“Hurrah for Uncle Sam!”

Billie and Adrian joined in the cry, at the same

time putting spurs to their horses, which sprang forward, upsetting the policemen and creating a tumult which quickly became a riot, as the Americans in the crowd took up the cry and shouted lustily for Uncle Sam.

In the confusion which followed shots rang out from every side, most of them fired into the air, and there was a general scurrying to shelter by the natives, who had learned to get out of the way when a crowd of track hands and cowboys began to shoot up the town. Taking advantage of this, the boys dashed out of the light of the plaza, and were soon well on their way to the river; and it was none too soon, for, attracted by the commotion, a band of rurales was ordered out to arrest every foreigner found on the street.

“It was some excitement while it lasted,” remarked Billie, as they gained the American side. “I think I’ll stay out of Mexico for a while.”

“What!” exclaimed Donald, “with Don Rafael still at large?”

“Yes,” said Adrian, “how about your promise?”

“By George!” exclaimed Billie. “The excitement had driven it entirely out of my mind—and besides, I must learn what has become of Villa.”

[CHAPTER XVI.—A VALUABLE DISCOVERY.]

It was late the next morning when the boys awoke and began calling to each other.