Page:Panama-past-present-Bishop.djvu/194

174 closed, and then the tremendously heavy rainfall—from ten to fifteen feet a year—will fill the lake in less than a twelvemonth. All the surplus water will run off through the spillway, and as it runs it will pass through turbines and turn dynamos to generate electricity for operating the machinery of the Gatun Locks that will lift ships over the dam.

These locks are in pairs, like the two tracks of a railroad, so that ships can go up and down at the same time; three pairs, like a double stairway, of great concrete tanks each big enough for a ship a thousand feet long, a hundred and ten feet wide, and forty-two feet deep to float in it like a toy boat in a bath-tub. You can get some idea of their size when you remember that the Titanic was only eight hundred and fifty-two feet long. Or, to put it another way: every one of these six locks (and there are six more on the Pacific side) contains more concrete than there is stone in the biggest pyramid in Egypt. The American people have been able to do more in half a dozen years than the Pharaohs in a century, for our machinery has given us the power of many myriads of slaves.

And wonderful machinery it is at Gatun, both human and mechanical. It is not easy for a visitor, standing on one of the lock walls—which, as you can see from the diagram, is as high as a six-story house—and looking down into the swarming, clanging lock-pits, to see any system, but if he look closely, he can trace its main