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All these pieces, after being cemented together, were tried again before being used. The trials were made by means of a Perreaux dynamometer, with strips about 2 inches wide by 4 inches long, under the control of Messrs. P. de Nordenfeld and Noël, engineers of the Nordenfeld Company, to whom Andrée had entrusted the task of testing the materials used in the construction of his balloon.

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.