Here now, at last, swimming slowly to its destiny, came the incredible sea snake of the mile-long tunnel that was both tunnel and bridge, an upside-down bridge that floated, that would pull up against its supports instead of hanging down, a steel and concrete, cunningly contrived bridge-tunnel that did indeed undulate like a snake as it swam along. The secret of its motion was the joints between sections, bellows-like constructions of solid steel, steel strong enough to resist the great pressures of the deeps, yet flexible enough to bend as needed. This was the mighty construction that would finish the Herculean labor at last, this was the final link in the tunnel between the continents.
It had been two long years in the building, the sections constructed at different sites and floated to the rendezvous up the Hudson River, below the ruined fortress of West Point, long associated with the heroic General Benedict Arnold. Here a new form of warfare was engaged; man against the elements, battling to conquer the endless sea. Section by section the bridge-tunnel had been joined together and tested until the incredible structure was completed. Then, on the ebb of the tide, it had been submerged and floated down to the sea, the beginning of the journey that was now reaching its final stages.
On the bridge O’Toole sat at the controls, or rather watched the controls because the computer set the course for this submarine as well.
“There are some things that take a bit of getting used to,” said he, arms folded so his fingers wouldn’t twitch towards the levers and buttons, eyeing the compass suspiciously as it swung a bit then steadied. “Now I know in theory that we are homing in on the sonar beacon at the bridge site, and that the infernal machine back in the bilges is pointing us all that way and running the engines and the rest, now I know that, but sure and I do not believe it.”
“I think you do,” Gus said, smiling as he bent over the plotting table and noted their slow but steady progress across the map. “All you want is a little action, a fist fight or a few drinks, or something like that.”
“How you blacken the name of O’Toole!” he cried, with no sincerity at all, but with a matching smile as well. “Though truth be known a jar of Guinness would not be refused, I’m thinking.”
A light glowed redly on the board and his fingers rushed to the controls and made certain adjustments. “Proximity to beacon ten miles, dead ahead.”
“Time to begin cutting our speed. We want to be at almost zero forward motion when we reach the canyon so we can use our maneuverability against the current.” He called down to the computer section and issued the needed commands.
Slower and slower the great snake drifted, taking many miles to slow down so great was its mass. The sonar beacons, strategically placed below, guided it to the correct spot where all forward motion ceased, where the final drop could begin. One mile straight down, out of the still waters into the bottom current which, slow moving as it was, still exerted a powerful force on anything as massive as this bridge-tunnel. The flow of the current had been carefully measured and this was one of the factors that was also taken into consideration by the computer so that when the bridge began the drop of the last mile it was still some miles upstream from the tunnel site. As the giant construction fell at a regular rate it would be carried along at a certain speed as well, theoretically to end up at the correct spot at the correct depth.
The last fall began. Delicate pressure mechanisms in each tunnel section admitted sea water to the ballast tanks as they drifted downwards so that while the pressure increased the tunnel always had the same slight positive buoyancy. Down and down and down—until at last ruddy lights were visible below and the computer had the laser beams as more definite navigation points. It digested this new information instantly and some of the submarines went faster while others slowed so the bridge bent and straightened again as it was turned slightly and aligned with the still invisible piers in the depths.
“There they are,” Gus said, pointing at the lights now visible on the television screen of the darkened bridge, television because the egg-shaped, thick-walled submarines that operated at these depths dared not have openings or ports of any kind in their hulls, so that all outside viewing was done by electronic means, with pickups at bow and stern, topside and in the keel. It was the keel pickup that now revealed the lights below and ahead of them. “We are on course to five decimal places,” said he, looking at the readout from the computer beside him.
Now the final, most delicate and most dangerous part of the mission was about to begin. The current here flowed steadily and smoothly at a speed of almost one and a half knots, hardly anything to speak of; if it had been on the surface a good swimmer could have breasted it, a rowing boat made progress in it, a fast launch ignored it. Even below the sea the submarines paid the current scarcely any heed—when they were on their own. But now, with their massive tow, it became their primary consideration, for the thirty-foot thick and mile-long bridge had an immense surface area that the current pushed against, so strongly that it was doubtful if the united force of all the submarines could have held it steady much less gained against its pull. Therefore the attempt to put the bridge sections into place must be right the very first time.
In order to accomplish this the cables had to be secured on each side of the valley at the same time and locked into place. The towing lines from the submarines were fastened to the much more massive cables of the bridge, each over a yard in diameter, for these served a dual function, now being used for towing, but upon arrival they would become the permanent mooring cables that held the bridge in the correct position. The ones from the center section were the longest—well over a half mile in length because they had to connect to the buttresses at each end—while the others grew shorter and shorter the closer they came to the end. When in position this skein of steel cable would hold the bridge inflexibly in place as its buoyancy pulled them taut. Now it was a matter of securing them.
Below the lip of each edge of the canyon there was a great area of smoothed rock that was illuminated brilliantly by numerous lights, for what had to be done next had to be done by eye, the human eye, and no automatic machines could be of aid here. Massive, monstrous anchors had been drilled and cemented into the solid stone to hold the bridge in place, while secured to them were hulking fittings to which would eventually be attached the giant turnbuckles that would be used to tension the cables correctly. But that would come later, now the cables had to be secured quickly and easily. In order to do this, massive, spring-loaded, forged steel jaws projected from each anchor. When a cable was pressed across one of these sets of jaws they would be sprung .like a titanic rattrap and would snap shut instantly, their corrugated jaws latching fast while automatic electric motors tightened them even more. This was the plan and it had been tested many times in training and it should work. It must work!
Down, down, down, the massive construction fell, with its attentive tugs laboring hard, now pulling this way, now that, under the continuous instruction of the Brabbage engine. There was almost complete silence inside the submarines, aside from the whisper from the ventilation louvers and the distant hum of the engines, an occasional word spoken between the operators of the great computer. Despite the silence and the lack of activity the air of tension was so thick inside every one of the subs that there were those who had some difficulty in breathing, for this was it, the irreversible decision, the unchangeable moment.
Down steadily while the brightly lit anchors below grew larger on the screens, the bold red numbers above each of them standing out stark and clear, and down still more with the cliff coming closer and closer. Fists tightened and knuckles whitened as the pilots simply watched their charges control themselves under the tutelage of the computer brain, this waiting and watching infinitely more trying than any complex control effort would have been. Down. Every detail of the ancient stone and the clean sharpness of the new construction clear before them. Down.