The Congreve rockets are susceptible of application to military uses, in a variety of ways, as like the common rocket by flight with the staff or shaft, for the purposes of conflagration, like carcass bombs; to convey shells with fuses to burst at any required number of seconds or minutes; to convey canister or spheres of shot or bullets which may be made so as to explode like grape or canister shot, at any required instant.

The rocket carcass of 32 pounds, whose range is 3000 yards, with the same quantity of combustible matter as is contained in the 10 inch spherical carcass; and 2500 yards with the same quantity as the 13 inch spherical carcass.

The 12 pounder rocket case shot, which is so portable that it may be used with the same facility as musketry, has a range nearly double that of field artillery, earrying as many musket balls as the 6 pounder spherical case; and it besides proceeds with a velocity which, instead of being retarded, is accelerated in its progress by the charge; and it is said that the desired velocity may be

increased by an ascertained method of fixing the charge of bursting powder.

Of this description of rocket it is alleged, that 3000 infantry can carry into action, in any situation where musketry can act, 300 rounds, and ten frames, from each of which 4 rounds may be fired in a minute. They may be also adapted to use for cavalry; four horses will carry 96 rounds and four frames, from which 16 rounds may be fired in a minute-and no horse carrying more than the ordinary burden of a dragoon horse.

The velocity with which it moves through the air is also described to be such, that it is not sensibly affected by the wind, unless it is at right angles with the line of flight, and then so little as to be easily provided against.

Its peculiar applicability for naval uses and bombardment is found in this quality, that it has no recoil even with the largest rockets; so that by this means, mortars hitherto employed for throwing carcasses are now dispensed with, and the largest carcasses may be thrown with the same facility from the smallest boats; oeing in fact, ammunition without ordnance. A vessel of 300 tons will carry 5000 of them, or more.

A gentleman of Portsea, in England, it is said, has submitted to the British government a shell, that at the immense distance of three miles will explode 20 balls of combustible matter of three inches diameter, and upwards of 1000 musket and pistol ballsthese will be scattered on the horizon within a circle whose diame. ter is 1400 yards. The weight of the shell will be upwards of 2cwt.

The president of the United States having transmitted to me by letter, about two ounces of the composition of a CONGREVE ROCKET picked up at Havre de Grace, after the late attack of the English upon that place; I made some experiments on the subject, and found that the specimen sent me had the following properties:

It tasted strongly of saltpetre.

It smelt of sulphur and resin.

It was not reduced to powder by chewing, and was only moderately brittle.

It was of a dirty brownish yellow colour, but somewhat variegated. Charcoal manifestly formed but a very small part of the composition.

It had a groove up the middle, of an inch in diameter, blackened by the explosion of gunpowder, with which the groove had manifestly been filled.

It burned with deflagration, emitting smoke, and a sulphureous odour.

The residuum was partly black, partly white.

The black residuum, was manifestly liver of sulphur to the taste; (sulphuret of potash.)

The white fused residuum was alkaline.

Hence I concluded, that it consisted of sulphur, resin and (probably linseed) oil, with a small portion of mealed gunpowder, and highly charged with saltpetre.

I dissolved a given portion in hot water, filtered and extracted the saltpetre. So that I found a composition of similar qualities, might be made as follows:

rate.

Powdered gunpowder

Linseed oil about one gill to a Ib. of the composition.

The sulphur and rosin should be slowly melted together, over a charcoal fire or in a sand-bath; taking care that the heat do not set fire to the sulphur, and that the smoke or evaporation is modeMelt the rosin first, then add the sulphur. Have ready in a separate vessel, the nitre previously powdered and kept hot for an hour, but not melted. Let it be again very finely powdered while hot, and when the rosin and sulphur are perfectly melted and fluid, stir in, first the mealed gunpowder, then the powdered nitre while hot. When all is well and accurately mixed over the fire, it will be, not fluid, but yet soft enough to put on an uniform appearance when cold. This I say will make a composition hardly distinguishable from the Congreve rocket such as I received. But I think the following composition full as good.

Melt the sulphur and rosin as above directed, then add half a pint of oil of turpentine previouly warmed. Then stir in the hot and finely-powdered nitre. I think the gunpowder may be spared. The finer the nitre is, the more effectual the composition. Either of these, may be lighted by a common cigar, and will continue burning with a hot, deflagrating, and spreading flame.

Capt. Beath, I believe, has greatly improved the mode of discharging rockets.-T. C.

GREEK FIRE.

MR. EDITOR, .

Having seen in your very respectable paper, a statement of the wonderful effect of the Greek fire, discovered by captain Maguire, an Irish gentleman of great ingenuity, I beg leave to state to you the exact particulars.

About a fortnight since, this gentleman, at the solicitation of several respectable persons, made an experiment, in the river near Chelsea water works, by sinking a bottle that held three pints of a liquid, much resembling in appearance common blacking for boots. To the neck of this bottle was fastened a small fuse, which was lowered over the wall into the river seven feet deep. The explosion was dreadful, and the effect equally so, it having blown up 24 feet of the wall, with large stones at least two hundred weight, that were clamped together with iron. The officers and gentlemen that were present, amongst whom were colonels Wilson and Lowe, general Barker, captains Mullen and Nunn, were positive that a column of not less than seven tons of water was, with the stones, &c. thrown to the height of sixty feet above the level of the river. Another property it possesses still more dreadful, and which no human foresight can prevent, is, that it will float on the surface of the water, as a vast liquid mass of fire; consequently, sending it into harbour with the tide, it will burn all before it.

The master general of the ordnance, with a true wish to encourage genius, has afforded Mr. Maguire every assistance in his power, as it was by his immediate desire, it is said, he came to this country. Was real merit thus countenanced in our own nation, there would not be such emigration of men of abilities to other kingdoms.

London paper.]

M. O'R.

I think there would not be much difficulty in making this composition.-T. C.

TORPEDOES.

The "Newengland Weekly Journal," a newspaper published in this town, in the year 1741, contains in the paper of May 5th, something like Mr. Fulton's plan, for defending the harbour of Newyork, by torpedoes.-Boston Rep.

For the information of the public I now advertise, that I, the subscriber, have projected a method for blowing up of shipping with powder under water, and am fully of the mind that engines may be so contrived and managed, by placing them across the channel, that if our enemies should attempt to invade us, they should not be able to pass the channel, but they should come upon one or other of them, so that their shipping and themselves should be destroyed.

An experiment of this nature was tried the 2d day of this instant, April, in the method and manner above proposed with a few pounds of powder, and the experiment was made upon a raft, and as the raft passed over the engine, it set the same on fire and was torn into splinters, that scarce a piece four foot long was to be found, and some of it was cast into the air divers rods, and was seen by a person that was above a mile; and there were near two hundred persons that were eye witnesses, and were of the mind that if a sufficient quantity of powder was in that engine, and a ́ship had passed over it, it would have set the engine on fire, and been destroyed thereby.

Lexington, April 30, 1741.

ANDREW PARKER.