Straight for the north Tom headed his craft, so as to throw the eagerly watching ones off the track. He intended to circle around and go west when out of sight.
And then the very thing Tom had predicted came to pass. The balloon was scarcely half a mile high when, as the young inventor looked down, he uttered a cry.
"See!" he said. "They're breaking camp to follow us."
And it was so. Riding along in one of the lightest ox carts was Delazes, his eyes fixed on the balloon overhead, while behind him came his followers.
"They're following us," said Tom, "but they're going to get sadly left."
In an hour Tom knew his balloon would not be visible to the Mexicans, and at the end of that time he pointed for the west. And then, flying low so as to use the trees as a screen, but going at good speed. Tom and his friends were well on their way to the city of gold.
"We must keep a good lookout down below," said Tom, when everything was in working order. "We don't want to fly over the plain of the ruined temple."
"We may in the night," suggested Ned.
"No night flying this time," said his chum. "We'll only move along daytimes. We'll camp at night."
For three days they sailed along, sometimes over vast level plains on which grazed wild cattle, again over impenetrable jungles which they could never have gotten through in their ox carts. They crossed rivers and many small lakes, stopping each night on the ground, the airship securely anchored to trees. Tom could make the lifting gas on board so what was wasted by each descent was not missed.