Of Sky-rocket Moulds.
As the performance of rockets depends much on their moulds, it is
requisite to give a definition of them and their proportions, which
are as follows: They are made and proportioned by the diameter of
their orifice, which is divided into six equal parts: as for example,
Fig. 6. represents a mould made by its diameter A B, its height from C
to D is six diameters and two thirds; from D to E is the height of the
foot, which is one diameter and two thirds; F the choak, or cylinder,
whose height is one diameter and one third; it must be made out of the
same piece as the foot, and fit tight in the mould; G an iron pin that
goes through the mould and cylinder, to keep the foot fast; H the
nipple, which is half a diameter high, and two thirds thick, and of
the same piece of metal as the piercer I, whose height is three
diameters and a half, and at the bottom is one third of the diameter
thick, and from thence tapering to one sixth of the diameter: the best
way to fix the piercer in the cylinder, is to make that part below the
nipple long enough to go quite through the foot, and rivet it at the
bottom. Fig. 7. is a former or rowler for the cases, whose length,
from the handle, is seven diameters and a half, and its diameter two
thirds of the bore A B; 8. the end of the former, which is of the same
thickness and one diameter and two thirds long, the small part; which
fits into the hole In the end of the rowler when the case is pinching,
is one sixth and a half of the mould’s diameter thick. Fig. 9, the
first drift, which must be six diameters from the handle, and this as
well as all other rammers must be a little thinner than the former, to
prevent the sacking of the paper, when you are driving in the charge:
in the end of this rammer is a hole to fit over the piercer; the line
K marked on this is two diameters and one third from the handle, so
that when you are filling the rocket, this line appears at top of the
case; you must then take the second rammer, 10, which from the handle
is four diameters; and the hole for the piercer is one diameter and a
half long. Fig. 11. is the short and solid drift which you use when
you have filled the case as high as the top of the piercer.
It is to be observed, that all rammers must have a collar of brass at
the bottom, to keep the wood from spreading or splitting; and that the
same proportion be given to all moulds, from one ounce to six pound. I
mentioned nothing concerning the handles of the rammers; however, if
their diameter be equal to the bore of the mould, and two diameters
long, it will be a very good proportion; but the shorter you can use
them the better, for the longer the drift, the less will be the
pressure on the composition, by the blow given with the mallet.
A Table of Dimensions for Rocket Moulds, in which the Rockets are
rammed solid.
Weight |Length of the |Interior diameter|Height of the
of rockets.|moulds without| of the moulds. | nipples.
| their feet. | |
-----------+--------------+-----------------+-------------
lb. oz. | Inches. | Inches. | Inches.
-----------+--------------+-----------------+-------------
6 0 | 34·7 | 3·5 | 1·5
4 0 | 38·6 | 2·9 | 1·4
2 0 | 13·35 | 2·1 | 1·0
1 0 | 12·25 | 1·7 | 0·85
0 8 | 10·125 | 1·333 &c. | 0·6
0 4 | 7·75 | 1·125 | 0·5
0 2 | 6·2 | 0·9 | 0·45
0 1 | 4·9 | 0·7 | 0·35
0 ½ | 3·9 | 0·55 | 0·25
6 drams | 3·5 | 0·5 | 0·225
4 drams | 2·2 | 0·3 | 0·2
The diameter of the nipple must always be equal to that of the former.
I have omitted the thickness of the moulds, it being very immaterial,
provided they are substantial and strong.
I would not advise any one who makes rockets for his private
amusement, to ram them solid, for it requires a very skilful hand, and
an expensive apparatus for boring them, which will be shewn
herereafter. Driving of rockets solid is the most expeditious method,
but not so certain as ramming them over a piercer, which I have found
by experience.
Of Moulds for Wheel Cases, or Serpents.
