PRESERVERS, LIFE, is a name which has been given to various mechanical contrivances, for saving the lives of individuals, either in cases of shipwreck, drowning, or ex posure to fire.
Under the article BOAT, Life, we have already given a full account of the life boats of Lukin, Wilson, Greathead, and Bremner, and of other inventions for preserving lives in cases of shipwreck, &c.
Different contrivances have, since that time, been pro posed for giving assistance in case of shipwreck ; but the most important of them is that of Captain Manby, which he has explained at length in his Essay on the Preserva tion of Shipwrecked Persons, Lond. 1812. This plan con sists in affixing a rope to a shot, and firing it from a light piece of ordnance over a vessel in distress, and near enough the shore. A communication with the .shore being thus established, a boat can be hauled to the relief of the crew.
This ingenious contrivance was in many cases eminently successful in saving the crew of different ships; and Captain Manby was honoured with a parliamentary reward for his apparatus, having previously received the gold medal of the Society of Arts in 1808. The following results of some of Captain Manby's experiments, will show the effects which are produced by the apparatus.
and a musket-bullet might be substituted is place of the mortar and hall of Captain Manhy's apparatus. Ile proposes to affix a line of whip-cord to arrows of ash, hickory, and sometimes iron, loosely filling the calibre of the musket, and to fire off these arrows with a charge of gunpowder, less than the usual quantity. The arrows are three or four inches longer than the barrel of the musket, and are shod with iron at the point, having an eye through which the line is thrown. The lower end enters a socket, which must be in complete contact with the wadding of the piece. The average distance to which an iron arrow and a log-line were projected, was about 230 feet, though, in one case, a rod was carried 233 feet; but in this case the line was favourably placed. Mr. Murray considered that whip-cord was strong enough to carry a log-line, and a log-line strong enough to carry a rope on board.
Mr. Murray has proposed the same method for project ing the arrow over lofty buildings on fire, and thus to car ry a line attached to a lengthened rope-ladder, which could be drawn over the roof to the other side, and thus instan taneously establish free egress for the unfortunate inmates.
The ends of the rope-ladder should be fastened into the pavement by means of iron staples.
An apparatus for saving lives, in cases of shipwreck, by Mr. H. Trengrouse, is described in the 38th volume of the Transactions of the Society of Arts, p. 161-165. The projecting force which he used in the apparatus is a rocket; and it was found that a rocket of 8 oz. with a mackerel line attached to its stick, ranged to the distance of 180 yards, and that a pound rocket, in similar circumstances, ranged 212 yards. The rocket is placed in a copper instru ment, at the end of a musket, charged with a small quan tity of powder, without wadding ; for the purpose merely of directing and igniting the rocket. The rocket, when lighted by the powder, burns a few seconds before it ac quires sufficient momentum to quit its situation; during which time the combustible would be ejected into the bar rel of the gun, if it were not prevented by a loosely sus pended valve, which opens to permit the passage of the charge, but immediately closes, and prevents the barrel from being choked by the retrograde discharge front the rocket.
In the year 1822, Captain Dansey, of the Royal Artil lery, communicated to the Society of Arts, the description of a kite and apparatus for obtaining a communication with vessels stranded on a lee-shore or otherwise, where bad ness of weather renders the application of the ordinary means impracticable. A sail of light canvass or Holland, being cut to the size, and adapted for the application of the principles of the flying kite, is launched over the vessel, or otner point to windward, of the space over which a communication is required, and as soon as it appears to be a sufficient distance, a simple mechanical apparatus is used to destroy its poise, and cause it to fall immediately, but remaining still attached by the line, and moored by a small anchor with which it is furnished. The result of the expe riments made by Captain Dansey, with a kite of sixty feet of surface, has been, in a strong breeze, the extension of a line of sixty pounds weight, 350 yards long, and 14 inch in circumference. In another experiment he extended a line of 37 pounds weight, 1100 yards long, and 4ths of an inch in circumference. In using this apparatus, little more at tention or skill is said to be necessary than in flying an or dinary kite.