The mob of mules and horses before them had been whipped and shouted into a furious run, and the thud of their hoofs was worth hearing. The best runners were streaming out ahead, and the heavier, slower animals were sagging behind as a sort of rear-guard. Sam worked vigorously for the rescue of those slow horses, and he hardly turned his head to take a look at the Indians. Cal imitated him as well as he could, except about the looking, and with every bound of the red mustang he justified Sam's remark: