Part 7

8. Twelve to fourteen ounce Rockets:--

Gunpowder two pounds four ounces, salt-petre nine ounces, sulphur three ounces, charcoal five ounces, iron-filings three ounces.

9. One pound Rockets:--

Gunpowder one pound, charcoal three ounces, sulphur one ounce.

10. Two pound Rockets:--

Gunpowder one pound four ounces, salt-petre two ounces, charcoal three ounces, sulphur one ounce, iron-filings two ounces.

11. Three pound Rockets:--

Gunpowder four ounces, salt-petre one pound, sulphur eight and a-half ounces, charcoal two ounces.

12. Four pound Rockets:--

Gunpowder half-a-pound, salt-petre fifteen pounds, sulphur two pounds, charcoal six pounds.

For Rockets of the largest size:--

To eight pounds of salt-petre, add twenty ounces of sulphur, and forty-four ounces of charcoal.

The several ingredients should be each ground separately, and sifted, and afterwards weighed and mixed together, in readiness for loading the cartridges

We now proceed to describe some of the various modifications which Rockets are susceptible of in their exhibitions; in which we shall endeavour to blend the most prominent features: were we to attempt to give the whole, it would annihilate the purpose of our work; indeed it is impossible to set limits to the field of variety which here opens itself; we shall therefore describe a few of the most particular, and leave the rest to the Tyro, assuring him it will afford a pleasing source of amusement, and furnish excellent matter for the exercise of his ingenuity.

1. TO CAUSE A ROCKET TO ASCEND IN A SPIRAL FORM.

The rod of a Rocket has been compared to the rudder of a ship, or tail of a bird; the purpose of which is to make the ship or bird turn towards that side to which it is inclined; a straight rod, as experience proves, causes a Rocket to ascend in a straight line, because the centre of gravity lays in, or is parallel to the centre line of the rod; but if we apply a crooked rod, or one that forms part of a circle, this will not be the case, for the first effect will be to make the Rocket incline towards that side to which it is bent; but the centre of gravity bringing it afterwards into a vertical position the result will be, that the Rocket will ascend in a spiral form.

Rockets exhibited in this way, evidently displace a greater volume of air, therefore as a consequence they cannot ascend so high as those that are impelled in a straight direction; but, nevertheless, their peculiar flight will produce a very pleasing effect.

2. TOWERING ROCKETS.

So called from their ascending to a greater height than any others; it is effected by fixing one Rocket on the top of another of superior dimensions:--thus, suppose the lower one to be a twelve-ounce, then the upper one should be a three-ounce Rocket; the larger one must have a small head formed round its own diameter, then place the mouth of the smaller one in it; the mouth should be rubbed with mealed powder wetted with spirits of wine; the bore in the charge should not be filled, but have inserted in it a bit of quick-match, the other end of which should enter the perforations at the top of the greater Rocket, which will form a communication between them. The large Rocket must be filled only half a diameter above the piercer; if filled higher, it will begin to descend before the upper has taken fire, and produce no additional effect.

The force by which the small Rocket goes off, will be sufficient to disengage it from the other, without the use of powder to effect it; one round of paper pasted round the juncture of the two Rockets will be sufficient to connect them together.

In regard to the rods for Towering Rockets, the same principles are to be applied as for the others.

3. HONORARY ROCKETS.

Take about a pound Rocket of our first description, such as is represented in fig. 23; then on the case, close to the top of the rod, tie on, in a transverse direction, a two-ounce case, which should be filled with a strong charge, and choaked quite close at both ends; then towards each end, and in the reverse sides, bore a hole of moderate size, and from each carry a leader into the top of the large Rocket. When the Rocket attains its greatest height, it communicates fire to the cross one at top; from the holes being made in a transverse direction, will turn round very fast, and represent in its return to the ground, a spiral of descending fire. There are several other methods of adjusting the small case; one consists in letting the rod rise about an inch or somewhat more above the top of the Rocket, and tying the case to it, so as to rest on the Rocket; when adjusted after this manner, the Rockets should be without their conical cap.

4. CADUCEUS[13] ROCKETS.

If two Rockets be fixed obliquely on the opposite sides of a rod, they will form in their flight two spiral lines; they must exactly balance each other on the opposite side of the rod, or they will not rise in a vertical direction. Both ends of the Rockets must be choaked close, without either head or bounce, for a weight attached to them would obstruct their ascent. The rod proper for these Rockets should be square, and at top equal to the breadth of a rod for a common single Rocket, of the same weight as those you intend to use, and long enough to be in equilibrium, when suspended one length of the Rocket from the cross piece A, fig. 24, whose length should be equal to about seven diameters of the Rocket, and placed about six diameters from the top of the large rod; so that when fixed, they will form with the perpendiculars an angle of about 55 or 60 degrees.

