Rocket. (1) The name (Fr. roquette, Lat. eruca, a kind of cabbage) of two species of plants. The one, Eruca saliva, is a cruciferous annual with white flowers veined with purple; the leaves have a sharp flavour and are used in southern Europe for salads. The other is a hardy perennial herbaceous plant, of the genus Hesperis, of which Hesperis matronalis is the most familiar species (see Horticulture).
(2) A cylinder of paper, pasteboard or metal, filled with an explosive mixture. This word, which appears in mary forms in various languages, is from the It. rocchetta, diminutive of rocca, a distaff, the obsolete English "rock"; the application Rockingham, Marquess Of is due to a resemblance in shape. Rockets are used in pyrotechny for purpose of display, scattering showers of stars, coloured balls, &c., on bursting (see Fireworks). They are also used in signalling, and especially as a part of lifesaving apparatus for wrecks (see Lifeboat and Life-Saving Service).
Large and heavy rockets, of which the head formed a projectile, had too a considerable vogue in the early part of the 19th century for war purposes. They were invented by Sir William Congreve and employed by him both afloat in coast operations and in field operations. Brought to the notice of all armies by the fact that a rocket battery of the Royal Artillery served in the allied army in the Leipzig campaign, war rockets were introduced in many armies, being sometimes issued as an additional portion of the equipment of ordinary field batteries, sometimes reserved for special rocket batteries. The Congreve rocket was in use in the British army as late as 1860. There were four natures3-pounder, 6-pounder, 12-pounder and 24-pounder. The case was of sheet-iron, on to which was screwed a cylindro-conoidal head forming the projectile. The head was made hollow and could be filled with a bursting charge if a shell effect was desired, a base fuze being provided. The iron case contained the rocket composition, and was closed at the rear end by a metal. plate with five holes or vents, and on the centre a bush into which the stick was screwed. These rockets were fired from rocket tubes on tripods, the tubes being provided with a tangent sight. Against masses of troops within easy range, the war rocket was considered an efficient engine; it was used also to set fire to buildings, but was always deficient in accuracy. Eventually the Congreve rocket was superseded by the Hale, of which two patterns were in use, the 9-pounder and the 24-pounder, for field and fortress warfare respectively. These had no sticks, and were centred by the arrangement of the vent, the gases, as they emerged from the vent, impinging upon a screw-formed tail, to which they imparted the necessary rotation. These rockets were fired from a trough. The maximum effective range of the 9-pounder Hale rocket was about 1200 yards. The use of these engines was discontinued in the British service about 1885. On the continent of Europe they had disappeared more than twenty years before. Austria, the last power to use them, broke up her rocket batteries in 1867.
