As soon as a vessel is ready and officered for the voyage, measures are taken to procure a crew. Slave-traders employ for this the services of 'runners,' who constitute a caste of pariahs of the most degraded kind. A conscientious scruple would seem never to enter into their calculations. They would hardly recognize a precept of the decalogue except by the circumstance of its violation. Earning their livelihood thus basely, debauchery and crime constitute their every-day history. These persons keep a record of the names of men who have served on slave ships, or been guilty of mutiny, or other villany. So accurate is their information and so expert are they in their estimate of character, that they seldom commit a blunder, or furnish a seaman who is not the man for the vocation. The crew which they select are indeed 'picked men.' They are of every nationality, and are taken from the seamen's boarding-houses in the lower wards of the city. A few years since, the information was received in New York that a yacht was lying in Long Island Sound, and that circumstances warranted the suspicion that she was intended for the slave-trade. The marshal, with a display of enthusiastic zeal for the execution of the laws, proceeded to the place with a strong force of assistants, and took charge of the yacht; but subsequent investigations failed to criminate her. The reputed owner declared that he had fitted her out for a pleasure excursion; that was all. The vessel was discharged, and a few months afterward landed a cargo of negroes on the coast of Georgia. So easy has it been to deceive the Federal officers. The owner of the yacht afterward declared that he paid ten thousand dollars to get his vessel clear of the harbor of New York. The obtaining of a clearance at the custom-house was not a very difficult matter. Slavers were never detained by any extraordinary curiosity on the part of those having cognizance of their departure. They had but to assume a transparent disguise, raise the American flag, and keep up the show till they arrived at the intermediate port. Here the national ensign was changed, the papers of the vessel were altered, and necessary arrangements were made for receiving a cargo of slaves.