“Deep!” said Uncle Dick; “that’s easily seen. Deep as it is from here to the bottom of the valley on the other side: eighty or ninety feet. I should say this embankment is over a hundred in perpendicular height.”
“Look here,” said Uncle Jack suddenly; “if I know anything about engineering, this great dam is not safe.”
“Not safe!” I said nervously. “Let’s get off it at once.”
“I daresay it will hold to-day,” said Uncle Dick dryly, “but you can run off if you like, Cob.”
“Are you coming?”
“Not just at present,” he said, smiling grimly.
I put my hands in my pockets and stood looking at the great embankment, which formed a level road or path of about twelve feet wide where we stood, and then sloped down, as I have said, like a railway embankment far down into the valley on our left, and to the water on our right.
“I don’t care,” said Uncle Jack, knitting his brows as he scanned the place well, “I say it is not safe. Here is about a quarter of a mile of earthen wall that has no natural strength for holding together like a wall of bonded stone or brick.”
“But look at its weight,” said Uncle Bob.
“Yes, that is its only strength—its weight; but look at the weight of the water, about a mile of water seventy or eighty feet deep just here. Perhaps only sixty. The pressure of this water against it must be tremendous.”