The heads of the Rockets should be placed on the opposite sides of the cross piece, and their ends on the same of the large rod; then their mouths must be connected by a leader, which, when they are fired, must be burned through the middle, and then they will exert their ascending forces at the same time.

5. SIGNAL ROCKETS.

These are of two kinds, namely, those which have reports and those which have not. The first kind may be made somewhat longer in proportion than ordinary, by about one or two diameters, and on their charge must be driven a greater quantity of clay than usual; afterwards their bounce, choak, and cap, may be effected after the manner before described.

When of the second kind their cases and rods must be made very light; in other respects they are similar to the common sky-Rocket when without any appendages.

Both the first and latter kind are frequently fired in groups of six, eight, ten, &c; and considered as signals for the exhibition of pieces of greater magnitude.

When several of these are properly fixed to one rod, and fired together, they form in their flight a most beautiful appearance, for being so connected, their emissions will unite, and form a tail of stupendous magnitude, and the bursting of so many heads at once, will produce a grand explosion, not unlike (though less productive of injury) the bursting of a balloon in the atmosphere. When Rockets are arranged in this manner, particular care must be observed, in their filling and ramming, as well as in their exact uniformity of weight, else success is precarious. The rod also must be of proper dimensions, the length of the rods (according to the table) for eight-ounce Rockets, which is the best size for this purpose, is six feet six inches; then if four or six of these be fixed on one rod, the length of it must be about ten feet; in its circumference at top must be made as many grooves as there are to be Rockets, and of length to correspond. The rod must be sufficiently large at top, to admit the Rockets lying close in the grooves without pressing each other too tight.

The Rockets must be firmly attached to the rod, or they will be liable by their ascending force to disengage themselves from it; but to prevent which, the best method of fixing them is to let the rod run about two inches above the Rockets, which will be sufficient to form a shoulder or stop to each Rocket, the groove being discontinued such a distance from the end; when this is done, a little binding round the whole will make it all quite fast. The upper part of the rod may be rounded off in the form of a cone, or which will be much better, a cap may be pasted over the whole, which (from their meeting with less resistance) will cause them to ascend to a greater height. The Rocket being properly fixed, a quick-match is to be carried from one mouth to the other, which being burnt in the middle, will communicate immediately to the whole.

When fired they must be suspended through the rings, as taught in the early part of this article.

6. TABLE ROCKETS.

This is a simple application of Rockets to the spokes of a wheel; to which when fixed they form the felloe. Their effect (when fired) in the ordinary manner is merely that of revolving round on a fixed centre, till their composition is consumed; and by their revolutions representing a vertical or an horizontal circle of fire.

The spokes must be firmly fixed into a block of wood, of lengths and at a distance from each other suitable to the lengths of the cases employed. The cases should be those of twelve or sixteen ounces; and filled with the composition given at No. 8 or 9: they must be carefully rammed.

When the ends of the Rockets are fixed to the spokes, which should be notched out proper to receive them and for the purpose of making them more secure, then in the side of each case, (outward from the wheel) bore a hole of common dimensions near the clay; these holes should be made in an oblique direction towards the charge, and in and from each must be carried a piece of quick-match to the centre of the wheel, where they must be tied together and lighted. At the centre of the wheel may be fixed a similar or larger case; which, being lighted at the same time, will add much to the exhibition.

The centre of the wheel is frequently fitted to a block of wood, and fired upon a table, when it forms an horizontal wheel; otherwise it revolves on an axis fixed to a post, and in this case a vertical wheel is represented; the centre case may be applied to either.

7. SCROLLS FOR ROCKETS.

These form a pleasing appendage to the heads of Rockets, that are of considerable magnitude.

They are made in cases, about four inches in length, and their interior diameter about three-eighths of an inch; both ends must be pinched quite close, one before, and the other after they are filled; then in the reverse sides make a small vent-hole to the composition, and prime them with meal powder, wetted with spirits of wine.

The heads of Rockets may be partly or wholly filled with these cases; when fired they burst quick from their confinement and form a beautiful spiral descent.

The composition may be that of Serpents, or the brilliant fire; when either are used it should be prepared strong.

8. COURANTINS,[14] OR LINE ROCKETS.

Among the various modes of exhibiting Rockets, none are more pleasing than the present.

Rockets proper for this purpose are those of about half, and three-quarter pounds; they are made after the manner of sky-rockets of the common kind. Any number, from one to eight or ten, may be used; but five or six will be found to answer the best. According to the number of cases used, the Courantins are said to be of so many changes. When one, two, or three are only used, they may conveniently be fixed to a small empty cartridge, (of the same length as the cases,) made on a wire former, a little larger than the line on which it is to run, and of considerable substance; but when more than this number are to be used, or a greater change is to be produced, a small perforated cylinder must be procured, of dimensions suitable to the purpose; this cylinder should be of some light wood, such as fine deal, or willow; the perforations must be made exactly through the centre lengthways. In the same direction, on its circumference, are to be made as many grooves as there are Rockets to be employed; in which they must be well secured by tying the whole with string.

