Leo Malvern had not been long in the city of the Naztecs ere he began to assist Dick in training the men how to fight.
Like his cousin, he desired to make his way to the Land of Hez and force a way to the outside world.
Neither allowed the Naztecs to become aware of what their intentions were after they had once defeated the Hezzians in battle, but trusted to luck to leave them in possession of Hez and force their way out.
While working about the soil near the city, Dick had discovered the materials for making a first-class blasting powder, and by means of this they hoped to blow open the door in the obelisk and thus find their way to freedom.
The discovery of a combustible substance that could be set off by a spark set Philander Owens to thinking.
He knew full well that the men of Hez outnumbered the party Dick and Leo intended to lead against them, by three or four to one.
Consequently, something more powerful in the line of weapons than spears and axes must be introduced.
Owens was an inventive sort of genius, and it did not take him long to figure out how a destructive weapon could be made.
There was a bed of copper ore in the vicinity of the underground city of the Naztecs, and Owens went to work mining a quantity of this.
He did not inform anyone of his intentions until he was forced to for want of help in his undertaking.