CHAPTER XX.
THE SPOIL OF THE LOCKS.
At eleven o'clock that night the workmen employed at the locks, thespillway, and the barrier of the Gatun dam found that their lights werenot working satisfactorily and sent word back to the electric departmentthat something was amiss.
The electric department sent word back to the men in the excavations thatthe lights were all right so far as they were concerned, that they weredoing their full duty efficiently, and that the men with the shovels, thedynamite and the dump cars might go chase themselves.
This expression of fact and permission did not make it any lighter at theworkings, but the men kept on, in the intermittent showers ofillumination, and grumbled while they excavated and piled in the concrete.At last, just before midnight, the incandescence did not come back to theglobes, and the men gathered in groups to discuss the matter and expressheated opinions of the efficiency of the men in charge of the lightingplant.
The workmen moved about here and there in the shadows and clambered likeants over the great bulk of the dam. No one looked to see that the menassembled in the workings all belonged there. At midnight four men who didnot belong there entered the excavation which leads from the bottom of thelower lock to the sea-level channel into Limon Bay, which is a child ofthe Caribbean Sea.
These four men moved about as if accustomed to the situation, only now andthen they halted and whispered together. Other men, workmen, were doingthat, however, and so these four passed on up to the foot of the spillwaywithout attracting attention.
Here they separated, one to the west, one to the east, where the locksare, and one to a position half way between the spillway and the west sideof the locks. The fourth man remained near the foot of the spillway.
Due primarily to its size, Gatun dam has received, perhaps, more attentionin the United States than is its due. There is nothing especiallydifficult or complicated about this dam, and many dams have beensuccessfully built in this country to withstand much larger pressures andgreater heads of water than the Gatun dam without being given one-quarterof the attention.
Gatun dam fills the opening between the hills at Gatun through which theChagres river flows to the Caribbean Sea. It consists, if it may beregarded in the light of a finished production, of a water-tight center orcore composed of sand and clay mixed in proper proportion and depositedhydraulically; that is by being pumped in.
On each side a wall of rock confines this core. The bulk of the dam restson impermeable material of sufficient supporting power. The locks andspillway are considered a part of the dam.
The locks are built in an excavation at the east end of the dam, in rock,and will lift vessels from the Atlantic level to the level of the Lake ofGatun. The spillway is a concrete-lined opening cut through a hill of rocknear the center of the dam. When supplied with suitable gates, it willregulate the level of the lake.
The dam proper is about 9,000 feet long over all, measured on its crest,including locks and spill way, but for only five hundred feet of thisgreat distance will it be subjected to great pressure. During this spacethere is, or will be, a weight of about eighty-five feet depth against thebarrier. For only about half its length will the head of water on the dambe over fifty feet.
It will be seen from the above description that the point of attack on thedam would naturally be where the pressure is greatest, also at the locks,which would make a mighty channel for the flood of water, and which wouldbe difficult to repair. The spillway, too, if enlarged by explosives,would make a nasty hole to build up.
Now another point which Ned had considered when he looked over the crudedrawings he had discovered. Hard rock underlies the dam near the surfaceof the ground except for about one-fifth of its entire length. Here therock dips down to a minimum depth below sea-level of from 195 feet in thedepression east of the spillway to 255 feet in that west of the spillway.Here, of course, would be another point of attack by one designingpermanent mischief.
These depressions or valleys have been slowly filled during past ages.Measured from sea-level down, the first 80 feet consists of sand and clay;the next 100 feet or so is stiff blue clay, while the last 20 to 60 feetis a conglomerate, composed of sand, shells and stone. It will be readilyseen that great damage might be done by a raging torrent boring into thesand and clay of the first strata.
Now, the outer walls of rock are 1,200 feet apart, the interval beingfilled with spoil from the canal and lock excavations. The south "toe," asit is called, has a height of 60 feet, while the north or down-stream"toe" is 30 feet high. Spoil from the excavations will be dumped outsidethe "toes" until the dam is 2,000 feet in width at the bottom. The top ofthe dam is, or will be, 30 feet above water level and have a width of 100feet. The channel of the spillway is 300 feet wide.
Ned had figured it out that one attacking the dam would naturally seek toenlarge the locks and the spillway and also to burrow in under the bulk ofthe dam where the sand and clay had been washed in below sea-level bycountless years of flood and storm. The locks and spillway, enlarged,would require years of active work for repair; the sand and clay, ifsubjected to high explosives, would cause the crest of the dam to drop inon the north side and so enfeeble the entire structure, requiring thegigantic work of constructing new foundations.
Therefore, when Ned saw the four men moving toward the spillway, saw thempart and seek the vulnerable points which have been described above, heknew that the time he had been waiting for had come. The treacherousrascals were there to do their wicked work that night--to carry out planslong formed and well considered--and they were opposed only by theinexperienced patrol leader from New York and his three chums, Frank Shaw,Glen Howard, and Peter Fenton. It will be remembered that Jimmie McGraw,Jack Bosworth, and Harry Stevens were at the old stone house on the roadto Las Cruces from Gamboa, and that George Tolford had accompanied Tony tothe Chester camp.
On reaching Gatun the boys had slipped out of the lights of the stationand descended immediately to the bottom of the cut. They were at onceaccosted by a foreman, but the explanation Ned gave seemed more thansufficient, for Dan Welch, the man in charge of a group of workers on thelocks, at once summoned his assistant to the job and remained with theboys.
"I have heard about you, Ned Nestor," Welch said; "in fact, about half themen in the workings at Gatun have heard of you."
"I don't understand how," replied the puzzled boy.
