An ingenious invention having the above title has recently been patented by R. G.SIBBALD, Esq., a surgeon, residing at Liver- pool. Its object is to enable a ship to carry a line to the land on a lee-shore, or to another vessel or boat, or to persons in the water.

Every person is aware of the great im- portance, under many circumstances, of; effecting such a communication by a line.

Of the many hundred thousand persons who have perished by shipwreck on a lee-shore, how many might have been saved could means have been found to convey a line either from the shore to their ship, or from the latter to the shore! It will likewise be known to most of our readers how many human lives have been saved in this country by means of lines thrown from the land by the instrumentality of the well-known mortar apparatus of Capt. MANBY, and the rockets of DENNETT and CARTE.

It will probably, however, have appeared to many that a still more simple and effi- cacious mode of effecting the same end would be to convey a line to leeward from a ship to the shore, rather than to windward from the shore to a ship; and that there- fore every vessel should be provided with means for effecting such communication.

And without doubt every ship should be so supplied, since she might chance to strand on other shores than our own, where no friendly line would be at hand to be hurled, despite the fury of the elements, to their aid; or she might be cast ashore, as frequently occurs, on parts of our own coasts where no mortar or rocket apparatus is supplied. As, how- ever, but few lives, comparatively speaking, have been saved by lines conveyed from ships to the land, we propose to consider what have been the obstacles to the adop- tion of such a natural means for providing for the safety of those on board them, before describing the character of Dr. SIBBALD'S invention.

Two methods obviously present them- selves by which a line might be conveyed from a wrecked vessel to a lee-shore, viz., by propelling it through the air by a mortar or rocket, or by floating it on the surface of the water by a buoy. By the former of these methods a line could be quite as cer- tainly, nay, with more certainty, be con- veyed to a lee-shore from a ship than from the former to the latter, since it could be propelled to a greater distance to leeward than to windward; and, however unskil- fully handled, it could not but reach some part of the shore, although it might go wide j i of the spot to which it was intended to be j i directed; whereas but a slight deviation i from the true direction would carry a line either on one or the other side of so small ! an object as a ship.

The difficulties which have stood in the | way of the adoption of any such means have i i been twofold: 1st. The provision of either I ] the rocket or mortar apparatus, with a suf- i | Relent supply of lines, on board a ship, | would involve considerable expense, whilst ! the law does not require any such provision i being made. Now it unfortunately happens i that the spirit of trade and the spirit of phi-lanthropy are not of kindred natures, and I that the shipowner therefore, as a general i rule, does not ask himself the question in ' I considering such a matter, What does my !! duty to my neighbour in this case require | j me to do ? but rather, What does the law compel me to do ? and, How can I comply with this requirement of the law at the least possible expense to myself? The result of this reasoning is, that no sufficient means are provided on board the great majority of vessels for promoting the safety of those on board them; whilst we regret to be obliged to add, that even in ships carrying passen- gers, which are required by law to make some such provision, the humane intention of the Legislature is too often defeated, by evasion of its spirit, whilst its letter is acted up to.

2nd. As regards the use of the rocket and mortar apparatus on ship-board, there are difficulties arising from the nature of the means themselves. In the first place, mer- chant seamen are not accustomed to or trained in the use of fire-arms; secondly, from their carelessness of character, there would be a probability, at all events in coasting and other smaller class of vessels, of the apparatus not being properly taken care of—the powder or rockets being per- haps allowed to get injured by damp, or the lines being appropriated to other uses; thirdly, the accompanying circumstances of shipwreck would often render the use of either rocket or mortar impracticable—such as the • sea breaking violently over the ship, inundating the decks and compelling the crew to lash themselves to the bulwarks or the rigging; or the vessel's hull becoming ' quickly wholly immersed; or her being j thrown on her beam ends, or in a greatly- ' inclined position; or her being subjected to j violent motion by the action of the sea, so as to endanger the falling of the masts and to make it difficult or impossible to stand on her decks. Excepting therefore in steam passenger ships and other large vessels, which certainly might with advantage be supplied with them, it may be questionable whether the supply of an apparatus requir- ing so much care and skill in its use would be appropriate.

