The boys saw what seemed to be two solid walls of steel slowly separated, by an unseen power, as the leaves of a book might open. In fact the gates of the locks are called "leaves." Slowly they swung back out of the way, into depressions in the side walls of the locks, made to receive them.
"Here we go!" cried the captain, the tug began to move slowly under the pull of the electric locomotives on the concrete wall above them. "Start your cameras, boys!"
Blake and Joe needed no urging. Already the handles were clicking, and thousands of pictures, showing a boat actually going through the locks of the Panama Canal, were being taken on the long strip of sensitive film.
"Oh, it is wonderful!" exclaimed Mr. Alcando. "Do you think—I mean, would it be possible for me to—"
"To take some pictures? Of course!" exclaimed Blake, generously. "Here, grind this crank a while, I'm tired."
The Spaniard had been given some practice in using a moving picture camera, and he knew about at what speed to turn the handle. For the moving pictures must be taken at just a certain speed, and reproduced on the screen at the same rate, or the vision produced is grotesque. Persons and animals seem to run instead of walk. But the new pupil, with a little coaching from Blake, did very well.
"Now the gates will be closed," said the tug captain, "and the water will come in to raise us to the level of the next higher lock. We have to go through this process three times at this end of the Canal, and three times at the other. Watch them let in the water."
The big gates were not yet fully closed when something happened that nearly put an end to the trip of the moving picture boys to Panama.
For suddenly their tug, instead of moving forward toward the front end of the lock, began going backward, toward the slowly-closing lock gates.
"What's up?" cried Blake.