IN the last number of this Journal we described an ingenious American invention for night-signalling, which we conceive would be especially valuable in cases of stranding, or other disaster to trading vessels. "We have now to notice another, also from that land which has been so fertile in the production of new inven- tions, viz., a new description of pro- jectile for conveying a line to a stranded ship.

As many of our readers will be aware, the first invention of this kind -which, was brought practically into use, and which was the means of saving, in the aggregate, numberless lives, was designed by the late Captain MANBY, in the early part of the present century. It consisted of a small brass mortar, from which a twenty-four- pound iron shot was thrown, with a line attached, which line, carried over a stranded vessel by the shot, was secured by the crew, who by its means were then enabled to haul on board a block having a strong but light line rove through it, both ends of the lino being left in the hands of the helpers on the shore.

Those on board had then only to make the block fast to the rigging or one of the masts, for which purpose a stout rope, termed a tail, was spliced to it, and those on the land, having command of both ends of the line, were enabled to haul off a strong hawser, along which they hauled the crew one by one, or sometimes two together, to the shore in a canvas cot suspended to and traversing on the hawser. As we have in earlier Numbers of this Journal fully described the MANBY apparatus in every detail, we will not repeat the same, but merely observe that, although rockets were subsequently adopted in lieu of the shot to carry the first line over a vessel, on account of their greater portability and longer range, in other respects the apparatus is but slightly changed, and that Captain MANBY is entitled to the whole credit of the original idea and of its first practical application.

The use of the rocket as a propeller or projectile for carrying the line, was first proposed by the late Mr. DENNETT, of Carisbrooke, in the Isle of Wight, and his rockets were supplied for many years, jointly with the Manby apparatus, by the Board of Customs, which had then the control of the Coastguard service.

On the Coastguard, however, being transferred to the Admiralty, and the supply and management of the Life-saving apparatus to the Board of Trade, under the provision of the Merchant Shipping Act of 1854, the latter Board exclusively adopted the rocket, in which a further improvement had been made by Colonel BOXER, of the Royal Artillery, whereby a considerably longer flight was obtained.

That apparatus is now especially known as the English Life-saving Apparatus, it not having been adopted, we believe, by any foreign countries, chiefly on ac- count of the expensive character of the rockets.

Mr. EDMUND J. HUNT, of Weymouth, Massachusetts, now comes into the field, and claims for his plan certain advan- tages over the rocket, viz., a longer range, a truer aim, especially in a high wind; and comparative cheapness.

It is a return to Captain MANBY'S plan, in so far as that it is a shot discharged from a gun; but the shot, or projectile, is of very peculiar character, its chief cha- racteristic being that it contains within it a large portion of the line to effect communication with the stranded ship, the result being: 1st. That the line, not having to be dragged along its whole length from the shore, but withdrawn from the projectile during its flight, the latter is not impeded by it, and a longer range is thereby obtained. 2nd. That the projectile and line are not carried to leeward of the line of fire by the force of the wind when the latter is blowing athwart its course, a truer direction being thereby obtained.

The projectile is, in fact, a tin cylinder or tube, 20 inches long, by 3J inches in diameter, with a solid leaden shot of the same diameter at one end, the remainder of the tube having tightly coiled within it a small, but strong flax line, saturated with paraffin, and said to have a breaking strain of about three hundredweight. The projecting end of this line, when a shot is about to be fired, is knotted to another coil in a cylinder on the shore, being a supplementary line to the other, a portion of it being drawn on upon the first starting of the projectile, and any further amount required towards the close of its flight, when it has dis- charged all the line within it. After being discharged, the line cannot be again re-coiled within the cylinder by hand, as it has to be done by a machine constructed for the purpose; but a sufficient number of the projectiles would be supplied to each station, and they could, after use, be re-filled at leisure, the cost of each dis- charge being under seven shillings, which is, we believe, much less than half that of a Boxer's rocket.

The weight of a projectile, ready for use, is 12 lb., that of the gun averaging about 60 Ib.

On the 14th March last an experi- mental trial of Mr. HUNT'S apparatus was made at Shoeburyness by the Royal Artillery stationed there, for the informa- tion of the Board of Trade, Commander PROWSE, K.N., the Superintendent under that Board of the Life-saving apparatus on the Coasts of the United Kingdom, being present, also the Colonel in com- mand at Shoeburyness, officers of the Royal Artillery, Mr. HUNT, the inventor, and others.

The results of the trial, as regards range, certainty, and accuracy of direction, were very favourable, the range varying from 300 to more than 500 yards, accord- ing to the amount of powder-charge; whilst the direction was so good that not a single shot would have failed to throw the line over an ordinary boat, and not a single line was broken. There was but little wind at the time, much to the regret of the inventor, who stated that in a high wind, either adverse or athwart, the merits of his invention would have been still more apparent.

There remain, however, two points which require to be tested by actual expe- rience before the relative advantages of the Government rocket apparatus and that of Mr. HUNT can be confidently stated, viz.: 1st. The greater weight of the gun and its bed as compared with the rocket-tube and stand.

2nd. The comparative smallness of Mr. HUNT'S lines.

At some stations portability is un- doubtedly of much importance, but there are many others where it is of compara- tively little, and the weight of this gun and bed, between 80 Ib. and 90 Ib., slung to a pole, could be carried readily by two men.

The smallness of the line is certainly a disadvantage, as, although it is said to bear a strain of 3 cwt., being only of the thickness of an ordinary goose-quill it would not be grasped so well by men hauling on it as would a stouter line, and would be liable to out their hands or slip through them should a severe strain be put on it. As it is, however, in actual use by the Massachusetts Humane Society at their life-saving stations, and has been favourably reported on by it, that question.

will in a short time be solved, if it has not been so already. That Society has handsomely presented to the NATIONAL LIFE-BOAT INSTITUTION one of Mr. HUNT'S guns, with projectile and lines complete.

Since, however, the Institution does not undertake the provision or management of any other life-saving material than that of the Life-boats, it has no practical use for the gun, &o., which it has therefore deposited at the Museum of the Royal United Service Institution, Whitehall Yard, London, where it may be seen by any one taking an interest in the subject.