Chapter X: Section VI: Rockets

We come now to that part of our work which treats on the most beautiful of all Pyrotechnic productions.

Rockets have ever held the first place among single fire-works since the invention of the art; and to which they are justly entitled, both for the pleasing appearance they produce when fired by themselves, and the extensive application of them to increase the beauty of the other exhibitions.

They are called by the Italians _Rochette_ and _Raggi_; by the Germans _Raketen_ and _Drachetten_; by the French _Fusées_; and by the Latins _Rochetæ_; from which appears to be derived the name given them by the English; so much for their names:--as to their invention it is most probable that it took place at a very early period, if not among the first productions of the art. By the ancient Pyrotechnicians, they were considered as the most difficult articles of manufacture, insomuch that it was the first task enjoined to the disciples of Prometheus,[8] or professors of the art; and the goodness of the article, furnished a criterion of their pretensions.

It is to be questioned whether the ancients had such a variety of these articles, as we now have; but it is pretty certain that they were well acquainted with the proper proportions of the moulds requisite for their manufacture, insomuch that in many of their treatises, we find them employing the most difficult mathematical calculations, and giving intricate algebraic formulæ, for the purpose of finding their true proportion; but many of such useless difficulties we shall endeavour to evade, and essay to render our explications familiar without wholly sacrificing scientific investigations.

Rockets consist of strong paper cylinders, which being filled with the proper composition rammed hard, and fire being applied to their apertures they are caused to ascend into the air, or in any required directions; they have generally a head fixed to them containing corn powder, sparks, and many other decorations, which, when the body of the Rocket is consumed, take fire, burst in the air, and produce a most beautiful appearance; these are called Sky-rockets. Others are made to run with great velocity along a line, and are therefore called Line-rockets, or Courantines. Some are fixed on the circumference, or on the axle of a wheel, and are denominated Wheel-rockets; while another kind have their cases made perfectly water-tight, and being filled with stronger composition, admit of being plunged in and under water without retarding their inflammation; these receive the significant appellation of Water-rockets.

1. _Sky-rockets._--Sky-rockets, in regard to size, are divided into three kinds, namely, those the calibre or internal diameter of which does not exceed that of a pound bullet; or having their orifice equal to a leaden bullet, which weighs exactly one pound; for the relative magnitude of Rockets is estimated by the diameter of lead balls or bullets, after the manner taught in the Article Gerbes. Those, therefore, the calibre of which does not exceed a pound bullet, are termed small-size Rockets; those whose calibre is from one to three pounds are of the middle size; and those whose calibres exceed the last dimensions, are termed Rockets of the largest size; or are named after their weight, estimated as above.

We now proceed to describe the moulds and apparatus requisite for making Rockets, for on the due proportion of which (as was before observed) depends much of the goodness of the article. These moulds are also requisite in order that any number of Rockets may be prepared of the same size and force. As Rockets are made of various sizes, it is evident that moulds of different diameters must be produced.

Fig. 1, plate 1, represents a mould made and proportioned by the diameter of its calibre, which is divided into equal parts and rendered into scale, by which the relative proportions may be understood, merely by a contemplation of the figure. Thus A B is the calibre, or diameter; C D its whole height, including the foot complete, and equal to eight diameters, as per scale: E is the thickness of the mould, and may be about half a diameter; it should be made of some hard wood, such as lignum vitæ, or box, and may be either ornamented or plain; F is an iron pin, which serves to fix the cylinder firm to its foot. Fig. 2, is the foot detached from the cylinder, and drawn in true proportion as per scale; G, H, I, J, is the base, and may be about one and half diameter high; K, the choak, which serves to connect the cylinder to the foot; L is the nipple, which is half a diameter high, and in thickness equal to the former, or five-eighths diameter; M is the piercer, whose height is three diameters and a-half from the nipple, and at the bottom one third or fourth diameter, from thence tapering to one-sixth diameter in thickness. This piercer should be of iron, and inserted firmly into the foot; its purpose is to preserve a vacuity in the centre of the charge, the nature of which we shall hereafter explain. Fig. 3, is a former in two pieces, connected by an iron pin, (in diameter equal to the bottom of the piercer,) to which both ends are rounded off, in order that the choak or contraction in the cartridge may be effected more easily; the diameter of this former must be the same as that of the nipple, or suppose the diameter of the mould be divided into eight equal parts, (which is done on one part of the scale,) then the diameter of the former must be equal to five of these parts.

