The automatic valve closing the appendage was suggested to Andrée by M. Lachambre, and was adopted. It measures 39 inches in external diameter, with a discharge orifice 34 inches in diameter. The valve disc, of threefold Pongee silk, is 35⅘ inches in diameter. It is provided with two glazed windows, in order to enable the aeronauts to inspect the interior of the balloon. This disc, which is slightly conical, is fitted upon a walnut-wood ring, which acts as a seat, in which it is held by the traction of six spiral springs of steel wire, fastened on one side to the end of the wooden spokes of the valve, and on the other side to the top of a small frame fixed on the seat. The frame, mounted on the wooden ring or crown, is formed by twelve nickeled steel tubes.
The valve is guided in its course by a central steel tube, sliding in another tube, which serves as an axis for the frame. A small cotter limits its action, the length of which is equal to one-half of the radius of the discharge orifice. The joint is rendered gas-tight at the periphery of the valve by means of a brass blade resting on a rubber band stretched in a groove of the seat.
The valve commences to open under the action of an internal pressure corresponding to ³⁄₁₀ inch water column. In order to fix it to the balloon, it is placed in the interior of the appendage, the margin of which, held between two rubber bands, is kept tight against the seat by an external belt or ring of brass, fastened by bolts.
“Rending Flap.”—The rending flap is 4½ yards high, and has a surface of 4⁷⁄₁₀ square yards. It is formed of threefold Pongee silk, and is rectangular in shape, terminating in a curvilinear triangle, the point of which is turned upwards. Its vertical axis is at an angular distance of 105 degrees from each of the two manipulating valves; the lower base, which is 35⅖ inches wide, reaches down to 19⅗ inches above the equator. The seams joining the material of the “rending flap” to that of the balloon are similar to the seams of the various widths, and are likewise covered with cemented strips.
In the interior of the balloon the upper extremity of the “rending flap” is of fourfold silk; its edge is put round a stick of hard wood, to which a rope for pulling is fixed, by means of which the rent is made. This rope descends to the car after having passed through the lower part of the envelope, near the appendage, in a tube.
In order to make the rent with ease, which will require an effort equal to a traction of about 220 or 250 pounds, Andrée intends to use a small grapnel, which he will attach to the end of this rope and throw to the ground at the proper moment.
THE BALLOON IN THE 96 FEET GALLERY OF THE CHAMP DE MARS EXHIBITION.