The population of New-York City was about ten thousand, about two thousand of whom were slaves. On the 18th of March the chapel in the fort took fire from some coals carelessly left by an artificer in a gutter he had been soldering. The roof was of shingles; and a brisk wind from the south-east started a fire, that was not observed until it had made great headway. In those times the entire populace usually turned out to assist in extinguishing fires; but this fire being in the fort, the fear of an explosion of the magazine somewhat checked their usual celerity on such occasions. The result was, that all the government buildings in the fort were destroyed. A militia officer by the name of Van Horne, carried away by the belief that the fire was purposely set by the Negroes, caused the beating of the drums and the posting of the "night watch." And for his vigilance he was nicknamed "Major Drum." The "Major's" apprehensions, however, were contagious. The fact that the governor reported the true cause of the fire to the Legislature had but little influence in dispossessing the people of their fears of a Negro plot. The next week the chimney of Capt. Warren's house near the fort took fire, but was saved with but slight damage. A few days after this the storehouse of a Mr. Van Zandt was found to be on fire, and it was said at the time to have been occasioned by the carelessness of a smoker. In about three days after, two fire alarms were sounded. One was found to be a fire in some hay in a cow-stable near a Mr. Quick's house. It was soon extinguished. The other alarm was on account of a fire in the kitchen loft of the dwelling of a Mr. Thompson. On the next day coals were discovered under the stables of a Mr. John Murray on Broadway. On the next morning an alarm called the people to the residence of Sergeant Burns, near the fort; and in a few hours the dwelling of a Mr. Hilton, near Fly Market, was found to be on fire. But the flames in both places were readily extinguished. It was thought that the fire was purposely set at Mr. Hilton's, as a bundle of tow was found near the premises. A short time before these strange fires broke out, a Spanish vessel, partly manned by Spanish Catholic Negroes, had been brought into the port of New York as a prize. All the crew that were Negroes were hurried into the Admiralty Court; where they were promptly condemned to slavery, and an order issued for their sale. The Negroes pleaded their freedom in another country, but had no counsel to defend them. A Capt. Sarly purchased one of these Negroes. Now, Capt. Sarly's house adjoined that of Mr. Hilton's; and so, when the latter's house was discovered to be on fire, a cry was raised, "The Spanish Negroes! The Spanish! Take up the Spanish Negroes!" Some persons took it upon themselves to question Capt. Sarly's Negro about the fires, and it is said that he behaved in an insolent manner; whereupon he was sent to jail.