"Mother," said Bert solemnly, "I am going to solve the mystery, if possible, make my father's evidence clear, and expose the real criminal. I am only a boy, and I don't know how I shall accomplish it, but I won't rest till I have done it." "May Heaven grant you success, my dear boy!" responded Mrs. Barton fervently. CHAPTER XXIV. THE OFFICE OF THE MAGNET MINE. Bert took the morning train to New York, and arrived about half-past seven o'clock. He met with no adventures on the way, and as soon as he reached the Grand Central Depot took a Fourth Avenue car down, as instructed by Uncle Jacob. In a large building of many stories on Nassau Street, on the sixth floor, was an office on the door of which Bert read MAGNET MINING CO. This, as he understood, was the office where Jacob Marlowe was employed. Bert was considering whether he ought to knock or not, when a brisk-looking gentleman stepped up, and, opening the door, entered. Bert followed him in. "Whom did you wish to see?" asked the brisk-looking man. "Mr. Jacob Marlowe. Is this the office where he is employed?" "Yes," answered the man, with a smile. Bert hardly needed this assurance, however, as he had already discovered Uncle Jacob sitting in an inner room, at a desk, conversing on business, apparently, with an elderly man of dignified appearance. "He will soon be at leisure," said the one who had just entered, and seated himself at another desk in the outer room. "That must be Uncle Jacob's employer," thought Bert. "What news do you hear of the mine?" he heard the elderly man ask. "Excellent," answered Uncle Jacob. "It has gone up five points within two weeks. The output is steadily increasing." "Do you know anything of it from your own knowledge?" "Certainly; I ought to, for I was myself its discoverer." This rather surprised Bert. "It was a rich find," continued Uncle Jacob, "and I have no hesitation in putting it on the New York market." "There are so many wild-cat mines, you know, that a man needs to be very cautious." "Quite true. In such mines it is only the men who capitalize them who make money. I would not lend myself to any such scheme of deception. I have a reputation to sustain, and I value that more than money. Our mine has found favor with some of the most conservative investors in the city." Here Uncle Jacob mentioned several names, so prominent that they were familiar to Bert, country boy though he was. "You may put me down for five hundred shares," said the elderly man, apparently convinced. "I will send you round a check to-morrow. To whom shall I make it payable?" "To me." "Very well." The old gentleman rose, drew on his gloves, and went out, Uncle Jacob accompanying him to the door. This brought him face to face with Bert. "So you have come, Bert," he said with a pleasant smile. "How did you leave your mother?" "Very well, uncle." "At what time did you breakfast?" "At half-past six."