The diameter of this cylinder should be such, that when laid into the groove, the cases may nearly touch each other.

The Rockets being all prepared, (and their apertures, or mouths, besprinkled a little with meal powder and spirits of wine,) they are to be laid into the groove, and in such a manner, that the head or mouth of the second lays at the same end of the cylinder as the tail of the first; the head of the third the same as the tail of the second; and so on with all the others; they must all be bound tight round with string.

Being thus fixed to the cylinder, you must from the tail of the first Rocket carry a leader to the mouth of the second; from the tail of the second, to the mouth of the third; and so with the whole number, taking care to fix every leader quite secure; and at the same time, that the quick-match does not enter but a very little way into the bore of the Rockets, or it will be liable to fire the charge or composition of the Rockets, and thereby destroy all your arrangements.

Your runner being now ready for action, a line is to be fixed in an horizontal direction between two posts, or other convenient objects, whose distance from each other (for half-pound Rockets) should be about 100 yards long; this line should be of some strong twine, or (which will answer much better) small brass or iron wire, stretched quite tight between its supports; remembering to put on the runner before you fasten both ends. Then (the mouth being next the end of the line) fire the first Rocket, which by its force will carry the whole to the end of the line, or nearly, for it will be best to have the line too long rather than too short, for if the latter is the case, it will of course make a stand at its extremity, till the remainder of the charge is consumed, which does not look well. But if on the contrary the line is a little too long there will be no such stoppage, not even during the communication of the fire to the next Rocket, for the force acquired in its first flight will be sufficient to continue it till such communication is effected; after which it will return in the same manner to the other extremity, and back again in the same order, and so on to the end of the charges arranged on the cylinder.

It is a pleasing exhibition of this kind of fire-works, to arrange them in such manner that when arrived at the extremity of the line, they may communicate fire to some other piece, properly arranged at the end of the line, which in this case should not be so long as before, that the runner may rest a moment before it returns, the better to ensure the communication.

To render the runners more agreeable, they are made (of light wood or tin) in the form of different animals, such as _Serpents_, _Dragons_, _Mercuries_, _Ships_, &c. When thus arranged they are very entertaining, especially when filled with various compositions, such as golden rain, fires of different colours, serpents, port-fires, &c.

The dragons may be made to discharge serpents from their mouths, and two of them arranged on one line, so as to meet each other in the middle, and there appear to contend, till the second case takes fire, when they will run back to the extremity of the line, and then return again with great violence, and produce much amusement both to the operator and spectator.

In the same manner two ships may be represented to contend, and (by filling them well with serpents) be made to pour their broad-sides at each other: or, if they are placed on two separate lines, at a small distance from each other, they may be caused to pass each other in opposite directions; in both cases they will produce a very pleasing appearance.

When the represented animals are made to meet in the middle, the line should be of much greater length, or they will rush together with too great a force.

9. REVOLVING COURANTINES.

These, while they fly along the line in a straight direction, are, by a simple application of another Rocket, caused to revolve, or turn round at the same time. This rotatory motion is easily effected, by fixing to the cases another Rocket, which must be placed in a transversal direction; the aperture of which, instead of being at the bottom, like those on the cylinder, must be made in the side, near one of the ends. This transversal Rocket must be filled with a very slow charge, or it will be consumed long before those are upon the cylinder; when several changes in the runners are intended, two should be fixed in the transversal direction; their diameters should be small, in proportion to their lengths.

The Courantines may be made to revolve by other means equally simple and effective. Prepare and fill a case the same as those for Catherine Wheels, and wind and tie it nicely round the Courantine; this, when lighted with the first case, will cause it to revolve in a very pleasing manner.

When the Courantines do not revolve, they may be made to carry on the upper side a Jet of Fire, or any other ornament which the operator may devize; taking care to suspend, by means of wire, a small weight to the under side, which will keep it always in an erect position.

10. TO REPRESENT BY ROCKETS VARIOUS FORMS IN THE AIR.

To the large cartridge, or head, of about a two pound Rocket, place round several small ones of about two or three ounces, the rods of which must be made quite fast to the head, and parallel to the rod of the larger; then, if these be set on fire while the large one is ascending, they will represent in a very pleasing manner, _a tree_, the trunk of which will be the large Rocket, and the smaller ones the branches.

If, by means of leaders, the small Rockets are caused to take fire when the large one is about half burned in the air, they will represent the form of a comet; and when the large one begins to descend in an inverted position, the small ones will represent a kind of fiery fountains.

