Tom Swift hesitated a moment, one hand on the starting lever and the other on the steering wheel. Then, with a glance at Ned, half whimsical and half resolute, Tom started Tank A on what might prove to be her last journey. Slowly the ponderous caterpillar belts moved around on the sprocket wheels. They ground with a clash of steel on the surface of the spanners. So long was the tank that the forward end, or the "nose," was halfway across the stream before the bottom part of the endless belts gripped the latticed bridge. "If we fall, we'll span the creek, not fall into it," murmured Ned, as he looked from the observation slot. "That's what I counted on," Tom said. "We'll get out, even if we do fall." But Tank A was not destined to fall. In another moment her entire weight rested on the novel and transportable bridge Tom Swift had evolved. Then, as the gripping ends of the girders sank farther into the soil, the tank went on her way. Slowly, at half speed, she crawled over the steel beams, making progress over the creek and as safely above the water as though on a regularly constructed bridge. On and on she went. Now her entire weight was over the middle of the temporary structures. If they were going to give way at all, it would be at this point. But they did not give. The latticed and triangular steel, than which there is no stronger form of construction, held up the immense weight of Tank A, and on this novel bridge she propelled herself across Tinkle Creek. "Well, the worst is over," remarked Ned, as he saw the nose of the tank project beyond the farthermost bank. "Yes, even if they collapse now nothing much can happen," Tom answered. "It won't be any worse than wallowing down into a trench and out again. But I think the spanners will hold." And hold they did! They held, giving way not a fraction of an inch, until the tank was safely across, and then, after a little delay, due to a jamming of one of the recovery cables, the spanners were picked up, slid into the receiving sockets, and the great war engine was ready to proceed again. "Hurrah!" cried Ned. "She did it, Tom, old man!" and he clapped his chum resoundingly on the back. "She certainly did!" was the answer. "But you needn't knock me apart telling me that. Go easy!" "Bless my apple pie!" cried Mr. Damon, who was as much pleased as either of the boys, "this is what I call great!" "Yes, she did all that I could have hoped for," said Tom. "Now for the next test." "Bless my collar button! is there another?" "Just down into a trench and out again." Tom said. "This is comparatively simple. It's only what she'll have to do every day in Flanders." The tank waddled on. A duck's sidewise walk is about the only kind of motion that can be compared to it. The going was easier now, for it was across a big field, and Tom told his friends that at the other end was a deep, steep and rocky ravine in which he had decided to give the tank another test.