CHAPTER XIX.
THE HIDALGO PLANS GRATITUDE Soon after an early breakfast Tom and Harry were afield.
From behind a window in the upper part of his big house, Don Luis, equipped with a powerful field glass, watched them keenly whenever they were in sight.
"What on earth are the Gringos doing ?" he wondered, repeatedly.
"Are they just walking about, aimlessly?
At times it looks like it.

At other times it doesn't." Then Montez sent for Tisco and discussed with him the seeming mystery of the actions of the young engineers.
"Don't ask me, Don Luis," begged the secretary.

"I am not clever at guessing riddles.

More, I have not pretended to understand this Gringo pair." "Are they, in the end, going to trick me, Carlos ?" "Who can say ?" demanded Dr.Tisco, with a shrug of his shoulders.
"Of course, they both know that it will be but a short cut to suicide if they attempt to fool you." "Their deaths will cause me no anxiety, Carlos, either before or after the sale," murmured Montez.

"In fact, my good Carlos--" "Say it," leered Dr.Tisco, as his employer paused.
"I may as well say it, for you have guessed it, Carlos.