"This invention relates to that class of projectiles whose path is intended to be entirely subaquatic and to that class of projectiles whose path is intended to be partly aerial and partly subaquatic. One object of the improvement is to effect such an automatic steering of the projectile in a vertical plane after it enters the water as to insure a true horizontal trajectory at a predetermined and fixed depth. For what may be termed "purely subaquatic" projectiles which are projected from a gun under water, this feature of automatic steering in a vertical plane is of great importance as the pitch of the vessel makes it difficult to expel such projectiles from the gun at the moment the vessel is level, and any slight inclination of the axis of the gun, either above or below the horizontal at the moment of firing will seriously effect the depth of submergence of the projectile at the end of its path. For what may be termed "aerial subaquatic" projectiles, which are projected from guns above water to strike vessels or bodies under water, the same feature of automatic steering in the vertical plane is as of great, if not greater importance, as it enables such projectiles to strike the water and reach the vessel or object aimed at even if entering the water at a considerable distance from it, thereby increasing the size of its horizontal target manifold. Another object of the improvement is to obtain as great a subaquatic range as possible for such projectiles."