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ILLUSTRATIONS.

• Page.
• PLATE I. A, View of dam, looking east toward power house; B, View of dam, looking west from power house 9
• II. A, Freshet flowing through gap in partially completed dam; B, River flowing through main gap in partially completed dam 12
• III. A, Closing gap in dam; B, Dam nearing completion, February, 1893 14
• IV. A, Head-gate masonry and penstocks; B, Laying the last stone, May 2,1893 16
• V. Resistance line of dam 24
• VI. A, Power-house foundations and outlet pipes from turbines; B, Limestone strata at head gate 26
• VII. A, Discharge of lake through dam, or the so-called "spring;" B, View showing two methods employed to stop leak 28
• VIII. A, Marble Falls, above Lake McDonald; B, View up river from Mount Bonnel, after destruction of dam 30
• IX. A, View of dam five minutes before failure on April 7, 1900; B, Flood pouring over dam on June 7,1899; lake level 9.25 feet above crest of dam 32
• X. A, View three minutes after failure of dam; B, View ten minutes after failure of dam 34
• XI. A, View about two hours after break; B, View one hour after break 36
• XII. A, View about 350 feet below dam, showing waves thought to be due to secondary dam formed by debris from wreck; B, Power house of Austin Water, Light, and Power Company, about 2 miles below broken dam 38
• XIII. A, View upstream one day after failure of dam; B, View westerly along line of dam one day after failure 40
• XIV. A, View of power house about two hours after failure of dam; B, Wreck of power house 42
• XV. A, Western portion of dam remaining after break; B, Portions of broken dam brought down by flood . 44
• XVI. A, Broken dam, showing, in foreground, sand bar left in main channel; B, Remnants of dam 46
• FIG. 1. Watershed of Colorado River above Austin, Texas 10
• 2. Index map of lines of soundings across Lake McDonald, above Austin,Texas 16
• 3. Cross sections of dam: Left side as proposed by Frizell; right side as constructed by Fanning 23
• 4. Saddle used on cable conveyor 26
• 5. Section and sketch plan of bulkhead, showing location of power house and penstocks 28
• 6. Cross sections of Lake McDonald, illustrating accumulation of sediment between 1893 and 1897 and between 1897 and 1900 37
• 7. Generalized cross section of Lake McDonald, showing accumulation ofsediment 38
• 8. Layer of silt remaining on plateau after destruction of dam 39
• 9. Curve illustrating progress of silting in Lake McDonald 41
• 10. Plan showing break in dam April 7,1900 42
• 11. Cross section showing undermining of toe of dam 47
• 12. Geologic section east and west along Colorado River at Austin, Texas, showing Balcones zone of faulting 48