of the abutment was proportioned 
with care to deflect the flood current in a predetermined direction so that 
it could not scour along the face of the power house foundation except as 
a return eddy. The return eddy flowing up stream would be weakest near 