If the barrels of some small tubes, or quills, filled with the composition of Flying Rockets, be placed on a large one, they will, when fire is communicated to them, represent a beautiful shower of fire.

If a number of small serpents be attached to the Rocket with a piece of pack-thread, by the ends that do not catch fire; and if the pack-thread be suffered to hang down two or three inches between every two, this arrangement, when properly managed, will produce a variety of agreeable and amusing figures.

11. TO CAUSE A ROCKET TO FORM AN ARC IN RISING.

Cut some circles, about three or four inches diameter, out of some tin, or other thin plate; then to the rod of each Rocket, and about twice the length of the case from its mouth, fix one of these pieces of tin, nearly at right angles from the rod, and make it quite fast by a bracket underneath. The fire acting upon this, as it proceeds from the mouth of the Rocket, will divide the tail in such a manner, that it will cause it to proceed in a circular course, and form a very pleasing appearance.

12. TO FIRE ROCKETS WITHOUT RODS.

Rockets may be made to rise in the air without rods, but in the place of which, they must have attached to them four triangular pasteboard wings, fixed lengthwise on the external of the cartridge, similar to those attached to arrows or darts. The length of these wings should be about three-fourths the length of the Rocket; their breadth at bottom should be half their length, and diminished off to nothing at top. The Rocket may be set over a hole in a board, and fired from the under side; or the four wings may rest on four iron pins, six or eight inches in length, drove into a board at suitable distances from each other, and the Rocket fired from between them.

Though the greatest care be employed in the exhibition of Rockets after this manner, still their ascent is by far less certain than when a rod is used; therefore the Tyro must not be disappointed if he chance to fail of success.

THEORY OF THE FLIGHT OF ROCKETS.

A Rocket, being properly constructed, with its rod and other appendages attached, fixed in a vertical position, and fire being applied to its mouth, it will (as experience proves) ascend in the air with a prodigious velocity: but upon inquiry into the cause of this ascent, we meet with difficulties little contemplated when we were viewing the beautiful path it described in the medium of its flight.

That this ascent is dependent on the medium (or air) in which it is generated, admits not of a doubt; but to describe how, or in what manner it is effected, has engaged the attention of some of the most eminent philosophers. In consequence several theories have been advanced for the explication of the phenomena, and among them those of Mariotte and Desaguliers have claimed the most particular attention.

Mariotte attributes the rise of Rockets to the resistance, or reaction of the air against the gas, which is generated by the combustion of the composition.

This hypothesis seems to explain the phenomena; but great objections have been brought against it, on account of the difficulty which attends the reduction of it to mathematical investigations:--this difficulty arises from the law which the propelling force must necessarily observe; that is, it will decrease as the velocity increases, in consequence of the partial vacuum left behind the Rocket in its flight; so that the velocity becomes as it were both a _datum_ and _quæsitum_; and the correct solution of the problem necessarily involves the integration of partial differences of the highest order.

The hypothesis of Desaguliers is somewhat different to the foregoing; it is much more familiar with mathematical investigations; as it reduces the whole theory to the most simple form; and we think it is not far from being consonant with the known principles of the phenomena; notwithstanding the argument brought against it by Dr. Rees, and his Editors; and which we shall endeavour to prove by citing higher authority than our own.

Dr. Desaguliers illustrates his hypothesis in the following manner:--Conceive the Rocket to have no vent at the choak, and to be set on fire in the conical bore; the consequence would be, either that the Rocket would burst in the weakest place, or that, if all parts were equally strong, and able to sustain the impulse of the flame, the Rocket would burn out immoveable. Now, as the force of the flame is equable, suppose its action downwards, or that upwards, sufficient to lift forty pounds; as these forces are equal, but their directions contrary, they will destroy each other’s action.

Imagine then the Rocket opened at the choak; by this mean the action of the flame downwards is taken away, and there remains a force equal to forty pounds acting upwards, to carry up the Rocket, and the stick or rod it is tied to.

Accordingly we find that if the composition of the Rocket be very weak, so as not to give an impulse greater than the weight of the Rocket and stick, it does not rise at all; or if the composition be slow, so that a small part of it only kindles at first, the Rocket will not rise.

To this we shall add the late Doctor Hutton’s philosophy, on the ascent of Rockets; who says, that at the moment when the powder begins to inflame, its expansion produces a torrent of elastic fluid, which acts in every direction; that is, against the air which escapes from the cartridge, and against the upper part of the Rocket; but the resistance of the air is more considerable than the weight of the Rocket, on account of the extreme rapidity with which the elastic fluid issues through the neck of the Rocket to throw itself downwards, and therefore the Rocket ascends by the excess of one of these forces over the other.