Fig. 12. represents a mould in which the cases are drove solid; L the
nipple[3], with a point[4] at top, which, when the case is filling,
serves to stop the neck, and prevent the composition from falling out,
which without this point it would do; and, in consequence, the air
would get into the vacancy in the charge, and at the time of firing
cause the case to burst. These sort of moulds are made of any length
or diameter, according as the cases are required, but the diameter of
the rollers must be equal to half the bore, and the rammers made quite
solid.
How to roll Rocket and other Cases.
Sky rocket cases are to be made six and a half of their exterior
diameter long, and all other cases that are to be filled in moulds
must be as long as the moulds, within half its interior diameter.
Rocket cases, from the smallest to four or six pound, are generally
made of the strongest sort of cartridge paper, and rolled dry; but the
large sort are made of pasted paste-board. As it is very difficult to
roll the ends of the cases quite even, the best way will be to keep a
pattern of the paper for the different sorts of cases, which pattern
should be somewhat longer than the case it is designed for, and on it
marked the number of sheets required, which will prevent any paper
being cut to waste: having cut your papers of a proper size, and the
last sheet for each case with a slope at one end, so that when the
cases are rolled it may form a spiral line round the outside, and that
this slope may always be the same, let the pattern be so cut for a
guide: before you begin to roll, fold down one end of the first sheet,
so far that the fold will go two or three times round the former;
then, on the double edge, lay the former with its handle off the
table, and when you have rolled on the paper, within two or three
turns, lay, on that part which is loose, the next sheet, and roll it
all on.
Having thus done, you must have a smooth board, about twenty inches
long, and equal in breadth to the length of the case; in the middle of
this board must be a handle placed length-ways; under this board lay
your case, and let one end of the board lay on the table; then press
hard on it, and push it forwards, which will roll the paper very
tight; do this three or four times before you roll on any more paper:
this must be repeated every other sheet of paper, till the case is
thick enough; but if the rolling board be drawn backwards, it will
loosen the paper: you are to observe, when you roll on the last sheet,
that the point of the slope be placed at the small end of the roller.
Having rolled your case to fit the mould, push in the small end of the
former F, about one diameter from the end of the case, and put in the
end piece within a little distance of the former; then give the
pinching cord one turn round the case, between the former and the end
piece; at first pull easy, and keep moving the case, which will make
the neck smooth, and without large wrinkles; when the cases are hard
to choak, let each sheet of paper (except the first and last in that
part where the neck is formed) be a little moistened with water:
immediately after you have struck the concave stroke, bind the neck of
the case round with small twine, which must not be tied in a knot, but
fastened with two or three hitches.
Having thus pinched and tied the case so as not to give way, put it
into the mould without it’s foot, and, with a mallet, drive the former
hard on the end piece, which will force the neck close and smooth;
this being done, cut the case to its proper length, allowing from the
neck to the edge of the mouth half a diameter, which is equal to the
height of the nipple; then take out the former, and drive the case
over the piercer with the long rammer, and the vent will be of a
proper size. Wheel cases must be drove on a nipple with a points in
order to close the neck, and make the vent of the size required;
which, in most cases, is generally one fourth of their interior
diameter: as it is very often difficult, when the cases are rolled, to
draw the roller out, you may make a hole through the handle, and put
in it a small iron pin, by which you may easily turn the former round,
and pull it out. Fig. 17. shews the method of pinching cases; P a
treddle, which, when pressed hard with the foot, will draw the cord
tight, and force the neck as close as you please; Q a small wheel or
pully, with a groove round it for the cord to run in.
Cases are commonly rolled wet, for wheels and fixed pieces; and when
they are required to contain a great length of charge, the method of
making those sort of cases is as follows: Your paper must be cut as
usual, only the last sheet must not be cut with a slope; having your
paper ready, paste each sheet on one side, then fold down the first
sheet as before directed, but be careful that the paste does not touch
the upper part of the fold, for if the roller be wetted, it will tear
the paper in drawing it out: in pasting the last sheet, observe not to
wet the last turn or two in that part where it is to be pinched, for
if that part be damp, the pinching cord will stick to it, and tear the
paper; therefore, when you choak those cases; roll a bit of dry paper
once round the case, before you put on the pinching cord; but this bit
of paper must be taken off after the case is choaked. The rolling
board, and all other methods, according to the former directions for
the rolling and pinching of cases, must be used to these as well as
all other cases.
