21st [September].ー This morning about one o'clock the officer of the watch called me, and gave information of a house in New York being on fire. I immediately went on deck, observed the fire to spread and catch several houses, and saw the fire break out at different parts of the city. Sent several boats on shore to the assistance of the place. Made the signal for all lieutenants, and ordered boats from each ship for the same purpose. It was evident from many circumstances that the city was maliciously set on fire, by the fires breaking out at different places at the same time; from lath wood, split in small slips, tarred and brimstoned, with tow and all manner of combustibles being placed in different parts of the city. Several people were taken up, against whom the .proof seemed very plain. These the sailors, soldiers, and mob immediately put to death; many others, perhaps thirty or forty, were put in jail on strong suspicion. This evening the fire is entirely out; but had the wind come to the westward and blown fresh, as it did when it first broke out, the whole city would have been consumed. The loss is not yet accurately ascertained, but I suppose there may be about one-third or one-sixth of the city burned.