The spanners would be pulled out from their sockets on the side of the tank by means of steel cables, which were operated from within. They would be run out across the gap and fastened in place. The tank was designed to travel along them to the other side of the gap, and, once there, to pick up the girders, slip them back into place on the sides, and the engine of war would travel on. "You are mightily excited, Tom. "I admit it, Ned. You see, I have not tried the grippers out except on a small model. They worked there, but whether they will work in practice remains to be seen. Of course, at this stage, I'm willing to stake my all on the results, but there is always a half-question until the final try-out under practical conditions." "Well, we'll soon see," said one of the workmen. "Are you ready, Mr. Swift?" "All ready," answered Tom. Tank A, as she was officially known, had come to a stop, as has been said, on the very edge of Tinkle Creek. The banks were fairly solid here, and descended precipitously to the water ten feet below. The shores were about twenty feet apart. "Suppose the spanners break when you're halfway over, Tom?" asked his chum. "I don't like to suppose anything of the sort. But if they do, we're going down!" "Can you get up again?" "That remains to be seen," was the non-committal reply. "Well, here goes, anyhow!" Going up into the observation tower, which was only slightly raised above the roof of the highest part of the tank, Tom gave the signal for the motors to start. There was a trembling throughout the whole of the vast structure. Tom threw back a lever and Ned, peering from a side observation slot, beheld a strange sight. Like the main arm of some great steam shovel, two long, latticed girders of steel shot out from the sides of the tank. They gave a half turn, as they were pulled forward by the steel ropes, so that they lay with their broader surfaces uppermost. Straight across the stream they were pulled, their clawlike ends coming to a rest on the opposite bank. Then they were tightened into place by a backward pull on the operating cables, and Tom, with a sigh of relief, announced: "Well, so far so good!" "Do we go over now?" inquired Ned. "Over the top--yes, I hope," answered Tom, with a laugh. "How about you down there?" he called to the engine room through a telephone which could only be used when the machinery was not in action, there being too much noise to permit the use of any but visual signals after that. "All right," came back the answer. "We're ready when you are." "Then here we go!" said Tom. "Hold fast, Ned! Of course there's no real telling what will happen, though I believe we'll come out of it alive." "Cheerful prospect," murmured Ned. The grippers were now in place. It only remained for the tank to propel herself over them, pick them up on the other side of Tinkle Creek, and proceed on her course.