Their general air of gloom he could of course lay to the weather and the fact that they had been traveling for about fourteen hours without any rest; but there was something more than that in the atmosphere.

He thought they had disagreed, and that he was the subject of their disagreement.
He screwed down the valve cap, coiled the pump tube and stowed it away in the tool box, opened the gas tank, and looked in--and right there he did something else; something that would have spelled disaster if either of them had seen him do it.

He spilled a handful of little round white objects like marbles into the tank before he screwed on the cap, and from his pocket he pulled a little paper box, crushed it in his hand, and threw it as far as he could into the bushes.

Then, whistling just above his breath, which was a habit with Bud when his work was going along pleasantly, he scraped the mud off his feet, climbed in, and drove on down the road.
The big car picked up speed on the down grade, racing along as though the short rest had given it a fresh enthusiasm for the long road that wound in and out and up and down and seemed to have no end.

As though he joyed in putting her over the miles, Bud drove.