The length of this former, or roller, is not particular, providing it be long enough to admit of good hand-hold in the rolling of the cases; the short part of the former A may be two diameters in length, and should have a line B marked round it in the middle, or one diameter from the end; the longer part may be seven or eight diameters, which will give good hand-hold in the rolling.

Fig. 4 and 5, are rammers, or drift pins, used in loading the cases, which must be pierced lengthwise to fit on to the piercer.

Fig. 4. The first rammer should be pierced the whole length of the piercer, the second rammer should be pierced one and a half diameter; when the case is loaded and rammed above the piercer, a short solid rammer must be used, and these rammers should be a little less than the former, to prevent injury to the inside of the cartridge, when driving in the charge. They should be made of some hard wood, and their extremities secured by ferrels of brass, or any other metal, which will keep them from splitting or extending: their lengths are of little consequence, providing they do not much exceed the relative depths of the cartridge; for, as the workmen say, the longer the rammer the less will be the pressure on the composition by the blow given by the mallet.

The proportion between the length of Rockets and their calibre, is not the same in Rockets of greater or less dimensions than those given above, but should vary nearly as their magnitude; that is to say, their length should be diminished as their calibre is increased. The length of the mould for small Rockets should be six times the calibre, but for Rockets of the mean and larger size, it will be sufficient if the length of the mould be five times, or even four times that of the calibre.

The following is a table computed to regulate the height and diameter of the mould according to the weight of the Rockets, when they are driven solid, or without the use of a piercer. It is extracted from an old treatise on fire-works by Lieutenant Robert Jones; and inserted for the assistance of those who may wish to construct Rockets without the piercer, a practice we would never recommend to those for whom our “Manual” is designed. To those who manufacture fire-works for sale it is certainly the most expeditious method to ram them solid, and with the machine to bore or pierce them afterwards; but to those who make Rockets for their own private recreation, it is by far the most eligible to load them over a piercer, for by the other method it will require a very expensive apparatus,[9] and at first more skill to use it than what the Tyro will possess, and at last he will never be certain that he has made a good article.

TABLE I.

DIMENSIONS OF ROCKETS.

Length of the
Weight of moulds without Interior diameter Heights of the
Rockets. their feet. of the moulds. nipples.
6 lbs. 34.7 inches. 3.5 inches. 1.5 inches.
4 do. 31.6 do. 2.9 do. 1.4 do.
2 do. 13.3 do. 2.1 do. 1.0 do.
1 do. 12.2 do. 1.7 do. 0.85 do.
8 ozs. 10.12 do. 1.3 do. 0.6 do.
4 do. 7.75 do. 1.12 do. 0.5 do.
2 do. 6.2 do. 0.9 do. 0.45 do.
1 do. 4.9 do. 0.7 do. 0.33 do.
½ do. 3.7 do. 0.55 do. 0.25 do.
6 drs. 3.5 do. 0.5 do. 0.22 do.
4 do. 2.2 do. 0.3 do. 0.2 do.

By this table we find that a six-pound Rocket rammed solid, must be thirty-four inches, seven-tenths in length; its external diameter three inches five-tenths or three and half inches, and the height of the nipple one inch and a-half. The diameter of the nipple in this and all other cases must be equal to that of the former, and in regard to its height I have never found it to answer better than when the cavity which it formed at the mouth of the Rocket was hemispherical, or equal in height to half its diameter.

We shall now, by the following table, shew the method of finding the calibre of Rockets according to their weight, which is computed by the principles already given; that is, a pound Rocket is such that its aperture will just admit a bullet of a pound weight, and so of the rest.

TABLE II.

OF THE CALIBRE OF ROCKETS OF A POUND WEIGHT AND BELOW.

16 ounces. 19½ lines.[10] 14 drams. 7¼ lines.
12 do. 17 do. 12 do. 7 do.
8 do. 15 do. 10 do. 6⅓ do.
7 do. 14¾ do. 8 do. 6¼ do.
6 do. 14¼ do. 6 do. 5⅔ do.
5 do. 13 do. 4 do. 4½ do.
4 do. 12⅓ do. 2 do. 3¾ do.
3 do. 11½ do.
2 do. 9⅙ do.
1 do. 6½ do.