To make Tourbillon Cases.
Those sorts of cases are generally made about eight diameters long,
but if very large, seven diameters will be sufficient: tourbillons
will answer very well from four ounces to two pound, but when larger
there is no certainty. The cases are best rolled wet with paste, and
the last sheet must have a streight edge, so that the case may be all
of a thickness: when you have rolled your cases, after the manner of
wheel cases, pinch them at one end quite close; then, with the rammer,
drive the ends down flat, and afterwards ram in about one third of a
diameter of dryed clay. The diameter of the former for these cases
must be the same as for sky rockets.
N. B. Tourbillons are to be rammed in moulds without a nipple, or in a
mould without its foot.
To make Balóón Cases, or Paper Shells.
First you must have an oval former turned of smooth wood; then paste a
quantity of brown or cartridge paper, and let it lay till the paste
has quite soaked through; this done, rub the former with soap or
grease, to prevent the paper from sticking to it; then lay the paper
on in small slips, till you have made it one third of the thickness of
the shell intended; having thus done, set it to dry, and when dry, cut
it round the middle, and the two halves will easily come off; but
observe, when you cut, to leave about one inch not cut, which will
make the halves join much better than if quite separated; when you
have some ready to join, place the halves even together, and paste a
slip of paper round the opening to hold them together, and let that
dry; then lay on paper all over as before, every where equal,
excepting that end which goes downwards in the mortar, which may be a
little thicker than the rest; for that part which receives the blow
from the powder in the chamber of the mortar consequently requires the
greatest strength: when the shell is thoroughly dry, burn a round vent
at top, with square iron, large enough for the fuze: this method will
do for balóóns from four inches two fifths, to eight inches diameter;
but if they are larger, or required to be thrown a great height, let
the first shell be turn’d of elm, instead of being made of paper.
For a ballóón of four inches two fifths, let the former be three
inches one eighth diameter, and five inches and a half long. For a
ballóón of five inches and a half, the diameter of the former must be
four inches, and eight inches long. For a ballóón of eight inches, let
the diameter of the former be five inches and fifteen sixteenths, and
eleven inches seven eighths long. For a ten inch ballóón, let the
former be seven inches three sixteenths diameter, and fourteen inches
and a quarter long. The thickness of a shell for a ballóón of four
inches two fifths, must be half an inch. For a ballóón of five inches
and a half, let the thickness of the paper be five eighths of an inch.
For an eight inch ballóón seven eighths of an inch. And for a ten inch
ballóón, let the shell be one inch and one eighth thick.
Shells that are designed for stars only, may be made quite round, and
the thinner they are at the opening the better; for if they are too
strong, the stars are apt to break at the bursting of the shell: when
you are making the shell, make use of a pair of calibers, or a round
gauge, so that you may not lay the paper thicker in one place than
another; and also to know when the shell is of a proper thickness;
ballóóns must always be made to go easy into the mortars.
Of the Method of mixing Compositions.
The performance of the principal part of fireworks depends much on the
compositions being well mixed; therefore great care ought to be taken
in this part of the work, particularly in the compositions for sky
rockets. When you have four or five pounds of ingredients to mix,
which is a sufficient quantity at a time (for a larger proportion will
not do so well), first put the different ingredients together, then
work them about with your hands, till you think they are pretty well
incorporated; after which put them into a lawn sieve with a receiver
and top to it; and if, after it is sifted, any remains that will not
pass through the sieve, grind it again till fine enough; and if it be
twice sifted it will not be amiss; but the compositions for wheels and
common works are not so material, nor need not be so fine. But in all
fixed works, from which the fire is to play regular, the ingredients
must be very fine, and great care taken in mixing them well together;
and observe that, in all compositions wherein are steel or iron
filings, the hands must not touch, nor will any works, which have iron
or steel in their charge, keep long in damp weather, without being
properly prepared, according to the directions given in the following
article.
