in a tone of concern

It so happened that he was after some papers, and did not immediately take up the envelope containing the government bonds. Philip was rather afraid he wouldn't, and ventured to remind him of them by a question. "How many government bonds have you in that envelope, pa?" he asked. "A little over a thousand dollars," answered Colonel Ross. "Will you let me look at one? I want to see how it looks." This question led the colonel to open the envelope. He took out a bond and handed it to Philip. "Are these coupons?" asked Philip, who knew perfectly well, but only wanted to fix his father's attention. "Yes, they are promises to pay interest semiannually. In January and July I cut off one of these little slips, and receive the interest it represents in gold." "That's very convenient, isn't it?" "Yes, for I can get the coupons cashed at any bank or broker's office." Almost mechanically, he began to draw out the bonds and count them. But his air of inattention was quickly replaced by a look of surprise and anxiety. He counted the bonds over again, more deliberately, but each time the number came short two. "That's strange," he said, in a low tone. "What is strange, pa?" "Two bonds seem to be missing," said his father, in a tone of concern. "I've got one, you know, in my hand." "Yes, yes. I reckoned that." "How large were they? Is it much of a loss?" "One hundred dollars apiece, and each worth a hundred and fifteen dollars, on account of the premium. Do you know anything about them?" and Colonel Ross fixed a piercing eye on his son. "I, pa? How should I know anything about them? Why, I didn't know exactly how they looked. When did you see them all last?" "Last evening. I happened to count them then." "They must have been taken from the trunk since then." "Then I am almost sure I know how it happened," said Philip, suddenly, as if a light had dawned upon him. "I should like to have you tell me, then." "You remember, pa, you left the keys on the desk?"