Black's face looked insane, as he backed toward the second car at the curb, whose engine was softly purring.

Purring softly, the big machine rolled toward the nearest corner.

At the end of the alley, a car was ready, purring softly, waiting to carry the killers to safety.

Webster cleared his mind and the machine purred softly at him.

It was about forty miles away, and the car purred softly through the moonlit night.

At the end of a rear alley, a car was waiting, its engine purring softly.

In an instant, he had the motor softly purring.

"Yesterday we read the business cards in your case," it purred softly.

The Minister opened his mouth to speak, but the one telephone, which sat in front of him, purred softly.

One of the three telephones at her side purred softly.