The use of _this_ table will be easily understood, for, as in the first instance, if a Rocket of 16 ounces ought to be nineteen and a-half lines in diameter, one of 12 must be 17 lines, one of 8 ounces 15 lines, one of 8 drams six and a-quarter lines; and so of the others.

If the diameter of the Rocket be given, we can as easily, by the reverse method, find the weight of the ball corresponding to that calibre. For example, if the diameter be 15 lines, it will be immediately seen, by seeking for that number in the column of lines, that it answers to a ball of eight ounces.

As the foregoing table extends only to Rockets of 16 ounces, or one pound, and from that downwards, the following will be found equally useful for those of superior dimensions.

TABLE III.

OF THE CALIBRE OF MOULDS FROM 1 TO 57 POUNDS BALL.

Pounds. Calibre. Pounds. Calibre. Pounds. Calibre.
1 100 20 271 39 339
2 126 21 275 40 341
3 144 22 282 41 344
4 158 23 284 42 347
5 171 24 288 43 350
6 181 25 292 44 353
7 191 26 296 45 355
8 200 27 300 46 358
9 208 28 304 47 361
10 215 29 307 48 363
11 222 30 310 49 366
12 228 31 214 50 368
13 235 32 317 51 371
14 241 33 320 52 373
15 247 34 323 53 376
16 252 35 326 54 378
17 257 36 330 55 380
18 262 37 333 56 382
19 267 38 336 57 385

By this Table, the weight of the ball being given, the size of the mould may be found after the following manner: suppose it be 18 pounds; opposite to it, in the column of calibres, is 262; then say by the rule of proportion, as 100 is to 19 and a half, so is 262 to a fourth term, viz. 51.09 which is the number of lines of the calibre required; therefore, the Calibre of a Rocket of 18 pounds, will be 52 lines nearly, or 4 inches and 4 lines. The calibre may be also found by multiplying the number answering to the pounds by 19½, and cutting off from the product the two last figures; thus suppose the number be 252, which multiply by 19½, the product 4914 separated by the decimal point will give 49.14, or four inches a line and one-eighth.

Now suppose the calibre to be given in lines, the weight of the ball may be found with equal ease, e. g. if the calibre given be 36 lines, then as 19½ : 100 :: 36 : 184; the nearest number in the table to this is 181, which shews that the weight of the ball will be rather more than six pounds; therefore a Rocket, the calibre of which is 36 lines, is a Rocket of a six pound ball.

REMARKS ON THE FOREGOING TABLES.

TABLE I gives the dimensions of Rocket moulds when the Rockets are rammed solid; it was calculated, as its Author informs us, from repeated experiments; we insert it for the information of our readers, but we would advise none to practise the method of solid ramming.

TABLE II.--This table may be perfectly understood by the explanation given of its use, and from considering that a lead bullet of a pound weight, is just 19½ lines in diameter, as may be proved by experiment; the inferior numbers are likewise the diameters of the inferior weight.

TABLE III.--This table is only an extension of the latter, although its arrangement is somewhat different; for if 19½, the diameter of a ball weighing one pound, be assumed as unity with any number of cyphers, answering to the number of parts which the same diameter is divided into, (which may be done by means of the diagonal scale,) let this number be 100, which answers to one in the column of pounds:--that is to say, if you assume 100 for the first number, and it be rose to the third power,[11] your first cube will be 1,000,000, the cube root of which (being 100) must be placed in your table as the first root, and answering to unity in the column of pounds: then for the second number, which is two pounds, we must extract the cube root of double that number, viz. 2,000,000, which will be 126 nearly, (or continued to more places 1,259,921) and this will be the second number in your Table; and in the same manner will the third number be found, that is, by trebling the first cube and extracting the root as before, which will be 144, and so of the fifth, sixth, &c. to the end of the table. These tables are indispensable in the making of Rockets, in order to preserve an uniformity in Rockets of the same kind, and to render more certain their effects, as has been corroborated by repeated experiments.

_Preparing the Cartridges._--For this purpose large stiff paper of a particular kind is to be used; namely, that which from being principally used for this purpose, is known by the name of _Cartridge paper_. For cases from the smallest size, up to five or six pounds, this is the best material we can employ; it must be wrapped round the former, (whose proportion to the mould we have already given) till it fits tight into the cylinder, and the last fold secured by means of common paste. If some thin paste is used throughout the rolling, the cases will be much improved.

