The central door of the ground floor opens upon a large vestibule, around which are arranged symmetrically the post, telegraph, telephone, and intelligence offices, etc. Beyond the vestibule there is a gallery that leads to the central court, upon the site of which has been erected the grand assembly hall. This latter, which measures 20 meters in length, 22 in width, and 6 in height, is lighted by a glazed ceiling, and contains ten rows of benches. These latter contain 900 seats, arranged in the form of circular steps, radiating around the president's platform, which is one meter in height. A special combination will permit of increasing the number of seats reserved for the labor associations on occasions of grand reunions to 1,200. The oak doors forming the lateral bays of the hall will open upon the two large assembly rooms and the three waiting rooms constructed around the faces of the large hall. In the assembly rooms forming one with the central hall will take place the deliberations of the syndic chambers. The walls of the hall will, ere long, receive decorative paintings.--_L'Illustration._ * * * * * MANUFACTURE OF ROLL TAR PAPER. Roofing paper was first used in Scandinavia early as the last century, the invention being accredited to Faxa, an official of the Swedish Admiralty. The first tar and gravel roofs in Sweden were very defective. The impregnation of the paper with a water-proofing liquid had not been thought of, and the roofs were constructed by laying over the rafters a boarding, upon which the unsaturated paper, the sides of which lapped over the other, was fastened with short tacks. The surface of the paper was next coated with heated pine tar to make it waterproof. The thin layer of tar was soon destroyed by the weather, so that the paper, swelled by the absorption of rain water, lost its cohesiveness and was soon destroyed by the elements. This imperfect method of roof covering found no great favor and was but seldom employed.