What is "cork jackets"

Cork \Cork\ (k[^o]rk), n. [Cf. G., Dan., & Sw. kork, D. kurk; all fr. Sp. corcho, fr. L. cortex, corticis, bark, rind. Cf. Cortex.]

1. The outer layer of the bark of the cork tree ( Quercus Suber), of which stoppers for bottles and casks are made. See Cutose.

2. A stopper for a bottle or cask, cut out of cork.

3. A mass of tabular cells formed in any kind of bark, in greater or less abundance.

   Note: Cork is sometimes used wrongly for calk, calker; calkin, a sharp piece of iron on the shoe of a horse or ox.

   Cork jackets, a jacket having thin pieces of cork inclosed within canvas, and used to aid in swimming.

   Cork tree (Bot.), the species of oak ( Quercus Suber of Southern Europe) whose bark furnishes the cork of commerce.