He bade the man enter and, without looking up from the papers he was studying, asked him to take a seat. Still without taking his eyes from the papers, he presently asked of the man, who had not accepted the invitation to sit: "Well, sir, what can I do for you?" "Nothing," answered the man. "I came to serve you, not to ask service." The voice seemed familiar to Duncan--almost startlingly familiar. He instantly looked up and exclaimed: "Why, it's Dick Temple!" "Yes," answered the other. "You and I quarreled very bitterly once. The quarrel was a very foolish one--on my side." "And on mine, too!" responded Duncan, grasping his former enemy's hand. "Let us forget it, and be friends." "With all my heart. It was in that spirit that I came hither to-night--I want to render you a service." Meanwhile Duncan had almost forced the miner into a chair. "Tell me," he said, "how is it that you----" "That I'm a miner? You think of me as an educated engineer, eh? Well, that's a long story and not at all so sad a one as you might suppose. I'll tell you all about it at another time. But it can wait, while there are some other things that should be said now--things that vitally affect the affairs you have in charge." "It is very good of you to come to me with suggestions, and they will be very welcome, I assure you, and very helpful, I've no doubt. For I have faith in your skill as an engineer." "My skill still remains to be proved," answered the other with the merest touch of sadness in his utterance. "But, at any rate, I've had the very best engineering education that the schools can give. Never mind that--and never mind me. I didn't come here to talk of myself. I want to talk to you about this mine." "Good. That is what I am here for. Go on." "Well, everything here is wrong. With your readiness of perception you must have seen that for yourself. With the general management I have nothing to do. I'm only one of the miners. But there is a problem of ventilation here that ought to be solved, and I have come simply to offer a solution, in the interest of the company that pays my wages and still more in the interest of the miners. Two of them were killed by choke-damp a little while ago, four of them are now ill from the same cause, while all of them are earning less than they should because the best and most easily accessible headings are closed." "Is there any very serious difficulty involved in the problem of ventilating the mine?" "None whatever--at least no engineering difficulty." "Just what do you mean?" "I prefer not to say." "Perhaps I can guess," said Duncan. "I have myself discovered a very serious difficulty in the personal equation of Mr. Davidson. He does not want to ventilate the mine--he has his own reasons, of course. That difficulty shall no longer stand in the way. I shall eliminate it at once. Go on, please, and tell me of the engineering problem."