"A bad bill?" exclaimed Ben, in genuine surprise. "No, I had no idea of it." "Who is this man who gave it to you? Do you know him?" "He said his name was Smithson, from Philadelphia. I never saw him before this morning." "What were you to do with the change I gave you back? Did he tell you to keep it?" "No, sir. I was to meet him in the park in an hour and give it to him." "He has been making a catspaw of you." "I don't understand," said Ben. "Knowing the bill to be bad, he did not venture to offer it himself, as it would make him liable to arrest." "Arrest!" exclaimed Ben, in dismay. "Yes. One who knowingly offers a counterfeit bill is liable to arrest and imprisonment." "I hope you don't think I knew anything about it," said Ben alarmed. "No; you look too honest to be a confederate of a scoundrel." "He ought to be ashamed of himself to impose upon me," said Ben indignantly. "What shall I do?" "Have you any other money?" Ben produced a two-dollar bill. "I will take pay out of this for your share of the dinner, and with your help I propose to arrest your companion." The cashier briefly explained his plan. A policeman was summoned, and Ben was instructed to meet Smithson at the time appointed, and tender him the change. He did so. Smithson looked up eagerly as Ben approached. "Have you got the change?" he asked. "Yes," said Ben. "Give it to me." Ben drew fro his vest-pocket three dollars and sixty-five cents, with which he had been provided, and tendered them to the young man, who eagerly took them. "Much obliged," said Smithson, looking elated at the supposed success of his plan. Just then, a quiet-looking man, a detective in citizen's clothes, stepped up and laid his hand on the swindler's arm. "Mr. Smithson, I want you." "What for?" inquired Smithson, turning pale. "For passing a counterfeit bill." "I have passed no counterfeit," faltered Smithson. "You employed this boy to do it for you." "There's some mistake," said Smithson stammering. "You can't prove anything." "With this boy's help we can. Don't trouble yourself to invent excuses. You have been suspected for some time." "The boy lies," said Smithson fiercely. "If he does it will be found out. Come along with me." Much against his will, Smithson walked arm-in-arm with the detective. Ben was notified to be in attendance at court the next morning, at ten o'clock, to testify against his new friend. "I am more of a greenhorn than I thought," Ben said to himself. "Who would have thought such a polite young man was a counterfeiter!" About four o'clock Ben went up-town to Mr. Manning's boarding-house, and remained there till the merchant arrived. Chapter XIII A Curious Old Lady The next morning Mr. Manning introduced Ben to his temporary ward, a bright, attractive little girl, who seemed to take an instant fancy to our hero. "Is he my brother?" she inquired of Mr. Manning.