"Well, through that bomb business at the cottage. You see, it leaked out.When the attempt to blow up the place was reported, the men naturallyasked what the dickens the scamps wanted to blow up a crowd of sightseersfor, and then it came out that you came here with Lieutenant Gordon, andthat's about all."
It was at this time that the lights suspended operation. Welch glancedabout the busy scene for an instant and sat down on a box which containedtools.
"No use," he said. "The electric men work as they please. We'll wait hereand lose our record. Did you say where Lieutenant Gordon is to-night?"
"I did not, because I wasn't asked," was the reply, "and because I don'tknow where he is."
"He's a good fellow, Gordon," Welch exclaimed. "I'd go far and fast to dohim a favor. I hope he's coming out of this game all right."
Then Ned sat down on the tool-box and told Welch the story of theabduction of the lieutenant, and also the story of what was going on therethat night, as he understood it. To say that Welch was profoundly exciteddoes not half express the foreman's state of mind as he listened.
"My God!" he cried, when Ned paused. "To think of the wickedness of thething. To destroy the work of years. To delay the completion of the canalfor a decade. What can we do? In this darkness, the spoilers can worktheir will."
"I think I know who they are," Ned said. "We must find them."
"It is too bad that the lights should fail us just at this time," theforeman said.
"I have an idea that the plotters arranged for that," Ned said, then.
"But how?" demanded Welch. "The plants are well
guarded. You know, ofcourse, that we are all on the lookout for something of the kind? Wethought we had provided against any sudden surprise. Where are we to lookfor them?"
Then Ned pointed out the probable points of attack, and Welch sprang tohis feet in a fuming passion.
"The spillway and the locks," he cried. "And the point where the softearth extends under the dam! Come!"
"Bring four of your men who can be trusted," Ned advised, not leaving thebox.
"Yes, and what then?"
"Send a man to the light station and have tracers sent out, but instructhim not to have the lights turned on until you give the signal."
"I understand," the foreman said. "We'll catch them with the goods!"
Four men, workmen, were strolling along the danger points within fiveminutes, and another moved toward the electric switches which governedthat part of the illumination. Ned and Welch remained near the spillway.The three boys, after whispered instructions from Ned, moved along theline passing word from man to man.
It was a long and heart-breaking half hour, seemingly double that time,that followed. The man from the switches came back and whispered to Welch,and at that moment a shrill bird-call sounded in the darkness. This, inturn, was followed by the report of a revolver, and then the light leapedinto the globes, making the place, the entire length of the canal dam, thespillway and the locks, as bright as day.
There came a half-hearted explosion from the direction of the locks,followed by more shots. Then everything was in confusion, and groups ofmen gathered in four spots along the line. There were more shots and thenthe three boys rushed, panting, to the position Ned and the foreman hadtaken.
"They've got them!" Frank cried. "They've got every man of them--four Japswith lighted fuses in their hands!"
"There must be more than four!" Welch cried.
"I think not," Ned replied. "This is hardly a job for many men to work on!The four dare not take others into their confidence. Come! Suppose wegather them in?"
"How do you boys know they've got them all?" demanded Welch. "The four menmust be some distance apart."
"Not too far for a revolver to carry a signal!" smiled Ned. "You probablynoticed four groups of shots? Well, the boys who have been acting asmessengers from man to man gave directions as to the number of shots foreach group!"
"I see!" said Welch. "You don't need any whiskers, boy, to do the brainwork of a man. Here comes the first batch!"
Itto and Gostel were the first ones brought in. Itto was wounded fatallyand Gostel was bleeding from a wound in the side. The other men were notinjured. They stood in a little group for a moment, and then Itto droppedto the ground.
The reports of the men who had been sent out to the danger points showedthat each one of the four had been caught lighting a fuse, the bombshaving been set.
"We were forced to work before we were ready," Gostel said, defiantly."Our government discovered what was going on, and we would have beenarrested to-morrow. So we were obliged to take the risk to-night. We wereworking for the glory of the Emperor, but he forbade it!"
"I did not believe the government of Japan would descend to any suchdespicable work," Ned said. "You fellows are cranks! You would have workedgreat harm to your Emperor if you had succeeded. By the way," he added,"what did you do with Lieutenant Gordon?"
Gostel glared at his questioner, but Itto beckoned Ned to his side.
"The old stone house on the road to Las Cruces!" he whispered.
"Where is that?" asked Welch, who had bent over the wounded man and heardthe words.
"I know," replied Ned. "One act of this tragedy has already been pulledoff there. Have your men take these cranks to Gatun and get a railroadmotor. We must get to Gamboa without loss of time. It is only a shortdistance from there to the place he speaks of. If they took LieutenantGordon there a prisoner, they are likely to have had a warm reception, forthree of my chums are there!"
But it was not necessary for them to go to the old stone house. At Gamboathey found Lieutenant Gordon and the three boys. Jimmie excitedly relatedthe sensational occurrences at the house.
"Jack and Harry came up," he concluded, "just as the two men, Pedro andGaga, were going together with knives. I was scared into a trance! Theboys covered them with guns an' we trussed 'em both. You never saw peoplemore surprised in your life. Then two men brought in Lieutenant Gordon,all nicely tied up, and went away, or started to go away. Well, theywasn't prepared for an attack from the bushes, and we have four prisonersin a cell of a jail at Gamboa, right over there!"
In an hour the boys were all back at Culebra, with Lieutenant Gordonlooking angry enough to eat sinkers, as Jimmie said. The officer thoughpleased at the general results, did not like to admit that he had beencaptured by the enemy and rescued by the Boy Scouts, the little fellows hewas guarding!