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.