The invaluable service of the telegraph was tested to-day, not merely in enabling General Brown and the commissioners to despatch men quickly to a threatened point, but to keep a force moving from one ward to another, as messages came in, announcing the incipient gathering in different districts. Word sent to the station in the neighborhood where they were acting, would instantly change their route; and knots of men, which if left alone would soon have swelled into formidable mobs, were broken up, for they found military and police force marching down on them before they could form a plan of action. Nor was this all. A force sent to a certain point, after dispersing the mob, would be directed to make a tour through the disaffected districts--all the time keeping up its communication with head-quarters, so that if any serious demonstration was made in that section of the city, it could be ordered there at once, thus saving half the time it would take to march from head-quarters. Thus, for instance, Captain Petty was ordered this morning to head-quarters from the City Hall, where he had passed the night, and directed to take two hundred men (including his own precinct force), and go to the protection of a soap factory in Sixteenth Street, Eighth and Ninth Avenues. He moved off his command, marching rapidly up Broadway and down Sixteenth Street. The mob saw it coming two blocks off, and immediately scattered in every direction, which awakened the supreme contempt of the captain. He now marched backward and forward, and through the cross streets, up as far as Nineteenth Street, scattering every fragment of the mob that attempted to hold together, and finally returned to head-quarters. This was a long march, but the men had scarcely rested, when the captain was hurried off to aid in the protection at the wire factory in Second Avenue. In the fierce fight that followed, he, with ten men at his back, charged up the broad stairway, fighting his way step by step to the fifth story. Caught up here at the top of the building, the rioters were clubbed without mercy. Some, to escape the terrible punishment, plunged down the hatchway; others attempted to dash past the men, and escape down the stairs. At one time eight bodies lay in the door-way, blocking it up. He then marched back to head-quarters. He had been marching and fighting all day. Similar exhausting duties were performed by other commands, both police and military. Inspector Dilks, with his force gathered from various precincts, passed the entire day in marching and fighting. The men, weary and hungry, would reach head-quarters or certain points, hoping to get a little rest and refreshment, when the hurried order would come to repair to a point a mile off, where the mob was firing and sacking houses, and off they would start on the double-quick. Uncomplaining and fearless of danger, and never counting numbers, both police and soldiers were everywhere all this day, and proved themselves