3rd. As regards the use of any floating apparatus to convey a line to a lee-shore, the principal obstacle has, perhaps, been the knowledge that such attempts are too often i unavailing. The force of the waves or of the wind on any of the ordinary casks or buoys in use on shipboard, might be insuf- ficient to carry it to the strand, or, after drifting close to it, the counteraction of the retreating waves rebounding from the shore, together with the weight of the line itself, would prevent its reaching within a certain distance of it. It would also larely happen that, unless expressly supplied for the pur- pose, any such cask or buoy, with a suffi- cient length of suitable line, would be avail- able in the midst of the alarm and confusion occasioned by a vessel's driving on shore.

We believe that, to a great extent, these difficulties are got over by Dr. SIBBALD'S in- vention ; and that a line might often, by its means, be floated to the shore, or sufficiently near, to be grappled by persons on the look- out for it, when the same could not be effected in any other manner. The nature, advantages, and peculiarities of Dr. SIB- BALD'S Communicator are as follows :— It consists of two flat-headed drums or cylinders, made of water-proof and air-tight, cloth, stretched on light wooden hoops, and so united at one end of each as to form, when inflated, somewhat the shape of a dumb- bell or a double-headed shot. (Fig. 1.) It is then about 3 feet in height, the diameter of the cylinders being about 30 inches : when collapsed it is in the form of a cheese, 6 inches in thickness, and, therefore, stowing- in a small compass. (Fig. 2.) A light manilla or other floating line, of 400 or 500 yards in length, is coiled round it between the two Fi». 1.

cylinders. When required for use, the two cylinders are inflated by simply pulling them asunder. The end of the line being then made fast on board the vessel, and the ma- chine launched, it will float on the head of one of the cylinders, which is ballasted with some lead to keep it in an upright position, and being very light, the wind and sea quickly take effect on it, and drive it fast to leeward, whilst the line unwinds itself as the machine advances, giving to the latter a rotatory motion. Provided the line be of sufficient length, it will then be speedily carried to the shore, or to whatever other object to leeward of the ship it may be desired to communicate with..

The peculiar advantages of this instru- ment are— 1st. Its extreme lightness, and its expo- sure of a large surface to the action of the wind.

2nd. Its carrying its own line, and veer- ing it as it progresses at the same rate as its own motion, instead of having to drag the weight of the whole line after it, which is the case when a line is merely made fast to a buoy or boat, and veered from the ship.

3rd. Its own line being always wound about it, and put to no other use, so that its readiness for service is thereby insured.

We have above alluded to the circum- stance of the reaction of the waves from a beach, beating back floating bodies, if veered by a line in the ordinary manner from a vessel. There is, however, in such cases, the drawback of the line itself, the whole weight of which has to be dragged after it by the floating body, and which, beyond a certain length, would of itself prevent its further progression, irrespective of the draw- back of the waves from the beach. Whether the greater power of the wind on Dr. SIB- BALD'S Communicator, and the fact of its being relieved of all drawback from the line itself, would in all cases suffice to insure its drifting quite to the beach through a heavy sea, remains yet to be proved. We are in- clined to think they would not. But at all events the probability of its doing so would be greatly increased, and, as before stated, it'would, perhaps, generally be carried near enough to the shore to be grappled by per- sons on the look-out for it.

Some trials which have been made of the Communicator in the river Mersey have been very satisfactory. We, therefore, think it well entitled to the notice and adoption of shipowners, as the most efficient and available means existing for. transmitting a line, whether from a vessel to the shore, or from one vessel to another. It might also be of service as a life-buoy, or to veer astern of a ship to a boat unable to fetch her in a strong tideway, or against a head-wind. Its cost, with 240 fathoms of manilla line attached, is 5?. Its price, therefore, can hardly be a bar to the adoption of so useful an article.