The entire police force of the city was set to work watching the pawn-shops and jewelry stores where the thief might try to dispose of the stolen property. Every ship-yard and boat-yard was searched for the identification of the "dog," but without success, and almost every mechanical establishment in the city where the instrument could have been used, was subjected to the same inspection, but without discovering anything. A list of the missing property, and the marks by which it could be identified, was given to the public and telegraphed all over the Union. Captain Jourdan declared that it was well to have as many people as possible looking for these articles. Every known or suspected criminal in the city was waited on by the police, and required to give an account of himself on the night of the murder, and it is said that there was a general exodus of the professional thieves from New York. The ten days immediately succeeding the murder were singularly free from crime, so close was the espionage exercised over the criminals by the police. It is safe to assert that the police never made such exertions in all their history, to secure a criminal, as in this case. Every sensible suggestion was acted upon, no matter by whom tendered. Neither labor nor expense was spared, and all with the same result. Captain Jourdan literally sank under his extraordinary exertions, his death, which occurred on the 10th of October, 1870, being the result of his severe and exhausting labors in this case. His successor, Superintendent Kelso, has been equally energetic, but thus far--nearly two years after the commission of the deed--no more is known concerning it than was presented to Jourdan and Kelso as they stood in the chamber of death, and nothing has occurred to destroy or shake their original theory respecting the murderer and his mode of committing the deed. The mystery which enshrouded it on that sad July morning still hangs over it unbroken. II. PRIVATE DETECTIVES. The Detectives, whose ways we have been considering, are sworn officers of the law, and it is their prime duty to secure the arrest and imprisonment of offenders. There is another class of men in the city who are sometimes confounded with the regular force, but who really make it their business to screen criminals from punishment. These men are called Private Detectives. Their task consists in tracing and recovering stolen property, watching suspected persons when hired to do so, and manufacturing such evidence in suits and private cases as they may be employed to furnish. There are several "Private Detective Agencies" in the city, all of which are conducted on very much the same principles and plan, and for the same purpose--to make money for the proprietors. Mr. Edward Crapsey, to whom I am indebted for much of the information contained in this chapter, thus describes a well-known Agency of this kind: