Littlefield was curious. The mysterious activity of the Professor of Chemistry seemed to him more than unusual. His perplexity was increased on the following day. Though on account of the holidays all work had been suspended at the College for the remainder of the week, Webster was again busy in his room early Wednesday morning. Littlefield could hear him moving about. In vain did the janitor look through the keyhole, bore a hole in the door, peep under it; all he could get was a sight of the Professor's feet moving about the laboratory. Perplexity gave way to apprehension when in the course of the afternoon Littlefield discovered that the outer wall of the lower laboratory was so hot that he could hardly bear to place his hand on it. On the outer side of this wall was a furnace sometimes used by the Professor in his chemical experiments. How came it to be so heated? The Professor had told Littlefield on Tuesday that he should not be requiring any fires during the remainder of the week. The janitor determined to resolve his suspicions. He climbed up to the back windows of the lower laboratory, found one of them unfastened, and let himself in. But, beyond evidences of the considerable fires that had been kept burning during the last few days, Littlefield saw nothing to excite peculiar attention. Still he was uneasy. Those he met in the street kept on telling him that Dr. Parkman would be found in the Medical College. He felt that he himself was beginning to be suspected of having some share in the mystery, whilst in his own mind he became more certain every day that the real solution lay within the walls of Professor Webster's laboratory. His attention had fixed itself particularly on the lavatory at the foot of the stairs connecting the upper and lower laboratories. This room he found to be locked and the key, a large one, had disappeared. He recollected that when the police officers had paid their visit to the college, the Professor had diverted their attention as they were about to inspect this room. The only method by which, unknown to the Professor and without breaking open the door, Littlefield could examine the vault of this retiring room was by going down to the basement floor of the college and digging a hole through the wall into the vault itself. This he determined to do. On Thursday, Thanksgiving Day, Littlefield commenced operations with a hatchet and a chisel. Progress was slow, as that evening he had been invited to attend a festal gathering. On Friday the janitor, before resuming work, acquainted two of the Professors of the college with his proposed investigation, and received their sanction. As Webster, however, was going constantly in and out of his rooms, he could make little further progress that day. The Professor had come into town early in the morning.