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Transactions Texas Academy of Science. 
[78] 
actually intact. The position of these sections, horizontal and upright, 
indicate that the cause of failure was a sliding out bodily on its base of 
that portion that failed. 
On account of the immense importance of the Austin dam as an engi- 
neering structure — it being the largest in the world across a flowing 
stream — the writer here submits the opinion of some of the engineers 
who were connected with it from time to time. 
Mr. Frizell has said that the location at Mormon Falls, two miles 
above the chosen site, presented points of decided superiority over the 
locality selected, but the Board of Public Works thought that location 
inconsistent with the purposes of the improvement. Mr. Frizell does not 
consider that the solubility of the rock had any bearing on the failure, 
and sees no reason to doubt that the immediate cause was the undermin- 
ing on the down stream side, caused by the abrasive action of the current 
and the constant stream of water coming from the power house and flow- 
ing along the toe of the dam, on its way to the open channel of the river. 
A progressive weakening is attested by the fact that during the preced- 
ing year the dam had withstood a flood substantially as great as the one 
in which it failed. The toe of the dam, which was left without support 
by the undermining, contained granite blocks of more than six tons 
weight. 
“It is on record that the breaking down of this unsupported toe was 
imminent, in which event each of these stones would become a mill-stone 
(propelled in such a flood by some two thousand horse power) in the 
work of grinding the friable rock bottom and extending the undermining. 
At the wooden dam across Connecticut river, at Holyoke, Massachusetts, 
an action of this kind became threatening in 1866. A pit twenty feet 
deep had formed on the down stream side of the dam. This danger was 
met by the construction of a massive apron of crib-work filled with stone, 
which prolonged the duration of the structure more than thirty years, or 
until the construction of the present stone dam. /At Austin the engineer 
had in contemplation from the beginning an analagous work, namely, an 
extension of the massive apron by a bed of concrete, to be applied as soon 
as the abrasive action had made sufficient progress to indicate the char- 
acter and extent of the work required for its suppression.” 
1ST. Werenskiold, one of the engineers of construction, in a letter to a 
friend in the latter part of 1900, said: 
“There can be no doubt that the failure was not caused by any defective 
work in the dam itself, but by the entire body being pushed down stream 
and broken from the lateral pressure on account of too small frictional 
resistance under the dam. It is also proven conclusively that this resist- 
ance against sliding had been materially diminished by erosion below the 
toe of the dam, and to that extent the failure is chargeable to lack of care 
in maintenance. 
