"The spurs of two men who hastily arose jingled; and Tonia almost smiled. The Knights, then, were not all turned to dust; nor were their rowels rust."

A cowboy's spurs were fixed on his heels,so that when heels
were pressed against horse's flank the resulting pain made the horse go. Rowels were disks mounted by a hole in their center, and were a loose enough fit to jingle when moved.