Tom had taken part in many speed contests, and he knew how to jockey with the best of them. He purposely let the freight slowly crawl up on even terms with him. This was due not only to the increased speed of the freight but also to Tom's slight slackening of his pace.
"I'll fool this bird!" he told Ned.
And when the engine was again up in front, so that the pilot was in line with the bumper of the House on Wheels, Tom turned on more gas, after a momentary cut-off, and again shot ahead.
He and Ned could almost see, in fancy, the chagrin on the faces of the engineer and fireman as they were thus gently mocked. But the railroad men were good sports and were not going to give up easily.
Again there was a frantic shoveling of coal, and there must have been a more advantageous adjustment of the draft, or perhaps a forced one was turned on, for suddenly the safety valve popped, which, at the speed the engine had already attained, showed an increased pressure of steam.
"He's coming right after us!" cried Ned, as they swayed along.
On no other road but this concrete highway would it have been safe to run the House on Wheels at the speed she was going. And few drivers other than Tom Swift would have been capable of handling the heavy machine with such skill and judgment.
The race was now on in earnest. Tom knew that it would not be safe to push his motor much faster. Not that it was not capable of a higher rate, but it would need to be broken in somewhat before he dared risk it. On the other hand, the locomotive was not thus limited. So if it was not yet at its maximum, there would be no danger in pushing the mechanism to that point. And if the maximum was greater than Tom's temporary one, then he would lose.
However, though forced draft was used, the big freighter appeared to have reached the limit. For perhaps half a mile she held her own on even terms with the House on Wheels. Then Ned asked:
"Can you do a bit better, Tom?"