For Rockets of a larger size, the cases must be made of some stronger material, such as pasteboard, of the thin and inferior kind, the folds of which must be well secured with some strong paste or glue. In making the cases a pattern of the outer fold, with one end sloped off, should be preserved for each size, and on it marked the number of sheets or folds requisite to make that size cartridge. This method will help to ensure a regularity in the make and formation of the cases.

The paper being prepared of the proper size, one part of the first sheet must be folded down so far, that the double thickness will go two or three times round the _former_; the _former_ is then to be laid on this double edge, and the handle projecting over the table, the paper is to be wrapt round within two or three turns; when a second sheet is to be laid on the loose part of the first, and then roll the whole of it tight and evenly on the former; these two sheets should be of lengths sufficient for the size of the case, but if they are not, a third must be added in the same manner as the second.

For the purpose of rolling the cases tight and even, they are passed two or three times under the _rolling-board_, (which is a smooth piece of deal about eighteen inches long, and in breadth equal to the length of the Rocket, with a handle at the top, when complete something similar to a plaisterer’s float;) taking care to roll them the same way as in rolling them on the former.

The cartridge being formed to the proper size, and the last fold being secured by paste, &c. it is now to receive the contraction, or, as it is generally termed, the choak; which is effected by the simple apparatus represented by Fig. 7. Let the former and small end-piece be now joined by means of their connecting wire, and let the short piece be thrust into the case as far as the line B, marked round it for the purpose; then pass the cord once round the case, exactly over the juncture of the formers, and at first press gently with the foot on the treadle, and keep rolling the case on the line, which will cause the choak to be free from wrinkles and other inequalities.

Cases of small dimensions may be easily contracted after the above manner, but when of larger size, they will present more resistance to the choaking cord than it will be able to overcome; but this difficulty may be obviated, by moistening with water the end of the case, and choaking it previous to the envelope of the last sheet; which may then be put on, and again choaked, and the contraction well secured by twine, or strong waxed thread, which must be passed several times round the cartridge, and afterwards secured by two or three running knots made one above another.

The case (still remaining on the former,) is now to be inserted into the cylindrical mould without its foot, and set upon some solid block, and the former driven hard upon its end-piece, so as to make the contraction smooth and close; after which the case is to be cut to its proper length, so as to rise a little above the mould, and allowing half a diameter from the choak to the edge of the mouth: the cutting the case to its proper length will be best effected while on the former, which when done, the former is to be pulled out, and the case being put again into the mould, having the foot and piercer properly fixed to it, must be driven down upon the piercer with the long perforated rammer, so as to make the contraction of the proper size.

_Filling and ramming the cases._--In this part of the operation, we must be as careful as in any of the past; for if any inequality exist in the density of the composition, produced by inattention to the ramming, the Rockets will not rise with an uniform motion, nor ascend to their proper height; but on the contrary, will observe a very erratic motion, and be deflected by every renitent particle they may meet with in their course.

To avoid this disappointment, and to render more certain the ascent of the Rockets, the following directions must be attended to:--

1. Your composition must not be too dry, or it will be liable to disperse, and fly about in a kind of subtile meal or dust, while you are driving it; but if you moisten it a little just to destroy its dusty nature with some of the liquid mentioned in the early part of our MANUAL, it will cause it to collect, and be more solidly compressed in the case of the Rocket.

2. No more of the composition should be put into the case at each ramming, than will cause it to rise one half of its interior diameter; and the filling must be thus gradually continued, till the charge rises exactly one diameter above the piercer.

3. Much has been said by writers on Pyrotechny respecting the number of blows proper to be given to the rammer, to each ladle full of composition, (a piece of copper made into the form of a scoop, and holding the proper quantity answers best for a ladle;) some have assigned to Rockets of four ounces sixteen strokes with the mallet, to those of one pound twenty-eight strokes, and so increasing the number of strokes by six, to every pound; but in our opinion these rules are more ridiculous than useful; for the same mallet, by possessing a different momentum, might produce an effect, at one time _double_, _treble_, or perhaps _less_, than at another. It is therefore impossible to assign any determinate number of strokes, to be given at each ramming; the only certain rule is, that the composition ought to be driven till it becomes quite firm and compact, and that its density (as near as possible) be the same throughout the whole of the charge. If the rules for the number of strokes assist in any way to impart this property to the charge, we have not the least wish to depreciate them.

