Don Luis dipped a pen in ink, then held it up.  Harry was about to take the pen when Tom Reade drawled: 

“It wouldn’t be quite right for us to sign this report, Don Luis.”

“Why not?” queried the Mexican, wheeling like a flash.

“Just for the simple reason,” Reade answered, “that to sign the report would be to state all the facts contained in the report as being of our personal observation.  We haven’t seen enough of the mine, as yet, for it to be right for us to sign the report.  An engineer’s signature to a report is his statement—­ON HONOR—­that he personally knows such report to be true.  So I am very certain you will understand that it would be a breach of honor for us to sign this document.”

“Ah!  He is clever—­and now the real trouble must begin!” Dr. Tisco told himself.  “These engineers are not easily duped, but in Don Luis’s hands they will destroy themselves!”

CHAPTER VI

WATCHING THE MIDNIGHT LIGHTS

Don Luis Montez laid down the pen.  Outwardly he was as amiable as ever; certainly he was all smiles.

“A thousand pardons, caballeros!” he murmured.  “Of course, you are quite right.  It had not occurred to me in that light before.  True, the report was intended only for my own pleasure in later years, but that does not alter the nice point of honor.”

Tom Reade was deceived by Don Luis’s manner.  He did not suspect that, at this very instant, the Mexican was consumed with demoniacal rage.

“I shall not be patient another time,” muttered Don Luis, between his teeth and under his breath.  Yet aloud he said: 

“We have had too much of business to-day.  We are tiring ourselves.  Until dinner time let us go outside and be gentlemen.  Business for to-morrow or next week.  And my dear daughter.  Brute!  I have been forgetting her.”

Senorita Francesca, a darkly beautiful girl of eighteen, shy and retiring from the convent schooling that had ended but lately, soon came downstairs at her father’s summons.  Dr. Tisco bowed low before the charming girl.  Tom and Harry were presented, and tried to make themselves agreeable to the young Mexican girl.  Senorita Francesca’s shyness, however, made this somewhat difficult, so the young engineers felt inwardly grateful when Dr. Tisco strolled down the porch with her.

Dinner proved to be a somewhat formal affair.  Yet, as soon as the meal was finished Senorita Francesca was escorted from the dining room by her father and returned to her room.

“What did you think of the young lady, Tom?” Harry asked his chum when he could do so privately.

“A fine-looking girl,” Reade answered briefly.  “But I fear she would be highly offended if she knew that, all through dinner, my every thought was on the mine and the problems that we shall find there.”

“I want to talk with you about that mine, and about some impressions that I have formed here,” murmured Hazelton.