“I will now show you,” promised Don Luis, “something of the problem that confronts the engineers of this mine.”

“Keep your eyes open, and your wits about you, Harry,” whispered Tom Reade.  “I may be wholly wrong, yet, somehow, I can’t quite rid myself of a notion that Don Luis wants us for some piece of rascally work, though of what kind I can’t imagine.”

“I shall watch these two Gringos like a cat,” reflected Dr. Tisco.  “I half suspect that they will foolishly sacrifice their lives sooner than serve us.”

CHAPTER IV

TOM DOES SOME SAMPLING

At sight of Don Luis’s party a Mexican foreman came running forward.

“How runs the ore this morning?” asked Don Luis.

“Not quite as well as usual, excellency,” replied the man, with a shrug of his shoulders.

“How!  Do you mean to tell me that the ore is running out for a streak!”

“Oh, no, excellency.  Yet it is the poorest ore that we have struck for a fortnight.  However, it will pay expenses and leave something for profit, too, excellency.”

“Show us what you have been doing,” Don Luis directed.

Leading the way with a lantern that threw a brilliant light, the foreman went on down the tunnel to the heading.  As he neared the end of the tunnel the man called loudly and a number of workmen stepped aside.

As they reached the spot, Tom’s quick eye saw that the morning’s blasts had loosened some eight tons or so of ore.  Drillers stood ready to drive through the rock for the next blast.

“Let us look at the ore, Senor Tomaso,” suggested the mine owner.

Tom began to delve through the piles of shattered, reduced rock.  The foreman held the lantern close, that the young engineer might have all the light he wanted, and called to miners to bring their lights closer.

Then Harry, also, began to examine the rock.  For some minutes the two young engineers picked up specimens and examined them.

“What do you make of it?” inquired Don Luis Montez at last.

“Is this what you call a run of poor luck?” Tom asked the foreman, dryly.

“Yes, senor; rather poor,” answered the foreman.

“Then it must be rather exciting here when the ore is running well,” smiled Tom.  “At a guess I should say that this ‘poor’ stuff before us will run thirty dollars to the ton.”

“It usually runs fifty, senor,” broke in Don Luis.  “Sometimes, for a run of a hundred tons, the ore will show up better than seventy-five dollars per ton.”

“Whew!” whistled Reade.  “Then no wonder you call this the land of golden promise.”

“By comparison it would make the mines in the United States look poor, would it not?” laughed the mine owner.

“There are very few mines there that show frequent runs of fifty dollars to the ton,” Harry observed.