CHAPTER XII
ALMOST AN ACCIDENT
"What's that big, long affair, jutting out so far from the locks?"asked Blake, when the tug had approached nearer.
"That's the central pier," the captain informed him. "It's a sortof guide wall, to protect the locks. You know there are threelocks at this end; or, rather, six, two series of three each. Andeach lock has several gates. One great danger will be thatpowerful vessels may ram these gates and damage them, and, toprevent this, very elaborate precautions are observed. You'll soonsee. We'll have to tie up to this wall, or we'll run into thefirst protection, which is a big steel chain. You can see it justahead there."
Joe and Blake, who had gotten all the pictures they wanted of theapproach to the lock, stopped grinding away at the handle of thecamera long enough to look at the chain.
These chains, for there are several of them, each designed toprotect some lock gate, consist of links made of steel threeinches thick. They stretch across the locks, and any vessel thatdoes not stop at the moment it should, before reaching thischain, will ram its prow into it.
"But I'm not taking any such chances," Captain Watson informed theboys. "I don't want to be censured, which might happen, and Idon't want to injure my boat."
"What would happen if you did hit the chain?" asked Blake. Theyhad started off again, after the necessary permission to enter thelocks had been signaled to them. Once more Blake and Joe weretaking pictures, showing the chain in position.
"Well, if I happened to be in command of a big vessel, say thesize of the _Olympic_, and I hit the chain at a speed of a mileand a half an hour, and I had a full load on, the chain would stopme within about seventy feet and prevent me from ramming the lockgate."
"But how does it do it?" asked Joe.
"By means of machinery," the captain informed him. "Each end ofthe chain fender goes about a drum, which winds and unwinds byhydraulic power. Once a ship hits the chain its speed willgradually slacken, but it takes a pressure of one hundred tons tomake the chain begin to yield. Then it will stand a pressure up toover two hundred and fifty tons before it will break. But beforethat happens the vessel will have stopped."
"But we are not going to strike the chain, I take it," put in Mr.Alcando.
"Indeed we are not," the captain assured him. "There, it is beinglowered now."
As he spoke the boys saw the immense steel-linked fender sink downbelow the surface of the water.
"Where does it go?" asked Blake.
"It sinks down in a groove in the bottom of the lock," the captainexplained. "It takes about one minute to lower the chain, and aslong to raise it."
"Well, I've got that!" Blake exclaimed as the handle of his cameraceased clicking. He had sufficient views of the giant fender. Asthe tug went on Captain Watson explained to the boys that eventhough a vessel should manage to break the chain, which was almostbeyond the bounds of possibility, there was the first, or safetygate of the lock. And though a vessel might crash through thechain, and also the first gate, owing to failure to stop in thelock, there would be a second gate, which would almost certainlybring the craft to a stop.
But even the most remote possibility has been thought of by themakers of the great Canal, and, should all the lock-gates be tornaway, and the impounded waters of Gatun Lake start to rush out,there are emergency dams that can be put into place to stop theflood.
These emergency dams can be swung into place in two minutes bymeans of electrical machinery, but should that fail, they can beput into place by hand in about thirty minutes.
"So you see the Canal is pretty well protected," remarked CaptainWatson, as he prepared to send his tug across the place where theChain had been, and so into the first of the three lock basins.
"Say! This is great!" cried Blake, as he looked at the concretewalls, towering above him. They were moist, for a vessel hadrecently come through.
Now the tug no longer moved under her own steam, nor had it beensince coming alongside the wall of the central pier. For allvessels must be towed through the lock basins, and towed not byother craft, but by electric locomotives that run alongside, onthe top of the concrete walls.
Two of these locomotives were attached to the bow of the tug, andtwo to the stern. But those at the stern were not for pulling, asJoe at first supposed, for he said:
"Why, those locomotives in back are making fast to us with wirehawsers. I don't see how they can push with those."
"They're not going to," explained Captain Watson. "Those in thestern are for holding back, to provide for an emergency in casethose in front pull us too fast."
"Those who built the Canal seem to have thought of everything,"spoke Blake with much enthusiasm.
"You'll think so, after you've seen some more of the wonders," thetug captain went on with a smile. "Better get your cameras ready,"he advised, "they'll be opening and closing the gates for us now,and that ought to make good pictures, especially when we areclosed in the lock, and water begins to enter."
"How does it come in?" asked Joe. "Over the top?"
"No, indeed. They don't use the waterfall effect," answered Blake,who had been reading a book about the Canal. "It comes in from thebottom; doesn't it, Captain Watson?"
"Yes, through valves that are opened and closed by electricity. Infact everything about the lock is done by electricity, though incase of emergency hand power can be used. The water fills the lockthrough openings in the floor, and the water itself comes fromGatun Lake. There, the gate is opening!"
The boys saw what seemed to be two solid walls of steel slowlyseparated, by an unseen power, as the leaves of a book might open.In fact the gates of the locks are called "leaves." Slowly theyswung back out of the way, into depressions in the side walls ofthe locks, made to receive them.
"Here we go!" cried the captain, the tug began to move slowlyunder the pull of the electric locomotives on the concrete wallabove 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 throughthe locks of the Panama Canal, were being taken on the long stripof sensitive film.
"Oh, it is wonderful!" exclaimed Mr. Alcando. "Do you think--Imean, 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 movingpicture camera, and he knew about at what speed to turn thehandle. For the moving pictures must be taken at just a certainspeed, and reproduced on the screen at the same rate, or thevision produced is grotesque. Persons and animals seem to runinstead of walk. But the new pupil, with a little coaching fromBlake, did very well.
"Now the gates will be closed," said the tug captain, "and thewater will come in to raise us to the level of the next higherlock. We have to go through this process three times at this endof the Canal, and three times at the other. Watch them let in thewater."
The big gates were not yet fully closed when something happenedthat nearly put an end to the trip of the moving picture boys toPanama.
For suddenly their tug, instead of moving forward toward the frontend of the lock, began going backward, toward the slowly-closinglock gates.
"What's up?" cried Blake.
"We're going backward!" shouted Joe.
"Yes, the stern locomotives are pulling us back, and the frontones seem to have let go!" Captain Watson said. "We'll be betweenthe lock gates in another minute. Hello, up there!" he yelled,looking toward the top of the lock wall. "What's the matter?"
Slowly the tug approached the closing lock gates. If she once gotbetween them, moving as they were, she would be crushed like aneggshell. And it seemed that no power on earth could stop themovement of those great, steel leaves.
"This is terrible!" cried Mr. Alcando. "I did not count on this inlearning to make moving pictures."
"You'll be in tighter places than this," said Blake, as he thoughtin a flash of the d
angers he and Joe had run.
"What'll we do?" asked Joe, with a glance at his chum.
"Looks as though we'd have to swim for it if the boat is smashed,"said Blake, who remained calm. "It won't be hard to do that. Thisis like a big swimming tank, anyhow, but if they let the otherwater in--"
He did not finish, but they knew what he meant. Slowly andirresistibly the great lock gates were closing and now the tug hadalmost been pulled back between them. She seemed likely to becrushed to splinters.
The Moving Picture Boys at Panama; Or, Stirring Adventures Along the Great Canal Page 12
