 The other ends of the strips lead back to a pocket that holds the projectile.The dominant hand grasps the pocket and draws it back to the desired extent to provide power for the projectile—up to a full span of the arm with sufficiently long bands.Slingshots depend on strong elastic materials, typically vulcanized natural rubber or the equivalent, and thus date no earlier than the invention of vulcanized rubber by Charles Goodyear in 1839 (patented in 1844).