Dr. Parkman was a less easy-going creditor. Forbearing and patient as long as he was dealt with fairly, he was merciless where he thought he detected trickery or evasion. His forbearance and his patience were utterly exhausted, his anger and indignation strongly aroused, when he learnt from Shaw that Webster had given him as security for his debt a bill of sale on the collection of minerals, already mortgaged to himself. From the moment of the discovery of this act of dishonesty on the part of Webster, Parkman pursued his debtor with unrelenting severity. He threatened him with an action at law; he said openly that he was neither an honourable, honest, nor upright man; he tried to appropriate to the payment of his debt the fees for lectures which Mr. Pettee, Webster's agent, collected on the Professor's behalf. He even visited Webster in his lecture-room and sat glaring at him in the front row of seats, while the Professor was striving under these somewhat unfavourable conditions to impart instruction to his pupils--a proceeding which the Doctor's odd cast of features must have aggravated in no small degree. It was early in November that Parkman adopted these aggressive tactics. On the 19th of that month Webster and the janitor of the College, Ephraim Littlefield, were working in the upper laboratory. It was dark; they had lit candles. Webster was reading a chemical book. As he looked up from the book he saw Parkman standing in the doorway leading from the lecture-room. "Dr. Webster, are you ready for me to-night?" asked Parkman. "No," replied the other, "I am not ready to-night." After a little further conversation in regard to the mortgage, Parkman departed with the ominous remark, "Doctor, something must be done to-morrow."