How to preserve Steel or Iron Filings.
It sometimes may happen, that fireworks may be required to be kept a
long time, or sent abroad; neither of which could be done with
brilliant fires, if made with filings unprepared; for this reason,
that the saltpetre being of a damp nature, it causes the iron to rust,
the consequence of which is, that when the works are fired, there will
appear but very few brilliant sparks, but instead of them a number of
red and drossy sparks, and besides, the charge will be so much
weakened, that if this should happen to wheels, the fire will hardly
be strong enough to force them round: but to prevent such accidents,
prepare your filings after the following manner.
Melt in a glazed earthen pan some brimstone over a slow fire, and when
melted throw in some filings; which keep stirring about till they are
covered with brimstone, this you must do while it is on the fire; then
take it off, and stirr it very quick till cold, when you must roll it
on a board with a wooden roller, till you have broke it as fine as
corn powder; after which sift from it as much of the brimstone as you
can. There is another method of preparing filings, so as to keep two
or three months in winter; this may be done by rubbing them between
the strongest sort of brown paper, which before has been moistened
with linseed oil.
N. B. If the brimstone should take fire, you may put it out, by
covering the pan close at top: it is not of much signification what
quantity of brimstone you use, so that there is enough to give each
grain of iron a coat, but as much as will cover the bottom of a pan,
of about one foot diameter, will do for five or six pound of filings:
cast iron for gerbes may be preserved by the above method.
The Method of Driving or Ramming Sky Rockets, &c.
Rockets which are drove over a piercer must not have so much
composition put in them at a time, as when drove solid, for the
piercer, taking up great part of the bore of the case, would cause the
rammer to rise too high: so that the pressure of it would not be so
great on the composition, nor would it be drove every where equal: to
prevent which, observe the following rule; that for those rockets,
that are rammed over a piercer, let the ladle[5] hold as much
composition as when drove, will raise the drift one half the interior
diameter of the case, and for those drove solid to contain as much as
will raise it half the exterior diameter of the case: ladles are
generally made to go easy in the case, and the length of the scoop
about one and a half of its own diameter.
The charge of rockets must always be drove one diameter above the
piercer, and on it must be rammed one third of a diameter of clay,
through the middle of which bore a small hole to the composition, in
order that, when the charge is burnt to the top, it may communicate
its fire, through the hole, to the stars in the head: great care must
always be taken, to strike with the mallet, and with an equal force,
the same number of strokes to each ladle-ful of charge; otherwise the
rockets will not rise with an uniform motion, nor will the composition
burn equal and regular; for which reason they cannot carry a proper
tail, for it will break before the rocket has got half way up; instead
of reaching from the ground to the top, where the rocket breaks and
disperses the stars, rains, or whatever is contained in the head. When
you are ramming, keep the drift constantly turning or moving; and when
you use the hollow rammers, knock out of them the composition now and
then, or the piercer will split them: to a rocket of four ounces, give
to each ladle-ful of charge sixteen strokes: to a rocket of eight
ounces twenty-one strokes: to a rocket of one pound, twenty eight: to
a two pounder, thirty-six: to a four pounder forty-two: and to a six
pounder fifty strokes; but rockets of a larger sort cannot be drove
well by hand, but must be rammed with a machine made in the same
manner as those for driving piles, which are so very common to be
seen, that I shall here omit giving a description of them.
The method of ramming of wheel cases, or any other sort, in which the
charge is drove solid, is much the same as sky rockets; for the same
proportion may be observed in the ladle, and the same number of
strokes given, according to their diameters, all cases being
distinguished by their diameters; in this manner, a case whose bore is
equal to a rocket of four ounces is called a four ounce case, and that
which is equal to an eight ounce rocket an eight ounce case, and so
on, according to the different rockets.