4. In ramming, it is best to keep the rammer constantly turning round in the case, and in using the perforated rammer, be sure to knock out the composition from the hollow every ramming, or it will be liable to be split by the piercer.

5. Invert the cartridge at the close of each ramming, in order that the loose particles of the composition which are not compressed may escape, for if suffered to remain in they would prove injurious to the article.

6. Rockets should always be rammed on a solid block, or on a post set fast into the earth; their ramming cannot be properly effected on any table whatever.

7. Rockets must be rammed with mallets somewhat proportionate to their magnitude; that is, if a Rocket of one pound can be properly rammed with a mallet weighing two pounds, a Rocket of two pounds should be rammed with a mallet of four pounds, or nearly in that proportion. Rockets above eight pounds cannot well be rammed by hand; but when wanted of such magnitude they must be rammed by means of a machine similar to that used for driving piles into the earth; Rockets of large dimensions, whose cases are made of a strong material, properly prepared, may be conveniently rammed without being placed in a cylinder, which will be an advantage, as so many moulds will not be required. But for this method of ramming we must be prepared with some _brass_ or _iron_ nipples, of the size proportionate to the Rocket, which should be made to screw into one part of the driving block; and for the purpose of making the case more firm upon it while ramming, a stake or upright piece must be made firm to the block, standing up the height of the case, and at a suitable distance from the nipple; the side of this stake next the case must be fluted out so that the case will fit closely into it; on the opposite side of the case must be applied a loose piece fluted in a similar manner; then with a cord tie the case and two half moulds (which these two pieces will nearly form) together, and the case will be ready for filling. The cartridges being filled to the proper height, i. e. one diameter above the piercer, if the Rocket is to be without furniture, separate with a wire of any kind, half the folds of the paper which remains above, and having turned them back on the composition, press them down with the rod and mallet in order to make them smooth and even. Then pierce three or four holes in the folded paper by means of a piercer, which must be made to penetrate to the composition of the Rocket. These holes are for the purpose of forming a communication between the body of the Rocket and the vacuity at the extremity of the carriage, as it is called, or that part which has been left empty. In small Rockets this vacuity is filled with granulated powder, (which serves to let them off when their charge is consumed;) they are then covered with paper, and either pinched quite close by means of the choaking apparatus, or crowned with a little conical cap, which will cause it to ascend to a greater height. If one hole only is made in the centre of the folded paper, it will answer the purpose of three or four, taking care that it be as straight as possible, and about one-fourth the diameter of the calibre of the case; in this hole a little of the composition of the rocket should be put that the fire may not fail to be communicated:--a Rocket finished after this manner is represented in fig. 23. In Rockets of larger dimensions, instead of granulated powder, the coffins, or pot containing the stars, serpents, petards, &c. are adapted to the top of the case: the petard is a small round box of tin-plate united to the diameter of the case, and filled with fine gunpowder; it is deposited on the composition after the ramming, and the remaining paper folded down over it to keep it secure; the petard produces its effect when the Rocket is in the air and the composition is consumed. The other furniture is attached to the Rocket by adjusting to its head an empty pot or cartridge of larger dimensions than itself, in order that it may contain the various appendages, which are to render it so superior to the others, in the beauty and splendour of its emication.

_Preparing and fixing the pots to the head of Rockets._--Rockets which have furniture attached to them, are rammed somewhat different to those which are without any appendages, but the difference is only in this particular; when rammed one diameter above the piercer, instead of turning down upon the composition the inner folds of the paper, ram on to the composition one-third diameter of pure dry clay, and through the centre of it bore a hole (about one fourth diameter) and put into it a little of the composition, in order that the charge may communicate with the powder, &c. in the head.

