LIFE MORTARS AND ROCKETS. When a life-boat is not at hand, or a raging sea and . a shoal coast render its use impracticable, a distressed ship may often receive help from shore, provided the distance be not too great for the throwing of a rope. A small rope imay draw a thicker, and. that a hawser, and the hawser may sustain a slinging apparatus for bringing the crew on shore. For short distances, capt. Ward's hearing-stwk has been found useful: it is a piece of stout cane 2 ft. long, loaded at one end with 2 lbs. of lead, .and at the other attached to a thin line. It is whirled round vertically 2 or 3 times, and then let go; but it cannot be relied on for more than 50 yards. Kites of various kinds 'have been employed, but are not found to be certain enough in action. The firing by gunpowder of some kind of missile, with a line or rope attached to it, is the method which has been attended with most success. In 1791 sergt. Bell, of the royal artillery, devised a mode of firing a shot and line from a distressed ship to the shore. It was afterwards found to be more practically useful to fire from the shore to the ship. In 1807 capt. Manby invented his life-mortar (see MANny). His mortar was an ordinary 5i-in. 24-pounder cohorn, fixed at a certain angle in a thick block of wood. The missile discharged from it was a shot with curved barbs, something like the flukes of an anchor, to catch hold of the rigging or bulwarks of a ship. How to fasten the shot to the rope was at first a difficulty: chains were not found to answer; but at length strips of raw-hide were found suitable. To assist in descrying the exact position of a distressed ship on a dark night, in order to aim the mortar-rope correctly, :Hanby used a chemical composi tion as a firework, which would shine out in brilliant stars when it had risen to a certain height. A third contrivance of his for replacing the shot by a shell filled with combus tibles, in order to produce a light which would render the rope visible to the crew, was not so successful.
Many variations have been made in the line-throwing apparatus. Col. Boxer has recently substituted a bolt for the shot,with four holes at the end; fuses thrust into these holes shed a light which marks the passage of the bolt through the air. Trengrove's
rocket-apparatus, invented in 1821, consisted of an ordinary 8-oz. sky-rocket (see Rom(Er). Certain practical difficulties, however, affected it, and it did not come much into use. In 1832 Dennett's apparatus was invented. It nearly resembled the old sky rocket, but with an iron case instead of a paper one, and a pole 8 ft. long instead of a mere stick; it weighed 23 lbs., was propelled by 9 lbs. of composition, and had a range of 230 yards. A ship's crew having been saved by the aid of this rocket at Bembridge, in the isle of Wight, the board of customs caused many of the coastguard stations to be supplied with the apparatus in 1834. Carte's apparatus, brought forward in 1842, depended on the use of a Congreve rocket (see RocHET) instead of au ordinary sky rocket. It does not appear that this apparatus was ever adopted by the authorities. Mr. Dennett next sought to improve the power of his apparatus, by placing two rockets side by side, attached to the same stick; and it certainly did increase the range to 400 yards; but as thc siinultaneous and equal action of the rockets could not be always insured, the scheme was abandoned. Col. Delvigne, of the French army, invented a life-arrow, to be fired from an ordinary musket. It is a stick of mahoolany, shaped something like a bil liard-cue; the thicker end presses on the powder; wriile the thinner end, loaded with lead, is fitted with loops of string; a line or thin rope is attached to the loops, and the thin end of the stick projects beyond the barrel. The jerk, when the arrow or stick is fired, causes the loops to rim down the stick to the thick end; this action has an effect like that of a spring, preventing the stick from darting forward so suddenly as to snap the line. The apparatus will send an arrow of 18 oz. to a distance of 80 yards, with a mackerel line attached. Another French contrivance, Tremblay's rocket with a barbed heaa, was soon adopted for the emperor's yacht; but as it is to be fired from the ship to the shore, it partakes of the same defects as sergt. Bell's original invention.