Having taught the method of ramming cases in moulds; we shall here say
something concerning those filled without moulds, which method, for
strong pasted cases, will do extremely well, and save the expence of
making so many moulds. The reader must here observe, when he fills any
sort of cases, to place the mould on a perpendicular block of wood,
and not on any place that is hollow, for we have found by experience,
that when cases were rammed on driving benches, which were formerly
used, the works frequently miscarried, on account of the hollow
resistance of the benches, which often jarred and loosened the charge
in the cases; but this accident has never happened since the driving
blocks[6] have been used.
When cases are to be filled without moulds, proceed thus; have some
nipples made of brass or iron, of several sorts and sizes, in
proportion to the cases, and to screw or six in the top of the driving
block; when you have fixed in a nipple, make, at about one inch and a
half from it, a square hole in the block, six inches deep and one inch
diameter; then have a piece of wood, six inches longer than the case
intended to be filled and two inches square; on one side of it cut a
groove almost the length of the case, whose breadth and depth must be
sufficient to cover near half the case; then cut the other end to fit
the hole in the block, but take care to cut it so that the groove may
be of a proper distance from the nipple: this half mould being made
and fixed tight in the block, cut, in another piece of wood nearly of
the same length as the case, a groove of the same dimensions as that
in the fixed piece; then put the case on the nipple, and with a cord
tie it and the two half moulds together, and your case will be ready
for filling.
The dimensions of the above described half moulds, are proportionable
for cases of eight ounces; but notice must be taken, that they differ
in size in proportion to the cases.
Note, the clay, mentioned in this article, must be prepared after this
manner; get some clay, in which there is no stones nor sand, and bake
it in an oven till quite dry; then take it out and beat it to a
powder, and afterwards sift it through a common hair sieve, and it
will be fit for use.
Of the Proportion of Mallets.
The best wood for mallets is dry beech, though some have preferred
other sorts of woods and have likewise pretended to determine their
exact weight, which is not of much signification; however, for the
better instruction of those who have not made a great progress in this
art, I shall here give a good proportion for mallets; but at the same
time would have every practitioner know, that if he makes use of a
common mallet, of a moderate size, in proportion to the rocket,
according to his judgment, and if that rocket succeeds, he may depend
on the rest, by using the same mallet; yet it will be necessary that
cases of different sorts be drove with mallets of different sizes.
The following proportion of the mallets for rockets of any size, from
one ounce to six pound, may be observed; but as rockets are seldon
made less than one ounce, or larger than six pound, I shall leave the
management of them to the curious; but all cases under one ounce, may
be rammed with an ounce rocket mallet. Your mallets will strike more
solid, by having their handles turned out of the same piece as the
head, and made in a cylindrical form: let their dimensions be worked
by the diameters of the rockets: for example; let the thickness of the
head be three diameters, and its length four, and the length of the
handle five diameters, whose thickness must be in proportion to the
hand.
Of the Proportion of Sky Rockets, with the Manner of heading them.
Fig. 13. represents a rocket compleat without its stick, whose length
from the neck is five diameters one sixth; the cases should always be
cut to this length, after they are filled: M the head, which is two
diameters high, and one diameter one sixth and a half in breadth; N
the cone or cap, whose perpendicular height must be one diameter one
third. Fig. 14. is the collar to which the head is fixed; this is
turned out of deal or any light wood, and its exterior diameter must
be equal to the interior diameter of the head; one sixth will be
sufficient for its thickness, and round the outside edge must be a
groove; the interior diameter of the collar must not be quite so wide
as the exterior diameter of the rocket; when this is to be glued on
the rocket, you must cut two or three rounds of paper off the case,
which will make a shoulder for it to rest upon. Fig. 15, a former for
the head; two or three rounds of paper well pasted will be enough for
the head, which, when rolled, put the collar on that part of the
former marked O, which must fit the inside of it; then with the
pinching cord, pinch the bottom of the head into the groove, and tie
it with small twine. Fig. 16, represents a former for the cone. To
make the caps, cut your paper in round pieces, equal in diameter to
twice the length of the cone you intend to make; which pieces being
cut into halves, will make two caps each, without wasting any paper;
having formed the caps, paste over each of them a thin white paper,
which must be a little longer than the cone, so as to project about
half an inch below the bottom; this projection of paper, being notch’d
and pasted, serves to fasten the cap to the head.
