Here it was that Chief-Engineer DECKER showed himself one of the bravest among the brave. After the entire building had been ransacked, and every article deemed worth carrying away had been taken -- and this included even the little garments for the orphans, which were contributed by the benevolent ladies of this City -- the premises were fired on the first floor. Mr. DECKER did all kindled, but to prevent the flames from bein??? kindled, but when he was overpowered by superior number, with his own hands he scattered the branch, and effectually extinguished the flames. A seeona??? attempt was made, and this time in three different parts of the house. Again he succeeded, with the aid of half a dozen of his men, in defeating the incendiaries. The mob became highly exasperated at his conduct, and threatened to take his life if he repeated the act. On the front steps of the building he stood up amid an infuriated and half-drunken mob of two thousand, and begged of them to do nothing so disgraceful to humanity as to burn a benevolent institution, which had for its object nothing but good. He said it would be a lasting disgrace to them and to the City of New-York.

These remarks seemed to have no good effect upon them, and meantime, the premises were again fired -- this time in all parts of the house. Mr. DECKER, with his few brave men again extinguished the flames. This last act brought down upon him the vengeance of all who were beat on the destruction of the asylum, and but for the fact, that some firemen surrounded him, and boldly said that Mr. DECKER could not be taken except ever their bodies, he would have been dispatched on the spot. The institution was destined to be burned, and after an hour and a half of labor on the part of the mob, it was in flames in all parts. Three or four persons were horribly bruised by the falling walls, but the names we could not ascertain. There is now scarcely one brick left upon another of the Orphan Asylum.

During the greater part of the day, a crowd, composed principally of overgrown boys, amused themselves by going around to the various newspaper offices down town, cheering the bulletins which announced the progress of the riot in the upper part of the City, groaning the editors of such journals as were deemed obnoxious by the mob, and chasing and beating every person of color who chanced to make his appearance. The Tribune, as a matter of course, came in for the principal share of the groans, and it is but fair to add, that the Daily News monopolized the cheers. Various hints were given out by the rioters that the Tribune would be attacked in the evening, but they were not credited, or if they were, no preparations appear to have been made to repel it. About 7 o'clock, however, the crowd of boys began to be swelled by a different class of roughs, who appeared on the ground with clubs in their hands, and from their appearance, had evidently been engaged in the more bloody work up town. They immediately gathered around the Tribune office and commenced a series of the most unearthly groans and demoniac yells. In a few moments one of the more forward among them commended an attack upon the door of the publication office, which was locked, but which soon gave way to the pressure of the mob, who, amid the crashing of broken door and windows, rushed in ??? In a ??? more files of the Tribune were thrown out to the crowd and torn and scattered to the winds. In less than five minutes the office was completely gutted, and the desks and counters upset and broken. At length a platoon of the First Ward Police came rushing up Nassau-street, and on seeing them the mob, which numbered not less than four hundred men and boys, ran like so many sheep, leaving Printing-house-square, in less than three minutes, almost as clear of people as it is of a Sunday morning. It was a striking illustration of the cowardice of a mob when confronted by a handful of determined officers of the law. Several shots were fired by the policemen at ringleaders of the mob -- but, so far as is known, none of them took effect. One of the policemen was also shot at by a rioter, the ball taking effect in the back. The wound is serious, but it is thought hot dangerous. Before leaving the office, the rioters set fire to the building, but it was extinguished by a policeman before much damage was done.

Among the most cowardly features of the riot, and one which indicated its political animus and the cunningly-devised cue that had been given to the rioters by the instigators of the outbreak, was the causeless and inhuman treatment of the negroes of the City. It seemed to be an understood thing throughout the City that the negroes should be attacked wherever found, whether then offered any provocation or not. As soon as one of these unfortunate people was spied, whether on a cart, a railroad car, or in the street, he was immediately set upon by a crowd of men and boys, and unless some man of pluck came to his rescue, or he was fortunate enough to escape into a building he was inhumanly beaten and perhaps killed. There were probably not less than a dozen negroes beaten to death in different parts of the City during the day. Among the most diabolical of these outrages that have come to our knowledge is that of a negro cartman living in Carmine-street. About 8 o'clock in the evening as he was coming out of the stable, after having put up his horses, he was attacked by a crowd of about 400 men and boys, who beat him with clubs and paving-stones till he was lifeless, and then hung him to a tree opposite the burying-ground. Not being yet satisfied with their devilish work, they set fire to his clothes and danced and yelled and swore their horrid oaths around his burning corpse. The charred body of the poor victim was still still hanging upon the tree at a late hour last evening.

Early in the afternoon the proprietors of such saloons and other places of business as bad negroes in their employ, were obliged to close up for fear that the rioters would destroy their premises. In most of them the negroes were compelled to remain over night, not daring to go home lest they be mobbed on the way.

At about five o'clock a large body of rioters, differently estimated from one hundred to three hundred, -- the latter much the nearer figure -- marched down Broadway with a banner, inscribed "No draft" with the American flag, and with every conceivable diabolical weapon. They amused themselves en route by cheering and groaning at will, and occasionally killing or maiming every "nigger" they met. When below Fourteenth-street they avowed their determination of entering the La Farge House and seizing every colored servant there. Fortunately they were met at Amity-street -- unexpectedly to them -- by a body of Police some two hundred strong, under Inspector CARPENTER and Sergeant COPELAND. The Police instantly formed company front, and, with Inspector CARPENTER far in advance, at once charged on the "double quick." The fight for a few moments was savage and terrific. Men fell by the dozen under the sturdy blows of the Police, who had orders to "make no prisoners," and in five minutes naught was left of the lawless horde but the bodies of those ruffians who were knocked senseless lying on the ground. Too much credit cannot be awarded to the Police for their behavior on this occasion. They did not know whether one hundred or five thousand of the lawless were their adversaries, nor did they wait to ascertain. On they charged, and in five minutes were masters of the situation. Capt. CARPENTER was far ahead of his men, with reckless courage, rushing into the midst of the mob, and handling his club against fearful odds. It is a wonder he was not killed. This charge, and its success, must have had a salutary effect, being the first regular fight with the organized mob, and showing them that the Police are their superiors.

The Police, at the time they met the mob, were on their way to Mayor OPDYKE's house, in Fifth-avenue, winch it was rumored was to be attacked. None of the Police were seriously injured in the encounter, while at least two of the rioters were tilled, and ten or fifteen more were so badly used up that they will not be likely to take a hand in another riot at present.