their determination to watch in it during the coming night.  As a preliminary to this course, however, they examined each piece of furniture and every picture and other object that they had removed from the room.  These told them nothing, and presently they restored the chamber in every particular, re-laid and nailed the carpet, and placed each article as it had stood when they arrived.  They continued to decline assistance, and made it clear that nobody was to approach the end of the corridor in which they worked.  Alive to the danger, but believing that, whatever its quality, four men could hardly be simultaneously destroyed, they prepared for their vigil.  Nor did they manifest any fear of what awaited them.  Facts, indeed, may be stubborn things, but even facts will not upset the convictions of a lifetime.  Not one of the four for an instant imagined that a supernatural explanation of the mystery existed.  Their minds were open, and their wits, long trained in problems obscure and difficult, assured them that the problem was capable of solution and within the power of their wits to solve.  They apprehended no discovery from the watch to be undertaken; but, at Frith’s orders, they set stolidly about it, as a preliminary to the proceedings of the following day.  Once proved that the murderous force was powerless against men prepared and armed against it, and the practical inquiry as to these strange deaths would be entered upon.

They came with full powers, and designed to search the house without warning on the following morning, and examine all who dwelt in it.

Sir Walter invited them to dine with him, and they did so.  There were present the master of Chadlands, Dr. Mannering—­who asked to spend the night there—­and Henry Lennox; while Masters and Fred Caunter waited upon them.  The detectives heard with interest the result of the post-mortem conducted during the morning, and related incidents in the life of Peter Hardcastle.  They were all unfeignedly amazed that a man with such a record—­one who had carried his life in his hand on many occasions—­should have lost it thus, at noonday and without a sound of warning to his fellow-creatures.  Dr. Mannering told how he had watched the medical examination, but not assisted at it.  All attempts to galvanize back life failed, as the experts engaged immediately perceived they must upon viewing the corpse; and during the subsequent autopsy, when the dead man’s body had been examined by chemist and microscopist, the result was barren of any pathological detail.  No indication to explain his death rewarded the search.  Not a clue or suspicion existed.  He was healthy in every particular, and his destruction remained, so far, inexplicable to science.  Hardcastle had died in a syncope, as the other victims; that was all the most learned could declare.

Impressed by these facts, the four made ready, and Lennox observed that they neither drank during their meal nor smoked after it.