Unless wounded Old Jack would not fail him.

He stole another of those fleeting glances backward.
Several of the Mexicans, their ponies spent, were dropping out of the race, but enough were left to make the odds far too great.

Ned now skimmed along the edge of the grove, and when he passed it he turned his horse a little, so the trees were between him and his nearest pursuers.
Then he urged Old Jack to his last ounce of speed.

The plain raced behind him, and fortunate clouds, too, now came, veiling the moon and turning the dusk into deeper darkness.

Ned heard one disappointed cry behind him, and then no sound but the flying beat of his own horse's hoofs.
When he pulled rein and brought Old Jack to a walk he could see or hear nothing of the Mexicans.