[Illustration: PLATE. 1]
When you load the heads of your rockets with stars, rains, serpents,
crackers, scroles, or any thing else, according to your fancy;
remember always to put one ladle-ful of meal powder, into each head,
which will be enough to burst the head, and disperse the stars or
whatever is contained therein: when the heads are loaded with any sort
of cases, let their mouths be placed downwards; and after the heads
are filled, paste on the top of them a piece of paper, before you put
on the caps. As the size of stars often differ, it would be needless
to give an exact number for each rocket, but this rule may be
observed, that the heads may be nearly filled with whatever they are
loaded.
Of the Decorations for Sky Rockets.
Sky rockets bearing the pre-eminence of all fireworks, it will not be
improper to treat of their various kinds of decorations which are
directed according to fancy; some are headed with stars of different
sorts, such as tailed stars, brilliant stars, white stars, blue and
yellow stars, &c. some with gold and silver rain; others with
serpents, crackers, fire-scroles, marrons; and some with small
rockets, and many other devices, as the maker pleases.
Dimensions and Poise of Rocket Sticks.
Weight | Length of |Thickness|Breadth |Square at| Poize from
of the |the stick. | at top. | at top.| bottom. |the point of
rocket.| | | | | the cone.
-------+-----------+---------+--------+---------+-------------
lb. oz.| ft. in. | Inches. | Inches.| Inch. | ft. in.
-------+-----------+---------+--------+---------+-------------
6 0 | 14 0 | 1·5 | 1·85 | 0·75 | 4 1·5
4 0 | 12 10 | 1·25 | 1·40 | 0·625 | 3 9·
2 0 | 9 4 | 1·125 | 1· | 0·525 | 2 9·
1 0 | 8 2 | 0·725 | 0·80 | 0·375 | 2 1·
8 | 6 6 | 0·5 | 0·70 | 0·25 | 1 10·5
4 | 5 3 | 0·3750 | 0·55 | 0·35 | 1 8·5
2 | 4 1 | 0·3 | 0·45 | 0·15 | 1 3·
1 | 3 6 | 0·25 | 0·35 | 0·10 | 11 0·
½ | 2 4 | 0·125 | 0·20 | 0·16 | 8 0·
¼ | 1 10½ | 0·1 | 0·15 | 0·5 | 5 0·5
The last column on the right in the above table, expresses the
distance from the top of the cone, where the stick, when tied on,
should ballance the rocket, so as to stand in an equilibrium on one’s
finger or the edge of a knife. The best wood for the sticks is dry
deal, made after the following manner; when you have cut and planed
the sticks according to the dimensions given in the table, cut on one
of the flat sides at top, a groove the length of the rocket, and as
broad as the stick will allow; then on the opposite flat side, cut two
notches for the cord, which ties on the rocket, to lay in; one of
these notches must be near the top of the stick, and the other facing
the neck of the rockets; the distance between these notches may easily
be known, for the top of the stick should always touch the head of the
rocket. When your rockets and sticks are ready, lay the rockets in the
grooves in the sticks and tie them on. Those who, merely for
curiosity, may chose to make rockets of different sizes, to what I
have expressed in the table of dimensions, may find the length of
their sticks, by making them for rockets, from half an ounce to one
pounds sixty diameters of the rocket long; and for rockets above one
pound, fifty or fifty-two diameters will be a good length; their
thickness at top may be about half a diameter, and their breadth a
very little more; their square at bottom is generally equal to half
the thickness at top. But, although the dimensions of the sticks be
very nicely observed, you must depend only on their ballance: for,
without a proper counterpoise, your rockets, instead of mounting
perpendicularly, will take an oblique direction, and fall to the
ground before they are burnt out.
