[Illustration: VALVES FOR WORKING THE BALLOON.] The circumference of the net, all the way up, consists of 192 meshes, the dimensions of which vary according to the area of the zone they are to cover. These meshes, the number of which is no less than 19,000, represent a length of twine amounting to nearly 16,404 yards. The lower part of the net is formed by a system of three zones of crowfeet or cringles, each zone reducing, by one-half, the number of meshes composing the next upper zone. The first row of crowfeet is mounted on thimbles of nickeled brass, the second and the third on wooden pulley-blocks, having sheaves of lignum vitæ; and forty-eight suspending cords, each fitted at its end with an eye, complete the net and form points for tying it to the retaining ring by means of toggles. These suspending cords have a diameter of ⁷⁄₁₀ inch, and a bearing-strain of no less than 6,613 lbs. The net thus constituted weighed 776 lbs. In order to preserve the cordage from moisture it was impregnated with vaseline, except in the upper part, which was covered with a projecting cover of varnished silk; after this operation the weight of the net was 974 lbs. Eight detachable equatorial cringles were fixed to the equator of the net. They were to serve for holding up the balloon, and preventing it from oscillating, in the shed which was to shelter it at Spitzbergen, while awaiting a favourable wind for the departure of the expedition. PROTECTING COVER.—A spherical _calotte_ of single silk, varnished with four coats and vaselined, and having an area of 1,560 square feet, covers the upper part of the balloon. It is finished in the same way as the balloon, being composed of overlapping widths to the number of 720. The seams, having a width of ¼ inch, are hooked together, and sewn with two rows of stitching with silk thread. They are not covered with cemented strips. Their total length is 656 yards. The vertex of the protecting cover, of conical shape, is of double silk. It rests on a small wooden structure, likewise of conical shape, the base of which, placed on the material at the upper pole of the balloon, is surrounded and held in place by the crown of the net. The lower zone, terminating the protecting cover, is of double silk. Its extreme edge is put round a hemp bolt-rope, ³⁄₁₀ inch in diameter, which is sewn into the material; ninety-six eyes made above this bolt-rope are intended to receive thongs for fixing the protecting cover to the meshes of the net. This protecting cover weighs 88 lbs. Its object is to protect the top of the balloon against rain, and more especially to prevent incrustation with snow between the meshes of the net. VALVES.—The balloon has no valve at the top, because its action would probably be affected by snow; but it is provided with two manipulating valves, of equal dimensions, one being placed at the equator, and the other one metre above the equator. These are at 150 degrees angular distance from each other.