VIEW OF THE LOWER PART OF THE BALLOON.
The tests gave the following results:—For double tissue, the breaking strains varied from 5,291 lbs. to 7,936 lbs. per yard, for threefold tissue from 6,854 to 12,125, and for fourfold tissue, made up of the best single pieces found, from 13,227 to 15,873 lbs. per yard.
The minimum resistance demanded by Andrée was fixed at 2,204 lbs. per yard and per single thickness of Pongee. This minimum was therefore greatly exceeded.
The cemented pieces were classified according to their strength, for distribution over the surface of the balloon as the strain demanded.
The upper part of the envelope is a disc 19 feet 8 inches in diameter, formed by twenty-four widths of fourfold silk. The adjoining part, consisting of threefold silk up to 13 feet 1 inch below the equator of the sphere, is composed of forty-one zones made up of forty-eight widths each.
The remainder of the balloon, down to the lower parallel, having a diameter of 23 feet, is of double material, being made up of twenty-two zones of forty-eight widths; and finally the lower part, including the appendage, is of threefold silk, and consists of five zones of forty-eight widths, and three zones of twenty-four widths each.
The portions made up of threefold and double Pongee are joined together by an intermediate zone in which the various widths of material are alternately made up, half of threefold and half of double tissue.
In each zone the various widths, or pieces of material, are identical in shape; twenty-seven different templates had to be designed in order to determine the exact shape of the various pieces or widths of material, the total number of which is 3,360. The cutting out of these pieces was effected with the aid of a cutting blade guided by a steel rule, following the outlines of a template. At first those belonging to one and the same zone were joined together, and the zones were then joined so that the various pieces or widths overlapped each other in such a manner as to give the balloon the aspect of a structure of bricks or freestone.