The Method of Boring Rockets which have been drove solid.
Plate 2, Fig. 18, represents the plan of an apparatus, or lath, for
boring of rockets; A the large wheel which turns the small one B, that
works the reammer C: these reammers are of different sizes according
to the rockets; they must be of the same diameter as the top of the
bore intended, and continue that thickness a little longer than the
depth of the bore required, and their points must be like that of an
auger; the thick end of each reammer must be made square and all of
the same size, so as to fit into one socket, wherein they are fastened
by a screw D: E the guide for the reammer, which is made to move
backwards and forwards; so that after you have marked the reammer
three diameters and a half of the rocket from the point, set the
guide, allowing for the thickness of the fronts of the rocket boxes,
and the neck and mouth of the rocket, so that when the front of the
large box is close to the guide, the reammer may not go too far up the
charge; F, boxes for holding the rockets, which are made so as to fit
one in another; their sides must be equal in thickness to the
difference of the diameters of the rockets, and their interior
diameters equal to the exterior diameters of the rockets. To prevent
the rockets turning round while boring, a piece of wood must be placed
against the end of the box in the inside, and pressed against the tail
of the rocket; this will also hinder the reammer from forcing the
rocket backwards. G, a rocket in the box. H, a box that hides under
the rocket boxes to receive the borings from the rockets, which falls
through holes made on purpose in the boxes; these holes must be just
under the mouth of the rocket, one in each box, and all to correspond
with each other.
Fig. 19, is a front view of the large rocket box. I, an iron plate, in
which are holes of different sizes, through which the reammer passes;
this plate is fastened with a screw in the center, so that when you
change the reammer, you turn the plate round, but always let the hole
you are going to use be at the bottom; the fronts of the other boxes
must have holes in them to correspond with them in the plate. K, the
lower part of the large box, which is made to fit the inside of the
lathe, in order that all the boxes may move quite steady.
Fig. 20, is a perspective view of the lathe. L, the guide for the
reammer, which is set by the screw at bottom.
Fig. 21, a view of the front of the guide facing the reammer. M, an
iron plate, of the same dimensions as that on the front of the box,
and placed in the same direction, and also to turn on a screw in the
center. N, the rocket box, which slides backwards and forwards: when
you have fixed a rocket in the box, push it forwards against the
reammer; and when you think the scoop of the reammer is full, draw the
box back, and knock out the composition; this you must do till the
rocket is bored, or it will be in danger of taking fire; and if you
bore in a hurry, wet the end of the reammer now and then with oil to
keep it cool.
Having bored a number of rockets, you must have taps of different
sorts according to the rockets. These taps are a little longer than
the bore, but when you use them, mark them three diameters and a half
from the point, allowing for the thickness of the rocket’s neck; then,
holding the rocket in one hand, you tap it with the other. In order to
explain these taps, I have represented one by Fig. 22. They are made
in the same proportion as the fixed piercers, and are hollowed their
whole length.
Of a Hand Machine used for boring of Rockets instead of a Lathe.
Those sort of machines answer very well, but not so expeditious as the
lathe, nor are they so expensive to make; they may be worked by one
man; but the lathe will require three. Fig. 23, represents the
machine. O, the rocket boxes, which are to be fixed and not to slide
as those in the lathe. P Q, are guides for the reammers, that are made
to slide together, as the reammer moves forward: the reammers for
these sort of machines must be made of a proper length, allowing for
the thickness of the front of the boxes, and the length of the mouth
and neck of the case: on the square end of these reammers, must be a
round shoulder of iron, to turn against the outside of the guide Q, by
which means the guides are forced forwards. R, the stock which turns
the reammer, and while turning must be pressed towards the rocket, by
the body of the man who works it; all the reammers are to be made to
fit one stock. This machine as well as the lathe is made by the scale
in the same plate.
The Manner of making large Gerbes.
