THE MOB SPIRIT WHICH HAS MANIFESTED ITSELF for some days in New York, has spread to this city, and last night made a demonstration on the newspaper offices.

For the present it has content itself with merely demanding the hoisting of the American flag, and this morning the stars and stripes wave over the Eagle office, where they have always floated when there was any patriotic occasion to be commemorated. Mobs are all but unknown in Brooklyn, and we had hoped that our city was indebted to New York for last nights demonstration, but we believe our city can claim all the credit or discredit of it.

So far as we can trace the origin of last nights assemblage it is as follows: Between eight and nine o'clock, three respectable looking citizens, one of them carrying a small American flag, made their appearance on Fulton avenue, followed by about twenty young men and boys. The party, as such parties always do, attracted followers at every step, and by the time they reached Hoyt street there was quite a large crowd. Here an unwary citizen hollered out, "three cheers for the South." This was received with groans and hisses, and cries of make him eat his words. Part of the crowd turned back, and as may be supposed, the said citizen was very soon convinced, by what in old times was believed to be the most convincing of arguments, that he was entirely in the wrong.

The ringleaders now gave the cue to their followers, and the word ran through the crowd, "Let us go to the Eagle office." The crowd then marched down Fulton street until they reached this office. The office had been closed for the night and except the engineer and his family, who reside in the building, there was nobody present. As soon as the crowd reached the office a couple of young men made a rush at the front door, and those inside of it thought it was their intention to force it open, it resisted the effort however. The crowd, which by this time numbered some hundreds, began to halloo out "Show your colors," "Up with the bunting," "Hang out your flag," "Let us see your colors." As soon as the engineer understood the object of the visit he hoisted the stars and stripes from the flag staff, from which they have always waved when there was any event to be signalized at the remembrance of which every patriotic heart beats quicker. The appearance of the flag was greeted with demonstrations of applause from the crowd assembled.

Mr. Folk, the Deputy Superintendent of Police, was on the ground and did his duty promptly and efficiently by placing himself at the door and protecting the office from the crowd, had they been disposed to inflict injury on the premises, which, however, did not seem to be the case. The crowd departed up Fulton street, with three cheers for the stars and stripes. It is but justice to say that a majority of those present were throughout good humored and even facetious, but there was a minority who were evidently ready for outrages that when once begun no man can tell where they will end. The keeper of a powder magazine to which a match has been applied has about as much control over it, as the leader of a mob over its action when it is once fairly under way.

From the Eagle office the crowd went up Fulton street and paid their respects to our cotemporaries. The News office was visited. The building in which it is printed was closed, and all was dark, except a window in the upper story, where an industrious type was seen distributing his type. The crowd hollowed out, "Show your colors," "Up with your flag." Typo was anxious enough to show his discretion and his patriotism, but it appears there was no flag at hand. The police said they could not guarantee the safety of the place unless the stars and stripes floated above it. Typo rushed over to Captain Hopkins, who fortunately had a piece of bunting by him, considerably the worse for wear and weather, however. The flag, such as it is, was given to the breeze, but it hardly satisfied the exacting patriotism of the crowd. One hollowed out, "That is not a Union flag," another doubted that all the stars was there, while another, who diluted his patriotism with facetiousness, said that was Major Anderson's flag, and that Capt. Hopkins had just come from the wars with it.

The crowd next visited the Standard office. The proprietor of that paper knowing how the tide ran, was forewarned and forearmed and appeared with an American flag in each hand, and assuming a theatrical position, he waved them from the window of his office, to the edification of the enthusiastic crowd. He called for three cheers for the American flag, which were given, and Mr. Del Vecchio pressed the beloved emblem to his breast after the manner of Hinkley, and with a profound obeisance retired, having refused the unanimous request of the crowd for a "speech," a " speech."

An old resident and a very careful observer, reminded the crowd of the existence of our venerable, respected and eminently patriotic contemporary, the Star. The office of that paper was visited, but the neighborhood had a depressing effect on the till now enthusiastic crowd, and with a modified demonstration they dispersed, after a speech from one of its leaders, against violence and in laudation of the satisfactory uniformity of opinion that existed in this community, and of this novel way of ascertaining and securing it.

HEMP ! HEMP! HEMP !

Handbills, of which the following is a copy, were posted in most of the public places of the city last night:

Hemp! Hemp! Hemp!

The Select Committee of those in favor of inflicting summary punishment upon Traitors, and those who justify or sympathize with treason, will meet on Thursday evening at 8 o'clock, for the purpose of organization and receiving their quota of Hemp Ropes.

By order of: Executioner-in-Chief

We suggest to those who invoke the terrible elements of popular passion, that they are not to be allayed by the power which invokes them.

The Excitement In New York

The following are the particulars of the doings of the crowd before the Daily News office, N.Y.: The Day Book, Express Journal of Commerce had been visited, and the crowd returned with greatly increased numbers to the scene of their former exploits and passing by the Day Book and Express offices, with derisive cheers, took up a position in front of the News office. Additional reinforcements to the police arrived from the 14th and other wards, and over two hundred and fifty disciplined men were congregated on the ground, amply sufficient to protect the threatened building from mob violence. 

Commissioner Acton appeared on the ground and took command of the men, who were under the immediate orders of four captains and twelve sergeants. Upon the reappearance of the crowd the city inspector had a large flag thrust from one of the windows of his office and his example was followed by Frank Leslie's Illustrated News. The publishers of the News, however, refused to display their flag, and declared that they would not be coerced by the move. One of the crowd had by some means entered the building but he was set upon and badly beaten. Mr. 

Acton now ordered the police to disperse the crowd and four detachments under the command of Captains Palmer, Dawling and Hutchins, and Sergeant Williams, made several charges which proved for some minutes to be of doubtful success, as the crowd each time returned to their former position. At length, however, they were forced to give way after several arrests had been made. A portion moved uptown with the intention of forcing the proprietor of the New York hotel to raise his flag, while a few passed down Chatham street and obliged the Staats-Zeitung and New York Democrat to show their bunting. The stars and stripes now float over the News office, the editors making a sort of compromise by contending that it waves freely, as it may always and floats over no American citizen by compulsion.