Our boys are familiar with the United States flag, with its historic stars and stripes, as it floats over public buildings and is carried in street parades. How many know it is used for a sign or a sign-board? Passing through any one of our large cities, we often see the flag drooping from a protruding staff over a common office doorway. Considering what it means, we go up to the door, and see on one side a flaming poster printed in colors, surmounted by a picture of many soldiers standing well grouped, in their bright attractive uniforms. On reading we find this to be an advertisement or an invitation on the part of the United States government to all able-bodied men so desiring to join the ranks of the army as private soldiers. It states that the man so volunteering to serve his government in this capacity will be well clothed, fed, and, besides, receive $13 per month in cash, less certain small sums retained from time to time by the government to be surrendered to the soldier upon his discharge from service. He must agree to serve faithfully, take an oath of fidelity to the United States, and to obey all superior officers for a period of three years. It was formerly five years. While reading the poster we have noticed, either leaning in the doorway or pacing up and down with erect carriage, in a neat tight-fitting blue uniform, a man who, upon being accosted, replies that he is a private, or, if we noticed a V-shaped braid upon his arm, a sergeant, belonging to some regiment of the army stationed at a distance. He is here to get men to enlist, and go back with him to his regiment and become soldiers. He enlarges upon the pleasures of the service--if cavalry, the riding, the scouting, the excitements of chasing Indians; if infantry, the enjoyments of camp life, the practice marches, the Indian campaigns, where deeds of gallantry and brave acts will be rewarded by medals and certificates of honor; if artillery, the use of heavy ordnance in defending our sea-coasts, with their pleasant stations.