The head of a Rocket must be about two diameters high, and one diameter one-sixth wide. The case must be rolled upon a former, having at the end opposite the handle a square indent, corresponding to the thickness and width of the collar, as is represented in fig. 9. Fig. 10 is the collar, turned out of lime-tree, poplar, or any light wood; its exterior diameter must be equal to the interior diameter of the case, or the same as the former, and its interior diameter, not quite so wide as the interior diameter of the Rocket case; in thickness it should be equal to one-sixth diameter, and round its edge should be a groove, so that the case for the head may be firmly fixed to it. To form the case, three or four rounds of paper or pasteboard must be rolled round the former, with the collar on, and well secured by paste; the end over the collar is to be pinched by means of the cord and choaking apparatus into the groove in its edge, and afterwards secured by some twine tied closely round it. The purpose of the collar is to keep the head in a proper form, to make a bottom for the filling of it, and to make it more firm and better connected to the case. When the head is thus made, being properly fixed to its collar, it is to be made fast (by means of ordinary glue) to the top end of the Rocket, in which operation the reason and use of making the interior diameter of the collar less than the exterior of the cartridge will plainly appear; it will be evident that the cartridge of the Rocket will be too large for the former, without some alteration, which alteration must be made in the following manner:--mark round the diameter of the Rocket the proper distance from the top, or so that the collar is about its thickness above the ramming of the cartridge, and take off about three rounds of paper, which will leave a shoulder to the case, on which the collar may rest, and be made quite secure by pasting paper round their joinings beneath.

In the manner of charging the pot above described we must almost leave the Tyro to himself, it depending chiefly on his taste and wishes, as he may either fill it with Serpents, Crackers, Saucissons, Marroons, Stars, Sparks, Showers of Fire, or any thing to which its capacity is adapted; it will be best however to unite several of the different articles in one head that the beauty of the exhibition may be increased.

In the filling of the head, the following directions must be observed:--

The paper over the charge of the Rocket must be pierced, and a little of the same composition shook into the holes; then arrange in the head the different articles with which it is to be charged, but take particular care that the quantity introduced is not heavier than the body of the Rocket. When the head is loaded, a few balls of paper should be put round the different articles so as to keep them properly in their places. At the top part of each head put a ladle full of meal powder, (the ladle you use in filling the cases is meant,) which will be enough to burst the head and disperse the stars or whatever it contains.

In loading the head with cases of any kind be sure to place their mouths downward without any touch-paper; the head may be nearly filled, with the articles they are loaded with, after which paste on the top of them a piece of ordinary paper; and over this must be placed a cone of the same material, made upon the conical former, fig. 8. To make the caps, describe (with a pair of compasses opened to the length of the former) a circle, which being divided into two equal parts, will make two caps; over which must be pasted another similar cap, but of larger dimensions, so that it extend below the bottom of the inner one; so that being just clipped a little and applied to the head, it may be pasted to it, which will be a sufficient fastening.

The last business in the manufacturing of a Rocket is that of fixing it to its rod, which we shall now describe, as much nicety being required in it as in any of the past operations.

The rod should be made of a clean piece of fir, perfectly straight, and its dimensions regulated by the size of the Rocket, in such manner, that when suspended on the edge of a knife or wire, about an inch from the choak, the rod and Rocket shall be in equilibrium. The following Table has been computed for the lengths and proportions of the rod, and may be relied on:--

Weight |[12]Length of | Thickness and | Square
of the | the Rods. | Width at top. | at
Rockets. | | | Bottom.
---------+--------------+---------------+--------
lb. oz. | Feet. Inches.| Inches. | Inches.
---------+--------------+---------------+--------
6 0 | 14 2 | 1½ by 1⅞ | 0 ¾
5 0 | 13 8 | 1¼ -- 1¾ | 0 ⅜
4 0 | 12 9 | 1¼ -- 1½ | 0 ⅝
3 0 | 10 8 | 1-1/7 -- 1⅛ | 0 ½
2 0 | 9 3 | 1⅛ -- 1 | 0 ½
1 0 | 7 10 | ¾ -- ⅞ | 0 ⅜
0 8 | 6 6 | ½ -- ¾ | 0 ¼
0 4 | 5 2 | ⅜ -- ⅝ | 0 ¼
0 2 | 4 1 | 3/10 -- ½ | 0 3/16
0 1 | 3 5 | ¼ -- ⅜ | 0 3/16
0 ½ | 2 3 | 3/16 -- ¼ | 0 ⅛
0 ¼ | 1 10 | ⅛ -- 3/16 | 0 ⅛

By the above Table we find that a Rocket of six pounds will require a rod 14 feet 2 inches long, which being properly planed to the other dimensions, is to be hollowed out on the side next the Rocket; and on the side opposite, two notches must be made, one about an inch from the end, (the rod going up to the under side of the head,) and the other opposite the choak of the Rocket, in order to admit the string with which it is tied, and that it may be more firmly attached to the rod. Although the foregoing Table has been carefully computed, and that from experiment, yet it will not be well to depend entirely upon it, but rather to produce an equilibrium between the rod and Rocket, (by means of a lighter or heavier rod,) when suspended as before. It is of consequence that this is attended to; for without a proper equilibrium, the Rocket will ascend in an oblique direction, and fall to the ground long before its composition is consumed.

