The early July morning broke tranquilly over the great city, and the rattling of vehicles was heard in some of the streets, where men were going to their places of business. In a large portion of it everything wore its usual air of tranquillity, yet a close observer would notice an uneasiness resting on the countenances of men. Furtive glances were cast down side streets, and people seemed on the watch, as though in expectation of something to come, and the very atmosphere appeared laden with evil omens. Around police head-quarters, and inside the building, were large bodies of policemen and the U. S. troops under General Brown. But uptown, in the vicinity of Thirteenth Street and Second and Third Avenues, crowds of men began early to assemble, though perfectly quiet in their demeanor, while smaller knots in the adjoining wards could be seen discussing the events of the day before. In the meantime, exciting reports came from Harlem and Yorkville--as early as five o'clock, the following telegram was sent to the Twentieth Precinct: "Notify General Sandford to go immediately to Eighty-sixth Street and Harlem--mob burning." Indeed the air was charged with electricity, but the commissioners now felt ready to meet the storm whenever and wherever it should burst. A large force of special policemen had been sworn in, while General Brown had over seven hundred troops, ready to co-operate with the police. The public buildings were all well guarded--Sandford had a strong force in the arsenal, and the military and civil authorities stood waiting the next movement of the mob. Telegrams arriving, showed that the northern part of the city was alive with gathering crowds, while from Sixth Avenue on the west nearly to Second Avenue in the east, and down almost to Broome Street, the streets were black with excited men. Stores were closed, factories emptied of their hands, who voluntarily joined the rioters, or were forced into their ranks, and there was evidently a gathering of the elements in those directions for a fearful storm. Soon immense crowds began to patrol the streets in different wards, showing that simultaneous action would be required at various points. The troops were called out and marshalled in Mulberry Street, and those companies selected for immediate action drawn up in line. Colonel Frothingham, after an earnest conversation with the officers, addressed the soldiers. He told them that the fate of the city was in their hands, and everything depended on their good conduct. Knowing the temptations to disorderly conduct in the midst of the great city, he urged on them especially to obey implicitly their officers under all circumstances. His manner and words were earnest, and listened to with profound attention. Soon a company headed by Sergeant Carpenter, with a police force two hundred and fifty strong, started for Second and Third Avenues, where the greatest gatherings were reported to be.