According to a clause of the agreement the envelope was to be inflated with air, and before the last varnishing to be submitted to an internal pressure equal to 3 inches water-column. This trial took place on the 3rd of May, in the presence of Messrs. de Nordenfeld, engineer of the Nordenfeld Company, Gaston Tissandier, Colonel Renard and Commander Renard, managers of the Central Establishment of Military Aerostation of Chalais-Meudon. The openings of the balloon were provisionally closed; the valve in the appendage was replaced by a wooden hoop covered by a disc of material containing a glazed window, 7⅘ inches in diameter, thus permitting inspection of the interior of the balloon. The latter was inflated by means of a ventilator supplying about 70,633 cubic feet of air per hour. Andrée’s experts, who had followed up the manufacture step by step, then examined minutely all the parts, and declared the material to be faultless, and quite in accordance with the desires expressed by Andrée. After this examination, which showed that the envelope inflated with air did not lose its contents to any appreciable extent, the balloon was emptied, and was then given the last coat of varnish. This having been done, it was again inflated for the purpose of drying. The net suspended by the crown, in the centre of the central dome, and with the suspending ropes attached to the balustrade of the first gallery, presented the appearance of a vast tent, the summit of which was 131 to 164 feet above the ground. [Illustration: STAFF-OFFICERS OF THE EXPEDITION.] The car, the valves, and in short all the articles made at Paris were exhibited at the Champ de Mars. A little balloon of 1,148 feet, fully equipped, and inflated with air, suspended by the side of the polar balloon, served for comparison. This exhibition, which was not arranged with a view to profit, was thrown open to the public from the 10th to the 14th of May. The 10th of May was reserved for special guests, and M. Félix Faure, President of the French Republic, was the first visitor. He took much interest in the various parts of the balloon, which he examined at length, and in the details of its construction. He expressed his best wishes for the success of this interesting expedition. There were present at the same time as the President, M. de Nordenfeld, Swedish engineer, M. Gaston Tissandier, Colonel Renard, and Commander Renard, who had also watched the work in its various stages, and had co-operated therein to a certain extent. The Swedish colony was represented by M. Dué, minister plenipotentiary, and Gustav Nordling, vice-consul. Among the other guests were Messrs. Poubelle, Prefect de la Seine, Admiral Sallandrouze de Larmornaix, General Mathieu, M. Decauville, senator, M. Coulet, solicitor to the Swedish Legation, etc.