Having settled this in his mind, Tom Reade sank into one of the roomy porch chairs, half closing his eyes.  He was soon in danger of being as sound asleep as was Harry Hazelton.

Certainly Reade would have been intensely interested had he been able to render himself invisible and thus to step into one of the rooms of the big, handsome house.

In a room that was half office, half library, Senor Luis Montez was now closeted with another man, whom neither of the engineers had yet met.  This man was short, slight of build and nervous of action and gesture—­a young man perhaps twenty-six years of age.  Carlos Tisco was secretary to Don Luis.  Tisco was a graduate of a university at the capital City of Mexico, a doctor of philosophy, no mean chemist, a clever assayer of precious metals and an engineer.  In a word Dr. Tisco had been so well trained in many fields of science that it was a wonder that Don Luis should feel the need of employing the two young American engineers.

“You have seen my new engineers, Carlos?” queried Don Luis, almost in a whisper, as the two men, bending forward, faced each other over a flat-top desk.

“Through the window shutters—­yes, Don Luis,” nodded the secretary, a strange look in his eyes.

“Then what do you think of the Gringo pair, my good Carlos?” pursued Don Luis.

“Gringo” is a word of contempt applied by some Mexicans to Americans.

“I—­I hardly like to tell you, Don Luis,” replied the younger man, with an air of pretended embarrassment.

“Ah!  Then no doubt you feel they are not as clever as they have been rated—­my two Gringos,” smiled the mine owner.  “Rest easy, Carlos.  It may be better if they be not too clever.”

“It—­it is that which I fear, Don Luis,” replied the secretary, in a still lower voice.  “I have been studying their faces—­especially their eyes as they spoke.  Don Luis, I much fear that they are very clever young men.”

“Ah!  Then again that is not bad,” laughed the master gayly.  “If they be clever, then they will not need so much explanation.”

Now the secretary became bolder.

“Don Luis, though you have spent many years in the United States, I fear you do not at all understand some traits of the Gringo character,” warned Dr. Tisco.  “For example, you want these young men for a special service, and you are willing to pay them generously—­lavishly in fact.  Has it escaped you, Don Luis, that some of these obstinate, mule-headed Gringos are guilty of an especial form of ingratitude which they term honor?”

“I know that some Gringos make much bombastic use of that term, while other Gringos scoff at the word ‘honor,’” replied the mine owner, thoughtfully.  “But even suppose that these Gringos have absurdly fanciful ideas of honor?  They will never guess for what I really want them.  Their work will be done, to my liking, and they will go away from here with never a suspicion of the kind of service they have performed for me.”