Fig. 24, represents a wooden former; 25, a gerbe compleat, with its
foot or stand. The cases for gerbes are made very strong, on account
of the strength of the composition; which, when fired, comes out with
great velocity; therefore, to prevent their bursting, the paper should
be pasted, and the cases made as thick at the top as at the bottom;
they ought also to have very long necks, for this reason; first, that
the particles of iron will have more time to be heated, by meeting
with greater resistance in getting out, than with a short neck, which
would be burnt too wide before the charge be consumed, and spoil the
effect: Secondly, that with long necks the stars will be thrown to a
great height, and will not fall before they are spent, or spread too
much; but, when made to perfection, will rise and spread in such a
manner as to form exactly a wheat-sheaf.
In the ramming of gerbes, there will be no need of a mould, the cases
being sufficiently strong to support themselves; but you are to be
careful, before you begin to ram, to have a piece of wood made to fit
in the neck; for if this be not done, the composition will fall into
the neck, and leave a vacancy in the case, which, as I said before,
will cause the case to burst as soon as the fire arrives at the
vacancy: you must likewise observe, that the first ladle of charge, or
two, if you think proper, be of some weak composition. When the case
is filled, take out the piece of wood, and fill the neck with some
slow charge. Gerbes are generally made about six diameters long, from
the bottom to the top of the neck; their bore must be one fifth
narrower at top than at bottom. The neck S is one sixth diameter and
three fourths long. T, a wooden foot or stand, on which the gerbe is
fixed. This may be made with a choak or cylinder, four or five inches
long, to fit the inside of the case, or with a hole in it to put in
the gerbe; both these methods will answer the same. Gerbes produce a
most brilliant fire, and are very when a number of them are fixed in
the front of a building, or a collection of fireworks.
N. B. Gerbes are made by their diameters, and their cases at bottom
one fourth thick. The method of finding the interior diameter of a
gerbe is thus: Supposing you would have the exterior diameter of the
case, when made, to be five inches, then, by taking two fourths for
the sides of the case, there will remain two inches and a half for the
bore, which will be a very good size. These sort of gerbes ought to be
rammed very hard.
Of small Gerbes or White Fountains.
Small gerbes may be made of four, eight ounces, or one pound cases,
pasted and made very strong, of what length you please; but, before
you fill them, drive in dry clay one diameter of their orifice high,
and when you have filled a case, bore a vent through the center of the
clay to the composition; the common proportion will do for the vent,
which must be primed with a slow charge. These sort of cases without
the clay, may be filled with Chinese fire.
To make Paste-board and Paper Mortars.
Fig. 26, a former, and 27, an elm foot for the mortar; 28, a mortar
compleat; these mortars are best when made with paste-board; your
paste-board must be well pasted before you begin; or, instead of
paste, you may use glue. For a coehorn mortar, which is four inches
two fifths diameter, roll the paste-board on the former one sixth of
its diameter thick; and, when dry, cut one end smooth and even, then
nail and glue it on the upper part of the foot; when done, cut off the
paste-board at top, allowing for the length of the mortar two
diameters and a half from the mouth of the powder chamber; then bind
the mortar round with a strong cord wetted with glue. U, the bottom
part of the foot, is one diameter two thirds broad, and one diameter
high; and that part which goes into the mortar is two thirds of it’s
diameter high. W, is a copper chamber for powder, made in a conical
form, and is one third of the diameter wide, and one and a half of its
own diameter long; in the center of the bottom of this chamber, make a
small hole a little way down the foot; this hole must be met by
another of the same size made in the side of the foot, as is shewn in
Fig. 28. If these holes are made true, and a copper pipe fitted into
both, the mortar when loaded will prime itself, for the powder will
naturally fall to the bottom of the first hole; then, by putting a bit
of quick-match in the side hole, your mortar will be ready to be
fired.
Mortars of five and a half, eight, and ten inches diameter, may be
made of paper, or paste-board, by the above method, and in the same
proportion; but if larger, it will be best to have them made of brass.
N. B. The copper chamber, must have a small rim round its edge with
holes in it, for screws to make it fast in the foot.