In firing these Rockets, two fixed rings must be screwed fast into an upright post, and exactly opposite to each other, the upper one near the top of the post, and the other about two-thirds the length of the rod downwards; the rod must be passed down them, and the mouth resting lightly on the upper one, the Rocket must be quite free from the post. When thus fixed and a lighted port-fire is applied to its mouth, it will (if properly made,) immediately ascend with a prodigious velocity, and having attained its greatest height will there burst and discharge its luminous beauties in the atmosphere. A Rocket with its head and rod complete is represented at fig. 22.

THE COMPOSITION FOR ROCKETS.

As we wish to complete the article Rockets in this section, we shall here give the composition proper for filling them, which must vary in the proportion of its ingredients according to the size of the Rocket; this variation in the strength of the composition, is positively necessary; for that which is proper for small Rockets, would be much too strong for large ones, therefore its strength should increase nearly as the dimensions of the Rockets decrease.

1. For one and two ounce Rockets, the ingredients for a proper composition should be--

One pound of gunpowder, two ounces of soft charcoal, and one ounce and a-half of salt-petre.

2. Two to three ounce Rockets:--

To four ounces of gunpowder, add one ounce of charcoal, or to nine ounces of powder, add two ounces of salt-petre.

3. Four ounce Rockets:--

To one pound of gunpowder, add four ounces of salt-petre, and one ounce of charcoal. The composition will be much stronger if in this proportion:--To ten ounces of powder, add three ounces and a-half of salt-petre, and three ounces of charcoal.

4. Five or six ounce Rockets:--

Gunpowder two pound five ounces, salt-petre half-a-pound, sulphur two ounces, charcoal six ounces, and iron-filings two ounces.

5. Seven or eight ounce Rockets:--

Gunpowder seventeen ounces, salt-petre four ounces, sulphur three ounces.

6. Eight to ten ounce Rockets:--

Gunpowder two pounds five ounces, salt-petre eight ounces, sulphur two ounces, charcoal seven ounces, iron-filings three ounces.

7. Ten or twelve ounce Rockets:--

Gunpowder one pound one ounce, salt-petre four ounces, sulphur three and a-half ounces, charcoal one ounce.

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.

This, however, would not be the case, unless the Rocket was pierced to a certain depth. A sufficient quantity of elastic fluid would not be produced; for the composition would inflame only in circular coats, of a diameter equal to that of the Rocket; and experience shows that this is not sufficient. Recourse then is had to the very ingenious idea of piercing the Rocket in a conical hole, which makes the composition burn in conical strata, which have much greater surface, and produce a much greater quantity of inflamed matter and fluid. This expedient was certainly not the work of a moment.

The stick serves to keep it perpendicular; for if the Rocket should begin to tumble, moving round a point in the choak, as being the common centre of gravity of Rocket and stick, there would be so much friction against the air by the stick, between the centre and the point, and the point would beat against the air with so much velocity, that the reaction of the medium would restore it to its perpendicularity. When the composition is burnt out, and the impulse upwards has ceased, the common centre of gravity is brought lower towards the middle of the stick, by which means the velocity of the point of the stick is decreased, and that at the point of the Rocket is increased; so that the whole will fall down, with the Rocket end foremost.

During the time the Rocket burns, the common centre of gravity is shifting and getting downwards, and still faster and lower as the stick is lighter; so that it sometimes begins to tumble before it is quite burnt out: but when the stick is too heavy, the common centre of gravity will not get so low, but that of the Rocket will rise straight, though not so fast.

From the experiments of Mr. Robins, and other Gentlemen, it was found that the Rockets of two, three, or four inches diameter, rise the highest; and they are found to rise to all heights in the air, from 400 to 1,254 yards, which is about three-quarters of a mile. For further particulars respecting the theory of the flight of Rockets our readers are referred to Robins’s Tracts, vol. 2.--Philosophical Transactions, vol. 46, page 578: and more particularly to Mr. W. Moor’s “Treatise on the motion of Rockets,” in which they will find the subject elegantly treated.